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. …