TITLE OF THE DATA SET                                                                                         
                                                                                                              
Historical Sunshine and Cloud Data in the United States                                                       
                                                                                                              
                                                                                                              
DATA CONTRIBUTORS                                                                                             
                                                                                                              
Peter M. Steurer and Thomas R. Karl                                                                           
National Oceanic and Atmospheric Administration                                                               
National Climatic Data Center                                                                                 
Asheville, North Carolina 28801                                                                               
                                                                                                              
                                                                                                              
SOURCE AND SCOPE OF THE DATA                                                                                  
                                                                                                              
a) Sunshine                                                                                                   
                                                                                                              
   Sunshine data for 240 U.S. stations (including Puerto Rico and nine islands in the Pacific Ocean)          
are presented for the years 1891-1987.  The periods of record of monthly and annual total hours of            
sunshine vary widely from station to station.  Many of the stations have discontinuous sampling               
periods and only 49 (20%) have periods of record equal to or greater than 90 years.  However, 192             
stations (80%) have periods of record equal to or greater than 30 years.                                      
   In addition to the total monthly and annual measurements of sunshine duration, total monthly               
and annual maximum possible sunshine duration and monthly and annual percentages of possible                  
sunshine duration are also provided.  Maximum possible sunshine values for the 240-station recording          
network range from a minimum of 4418 h at the southernmost station (Tofuna, Pacific Ocean) to a               
maximum of 4591 h at the northernmost station (Fairbanks, Alaska).  The highest annual sunshine               
amount ever recorded in the United States was at Yuma, Arizona, with 4272 h (96% of possible) in              
1958, and the lowest ever recorded was at Mt. Washington, New Hampshire, with 1181 h (26% of                  
possible) in 1943.                                                                                            
   In terms of annual percentage of possible sunshine, the highest amount ever recorded was 96%               
at Yuma, Arizona, in 1958 and the lowest amount ever recorded was 18% at Juneau, Alaska, in 1939.             
In the continental United States, the lowest annual percentage of possible sunshine ever recorded             
was 23% at Quillayute, Washington, in 1986.                                                                   
                                                                                                              
                                                                                                              
b) Clouds                                                                                                     
                                                                                                              
   Cloud amount data for 197 U.S. stations are presented for the years 1871-1987.  Most of the                
stations in the cloud observing network are also present in the sunshine recorder network, but the            
earlier opening of several stations for cloud observing purposes, coupled with a higher percentage            
of stations remaining open through 1987 to measure cloud amount, has resulted in the cloud amount             
data set being longer and more complete than the sunshine data set.  For example, 100 stations                
(51%) have periods of record at least 90 years in length and 194 stations (98%) have records for at           
least 30 years.                                                                                               
   In compiling the cloud amount data set, only monthly sunrise to sunset cloud amount averages               
(percentages) were used.  This eliminated problems associated with nighttime measurements and also            
maintained consistency in any comparisons with the monthly sunshine data.                                     
                                                                                                              
                                                                                                              
c) Estimates for Missing Data                                                                                 
                                                                                                              
   The high correlation between clouds and sunshine has led to the development of a procedure that            
produces an estimate when data are missing in either of the two data sets.  Usually, data are fitted          
to a least-squares regression line where a slope and y-intercept are computed.  A given value in one          
series can then be used to predict a missing value in the other series.  Similarly, suspect values can        
be flagged for inspection if the value falls outside of some arbitrary range.  Unfortunately, these           
suspect values can seize control of the best-fit line and give totally misleading regression line statistics. 
Preprocessing of the data by eliminating all extreme values is one method of avoiding this difficulty.        
Another method is the resistant regression (Emerson and Hoaglin 1983).  Resistant regression                  
essentially provides resistance against unusual data points so that these points will have only a small       
effect on the fitted line.  This is done by sorting the predictor variable (values of x) in ascending         
order and then dividing the data points into three groups.  Within each group, the median of the x            
and y values are determined.  A slope and y-intercept is then found using these median values.  This          
initial line is then adjusted by an iterative process using the actual data points.  The iterations           
continue until the adjustments cause less than a 1% change in the slope.  The resulting line provides         
resistance to those unusual data points that depart substantially from the primary pattern.  It is            
important to note that the fewer the number of extraneous points, the closer the regression and               
resistant lines become with regard to slope and y-intercept.                                                  
   Seasonal and annual resistant line statistics were computed for all stations that recorded at least        
10 years of simultaneous monthly cloud and sunshine data during the 1953-1987 period.  This                   
reference period was chosen because of the impression that from 1953 onward, all stations in the              
sunshine recording network were using the photoelectric type of sunshine recorder.  Because the               
performance characteristics of the three types of sunshine recorders used through the years are               
known to vary, only the modern-day instrument period was desired for deriving the resistant line              
statistics.  Subsequent to the calculation of these statistics, it was realized through detailed inspection   
of station histories that most stations had not implemented the photoelectric recorders by 1953.              
Many did so through the latter years of that decade, and some stations did not switch over until the          
mid-1960s (see Table 1 of the accompanying documentation).                                                    
   Two sets of seasonal and annual statistics were computed:  one using clouds and the other using            
sunshine as the predictor variable.  The seasons were based on the standard climatological periods            
(i.e., winter being December, January, and February; spring being March, April, and May; etc).  An            
estimate for a missing value in one series was produced by using the corresponding monthly value and          
seasonal predictor statistics of the other series when both were available for a given month.  The            
cloud amount data set has far fewer missing observations than does the sunshine data set, which in            
the case of some stations, has blocks of several years in which estimates were substituted.  These            
estimates should prove very useful, as they often create continuous monthly and annual records for            
many stations that would otherwise suffer from numerous gaps.  However, some caution should be                
used with these data, since, in the case of some stations, they were derived from regression statistics       
that may have been adversely affected by using sunshine data from a thermometric recorder together            
with those from a photoelectric recorder.                                                                     
                                                                                                              
                                                                                                              
DATA FORMAT                                                                                                   
                                                                                                              
   Thirteen files are provided in this subdirectory including this documentation file (NDP021.TXT):  four       
FORTRAN input/output routines (NDP021R1.F2,3,4, and 5); four SAS input/output routines; one file containing 
monthly and annual values of measured hours of sunshine (NDP021R1.F10); one file containing monthly and    
annual values of the maximum possible hours of sunshine (NDP021R1.F11); one file containing monthly and    
annual values of measured sunshine expressed as a percentage of that possible (NDP021R1.F12); and one file 
(NDP021R1.F13) containing monthly and annual cloud amounts (percentage).                                   
                                                                                                              
                                                                                                              
MEASURED HOURS OF SUNSHINE FILE                                                                               
                                                                                                              
   The measured hours of sunshine file (NDP021R1.F10) contains monthly and annual                          
hours of sunshine for each year from each of the 240 sunshine stations.  The data are sorted by               
WBAN (Weather Bureau Army Navy) station number, with each record containing the WBAN                          
station number, information on any previous WBAN station number, state name and station name,                 
monthly values of hours of sunshine, and an annual value of hours of sunshine.  Missing sunshine              
amounts are set to -99.                                                                                       
                                                                                                              
   The file may be read using the following FORTRAN format:                                                   
                                                                                                              
                                                                                                              
       INTEGER WBAN, PWBAN, MON, YEAR, HRSSUN(12), TOTAL                                                      
       CHARACTER*18 STNAME                                                                                    
                                                                                                              
       READ (5,100,END=99)WBAN,PWBAN,MON,STNAME,YEAR,(HRSSUN(I),I=1,12),                                      
    + TOTAL                                                                                                   
100   FORMAT(2(1X,I5),1X,I2,2X,A18,2X,I4,12(2X,I3),3X,I4)                                                     
                                                                                                              
                                                                                                              
or by using the SAS format:                                                                                   
                                                                                                              
 INPUT WBAN 2-6 PWBAN 8-12 MON 14-15                                                                          
       STNAME $ 18-35 YEAR 38-41                                                                              
       JAN 44-46 FEB 49-51 MAR 54-56 APR 59-61                                                                
       MAY 64-66 JUN 69-71 JUL 74-76 AUG 79-81                                                                
       SEP 84-86 OCT 89-91 NOV 94-96 DEC 99-101 TOTAL 105-108;                                                
                                                                                                              
                                                                                                              
Stated in tabular form, the contents include the following.                                                   
                                                                                                              
                                                                                                              
                      Variable        Variable         Starting      Ending                                   
Variable                type            width           column       column                                   
                                                                                                              
                                                                                                              
WBAN                     Numeric         5                2             6                                     
PWBAN                    Numeric         5                8            12                                     
MON                      Numeric         2               14            15                                     
STNAME                   Character      18               18            35                                     
YEAR                     Numeric         4               38            41                                     
JAN                      Numeric         3               44            46                                     
FEB                      Numeric         3               49            51                                     
MAR                      Numeric         3               54            56                                     
APR                      Numeric         3               59            61                                     
MAY                      Numeric         3               64            66                                     
JUN                      Numeric         3               69            71                                     
JUL                      Numeric         3               74            76                                     
AUG                      Numeric         3               79            81                                     
SEP                      Numeric         3               84            86                                     
OCT                      Numeric         3               89            91                                     
NOV                      Numeric         3               94            96                                     
DEC                      Numeric         3               99           101                                     
TOTAL                    Numeric         4              105           108                                     
                                                                                                              
                                                                                                              
where                                                                                                         
                                                                                                              
WBAN            is the 1987 WBAN station number or the number during the final year of a                      
                station's record;                                                                             
                                                                                                              
PWBAN           is the actual WBAN number that was assigned during that year in the record                    
                (set to 0 after the first year in which the latest WBAN number was assigned,                  
                set to 99999 for years in which the WBAN number was not known or not                          
                assigned);                                                                                    
                                                                                                              
MON             is the month when a new WBAN number went into effect (set to 0 for years                      
                when no change took place);                                                                   
                                                                                                              
STNAME          is the state abbreviation and station name;                                                   
                                                                                                              
YEAR            is the year of the data;                                                                      
                                                                                                              
JAN-DEC         are the monthly measured hours of sunshine values (nearest whole hour);                       
                and                                                                                           
                                                                                                              
TOTAL           is the total hours of sunshine recorded in that year (nearest whole hour).                    
                                                                                                              
                                                                                                              
MAXIMUM POSSIBLE HOURS OF SUNSHINE FILE                                                                       
                                                                                                              
      The maximum possible hours of sunshine file (NDP021R1.F11) contains monthly                          
and annual values for the maximum hours of sunshine that could be received at each station.  The              
file is sorted by WBAN station number, with each record containing WBAN station number, state                 
and station name, monthly and annual maximum possible sunshine amounts (hours) for non-leap                   
years, and an adjustment factor (hours) to be added to the February and annual values in leap years.          
                                                                                                              
                                                                                                              
      The file may be read using the following FORTRAN format:                                                
                                                                                                              
       INTEGER WBAN, MAXSUN(12)                                                                               
       REAL TOTAL, ADJ                                                                                        
       CHARACTER*18 STNAME                                                                                    
       READ (5,100,END=99) WBAN, STNAME, (MAXSUN(I),I=1,12), TOTAL, ADJUST                                    
 100 FORMAT(1X,I5,1X,A18,12(1X,I3),1X,F6.1,1X,F4.1)                                                           
                                                                                                              
or by using the SAS format:                                                                                   
                                                                                                              
 INPUT WBAN 2-6  STNAME $ 8-25                                                                                
       JAN 27-29 FEB 31-33 MAR 35-37 APR 39-41 MAY 43-45 JUN 47-49 JUL 51-53                                  
       AUG 55-57 SEP 59-61 OCT 63-65 NOV 67-69 DEC 71-73 TOTAL 75-80                                          
       ADJUST 82-85;                                                                                          
                                                                                                              
Stated in tabular form, the contents include the following.                                                   
                                                                                                              
                                                                                                              
                Variable        Variable         Starting      Ending                                         
Variable          type            width           column       column                                         
                                                                                                              
                                                                                                              
WBAN             Numeric           5                2             6                                           
STNAME           Character        18                8            25                                           
JAN              Numeric           3               27            29                                           
FEB              Numeric           3               31            33                                           
MAR              Numeric           3               35            37                                           
APR              Numeric           3               39            41                                           
MAY              Numeric           3               43            45                                           
JUN              Numeric           3               47            49                                           
JUL              Numeric           3               51            53                                           
AUG              Numeric           3               55            57                                           
SEP              Numeric           3               59            61                                           
OCT              Numeric           3               63            65                                           
NOV              Numeric           3               67            69                                           
DEC              Numeric           3               71            73                                           
TOTAL            Numeric           6               75            80                                           
ADJUST           Numeric           4               82            85                                           
                                                                                                              
                                                                                                              
where                                                                                                         
                                                                                                              
WBAN       is the WBAN station number;                                                                        
                                                                                                              
STNAME     is the state abbreviation and station name;                                                        
                                                                                                              
JAN-DEC    are the monthly values of the maximum hours of sunshine possible at that                           
           station (nearest whole hour);                                                                      
                                                                                                              
TOTAL      is the maximum hours of sunshine possible at that station in a non-leap                            
           year (given to the nearest tenth of an hour, e.g., 4447.3); and                                    
                                                                                                              
ADJUST     is the number of hours to add to FEB and TOTAL for leap years (also given                          
           to the nearest tenth of an hour, e.g., 11.4).                                                      
                                                                                                              
                                                                                                              
PERCENTAGE OF POSSIBLE SUNSHINE FILE                                                                          
                                                                                                              
      The percentage of possible sunshine file (NDP021R1.F12) contains                                     
monthly and annual values of percentage of possible sunshine for each year from each of the                   
240 sunshine stations.  The file is sorted by WBAN station number, with each record                           
containing WBAN station number, state and station name, monthly sunshine percentages                          
(missing values are set to -9999) with each month's four respective data flags, and an annual                 
sunshine percentage (the mean of the monthly values, if none are set to missing; otherwise                    
set to the missing indicator -9999).                                                                          
                                                                                                              
     The file may be read using the following FORTRAN format:                                                 
                                                                                                              
                                                                                                              
        INTEGER WBAN, YEAR, SUNPCT(12), MEANC                                                                 
        CHARACTER FLAG1(12), FLAG2(12), FLAG3(12), FLAG4(12)                                                  
        CHARACTER*18 STNAME                                                                                   
        READ (5,100,END=99) WBAN, STNAME, YEAR,                                                               
     +  (SUNPCT(I),FLAG1(I),FLAG2(I),FLAG3(I),FLAG4(I),I=1,12), MEAN                                          
 100   FORMAT(1X,I5,1X,A18,1X,I4,12(I5,4(A1)),1X,I5)                                                          
                                                                                                              
                                                                                                              
or by using the SAS format:                                                                                   
                                                                                                              
                                                                                                              
INPUT WBAN 2-6 STNAME $ 8-25 YEAR 27-30                                                                       
 JAN 31-35 JANFL1 $ 36 JANFL2 $ 37 JANFL3 $ 38 JANFL4 $ 39                                                    
 FEB 40-44 FEBFL1 $ 45 FEBFL2 $ 46 FEBFL3 $ 47 FEBFL4 $ 48                                                    
 MAR 49-53 MARFL1 $ 54 MARFL2 $ 55 MARFL3 $ 56 MARFL4 $ 57                                                    
 APR 58-62 APRFL1 $ 63 APRFL2 $ 64 APRFL3 $ 65 APRFL4 $ 66                                                    
 MAY 67-71 MAYFL1 $ 72 MAYFL2 $ 73 MAYFL3 $ 74 MAYFL4 $ 75                                                    
 JUN 76-80 JUNFL1 $ 81 JUNFL2 $ 82 JUNFL3 $ 83 JUNFL4 $ 84                                                    
 JUL 85-89 JULFL1 $ 90 JULFL2 $ 91 JULFL3 $ 92 JULFL4 $ 93                                                    
 AUG 94-98 AUGFL1 $ 99 AUGFL2 $ 100 AUGFL3 $ 101 FEBFL4 $ 102                                                 
 SEP 103-107 SEPFL1 $ 108 SEPFL2 $ 109 SEPFL3 $ 110 MARFL4 $ 111                                              
 OCT 112-111 OCTFL1 $ 117 OCTFL2 $ 118 OCTFL3 $ 119 OCTFL4 $ 120                                              
 NOV 121-125 NOVFL1 $ 126 NOVFL2 $ 127 NOVFL3 $ 128 NOVFL4 $ 129                                              
 DEC 130-134 DECFL1 $ 135 DECFL2 $ 136 DECFL3 $ 137 DECFL4 $ 138                                              
 MEAN 140-144;                                                                                                
                                                                                                              
Stated in tabular form, the contents include the following.                                                   
                                                                                                              
                                                                                                              
                Variable          Variable       Starting      Ending                                         
Variable          type              width         column       column                                         
                                                                                                              
                                                                                                              
WBAN             Numeric             5              2             6                                           
STNAME           Character          18              8            25                                           
YEAR             Numeric             4             27            30                                           
JAN              Numeric             5             31            35                                           
JANFL1           Alphanumeric        1             36            36                                           
JANFL2           Alphanumeric        1             37            37                                           
JANFL3           Alphanumeric        1             38            38                                           
JANFL4           Alphanumeric        1             39            39                                           
FEB              Numeric             5             40            44                                           
FEBFL1           Alphanumeric        1             45            45                                           
FEBFL2           Alphanumeric        1             46            46                                           
FEBFL3           Alphanumeric        1             47            47                                           
FEBFL4           Alphanumeric        1             48            48                                           
MAR              Numeric             5             49            53                                           
MARFL1           Alphanumeric        1             54            54                                           
MARFL2           Alphanumeric        1             55            55                                           
MARFL3           Alphanumeric        1             56            56                                           
MARFL4           Alphanumeric        1             57            57                                           
APR              Numeric             5             58            62                                           
APRFL1           Alphanumeric        1             63            63                                           
APRFL2           Alphanumeric        1             64            64                                           
APRFL3           Alphanumeric        1             65            65                                           
APRFL4           Alphanumeric        1             66            66                                           
MAY              Numeric             5             67            71                                           
MAYFL1           Alphanumeric        1             72            72                                           
MAYFL2           Alphanumeric        1             73            73                                           
MAYFL3           Alphanumeric        1             74            74                                           
MAYFL4           Alphanumeric        1             75            75                                           
JUN              Numeric             5             76            80                                           
JUNFL1           Alphanumeric        1             81            81                                           
JUNFL2           Alphanumeric        1             82            82                                           
JUNFL3           Alphanumeric        1             83            83                                           
JUNFL4           Alphanumeric        1             84            84                                           
JUL              Numeric             5             85            89                                           
JULFL1           Alphanumeric        1             90            90                                           
JULFL2           Alphanumeric        1             91            91                                           
JULFL3           Alphanumeric        1             92            92                                           
JULFL4           Alphanumeric        1             93            93                                           
AUG              Numeric             5             94            98                                           
AUGFL1           Alphanumeric        1             99            99                                           
AUGFL2           Alphanumeric        1            100           100                                           
AUGFL3           Alphanumeric        1            101           101                                           
AUGFL4           Alphanumeric        1            102           102                                           
SEP              Numeric             5            103           107                                           
SEPFL1           Alphanumeric        1            108           108                                           
SEPFL2           Alphanumeric        1            109           109                                           
SEPFL3           Alphanumeric        1            110           110                                           
SEPFL4           Alphanumeric        1            111           111                                           
OCT              Numeric             5            112           116                                           
OCTFL1           Alphanumeric        1            117           117                                           
OCTFL2           Alphanumeric        1            118           118                                           
OCTFL3           Alphanumeric        1            119           119                                           
OCTFL4           Alphanumeric        1            120           120                                           
NOV              Numeric             5            121           125                                           
NOVFL1           Alphanumeric        1            126           126                                           
NOVFL2           Alphanumeric        1            127           127                                           
NOVFL3           Alphanumeric        1            128           128                                           
NOVFL4           Alphanumeric        1            129           129                                           
DEC              Numeric             5            130           134                                           
DECFL1           Alphanumeric        1            135           135                                           
DECFL2           Alphanumeric        1            136           136                                           
DECFL3           Alphanumeric        1            137           137                                           
DECFL4           Alphanumeric        1            138           138                                           
MEAN             Numeric             5            140           144                                           
                                                                                                              
                                                                                                              
where                                                                                                         
                                                                                                              
WBAN       is the WBAN station number;                                                                        
                                                                                                              
STNAME     is the state abbreviation and station name;                                                        
                                                                                                              
YEAR       is the year of the data;                                                                           
                                                                                                              
JAN-DEC    are the monthly percentages of possible sunshine (nearest whole percent), with                     
           missing values set to -9999; and                                                                   
                                                                                                              
MEAN       is the mean of the monthly sunshine percentages, if all 12 are available;                          
           otherwise set to the missing indicator -9999.                                                      
                                                                                                              
                                                                                                              
Flag codes for the data                                                                                       
                                                                                                              
     The use of flags in the percentage of possible sunshine file was generally modeled after                 
the U.S. Historical Climatology Network (HCN) format, examples of which may be found in                       
Karl et al. (1990).  This meant that each monthly data value had four flag positions.  For                    
consistency, these flag positions are retained in the percentage of possible sunshine file, but               
their use has been simplified as follows.                                                                     
                                                                                                              
                                                                                                              
(JAN-DEC) FL1  is a general data type flag.  The codes are as follows:                                        
                                                                                                              
               Z = value has been estimated by resistant regression on cloud data, and                        
               Blank = value based on observations (see Flag 2 for details).                                  
                                                                                                              
(JAN-DEC) FL2  is the data source code.  The codes are as follows:                                            
                                                                                                              
               3 =  Manuscript-Original National Climatic Data Center Records;                                
               7 =  LCD-Local Climatological Data, published monthly by the                                   
                    National Climatic Data Center (NCDC), Asheville, North                                    
                    Carolina;                                                                                 
               T =  NCDC Tape Deck 9788;                                                                      
               I =  NCDC Tape Deck 9788-value is an estimate because of                                       
                    incomplete data for the month [i.e., at least one missing day                             
                    (actual number not available)];                                                           
               C =  NCDC Tape Deck 9788-value from deck has been edited after                                 
                    comparison with the monthly cloud amount from the station; and                            
               Z =  value has been estimated by resistant regression on cloud amount.                         
                                                                                                              
(JAN-DEC) FL3  has the same meaning as Flag 1.                                                                
                                                                                                              
(JAN-DEC) FL4  has the same meaning as Flag 1.                                                                
                                                                                                              
                                                                                                              
CLOUD AMOUNT FILE                                                                                             
                                                                                                              
     The cloud amount file (NDP021R1.F13) contains monthly and annual                                      
cloud amounts (percentage of sky cover) for each year from each of 197 stations.  The file                    
is sorted by WBAN station number, with each record containing WBAN station number, state                      
and station name, monthly cloud amounts (missing values are set to -9999) with each month's                   
4 respective data flags, and an annual cloud amount (the mean of the monthly values if none                   
are set to missing; otherwise set to the missing indicator -9999).                                            
                                                                                                              
     The file may be read using the following FORTRAN format:                                                 
                                                                                                              
                                                                                                              
        INTEGER WBAN, YEAR, CLDPCT(12), MEAN                                                                  
        CHARACTER FLAG1(12), FLAG2(12), FLAG3(12), FLAG4(12)                                                  
        CHARACTER*18 STNAME                                                                                   
        READ (5,100,END=99) WBAN, STNAME, YEAR,                                                               
     +  (CLDPCT(I),FLAG1(I),FLAG2(I),FLAG3(I),FLAG4(I),I=1,12), MEAN                                          
 100   FORMAT(1X,I5,1X,A18,1X,I4,12(I5,4(A1)),1X,I5)                                                          
                                                                                                              
or by using the SAS format:                                                                                   
                                                                                                              
INPUT WBAN 2-6 STNAME $ 8-25 YEAR 27-30                                                                       
 JAN 31-35 JANFL1 $ 36 JANFL2 $ 37 JANFL3 $ 38 JANFL4 $ 39                                                    
 FEB 40-44 FEBFL1 $ 45 FEBFL2 $ 46 FEBFL3 $ 47 FEBFL4 $ 48                                                    
 MAR 49-53 MARFL1 $ 54 MARFL2 $ 55 MARFL3 $ 56 MARFL4 $ 57                                                    
 APR 58-62 APRFL1 $ 63 APRFL2 $ 64 APRFL3 $ 65 APRFL4 $ 66                                                    
 MAY 67-71 MAYFL1 $ 72 MAYFL2 $ 73 MAYFL3 $ 74 MAYFL4 $ 75                                                    
 JUN 76-80 JUNFL1 $ 81 JUNFL2 $ 82 JUNFL3 $ 83 JUNFL4 $ 84                                                    
 JUL 85-89 JULFL1 $ 90 JULFL2 $ 91 JULFL3 $ 92 JULFL4 $ 93                                                    
 AUG 94-98 AUGFL1 $ 99 AUGFL2 $ 100 AUGFL3 $ 101 FEBFL4 $ 102                                                 
 SEP 103-107 SEPFL1 $ 108 SEPFL2 $ 109 SEPFL3 $ 110 MARFL4 $ 111                                              
 OCT 112-111 OCTFL1 $ 117 OCTFL2 $ 118 OCTFL3 $ 119 OCTFL4 $ 120                                              
 NOV 121-125 NOVFL1 $ 126 NOVFL2 $ 127 NOVFL3 $ 128 NOVFL4 $ 129                                              
 DEC 130-134 DECFL1 $ 135 DECFL2 $ 136 DECFL3 $ 137 DECFL4 $ 138                                              
 MEAN 140-144;                                                                                                
                                                                                                              
Stated in tabular form, the contents include the following.                                                   
                                                                                                              
                                                                                                              
                 Variable         Variable       Starting      Ending                                         
Variable           type             width         column       column                                         
                                                                                                              
                                                                                                              
WBAN             Numeric             5              2             6                                           
STNAME           Character          18              8            25                                           
YEAR             Numeric             4             27            30                                           
JAN              Numeric             5             31            35                                           
JANFL1           Alphanumeric        1             36            36                                           
JANFL2           Alphanumeric        1             37            37                                           
JANFL3           Alphanumeric        1             38            38                                           
JANFL4           Alphanumeric        1             39            39                                           
FEB              Numeric             5             40            44                                           
FEBFL1           Alphanumeric        1             45            45                                           
FEBFL2           Alphanumeric        1             46            46                                           
FEBFL3           Alphanumeric        1             47            47                                           
FEBFL4           Alphanumeric        1             48            48                                           
MAR              Numeric             5             49            53                                           
MARFL1           Alphanumeric        1             54            54                                           
MARFL2           Alphanumeric        1             55            55                                           
MARFL3           Alphanumeric        1             56            56                                           
MARFL4           Alphanumeric        1             57            57                                           
APR              Numeric             5             58            62                                           
APRFL1           Alphanumeric        1             63            63                                           
APRFL2           Alphanumeric        1             64            64                                           
APRFL3           Alphanumeric        1             65            65                                           
APRFL4           Alphanumeric        1             66            66                                           
MAY              Numeric             5             67            71                                           
MAYFL1           Alphanumeric        1             72            72                                           
MAYFL2           Alphanumeric        1             73            73                                           
MAYFL3           Alphanumeric        1             74            74                                           
MAYFL4           Alphanumeric        1             75            75                                           
JUN              Numeric             5             76            80                                           
JUNFL1           Alphanumeric        1             81            81                                           
JUNFL2           Alphanumeric        1             82            82                                           
JUNFL3           Alphanumeric        1             83            83                                           
JUNFL4           Alphanumeric        1             84            84                                           
JUL              Numeric             5             85            89                                           
JULFL1           Alphanumeric        1             90            90                                           
JULFL2           Alphanumeric        1             91            91                                           
JULFL3           Alphanumeric        1             92            92                                           
JULFL4           Alphanumeric        1             93            93                                           
AUG              Numeric             5             94            98                                           
AUGFL1           Alphanumeric        1             99            99                                           
AUGFL2           Alphanumeric        1            100           100                                           
AUGFL3           Alphanumeric        1            101           101                                           
AUGFL4           Alphanumeric        1            102           102                                           
SEP              Numeric             5            103           107                                           
SEPFL1           Alphanumeric        1            108           108                                           
SEPFL2           Alphanumeric        1            109           109                                           
SEPFL3           Alphanumeric        1            110           110                                           
SEPFL4           Alphanumeric        1            111           111                                           
OCT              Numeric             5            112           116                                           
OCTFL1           Alphanumeric        1            117           117                                           
OCTFL2           Alphanumeric        1            118           118                                           
OCTFL3           Alphanumeric        1            119           119                                           
OCTFL4           Alphanumeric        1            120           120                                           
NOV              Numeric             5            121           125                                           
NOVFL1           Alphanumeric        1            126           126                                           
NOVFL2           Alphanumeric        1            127           127                                           
NOVFL3           Alphanumeric        1            128           128                                           
NOVFL4           Alphanumeric        1            129           129                                           
DEC              Numeric             5            130           134                                           
DECFL1           Alphanumeric        1            135           135                                           
DECFL2           Alphanumeric        1            136           136                                           
DECFL3           Alphanumeric        1            137           137                                           
DECFL4           Alphanumeric        1            138           138                                           
MEAN             Numeric             5            140           144                                           
                                                                                                              
                                                                                                              
where                                                                                                         
                                                                                                              
WBAN       is the WBAN station number;                                                                        
                                                                                                              
STNAME     is the state abbreviation and station name;                                                        
                                                                                                              
YEAR       is the year of the data;                                                                           
                                                                                                              
JAN-DEC    are the monthly cloud amounts (nearest whole percent of sky cover); and                            
                                                                                                              
MEAN       is the mean of the monthly cloud amounts, if all 12 are present; otherwise                         
           set to the missing indicator -9999.                                                                
                                                                                                              
                                                                                                              
Flag codes for the data                                                                                       
                                                                                                              
     The use of flags in the cloud amount file was also generally modeled after the U.S.                      
HCN format (Karl et al. 1990).  The four flag positions normally associated with each monthly                 
value are retained in the file, but their use has been customized as follows.                                 
                                                                                                              
                                                                                                              
(JAN-DEC) FL1  is a dual purpose code pertaining to either (1) the number of daily                            
               values not available in computing the monthly mean cloud amount or (2)                         
               how an estimate of the monthly mean cloud amount has been produced.                            
               The codes and their meanings are as follows:                                                   
                                                                                                              
               A,B,C, . . . I corresponds to 1,2,3 . . . 9 days missing;                                      
               Blank = no missing days;                                                                       
               X = value has been estimated from manuscript entries (see Flag 2); and                         
               Z = value has been estimated by resistant regression on percentage of                          
                   possible sunshine.                                                                         
                                                                                                              
                                                                                                              
(JAN-DEC) FL2  is the data source code.  The codes and their meanings are as follows:                         
                                                                                                              
               1 =  NCDC Tape Deck 3210, Summary of the Day, First Order;                                     
               3 =  Manuscript-Original National Climatic Data Center Records;                                
               5 =  Climate Record Book-for a description, see History of                                     
                    Climatological Record Books, U.S. Department of Commerce,                                 
                    Weather Bureau, U.S.G.P.O., 1960;                                                         
               7 =  LCD-Local Climatological Data, published monthly by NCDC;                                 
               M =  Monthly Weather Review, U.S. Weather Bureau, U.S.G.P.O.,                                  
                    1872-1966;                                                                                
               R =  Report of the Chief of the Weather Bureau, U.S. Weather Bureau,                           
                    U.S.G.P.O., 1891-1934;                                                                    
                    United States Meteorological Yearbook, U.S.G.P.O., 1935-1949; or                          
                    Climatological Data, National Summary, U.S. Weather Bureau,                               
                    Asheville, North Carolina, 1950-1980; and                                                 
               Z =  value has been estimated by resistant regression on percentage of                         
                    possible sunshine.                                                                        
                                                                                                              
                                                                                                              
(JAN-DEC) FL3  is the location code.  The codes and their meanings are as follows:                            
                                                                                                              
               0 =  primary station location is current;                                                      
               U =  previous station number unknown;                                                          
               1 =  prior city or airport location;                                                           
               2 =  second city or airport location;                                                          
               3 =  third airport location; and                                                               
               Z =  value has been estimated by resistant regression on percentage of                         
                    possible sunshine.                                                                        
                                                                                                              
(JAN-DEC) FL4  is an additional source qualifier.  The codes and their meanings are as                        
               follows:                                                                                       
                                                                                                              
               C =  computed by technician from data available in the nondigital                              
                    source specified by Flag 2;                                                               
               Blank =   data are directly from the source specified by Flag 2; and                           
               Z =  value has been estimated by resistant regression on percent of                            
                    possible sunshine.                                                                        
                                                                                                              
                                                                                                              
REFERENCES                                                                                                    
                                                                                                              
Emerson, J. D., and D. C. Hoaglin. 1983.  Resistant lines for y versus x.  pp. 129-65.                        
     IN D. C. Hoaglin, F. Mosteller, and J. W. Tukey, eds., Understanding Robust and                          
     Exploratory Data Analysis.  John Wiley & Sons.                                                           
                                                                                                              
Karl, T. R., and P. M. Steurer. 1990.  Increased cloudiness in the United States during the                   
     first half of the twentieth century: Fact or fiction?  Geophysical Research Letters                      
     17(11):1925-28.                                                                                          
                                                                                                              
Karl, T. R., C. N. Williams, Jr., and F. T. Quinlan. 1990.  United States Historical Climatology              
     Network (HCN) serial temperature and precipitation data.  ORNL/CDIAC-30, NDP-                            
     019/R1.  Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory,                      
     Oak Ridge, Tennessee.                                                                                    


