WEEKLY WATER NEWS

DataStreme WES Week Four: 24-28 September 2007

Water in the News

(Thurs.) Three decades of changes in land use seen in the Washington-Baltimore metro area -- Comparison of images taken by NASA's Landsat 1 in 1973 and Landsat 7 in 2002 across the Washington, DC-Baltimore, MD metropolitan areas show the dramatic changes in land use from rural to suburban and urban. These land use changes have the potential for affecting the local hydrologic cycle and the local weather and climate patterns, such as the urban heat island effect. [NASA Earth Observatory]
(Thurs.) Human activity could increase atmospheric water content -- Researchers at several international research centers including Lawrence Livermore National Laboratory claim that satellite observations and climate model results indicate that human activity has not only increased global temperatures, but also the amount of water vapor in the atmosphere due to increased evaporation over the world's oceans. [EurekAlert!]
(Thurs.) Volatile organic compounds monitored in the field by new micro-sensors -- Researchers at the Georgia Institute of Technology have developed a micro-sensor that can be used to measure the concentration of volatile organic compounds in both the atmosphere and water in the field, rather than later in a laboratory. [EurekAlert!]
(Thurs.) Fish would respond quickly to changes in mercury deposition -- Scientists at the Smithsonian Environmental Research Center, the University of Maryland and the University of Connecticut claim that a reduction in the atmospheric mercury emissions should quickly reduce in methylmercury levels in lake fish. [EurekAlert!] These conclusions have been reached based upon a groundbreaking US and Canadian study called METAALICUS - Mercury Experiment to Assess Atmospheric Loading in Canada and the United States, that also involved biologists from the University of Alberta. [EurekAlert!]
(Thurs.) Lessons learned from a Carolina drought -- Based upon the lessons learned from a five-year drought across South Carolina that ended in 2002, governmental and water management officials have been able to endure the current drought more easily. [US Water News Online]
(Tues.) Satellites provide information on drought conditions around the world --
- Images of the rainfall anomaly (the arithmetic difference between observed and average totals) across Brazil obtained from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite between July and September 2005 and the Vegetation Greenness Anomaly, a measure of the health of vegetation, produced from the MODIS instrument on the NASA Terra satellite during that concurrent time show that the vegetation did not suffer despite drought conditions across the region. [NASA Earth Observatory]
- A MODIS image obtained from data collected by NASA's Terra satellite shows a vegetation index called the NDVI (Normalized Difference Vegetation Index) across western Australia, where a long-term drought has persisted. [NASA Earth Observatory]
(Tues.) Volcanic eruption in Tanzania seen from space -- An image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA's Terra satellite shows the plume of ash and steam being ejected from Tanzania's Ol Doinyo Lengai Volcano that erupted earlier this month. This volcano produces natrocarbonatite lava that contains minerals that react readily with atmospheric water vapor. [NASA Earth Observatory]
(Tues.) Antarctic snowmelt detected well inland -- Analyzing 20 years of data obtained from sensors on orbiting satellites have led NASA scientists to claim that the Antarctic snow and ice is currently melting farther inland from the coast and at higher altitudes than back when the satellite surveillance began. They also noted increased melting on the Ross Ice Shelf, Antarctica's largest ice shelf. [NASA Goddard]
(Tues.) Ten years of ocean color measurements by satellite show climate impacts on ocean health -- NASA recently celebrated the 10th anniversary of measurements of ocean color by its SeaWiFS (Sea-viewing Wide Field-of-view Sensor) instrument, noting that the decade-long data set collected shows how changes in ocean color can be used to see how ocean health can be affected by ongoing changes in climate. [NASA]
(Tues.) Emissions could violate ocean-quality standards -- A team of scientists from The United States, Norway, the United Kingdom, Australia, Japan and Monaco warn that future emissions of carbon dioxide by human activity would alter ocean chemistry sufficiently within the next half century and could result in ocean waters violating ocean water quality criteria set by the US Environmental Protection Agency. [EurekAlert!]
(Tues.) Effects of flooding Chad are documented -- Two images made by the MODIS sensor on NASA's Terra satellite nearly 11 weeks apart in July and September 2007 show the changes in lake size and a rain-swollen river system in the African nation of Chad following heavy monsoonal rains in August and September. [NASA Earth Observatory]
(Tues.) Arsenic is a global water threat -- A geographer from the University of Cambridge states that many of the 137 million people in 70 countries around the world are unknowingly exposed to unsafe levels of arsenic in their drinking water, the result of contamination from natural ground deposits or a variety of agricultural and industrial practices. A scientist from the University of California also states that arsenic poses longer-term health risks than essentially every other potential water contaminant. [US Water News Online]
Eye on the tropics -- During the last week several tropical cyclones (low pressure systems that form over tropical or subtropical oceans) developed and moved across tropical waters:
- In the North Atlantic basin, an area of low pressure that had formed along a frontal boundary off the coast of northeast Florida moved across the Florida Peninsula late last week and once over the northeastern Gulf of Mexico became Tropical Depression 10 on Friday. By Friday evening, it had made landfall along the western coast of the Florida Panhandle, accompanied by locally heavy rain. This system spared New Orleans, LA, which uneasily awaited the approach of this tropical depression. [USA Today]
  Subtropical Storm Jerry formed over the central North Atlantic on Sunday and moved to the north.
- In the eastern North Pacific, the ninth named tropical storm of the season in that basin formed from a tropical depression last week off the Mexican coast and was named Ivo. Near the end of the week this tropical storm had intensified to a Category 1 hurricane on the Saffir-Simpson Scale, but by the weekend, it had weakened to a tropical storm and then a tropical depression as it approached the southern tip of Mexico's Baja California. [USA Today] An image obtained from NOAA's GOES-11 satellite shows the clouds spiraling around Hurricane Ivo late last week. [NOAA OSEI]
- In the western North Pacific, Typhoon Wipha became a supertyphoon at the start of last week as maximum sustained surface winds exceeded 150 mph. This category 4 typhoon on the Saffir-Simpson Scale traveled to the northwest and made landfall along the eastern China coast by midweek. An image from the MODIS instrument on NASA's Aqua satellite shows the broad counterclockwise spiral of clouds around the central eye as Wipha passed to the northeast of Taiwan. After making landfall Typhoon Wipha weakened to a tropical storm as it moved across eastern China, but the winds and the heavy rain that produced landslides were responsible for at least nine deaths and millions of dollars in damage. [USA Today]
  A new tropical storm, with the name Francisco, developed in the South China sea over the weekend and was moving to the west-northwest toward southern China.
Humberto set a record -- Meteorologists at the National Hurricane Center recently reported that the one day that Hurricane Humberto took to develop from a tropical depression off the Texas Gulf coast to a category 1 hurricane (on the Saffir-Simpson Scale) represents a record development in North Atlantic hurricane records maintained at the center in over one century. Images obtained from the radar and microwave imager on NASA's the Precipitation Radar on the Tropical Rainfall Measuring Mission (TRMM) satellite, show the clouds and rainfall rates with the circulation regime when the tropical depression formed and when it made hurricane status just before landfall over one week ago. [NASA Earth Observatory]
DART and ATLAS buoys deployed in Indian Ocean -- NOAA officials and their counterparts in the Indonesian scientific community recently deployed one Deep-ocean Assessment and Reporting of Tsunami (DART™) II buoy and four ATLAS (Autonomous Temperature Line Acquisition System), which are climate monitoring buoys in the waters of the Indian Ocean. The DART buoy is the second tsunami monitoring buoy to have been on station in the Indian Ocean off Indonesia, the site of the disastrous tsunami of 2004, while the ATLAS buoys are part of the Global Earth Observation System of Systems (GEOSS), an international effort to monitor and predict changes in the global environment. [NOAA News]
Ice cover record set -- Researchers at the National Snow and Ice Data Center reported that as of one week ago the areal extent of the Arctic sea ice appears to have reached a summer minimum, which marks a record minimum size within the last 28 years of satellite surveillance. [EurekAlert!]
Changes in winter sea ice extent in Arctic depends on location -- Using 26 years of satellite data, researchers at Rutgers University have found that rising surface temperatures across the Barents Sea, located to the northeast of the Scandinavian Peninsula, have contributed to the shrinkage of winter ice across that portion of the Arctic basin, while the extent of the sea ice in the Bering Sea between Siberia and Alaska appears to remain relatively steady. [Rutgers University]
Microburst could have been responsible for Thai air disaster -- Aviation experts suggest the reason for a jetliner crashing while landing at Phuket, Thailand and killing 89 people early last week could have been a microburst that created dangerous wind shear. [USA Today]
Indian monsoon flooding is deadly -- Torrential rain associated with the southwest summer monsoon fell across southern India last week, producing flooding that killed 63 people across the region. [USA Today]
Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, including drought, floods, and storms during the current month. [NCDC]
Global Water News Watch -- Other water news sources can be obtained through the SAHRA Project at the University of Arizona [SAHRA Project]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Controlling Indoor Humidity

In public buildings as well as individual homes, it is sometimes desirable to alter extremes of relative humidity so that living spaces are more comfortable. For human comfort, optimum relative humidity is between about 30% and 50%. When indoor air is exceptionally dry, a humidifier may be used to add water vapor to the air, but when indoor air is excessively muggy, a dehumidifier may be used to remove water vapor from the air.

As cold, dry winter air is drawn indoors and heated by a furnace, its relative humidity declines--sometimes to uncomfortably low levels. Suppose, for example, that outdoor air has a temperature of -20ºC (-5ºF) and relative humidity of 50%. If that air were brought indoors and heated to 21ºC (70ºF), its relative humidity drops to about 2% -- well below the optimal winter indoor relative humidity of 30% to 50%. At such very low relative humidity values, people often feel discomfort caused by dry skin and irritation of the mucus membranes in their nose and throat. Also, wood furniture dries out and may crack and become unjointed. Discharge of static electricity (e.g., after walking across a carpet and touching a metal doorknob) can be a nuisance in dry rooms.

One remedy for excessively low indoor relative humidity is a device known as a humidifier. A humidifier elevates the relative humidity of indoor air to more comfortable levels by evaporating water into the air (increasing the vapor pressure). A common humidifier design consists of a wheel that continually rotates a porous belt (or pads) into and out of a reservoir of water. A fan blows air through the wetted belt, water evaporates into the air stream, and the more humid air circulates through the dwelling.

On the other hand, a dehumidifier may be desirable during warm muggy summer days. In addition to discomfort caused by reduced evaporative cooling, high values of indoor humidity can increase the incidence of mold and mites. A dehumidifier lowers the relative humidity of indoor air to more comfortable levels by inducing condensation of water vapor (decreasing the vapor pressure). In a standard dehumidifier, a fan draws humid air past a cold refrigerated coil. Air in contact with the coil is chilled to saturation, water vapor condenses on the coils and liquid water drips from the coils into a collection reservoir or through a hose into a drain. Most dehumidifiers function best when the air temperature is at or above 18ºC (65ºF).

Click on forecast map for locations across the country where today's indoor relative humidity is expected to be too high or too low in the absence of any controls on indoor humidity. For an interactive applet (from the University of Wisconsin-Madison) that explores the relationships among temperature, dewpoint, and relative humidity, go to http://profhorn.meteor.wisc.edu/wxwise/museum/a7/a7exercise1.html. Follow instructions and note how the indoor relative humidity changes with changes in outdoor conditions.

Concept of the Week: Questions

A humidifier elevates the relative humidity by causing [(evaporation)(condensation)].
A dehumidifier reduces the relative humidity by causing [(evaporation)(condensation)].

Historical Events

25 September 1939...A West Coast hurricane moved onshore south of Los Angeles bringing unprecedented rains along the southern coast of California. Nearly five and a half inches of rain drenched Los Angeles during a 24-hr period. The hurricane caused $2 million in damage, mostly to structures along the coast and to crops, and claimed 45 lives at sea. "El Cordonazo" produced 5.66 in. of rain at Los Angeles and 11.6 in. of rain at Mount Wilson, both records for the month of September. (David Ludlum) (The Weather Channel)
25 September 1997...While much of San Bernardino and Inyo Counties in California are desert, between 1 to 2 inches of rain from former Pacific Hurricane Nora fell across a large portion of these counties. State highway 190 was washed out between Panamint Springs and Stove Pipe in Death Valley National Park. Flooding also shut down many other park roads. (Accord Weather Calendar)
25-26 September 1962...Torrential rains from severe thunderstorms over the hilly regions to the west and north of Barcelona, Spain resulted in flooding and considerable property damage. Many buildings collapsed. Tarassa was particularly hard hit with approximately 500 deaths reported. (Accord Weather Calendar)
28 September 1986...Flash flooding swept a car into a swollen creek from off the Kamehameha Highway on the Hawaiian island of Oahu. The driver held onto some branches until help arrived, but the strong current stripped him of his clothes and watch. (Accord Weather Calendar)
28 September 1986...Torrential rains and floods were responsible for South Africa's worst natural disaster in Natal. As much as 35 in. of rain fell between the 25^th and 29^th to the northeast of Empangen, resulting in 317 deaths and 163 people missing. Topsoil from some farms was completely washed away leaving only bedrock. (Accord Weather Calendar)
29 September 1959...Hurricane Gracie made landfall near Beaufort, SC with sustained winds of 97 mph and a peak gust of 138 mph. Ten people were killed in South Carolina and Georgia. As the weakening storm moved through Virginia on the 30th, the storm spawned an F3 tornado at Ivy, VA, which killed 11 people. On the same day, a storm produced 28 inches of snow in Colorado Springs, CO. (David Ludlum)
29 September 1983...Heavy rains began in central and eastern Arizona that culminated in the worst flooding in that state's history. Eight to ten inch rains across the area caused severe flooding in southeastern Arizona that resulted in thirteen deaths and $178 million in damage. President Reagan declared eight counties of Arizona to be disaster areas. (The Weather Channel)
30 September 1882...The world's first hydroelectric power plant (later known as Appleton Edison Light Company) began operation on the Fox River in Appleton, WI using a 42-inch waterwheel that powered two direct current generators to provide a total of 25 kilowatts of power. (Wikipedia, Energy Quest)
30 September 1932...Tropical cyclone rainfall of 4.38 inches at Tehachapi in southern California over 7 hours caused flash floods on Agua Caliente and Tehachapi Creeks resulting in 15 deaths. (The Weather Doctor)
30 September 1935...The Boulder Dam, renamed the Hoover Dam in 1947, was dedicated at Boulder City, NV. This concrete-arch dam supplied the first U.S. hydroelectric plant to produce a million kilowatts, with much of the power serving the Los Angeles area. (Today in Science)