Microwave and Millimeter-Wave Radiometric and Radiosonde Observations in an Arctic Environment

Westwater, E. R., University of Colorado

Radiation Processes

Radiative Processes

Mattioli V, ER Westwater, D Cimini, AJ Gasiewski, M Klein, and V Leuski. 2008. "Microwave and Millimeter-Wave Radiometric and Radiosonde Observations in an Arctic Environment." Journal of Atmospheric and Oceanic Technology, 25(10), 10.1175/2008jtecha1078.1.

Mattioli V, ER Westwater, D Cimini, J Liljegren, BM Lesht, SI Gutman, and FJ Schmidlin. 2007. "Analysis of Radiosonde and Ground-Based Remotely Sensed PWV Data from the 2004 North Slope of Alaska Arctic Winter Radiometric Experiment." Journal of Atmospheric and Oceanic Technology, 24(3), 10.1175/jtech1982.1.


Scatterplots of differences between calculations and MWRP measurements at (A) 22.235 GHz, and (B) 23.835 GHz.


Scatterplots of differences between calculations and GSR measurements at 183.31 ± 1 GHz. All statistical quantities refer to calculated – measured. Avg, std, int, and sde are in Kelvin (K).


Scatterplots of differences between calculations and MWRP measurements at (A) 22.235 GHz, and (B) 23.835 GHz.

Scatterplots of differences between calculations and GSR measurements at 183.31 ± 1 GHz. All statistical quantities refer to calculated – measured. Avg, std, int, and sde are in Kelvin (K).

In a recent paper by Mattioli et al. (2007), a significant difference was observed between upper tropospheric-lower stratospheric water vapor profiles as observed by two radiosonde systems operating in the Arctic. The first was the Vaisala RS90 system operated by the Department of Energy’s Atmospheric Radiation Measurement Program; the second was the operational radiosondes launched by the U. S. National Weather Service (NWS) that used the Sippican VIZ-B2 type. Observations of precipitable water vapor by ground-based microwave radiometers and a global positioning unit (GPS) did not reveal these differences. However, both the Microwave Radiometer Profiler (MWRP) and the Ground-based Scanning Radiometer (GSR) contain channels that receive a significant response from the upper tropospheric region. In our new paper (Mattioli et al., 2008), it is shown that brightness temperature (Tb) observations from these instruments are in consistent agreement with calculations based on the RS90 data, but differ by several degrees with calculations based on the VIZ radiosondes. It is also shown that calculations of Tb can serve as a gross quality control of upper tropospheric soundings.

This paper confirms, using remote sensing data of the ARM Climate Research Facility (ACRF) Microwave Radiometer Profiler (MWRP) and the University of Colorado's Ground-based Scanning Radiometer (GSR), that the National Oceanic and Atmospheric Administration (NOAA) NWS radiosonde soundings of upper tropospheric-lower stratospheric water vapor are incorrect. It also is demonstrated that observations of brightness temperature, using either the MWRP or the GSR, can identify the spurious radiosonde soundings.

The ARM radiosonde observations at the North Slope of Alaska (NSA) are now taken twice-daily at times 6 hours different from the synoptic soundings of the NWS at Barrow. Because of problems with the NWS humidity soundings, attempts to use combined NWS-ARM radiosonde data to study 24-hr humidity cycles would be problematic. Furthermore, any use of the NWS data to validate satellite humidity soundings or RTE models, would be incorrect. It would be advantageous, both to ARM and to the meteorological community at large, if the NWS VIZ humidity elements were replaced by the much more accurate Vaisala RS92 humidity sensors.