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High Lapse Rates in AIRS Retrieved Temperatures in Cold Air OutbreaksThe Atmospheric Infrared Sounder (AIRS) experiment, on NASA's Aqua spacecraft, uses a combination of infrared and microwave observations to retrieve cloud and surface properties, plus temperature and water vapor profiles comparable to radiosondes throughout the troposphere, for cloud cover up to 70%. The high spectral resolution of AIRS provides sensitivity to important information about the near-surface atmosphere and underlying surface. A preliminary analysis of AIRS temperature retrievals taken during January 2003 reveals extensive areas of superadiabatic lapse rates in the lowest kilometer of the atmosphere. These areas are found predominantly east of North America over the Gulf Stream, and, off East Asia over the Kuroshio Current. Accompanying the high lapse rates are low air temperatures, large sea-air temperature differences, and low relative humidities. Imagery from a Visible / Near Infrared instrument on the AIRS experiment shows accompanying clouds. These lines of evidence all point to shallow convection in the bottom layer of a cold air mass overlying warm water, with overturning driven by heat flow from ocean to atmosphere. An examination of operational radiosondes at six coastal stations in Japan shows AIRS to be oversensitive to lower tropospheric lapse rates due to systematically warm near-surface air temperatures. The bias in near-surface air temperature is seen to be independent of sea surface temperature, however. AIRS is therefore sensitive to air-sea temperature difference, but with a warm atmospheric bias. A regression fit to radiosondes is used to correct AIRS near-surface retrieved temperatures, and thereby obtain an estimate of the true atmosphere-ocean thermal contrast in five subtropical regions across the north Pacific. Moving eastward, we show a systematic shift in this air-sea temperature differences toward more isothermal conditions. These results, while preliminary, have implications for our understanding of heat flow from ocean to atmosphere. We anticipate future improvements in the AIRS retrieval algorithm will lead to improved understanding of the exchange of sensible and latent heat from ocean to atmosphere, and more realistic near-surface lapse rates.
Document ID
20070023751
Acquisition Source
Jet Propulsion Laboratory
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Fetzer, Eric J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Kahn, Brian
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Olsen, Edward T.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Fishbein, Evan
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 23, 2013
Publication Date
August 9, 2004
Subject Category
Earth Resources And Remote Sensing
Meeting Information
Meeting: 13th Conference on Interactions of the Sea and Atmosphere
Location: Portland, ME
Country: United States
Start Date: August 9, 2004
End Date: August 13, 2004
Sponsors: American Meteorological Society
Distribution Limits
Public
Copyright
Other
Keywords
cold air outbreak
Atmospheric Infrared Sounder (AIRS)
remote sounding
meteorology
atmosphere-oean temperature

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