The content of the ARM website is available to any browser, but for the best experience we highly recommend you upgrade to a standards-compliant browser such as Firefox, Opera or Safari.
VIEW CART
primary link menu HOME SITE INDEX PEOPLE
skip to main content ABOUT ARMABOUT ACRFSCIENCESITESINSTRUMENTSMEASUREMENTSDATAPUBLICATIONSEDUCATIONFORMS
Cover image

AERI Observations in the Arctic: Monthly-Average Radiance Spectra and Longwave Cloud Radiative Forcing

Walden, V.P., Revercomb, H.E., Knuteson, R.O., Best, F.A., Ciganovich, N., Dedecker, R.G., Dirkx, T., Garcia, R.K., Herbsleb, R., Howell, H.B., McRae, D., Short, J., and Tobin, D., Cooperative Institute of Mesoscale Meteorological Studies/Space Science and Engineering Center/University of Wisconsin
Ninth Atmospheric Radiation Measurement (ARM) Science Team Meeting

Atmospheric Emitted Radiance Interferometers (AERIs) were operated at the Surface Heat Budget of the Arctic Ocean (SHEBA) Ice Camp from November 1997 until June 1998 and at the North Slope of Alaska/Adjacent Arctic Ocean (NSA/AAO) Atmospheric Radiation Measurement (ARM) site at Point Barrow, Alaska, beginning in February 1998. Both instruments operated during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment-Aerosol Characterization Experiment (FIRE-ACE). The spectral range of these instruments is 400 to 3000 cm-1 with a spectral resolution of 0.5 cm-1. The monthly average radiance spectra for clear-, cloudy- and all-sky conditions are determined using downwelling longwave radiance data from both AERIs. The spectral longwave cloud forcing at the surface is estimated by subtracting the average clear-sky net flux from the average all-sky net flux. The variability of the downwelling radiance is investigated by examining the transparent portion of the longwave spectrum, which gives insight into how clouds affect the surface radiation budget. The longwave cloud forcing is small in winter (10 Wm-2) and reaches values of 50 to 60 Wm-2 in summer. The most important spectral region for longwave cloud forcing is the 11-µm window region. The water vapor rotational band contributes significantly to the forcing in the autumn, winter and spring, but not in summer when emission from the water vapor continuum is large. The 9-µm window region contributes significantly to the longwave forcing in summer.

Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).