Progress report of FY 1999 activities: Continued development of an integrated sounding system in support of the DOE/ARM experimental program

• Main Authors: Westwater, Edgeworth R., Han, Yong, Leuskiy, Vladimir
• Other Authors: United States. Department of Energy.
• Format: Report
• Language: English
• Published: United States. National Oceanic and Atmospheric Administration. 1999
• Subjects: Calibration; Water Vapor; Wavelengths; Brightness; Radiometers; Clouds; Solar Radiation; Sensitivity; Arctic Ocean; 54 Environmental Sciences; Algorithms; Arctic; Barrow; north slope; Alaska
• Online Access: https://doi.org/10.2172/762788; https://digital.library.unt.edu/ark:/67531/metadc717046/

Both during September 15-30, 1996 and September 15-October 5, 1997, the Environmental Technology Laboratory (ETL) participated in experiments at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site that was designed to study many of the ways that ARM is measuring water vapor. Because of some inconsistencies between ETL and ARM Microwave radiometers (MWR) during these experiments, called the Water Vapor Intensive Operating Periods (WVIOPs), we applied to both sets of data a newly developed correction algorithm for tipping curve calibration. We found that this algorithm reduces the differences between the radiometers, there are still some unexplained features of scanning ARM MWR data. Measurements of water vapor at the North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) CART site in Barrow, Alaska, area potential problem because of the difficulty of radiosondes to measure low amounts of vapor during cold and extremely dry conditions. The applicability of MWR scaling to radiosondes is questionable because of the low sensitivity of these instrument during dry conditions. It has been suggested by the ARM Instantaneous Radiative Flux Working Group and others that measurements of brightness temperature around 183 GHz could be used to scale radiosondes during the coldest and driest periods. However, the millimeter wavelengths are vulnerable to cloud effects from both liquid and ice. During March 1999, we participated in the joint NASA/NOAA Millimeter wave Arctic Experiment to evaluate microwave and millimeter wave radiometers during extremely cold conditions. ETL tested, both in an experiment at the Boulder Atmospheric Observatory and during the two Water Vapor Intensive Operating Periods in 1996 and 1997, a 5-mm scanning radiometer that measures low-altitude temperature profiles; both profiles of lapse rate and absolute temperature can be measured with the instrument. Results of these tests were published in the open literature. In addition, the ETL scanning radiometer was operated at the NSA/AAO in March 1999.