DataStreme ECS WEEK THREE: 19-23 September 2011

• The Autumnal Equinox -- The Autumnal Equinox will occur early this Friday morning (officially at 0905Z, 23 September 2011 or 5:05 AM EDT or 4:05 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 Thursday, 22 December 2011.
  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.
• Free admission into the National Parks -- This coming Saturday, 24 September 2011, has been designated by the National Park Service as a fee free day in honor of National Public Lands Day. In addition, Worldwide Day of Play will be observed in Washington, DC. This fee waiver will cover entrance and commercial tour fees in many of the national parks and monuments administered by the Park Service. [National Park Service Fee Free Days]
• Coral expert wins a prestigious award-- During this past week, Joan Kleypas, a marine ecologist and geologist at the National Center for Atmospheric Research was named a recipient of the prestigious Heinz Award for her pioneering research into the effects of climate change on coral reefs. [UCAR/NCAR News]

• Review of August and boreal summer 2011 global temperatures -- Preliminary data analyzed by scientists at NOAA's National Climatic Data Center indicated that the global combined land and ocean average surface temperature for August 2011 was nearly one Fahrenheit degree above the 20th-century average for the month. Last month's global average temperature tied for the eighth highest August monthly temperature since global temperature records began in 1880. When considered separately, the monthly temperature of the land surface for this recently concluded month was the second highest August temperature on record, while the ocean temperature for the month was the twelfth highest. The researchers also noted that the global land and ocean average temperature for the three-months of June, July and August (meteorological summer in the Northern Hemisphere) was the seventh highest for that three-month period since 1880. [NOAA News]
• Summer's Arctic sea ice extent reaches a minimum -- Researchers at the University of Colorado at Boulder's National Snow and Ice Data Center report that as of mid September, the extent of Arctic sea ice appears to have reached a minimum for the 2011 summer season. According to the researchers, last week's areal extent of the Arctic sea ice represents the second smallest since routine satellite surveillance commenced in 1979. [University of Colorado] Data and graphs are available. [National Snow and Ice Data Center]
• August drought report -- The National Climate Data Center has posted its August 2011 drought report online. Using the Palmer Drought Severity Index, approximately 26 percent of the coterminous United States experienced severe to extreme drought conditions at the end of August, while 29 percent of the area had severely to extremely wet conditions.

• Preparation made for multi-year airborne investigation of hurricanes -- A group of scientists are at NASA's Dryden Flight Research Center preparing the agency's Global Hawk remotely operated unmanned aircraft for NASA's Hurricane and Severe Storm Sentinel (HS3) investigation that will commence next year. This multi-year study will collect weather data collected by instruments onboard the Global Hawk to determine the processes underlying hurricane formation and intensity change over the Atlantic Ocean basin. [NASA Dryden Flight Research Center]
• 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]

• Increased evaporation from trees could cool global climate -- Researchers from the Carnegie Institution and their colleagues have found that water evaporated from vegetation would help cool the entire atmosphere and the planet on a global basis, not just in the local area where the evaporation took place. In addition to the evaporative cooling at the surface, the increased water vapor in the atmosphere could cause the formation of low clouds that would serve as a sunscreen. The researchers feel that their findings have major implications for land-use decision making. [Carnegie Institution for Science]

• Classic origins of life experiment revisited -- Using modern techniques, a team of scientists including those from the Carnegie Institution's Geophysical Laboratory have been analyzing samples that have been recently from the classic series of experiments performed by Stanley Miller in the 1950s that initially demonstrated that organic compounds could be created in an environment similar to primordial Earth. The new findings indicate the possible importance of volcanoes and sulfur in the formation of amino acids, and possibly life, on Earth. [Carnegie Institution for Science]
• Plants create a water reserve in the soil -- Scientists from Germany's Helmholtz Centre for Environmental Research, the University of Potsdam and the University of Göttingen and the University of California Davis have performed experiments that indicates that a zone of higher water concentration exists around the roots of a plant, a finding that is contrary to earlier belief. This water reserve around the plant roots may help the plants survive through short periods of drought. [Helmholtz Centre for Environmental Research]

• Three-month seasonal climate outlook for the nation issued -- Last week, forecasters with NOAA's Climate Prediction Center issued their outlooks for temperature and precipitation across United States for the three months of October through December 2011. This span covers the last two months of meteorological autumn in the Northern Hemisphere (October and November) and the first month of boreal winter (December). The temperature outlook indicates that a large section of the nation extending from the southern Plains and southern Rockies northeastward into the western Great Lakes would have a better than even chance of experiencing higher than normal temperatures. On the other hand, southern sections of the Florida Peninsula could expect a good chance of below average temperatures. Elsewhere, the outlook for sections of the Northwest and the East Coast does not appear to have a strong signal, resulting in an outlook that calls for equal chances of above or below average fall temperatures.
  The precipitation outlook for Fall and early winter 2011 indicates that the Southwest, centered on the Four Corners region (Arizona, Utah, Colorado and New Mexico), the southern Plains, the mid-South and sections of the Southeast would have a better than even chance of below average precipitation for these three-months. The forecasters anticipate that the Pacific Northwest would have a good chance of above average fall/early winter rainfall. Elsewhere, the outlook called for equal chances of above or below average precipitation. [NOAA Climate Prediction Center]
• National seasonal drought outlook issued -- The forecasters with NOAA's Climate Prediction Center also issued their US Seasonal Drought Outlook that would run from late August through November 2011, covering meteorological autumn. These forecasters foresee that the current drought conditions across the southern tier of states, extending from Arizona eastward to Georgia and South Carolina, along with scattered sections of the Midwest, should persist or expand. However, improvement in the current drought conditions was anticipated across the Piedmont and coastal areas of North Carolina. [NOAA Climate Prediction Center]

• Indigenous Alaskans observe effects of climate change --- US Geological Survey scientists recently conducted personal interviews with Alaska natives in the 49th State's Yukon River Basin that provided unique insights on how these peoples viewed climate change and its impacts upon their Arctic and sub-Arctic environment. The hope is that these interviews will help in developing adaptation strategies for these local communities. [USGS Newsroom]
• Evaluation of human influences on wildfires is developed -- An international team of researchers has produced a new framework for evaluating human influences on wildfires based on the Earth's pre-human fire history, along with ways that humans have used and managed fire. This effort also involves planning for future risks from wildfires. [NSF News]
• Europeans foresee major threats due to changing marine environments -- Last week, Project CLAMER (Climate Change and European Marine Ecosystem Research) released the results of a public poll and a compilation of academic papers at summary conference in Brussels, Belgium. The poll indicates that Europeans are concerned about sea-level rise and coastal erosion because changing climate. Ultimately, they will face greater risk of illness, property damage and job losses because of the climate-induced changes on the surrounding oceans. Research by scientists at 17 European marine institutes is concerned with the physical, chemical and biological marine changes that could occur. [EurekAlert!]
• 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.

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).

1. 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.
2. 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.

• 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)
• 24 September 1888...The earliest frost of record hit the southern states covering South Carolina, Georgia and northern Florida (Intellicast)
• 24 September 1926...The temperature at Riverside Ranger Station in Yellowstone Park dipped to nine degrees below zero, the lowest reading of record in the U.S. during September. (This record was broken by a 15 degree below zero reading at Big Piney, WY in September 1983.) Severe freezes were widespread over the northwestern U.S. causing great crop destruction. In Washington State, Spokane County experienced their earliest snow of record. Harney Branch Experiment Station in Oregon reported a temperature of 2 degrees above zero to establish a state record for the month of September. (David Ludlum) (The Weather Channel)
• 24-26 September 1950...A smoke pall from western Canada forest fires covered much of the eastern U.S. Daylight was reduced to nighttime darkness in parts of the Northeast. The color of the sun varied from pink to purple, blue, or lavender. Yellow to gray-tan was common. (24th-30th) On the 26th, residents of the northeastern U.S. observed a blue sun and a blue moon from the smoke. (David Ludlum) (The Weather Channel)
• 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)

Return to DataStreme Earth Climate Systems Homepage

Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2011, The American Meteorological Society.