WEEKLY CLIMATE NEWS

DataStreme ECS Week Twelve: 30 November-4 December 2015

ITEMS OF INTEREST

United Nations climate change conference to commence in Paris -- The 2015 2015 Paris Climate Conference, officially known as COP21 (for the 21st Conference of Parties), will commence on Monday (30 November). This conference is expected to attract 50,000 participants including 25,000 official delegates from government, intergovernmental organizations, UN agencies, non-governmental organizations and the public society and is intended to achieve a legally binding and universal agreement on climate, with the aim of keeping the global temperature rise below 2 Celsius degrees. [COP21 Paris]
Beginning of meteorological winter season -- The winter meteorological season in the Northern Hemisphere starts on Tuesday (1 December). Recall that climatologists and meteorologists have elected to use a standard three-month grouping to identify each meteorological season. Hence, the months of December, January and February are considered the winter meteorological season. You will note that the winter solstice, marking the day where the length of daylight is least in the Northern Hemisphere is still three weeks away, falling on Monday, 21 December 2015. Since the lowest temperatures typically fall in mid to late January, the meteorological winter tends to be centered on the coldest time of the year in the Northern Hemisphere.
The 2015 hurricane seasons reviewed -- With the end of the official 2015 hurricane season in both the North Atlantic and North Pacific on Monday (30 November 2015), a quick review of this year's tropical cyclone statistics for the official 2015 hurricane season has been made for both basins. [AMS DataStreme Atmosphere]
For those who are interested in obtaining historic hurricane information, the "Historical Hurricanes Mapping & Analysis Tool" developed by NOAA allows the search and display of detailed data for more than 6000 tropical cyclones in seven of the planet's major ocean basins based upon a data set that runs from 1842 to 2014. Coastal population trends are also available for the Atlantic and Gulf Coasts of the United States.
Tropical cyclone climatologies of North Atlantic and the eastern North Pacific -- The National Hurricane Center (NHC) has an updated and revised edition of its "Tropical Cyclones of the North Atlantic Ocean, 1851-2006." While a paper copy of this book is available for a cost from NHC, a 243-pg pdf file of this edition can be downloaded for free. NHC also released the first edition of "Tropical Cyclones of the Eastern North Pacific Ocean, 1949-2006." In addition to a paper copy is available for sale, a free 164-page pdf file is available. Both of these climatologies have numerous graphics that show long-term changes in tropical cyclone frequency in the two basins.
A climatology of tropical cyclones in the central North Pacific from the 1950s to 2008 is available from the CPHC climatology website maintained by the Central Pacific Hurricane Center (CPHC) in Honolulu, HI.
High-quality maps of December temperature and precipitation normals across US available -- The PRISM Climate Group at Oregon State University's website has prepared high-resolution maps depicting the normal maximum, minimum and precipitation totals for December and other months across the 48 coterminous United States for the current 1981-2010 climate normals interval. These maps, with a 800-meter resolution, were produced using the PRISM (Parameter-elevation Regressions on Independent Slopes Model) climate mapping system.
December weather calendar for a city near you -- The Midwestern Regional Climate Center maintains an interactive website that permits the public to produce a ready to print weather calendar for any given month of the year, such as December, at any of approximately 270 weather stations around the nation. (These stations are NOAA's ThreadEx stations.) The entries for each day of the month includes: Normal maximum temperature, normal minimum temperature, normal daily heating and cooling degree days, normal daily precipitation, record maximum temperature, record minimum temperature, and record daily precipitation; the current normals for 1981-2010.
"Coldest day of the year" is on the horizon -- NOAA's National Centers for Environmental Information (NCEI) produced a set of "Coldest Day of the Year" maps for the contiguous United States, Alaska, Hawaii and Puerto Rico showing the dates of the lowest daily minimum temperatures of the year as calculated from the 1981-2010 climate normals. Many places across the West will experience their lowest daily temperatures starting during the next two to three weeks in early December. On the other hand, some areas across the West will not reach their lowest daily temperatures of the year until late January. [NOAA NCEI News]
[Notes: (1.) According to the seasonal variations in the long-term average or "normal" temperatures, many locations across the nation not along the coasts typically have their lowest normal daily high and low temperatures during the third week of January, nearly one month after the winter solstice.
(2.) For comparison purposes, check the corresponding map for the "Warmest Day of the Year" that shows the dates of occurrence of the highest maximum temperatures. EJH]
It's Sure Dark! -- Have you noticed that the sun is setting early these days? During the first ten days of December, many locations throughout the country will experience their earliest sunset times of the year. The exact day for the earliest sunset depends upon the latitude, so you may want to check the date in your locale from the sunrise tables appearing in an on-line, interactive service available for the entire year at most cities in the United States. The reason for the earliest sunsets occurring in early December rather than on the winter solstice (during the evening hours of Monday, 21 December 2015) is that the sun is not as precise a timekeeper as our watches. Because of a combination of factors involved with Earth's elliptical orbit about the sun and the tilt of Earth's spin axis with respect to the plane of the ecliptic, the sun appears to "run fast" by as much as 15 minutes as compared with clock time in November. However, with the approach of the winter solstice and perihelion (the smallest earth-sun distance during the late afternoon of 2 January 2016), the apparent sun slows during December and finally lags the clock by 12 minutes in February. Consequently, a noticeable and welcome trend toward later sunsets can be detected by the end of December, especially by those residents in the northern part of the country. However, the latest sunrises occur at most locales in early January, meaning that early risers will continue seeing dark and dreary mornings for another month.
Worldwide GLOBE at Night 2015 Campaign continues -- The twelfth in a series of GLOBE at Night citizen-science campaigns for 2015 will continue with a 10-night campaign starting on 2 December and running through 11 December. GLOBE at Night is a worldwide, hands-on science and education program designed to encourage citizen-scientists worldwide to record the brightness of their night sky by matching the appearance of a constellation (Perseus in the Northern Hemisphere and Grus in the Southern Hemisphere) with the seven magnitude/star charts of progressively fainter stars. Activity guides are also available. The GLOBE at night program is intended to raise public awareness of the impact of light pollution. The 2016 campaign will commence starting 1 January and running through 10 January 2016. [GLOBE at Night]
State, national and global instrumental records -- Temperature and precipitation data have been collected around the world since the mid-19th century. Beginning in the 1890s, a sufficiently dense climate network has been established in the United States and its territories. The records from around the nation and from around the global have been collected and archived at several central locations, such as NOAA's National Centers of Environmental Information (NCEI). Scientists at NCEI along with colleagues at NASA's Goddard Institute for Space Studies and in the United Kingdom have produced time series of area-average monthly and annual temperatures for over a century on state, national and global space scales. For more details on these records and how to access them, please read this week's Supplemental Information...In Greater Depth.
Graphical depictions of statewide annual and seasonal time series are available -- NOAA's National Centers for Environmental Information (NCEI) are making graphics available that depict the variations in the historical temperature averages each year or each season since 1895 for each of the 48 contiguous United States. These graphs are derived from the current nClimDiv version of the US Climate Division Database. [NOAA NCEI News]

CURRENT CLIMATE MONITORING

Assessing nation's soil moisture from satellite and ground-based observations -- Maps were generated that showed the quantity of moisture in the top 5 centimeters of the soil across the 48 contiguous United States during late May as generated from data collected by the sensors on NASA's Soil Moisture Active Passive (SMAP) satellite and from more than 1200 ground-based sensors scattered around the nation. [NASA Earth Observatory]

CLIMATE AND THE BIOSPHERE

Satellite data used to predict malaria risk -- Researchers with the NOAA Satellite and Information Service have been using reflected visible and near-infrared radiation data collected by the Advanced Very High Resolution Radiometer (AVHRR) sensors onboard the NOAA POES (Polar Orbiting Environmental Satellite) fleet to produce imagery of green vegetation on the tropical landscape, which would then be used to determine if sufficiently moist and warm conditions would be favorable for mosquito survival especially in Sub-Saharan Africa, a region of high malaria risk to humans. The researchers are attempting to use the satellite data to predict the times when and the regions where the highest malaria risk would occur, with a one to two-month lead time. [NOAA NESDIS News Archive]

CLIMATE FORCING

Carbon content of temperate forests may be overestimated -- Scientists at NASA's Goddard Space Flight Center and the University of Maryland, College Park who have employed laser-based (lidar) airborne measurements made by Goddard's Lidar, Hyperspectral and Thermal instrument (G-LiHT) are questioning earlier estimates of the carbon content of living trees in temperature forests that were made by cutting down large trees. These new findings suggest that the carbon content of these forests were overestimated, which would necessitate a reassessment of the impact that trees would have on the amount of atmospheric carbon compounds. [NASA Goddard Space Flight Center]
Seasonal variations found in Twin Cities heat island -- Researchers at the University of Minnesota recently reported on the results of a study of the urban heat island associated with Minnesota's Twin City metropolitan area that includes Minneapolis and St. Paul. Using a network of 180 temperature sensors distributed across the metropolitan area that recorded the air temperature every 15 minutes over a three-year span (2011-2012), the researchers found that temperatures in the urban areas within the heat island could be as much 9 Fahrenheit degrees higher than surrounding less urban communities during a July 2012 heat wave. In addition, the Twin Cities urban heat island was stronger at night than during the day in the summer months, while in the winter the effect was stronger during the day. [University of Minnesota Discover News]
Earth's magnetic field may be returning to normal -- Scientists from Columbia University's Lamont-Doherty Observatory, the Massachusetts Institute of Technology and France's Aix-Marseille Université claim that the apparent weakening in the Earth's magnetic field may be merely a reduction in intensity than to a reversal in the polarity of the magnetic field. Using a new technique to measure changes in the magnetic field's strength in the past, the scientists found that its long-term average intensity over the past 5 million years was only about 60 percent of the field's strength today, much weaker than the global database of paleo-intensity suggests. [Lamont-Doherty Earth Observatory News]

CLIMATE FORECASTS

Australian tropical cyclone season outlook issued -- Forecasters at the Australian Government's Bureau of Meteorology recently released an outlook for the upcoming 2015-16 Australian tropical cyclone season that typically begins in November and runs through April. These forecasters foresee that a 90 percent chance exists for a below average tropical cyclone activity in the five regions that surround that continent. Their outlook for a less active season is based upon the strong El Niño conditions that are occurring across the tropical Pacific Ocean. Typically, the waters around Australia experience fewer tropical cyclones during El Niño events and few of these systems make landfall on the continent. [Australian Bureau of Meteorology]

CLIMATE AND THE BIOSPHERE

Algal toxin closes California's Dungeness and razor clam fisheries -- Earlier in November the California Fish and Game Commission closed the state's year-round rock crab fishery north of Ventura and delayed the opening of the recreational and commercial Dungeness crab fishery due to potentially toxic levels of harmful algae. These closures are the most recent record algal bloom along the West Coast because of the unusually warm water that has persisted along the coast during this summer and fall. The current major El Niño event has contributed to the above average temperatures across the eastern North Pacific. [NOAA Climate.gov News]

CLIMATE AND SOCIETY

Earthweek -- Diary of the Planet [earthweek.com]

Concept of the Week: Climate Sensitivity

Climate sensitivity is a relatively new and powerful concept in climate science. It is a measure of how responsive the temperature of Earth's climate system is to a change in radiative forcing due to increases in atmospheric carbon dioxide, an important greenhouse gas, combined with the contributions of feedbacks within the system. Specifically, the term is defined as how much the global mean surface temperature will increase if there is a doubling of atmospheric greenhouse gases (in terms of equivalent CO₂), once the planet has had a chance to settle into a new equilibrium after the increase occurs. In other words, it's an assessment of how Earth's climate will respond to that doubling.

According to NASA climate scientist James Hansen, the concept of climate sensitivity has its origins in a request made by President Jimmy Carter in 1979 for the National Academy of Sciences (NAS) to report on the potential impact on climate of the increasing atmospheric concentration of carbon dioxide. Jule G. Charney (1917-1981) of the Massachusetts Institute of Technology (MIT) led the Academy investigation team. He designed a now classic experiment where computer models of Earth's climate system had the atmospheric concentration of CO₂ doubled while all other variables (except temperature) were held constant.

The addition of CO₂ makes the atmosphere more opaque for outgoing infrared radiation (heat), warming the lower atmosphere and cooling the upper atmosphere. Applying basic radiation laws, Charney found that doubling the atmospheric CO₂ concentration would reduce the net radiative flux (from Earth to space) at the tropopause by a global average of about 4 watts per square meter (W/m²). How much warmer would Earth's surface become as a consequence of this enhanced greenhouse effect? According to the Stefan-Boltzmann law, the radiation emitted by an object is directly proportional to the fourth power of the object's absolute temperature. To reestablish radiative equilibrium following a doubling of atmospheric CO₂, Earth must radiate to space an additional 4 W/m², brought about by a global warming of 1.2 Celsius degrees (or 0.3 Celsius degrees per W/m²).

Charney's initial experiment accounted for the effect of a forcing agent (i.e., atmospheric CO₂) on global climate but not the influence of feedbacks. As noted in the Concept of the Week for Week 2, forcing agents and mechanisms drive climate change, while feedbacks determine the magnitude of climate change. Hence, Charney's "no-feedback" experiment significantly underestimates the amount of global warming likely to accompany a doubling of atmospheric CO₂. With inclusion of feedbacks, the 1979 Academy study indicated that global warming could range from 2 to 3.5 Celsius degrees. The most recent IPCC report (AR4) estimates the magnitude of warming with feedbacks incorporated as 3 Celsius degrees with a range of uncertainty of 2 to 4.5 Celsius degrees. This greater sensitivity depends primarily on all the different feedbacks, both positive and negative, that either amplify or diminish the greenhouse effect. The three primary feedbacks involve clouds, sea ice, and water vapor.

In summary, climate sensitivity is usually expressed in terms of the equilibrium change in global mean annual surface temperature caused by an increment in downward infrared radiative flux that would result from sustained doubling of atmospheric CO₂ concentration compared to its pre-industrial level (taken to be 280 ppmv).

Concept of the Week: Questions

All other factors being equal, the addition of CO₂ to the atmosphere [(increases) (decreases)(has no effect upon)] the flux of infrared radiation from Earth's surface to space.
Charney's initial estimate of the amount of global warming that would accompany a doubling of atmospheric CO₂ [(did)(did not)] account for the temperature change(s) likely to accompany feedbacks in Earth's climate system.

Historical Events:

1 December 1831...The coldest December of record in the northeastern U.S. commenced. Temperatures in New York City averaged 22 degrees, with just four days above freezing, and at Burlington, VT the temperature never did get above freezing. The Erie Canal was closed the first day of December, and remained closed the entire month. (David Ludlum)
1 December 1913...A six day Front Range snowstorm began, ultimately producing 45.7 inches of snow at Denver, CO, the biggest single snowstorm on record for that city. It produced a record total of 46 inches at Denver, CO. (David Ludlum) (Intellicast)
3-10 December 1926...Record rain fell on Yuma, AZ over a one-week period. On the 4^th 1.10 inches of rain fell, and by the 10^th a total of 4.43 inches had fallen, to set an all-time December monthly record. The mean annual precipitation for Yuma is only 3.38 inches. (Accord Weather Guide Calendar)
3 December 1982...Big Fork, AR received 14.06 inches of rain, setting a 24-hour maximum precipitation record for the state. (NCDC)
4 December 1982...The temperature in New York City's Central Park reached 72 degrees to establish a record high for December. The month as a whole was also the warmest of record. (The Weather Channel)
5 December 1941...The temperature at Enosburg Falls soared to 72 degrees to establish a state record for Vermont for the month of December. (The Weather Channel)
6 December 1950...Duluth, MN had their greatest 24-hour snowfall when 25.4 inches fell. (Intellicast)

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