WEEKLY CLIMATE NEWS

DataStreme ECS WEEK THREE: 17-21 September 2012

ITEMS OF INTEREST

The Autumnal Equinox -- The Autumnal Equinox will occur early this Saturday morning (officially at 1449Z, 22 September 2012 or 10:49 AM EDT or 9:49 AM CDT, etc.). At that time the noontime sun will appear directly above the equator, representing one of the two times during the year for such an occurrence, with the other being at the vernal equinox in March. The term "equinox" arises from the fact that this time of year represents "equal night" and equal day essentially everywhere. Within the subsequent several days, the length of daylight will become noticeably shorter. This decrease in daylight will continue for another three months to the winter solstice during the early morning hours of Friday, 21 December 2012.
Editor's note: John White, a meteorologist from North Carolina involved with the AMS Education program, reported that the geosynchronous (or geostationary) satellites make an "satellite eclipse" of the sun near the spring and autumnal equinoxes because of their equatorial orbit, such that these satellites pass through the earth's shadow and the satellite is powered down when the solar array does not receive sufficient sunlight. [For more information, consult NWS Southern Region GOES Satellite FAQ] EJH.
Monitoring the seasonal motions of the sun -- If you would like more background information concerning how the sun appears to across your local sky, along with the times of local sunrise and local sunset, for your hometown on any day throughout year, please read this week's Supplemental Information…In Greater Depth.
All-time world record high temperature invalidated -- Late last week the World Meteorological Organization (WMO) issued a news release that invalidated the world record high temperature reading of 136.4 degrees Fahrenheit recorded at El Azizia, Libya on 13 September 1922. According to a professor at Arizona State University who is the s the Rapporteur of Climate and Weather Extremes for the WMO, the WMO Commission on Climate Extremes thoroughly investigated the record and found a number of concerns, including problematic instrumentation, observation site that was over a paved surface, and poor matching to surrounding measurements. Consequently, this record high temperature for the planet is now the 134-degrees Fahrenheit reading taken at Greenland Ranch, now known as Furnace Creek, in Death Valley, CA. [Arizona State University News]

CURRENT CLIMATE STATUS

US national weather and climate reviewed for August and Summer 2012 -- Based upon preliminary data, scientists at NOAA's National Climatic Data Center report that August 2012 was the sixteenth warmest August across the coterminous United States since sufficiently reliable climate records began in 1895. Nevada tied its warmest August on record, while all but two states west of the Rockies had statewide temperatures that were among the ten highest. In the East, the New England States and Delaware experienced August statewide temperatures within the ten highest. Furthermore, the recently concluded meteorological summer of 2012 (June, July and August) was the third warmest summer across the coterminous United States since sufficiently reliable climate records began in 1895. Colorado and Wyoming had their hottest (June-August) summers on record.
The nationwide August 2012 average precipitation was close to the 20th century (1901-2000) average, while the nationwide summer precipitation was below average, making it the eighteenth driest summer since 1895. Washington, Wyoming and Nebraska reported their driest August on record,while Mississippi and Louisiana had their second wettest August, due to Hurricane Isaac. Wyoming and Nebraska also experienced their driest summer on record. [NOAA/NCDC State of the Climate] [NOAA ClimateWatch Magazine]

CURRENT CLIMATE MONITORING

The "gravity of water" monitored from space -- Using gravity data collected from NASA's twin satellites known as GRACE (Gravity Recovery and Climate Experiment), researchers at the University of Texas at Austin have been able to measure changes in groundwater. Knowledge of groundwater changes has become critically important during this year's drought that has been gripping a large section of the nation. [NASA Earth Observatory]
Himalayan glaciers retreat at uneven rates -- A new report entitled "Himalayan Glaciers: Climate Change, Water Resources, and Water Security" from the National Research Council has found that while glaciers in the eastern and central regions of Asia's Himalayan Mountains appear to be retreating at accelerating rates, glaciers in the western Himalayas are more stable, with some experiencing growth. The varying changes in the Himalayan glaciers due to changing climate conditions could affect the area's river systems, water supplies, and the South Asian population in ways that currently remain unclear. [The National Academies]
US involved in international flash flood project in Europe -- During the next three months, US scientists from NOAA, NASA and the University of Connecticut will be participating in the Hydrological Cycle in the Mediterranean Experiment (HyMeX), the largest weather field research project in European history. This field experiment is a 10-year international effort designed to improve the understanding and the modeling of the hydrologic cycle in support of improved forecasts and warnings of flash floods in the Mediterranean region that includes sections of Italy, southern France and several of the Mediterranean islands. The American researchers hope that the project will provide important findings that would be beneficial to the United States. [NOAA News]
An All-Hazards Monitor -- This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [ NOAAWatch]
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]

CLIMATE FORECASTS

More accurate method for predicting hurricane activity devised ....-- North Carolina State University researchers have developed a new method for forecasting seasonal hurricane activity that they claim is 15 percent more accurate than previous techniques. This method involves a "network motif-based model" involving statistical modeling. [North Carolina State University Newsroom]
Storms could be triggered by parched soils --An international team of researchers from the United Kingdom, Holland, Austria and France claim that their examination of imagery from weather satellites across six continents indicate that afternoon convective storms are more likely to develop when soils across a region are parched. They also believe that their results have important implications in global climate models that currently have predicted an excessive number of droughts. [Natural Environment Research Council]

CLIMATE FORCING

Response of ice sheets to climate change is studied -- Researchers at the University at Buffalo and their colleagues at other research institutions report their analysis of glaciers on Baffin Island in the Arctic indicates that prehistoric glaciers appear to have react rapidly to changes in climate, such as a brief cold snap of 150 years duration approximately 8200 years ago. They claim that their discovery shows ice sheets have reacted rapidly to changing climate conditions. [University at Buffalo NewsCenter]

CLIMATE AND THE BIOSPHERE

New national Plant Zone Map may be obsolete -- A researcher at the City College of New York published a study in which he showed that the map showing the Plant Hardiness Zones across the United States that was released by the US Department of Agriculture this last January is now out of date as the climate continues to change and winters become milder. He developed a new method to map cold-weather zones across the nation that accounts for rapidly rising temperatures. [City College of New York]
Arctic crustaceans need to be resourceful to survive melting sea ice -- Researchers from the University of Delaware and several Norwegian research institutions have discovered that Arctic crustaceans appear to use ocean currents and deep-water migration to survive the melting of sea ice covering the Arctic Ocean. [University of Delaware]

CLIMATE AND SOCIETY

Impact of current drought felt far and wide -- The current drought that has affected at least 40 states during this summer has created a crisis that extends well beyond farmers and ranchers of these states. Outdoor activities, commercial transportation and wildlife also have been impacted by the drought, in numerous ways. [CNN News]
Data gap could be filled in predicting historical air pollution exposure -- A researcher at Tufts University who analyzed relationships between air quality and unemployment levels has developed a new statistical model that can estimate air pollution exposure for previous time periods where such information is not available. She based her analysis on traffic-related air pollution levels and unemployment in four regions in California between 1980 and 2000. In addition, the study showed that air quality improved when unemployment rose. [Tufts University]
Website for human dimensions of climate change -- An interagency effort within the US federal government that included NOAA, the Bureau of Land Management and the US Forest Service, has resulted in a website called HD.gov (for HumanDimensions.gov) that provides users, such as natural resource managers, with information on the human dimensions on a variety of topics of interest such as climate change. [HD.gov]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

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

17 September 1829...The Siebold Typhoon, Japan's most catastrophic typhoon, inflicted widespread damage over much of Japan. On the southern island of Kyushu, the storm surge off the Ariake Sea kills 10,000. (The Weather Doctor)
17 September 1932...Westerly, RI received 12.13 inches of rain, which set a 24-hour precipitation record for the state. (NCDC)
17 September 1963...Nearly 2.5 inches of rain fell in 24 hours, the most intense rain for Yuma, AZ during the period between 1909 and 1977. (The Weather Doctor)
18 September 1991...2.4 inches of snow fell at Duluth, MN to set a new record for September. (Intellicast)
19 September 2004...The single-day rainfall record at Vancouver (British Columbia) International Airport was set 3.59 inches. The accumulation came in a month when rainfall is exceptional across the region. By mid-month, dozens of stations in British Columbia broke all-time September rainfall totals. (The Weather Doctor)
20-23 September 1942...A rainstorm deluged the Maritime Provinces. Four-day totals included 13.99 inches at Stellarton, Nova Scotia and 10.83 inches at Charlottetown, Prince Edward Island. Halifax, Nova Scotia recorded 9.40 inches of rain on the 21 September climatological day. (The Weather Doctor)
20 September 1967...Hurricane Beulah moved into South Texas, spawning a record 115 tornadoes for a hurricane. (David Ludlum) (Intellicast)
20 September 1973...Britain's greatest September daily rainfall floods Kent with 7.51 inches of rain. (The Weather Doctor)
22 September 1913...Des Moines, IA experienced their earliest freeze of record. (The Weather Channel)
22 September 1934...Edmonton, Alberta reported its greatest September snowstorm to date with 8.7 inches of snow. (The Weather Doctor).
23 September 1904...The temperature at Charlotteburg, NJ dipped to 23 degrees, the lowest reading of record for so early in the autumn for the state. (The Weather Channel)

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