Atmospheric News
WMO Retires Five Hurricane Names
The World Meteorological Organization has permanently withdrawn the names Dennis, Katrina, Rita, Stan and Wilma from the alphabetical list of tropical storms for the Atlantic Basin. The WMO said 2005 hurricanes with these names caused serious loss of life and damage, and their names were removed from the list as a mark of respect for the victims.
Tropical storm name Dennis will be replaced with Don; Katrina with Katia; Rita with Rina; Stan with Sean and Wilma with Whitney. The replacements will be added to the list for 2011 (lists rotate every six years). The 2005 hurricane season saw a record 27 named storms including 15 hurricanes. Retirement of five names for a single season is unprecedented; four were removed in 2004, 1995 and 1955.
Names selected must be short, readily understood when broadcast and culturally sensitive to reflect the mix of English, French and Spanish cultures throughout the 24 countries in the Atlantic Basin, which incudes the Caribbean Sea and the Gulf of Mexico.
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U.S. Climate Change Report Reconciles Temperature Trends
The U.S. Climate Change Science Program issued a report on 2 May saying there is no longer a discrepancy in the rate of global average temperature increase for the surface compared with higher levels in the atmosphere.
This discrepancy had previously been used to challenge the validity of climate models used to detect and attribute the causes of observed climate change. This is an important revision to and update of the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change.
The report is the first of 21 Synthesis and Assessment S&A Products May with findings that improve understanding of climate change and human influences on temperature trends.
“Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences,” also referred to as S&A Product 1.1, tackles some of the long-standing difficulties that have impeded understanding of changes in atmospheric temperatures and the basic causes of these changes.
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“This synthesis and assessment report exposes the remaining differences among different observing systems and data sets related to recent changes in tropospheric and stratospheric temperature,” said Chief Editor Dr. Thomas Karl, director of NOAA’s National Climatic Data Center. “Discrepancies between the data sets and the models have been reduced and our understanding of observed climate changes and their causes have increased. The evidence continues to support a substantial human impact on global temperature increases. This should constitute a valuable source of information to policymakers.”
The U.S. Climate Change Science Program says S&A Product 1.1 corrects errors that have been identified in the satellite data and other temperature observations. These and other analyses have increased confidence in the understanding of observed climatic changes and their causes. The published report also states that research to detect climate change and attribute its causes using patterns of observed temperature change in space and time shows clear evidence of human influences on the climate system due to changes in greenhouse gases, aerosols, and stratospheric ozone. Also, the observed patterns of change over the past 50 years cannot be explained by natural processes alone, nor by the effects of short-lived atmospheric constituents such as aerosols and tropospheric ozone alone.
The previously reported discrepancy between surface and atmospheric temperature trends is no longer apparent on a global scale. These trends are consistent with climate model simulations. One issue does remain however, and that is related to the rates of warming in the tropics. Here, models and theory predict an amplification of surface warming higher in the atmosphere. However, this greater warming aloft is not evident in three of the five observational data sets used in the report. Whether this is a result of uncertainties in the observed data, flaws in climate models, or a combination of these is not yet known. Using the evidence available, the author team favors the first explanation.
The report can be found online at http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm
For more information on the U.S. Climate Change Science Program see: http://www.climatescience.gov
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UCAR Researchers Pin Slowdown in Tropical Pacific Flow on Climate Change
The vast loop of winds that drives climate and ocean behavior across the tropical Pacific has weakened by 3.5% since the mid-1800s, and it may weaken another 10% by 2100, according to a study led by University Corporation for Atmospheric Research (UCAR) scientist Gabriel Vecchi.
In their paper, "Weakening of Tropical Pacific Atmospheric Circulation Due to Anthropogenic Forcing," the authors used observations as well as state-of-the-art computer climate model simulations to verify the slowdown and determine whether the cause is human-induced climate change.
The study concludes that human-induced climate change is the only plausible explanation for the slowdown. . The findings appeared in the May 4 issue of Nature. The work was performed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL), where Vecchi is stationed through the UCAR Visiting Scientist Programs. His coauthors include Brian Soden (University of Miami) and the GFDL team of Andrew Wittenberg, Isaac Held, Ants Leetmaa, and Matthew Harrison.
The Walker circulation, which spans almost half the circumference of Earth, pushes the Pacific Ocean's trade winds from east to west, generates massive rains near Indonesia, and nourishes marine life across the equatorial Pacific and off the South American coast. Changes in the circulation, which varies in tandem with El Niño and La Niña events, can have far–reaching effects.
The Walker circulation is a loop with rising air in the western tropical Pacific, sinking air in the eastern tropical Pacific, west-to-east winds a few miles high, and east-to-west trade winds at the surface. The trade winds also steer ocean currents. Any drop in winds produces an even larger reduction in wind-forced ocean flow—roughly twice as much in percentage terms for both the observed and projected changes, says Vecchi.
Based on observations since the mid-1800s, the paper reports a 3.5% slowdown in the Walker circulation, which corresponds closely to the number predicted by theory. To establish whether human-induced climate change is at work, the authors analyzed 11 simulations using the latest version of the GFDL climate model spanning the period 1861 to 2000. Some of the simulations included the observed increase in greenhouse gases; others included just the natural climate-altering factors of volcanic eruptions and solar variations. Only the simulations that included an increase in greenhouse gases showed the Walker circulation slowing, and they did so at a rate consistent with the observations.
or more see http://www.ucar.edu/news/releases/2006/walker.shtml
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NOAA Issues Greenhouse Gas Index
NOAA’s Annual Greenhouse Gas Index (AGGI), issued on 1 May, reflects an increase in carbon dioxide (CO2) and nitrous oxide (N2O) but a leveling off of methane (CH4), and a decline in two chlorofluorocarbons (CFCs), gases that contribute to the Antarctic ozone hole.
Overall, the agency’s benchmark measurement of tmospheric gases that affect the Earth’s climate shows a continuing, steady rise in the amount of heat-trapping gases. .
The AGGI is referenced to a baseline value of 1.00 for the greenhouse gas levels that were present in the atmosphere in 1990. The value of the AGGI for 2005 is 1.215, reflecting a continuing upward trend in the accumulation of greenhouse gases, as well as the change in the amount of radiative forcing. Radiative forcing refers to the balance between radiation coming into the atmosphere and radiation going out. Positive radiative forcing tends on average to warm the surface of the Earth, and negative forcing tends on average to cool the surface. Radiative forcing, as measured by the index, is calculated from the atmospheric concentration of each contributing gas and the per-molecule climate forcing of each gas.
NOAA says CO2 is causing most of the increase in radiative forcing measured since 1990. CO2 forcing now accounts for approximately 62 percent of the radiative forcing by all long-lived greenhouse gases. During 2005, global CO2 increased from an average of 376.8 parts per million (ppm) in 2004 to 378.9 ppm. This increase of 2.1 ppm means that for every one million air molecules there were slightly more than two new CO2 molecules in the atmosphere. The pre-industrial CO2 level was approximately 278 ppm.
The AGGI is based on the analyses of atmospheric levels of all the major and minor long-lived greenhouse gases, and factors in the relative strengths of each gas in its ability to trap heat. The gases include carbon dioxide, methane, nitrous oxide, CFCs and the current replacements for CFCs, and have been measured since 1979 by NOAA’s global sampling network.
Atmospheric greenhouse gas levels change from year to year depending on natural and human-influenced processes. The largest annual increase in the AGGI, 2.8 percent, occurred between 1987 and 1988. The smallest was .81 percent from 1992 to 1993. While the index has increased in every year since NOAA’s global measurements began in 1979, the increase during 2005 was 1.25 percent.
For details see the Global Monitoring Division (Formerly CMDL): http://www.cmdl.noaa.gov/aggi/
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Two New Satellites for Weather, Climate, Air-Quality Studies Launched
NASA launched two satellites 28 April 2006 from Vandenberg Air Force Base, Calif., on missions to reveal the secrets of clouds and aerosols, tiny particles suspended in the air.
CloudSat and CALIPSO -- Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations --thundered skyward at 6:02 a.m. EDT atop a Boeing Delta II rocket. The two satellites will eventually circle approximately 438 miles above Earth in a sun-synchronous polar orbit, which means they will always cross the equator at the same local time. Their technologies will enable scientists to study how clouds and aerosols form, evolve and interact.
Each spacecraft will transmit pulses of energy and measure the portion of the pulses scattered back to the satellite. CloudSat's Cloud-Profiling Radar is more than 1,000 times more sensitive than typical weather radar. It can detect clouds and distinguish between cloud particles and precipitation. CALIPSO's polarization lidar can detect aerosol particles and distinguish between aerosol and cloud particles. Lidar, similar in principle to radar, uses reflected light to determine the characteristics of the target area.
Sixty-two minutes after liftoff, CALIPSO separated from the rocket's second stage. CloudSat followed 35 minutes later. Ground controllers successfully acquired signals from both spacecraft, and initial telemetry reports show both in excellent health. Over the next six weeks, system and instrument checks will be performed, and the satellites will maneuver into their final orbits.
For more information about CloudSat and CALIPSO, visit:
http://www.nasa.gov/cloudsat and http://www.nasa.gov/calipso
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NOAA Finds Area Where Hurricanes Develop is Warmer
The region of the tropical Atlantic where many hurricanes originate has warmed by several tenths of a degree Celsius over the 20th century, and new climate model simulations suggest that human activity, such as increasing greenhouse gas emissions into the atmosphere, may contribute significantly to this warming, according to new research from NOAA. This new finding is one of several conclusions reported in a study by scientists at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J., published in the 1 May issue of the Society’s Journal of Climate.
The region, which extends from 10°N to 20°N in the area of the Cape Verde Islands, has been identified as the origin for a large portion of major hurricanes in the tropical North Atlantic, and is known as the "Main Development Region." Ocean surface temperatures in this region warmed over the 20th century, roughly tracking the global mean, or average, but this region has greater multi-decadal variability than the global mean does when looking at long-term trends.
The climate model simulations are based on a new state-of-the-art coupled atmosphere-ocean model developed over several years at GFDL. The new simulations include improved representations of a number of environmental factors that can affect climate, such as greenhouse gases, volcanic eruptions, solar variability, land-use changes and atmospheric aerosols, very fine particulate matter in the air. More research is being conducted to improve the representation of these forcings, and of the aerosol effects in particular.
The new model simulations used current best estimates of a number of historical climate forcings to simulate climate variations over the 20th century. In the Main Development Region, the observed warming during the 20th century is simulated much more realistically in the models that include anthropogenic forcing than in models with only natural effects.
The results suggest that the century-scale warming tendency in the Main Development Region may have been caused largely by anthropogenic forcing, including increases in atmospheric greenhouse gas concentrations.
The causes of Atlantic hurricane variability is the subject of intensive scientific investigations. Earlier studies suggest that warmer tropical sea surface temperatures can lead to hurricanes of greater intensity. Other studies at NOAA have concluded that warmer sea surfaces are one of several important factors affecting Atlantic hurricane activity. Ongoing research continues to address uncertainties in the observed trend, past climate forcing estimates, internal variability and climate sensitivity.
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Thomas J. Bogdan Named Director of NOAA Space Environment Center
The National Oceanic and Atmospheric Administration has named Thomas J. Bogdan, Ph.D, as the director of the Space Environment Center. SEC's new director comes to NOAA after eight years as the senior scientist at the National Center for Atmospheric Research. He also brings vast knowledge of space plasma physics and experience as a senior science program leader at the National Science Foundation. Additionally he was the designated leader of the inauguration of the societal impacts laboratory at NCAR.
Bogdan earned his Ph.D. (1984) and M.S. (1981) degrees in Physics at the University of Chicago and his B.S. (1979) degree at the State University of New York at Buffalo.
The SEC is located in Boulder, Colo. Bogdan will begin his new assignment in May. For more on the Space Environment Center see http://www.sec.noaa.gov
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AccuWeather, Inc. Acquires WeatherData, Inc.
AccuWeather, Inc. has completed the purchase of WeatherData, Inc. WeatherData specializes in weather-risk management consulting and severe weather forecasting and services to utility, transportation, manufacturing, educational and governmental clients throughout the U.S., Canada and Mexico. The company holds significant patents for weather forecasting technology. For more information on the acquisition and both companies see www.accuweather.com
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