Progress report of FY 1998 activities: Continued development of an integrated sounding system in support of the DOE/ARM experimental program
Description: Both during September 15-30, 1996 and September 15-October 5, 1997, the Environmental Technology Laboratory (ETL) participated in an experiment 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. These experiments, called the Water Vapor Intensive Operating Periods (WVIOPs), produced some results of significant importance to ARM water vapor measurements. We have spent the major portion of this years activities in analyzing results of these experiments, and improving algorithms for improving the measurement of precipitable water vapor (PWV) from instruments available at ARM. The most important ARM instrument for this measurement continues to be the Microwave Radiometer (MWR). 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 during the coldest and driest periods. However, the millimeter wavelengths are vulnerable to cloud effects from both liquid and ice. We have participated in the planning and will participate in the Millimeter wave Arctic Experiment that will evaluate microwave and millimeter wave radiometers during extremely cold conditions. ETL has 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. The technique ...
Date: September 6, 1998
Creator: Westwater, Edgeworth R.; Han, Yong & Leuskiy, Vladimir
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