Validation of GOES-R Total Precipitable Water (TPW) Using GPS derived TPW

Seth. I. Gutman1, Daniel.L.Birkenheuer1, Chris Barnet2

Jaime Daniels2, M.K. Rama Varma Raja3, Timothy J. Schmit4 and James G. Yoe2

1 NOAA Earth System Research Laboratory, 325 Broadway R/GSD, Boulder, CO 80305-3328

2 NOAA/NESDIS/ORA, NOAA Science Center, 5200 Auth Road, Camp Springs, MD-20746-4304

3 I. M. Systems Group, Inc., 3401 Blexhill Place, Kensington, MD 20895

4 NOAA/NESDIS Satellite Applications and Research, 1225 West Dayton Street, Madison, WI 53706

Abstract

The data and products from GOES-R will be used in conjunction with next generation surface, air and space-based observing systems to play a critical role in NOAA’s weather and water, climate, commerce and transportation, and ecosystems missions. To insure the highest data quality, especially for numerical weather prediction (NWP) and climate applications, techniques to monitor the instruments, detect problems, and take corrective actions in near real-time must be developed and implemented. Based on preliminary studies conducted by the authors, we propose the use of surface-based Global Positioning System (GPS) receivers as part of the system to continuously monitoring total precipitable water (TPW) under all weather conditions as an effective and low cost way to monitor and assess GOES-R Hyperspectral Environmental Suite (HES) long-term sensor performance and retrieval accuracy. The strategy would be to form coincident pairs of GOES-R HES and GPS TPW observations within prescribed space and time windows over CONUS. Currently a network of about 400 GPS receivers, providing TPW measurements every 30 minutes for NWP and regional forecasting applications, is available to do this. Through international cooperation in the hemisphere, the network can be expanded to cover most of North America. The temporal resolution of GPS total water vapor measurements combined with the large number of GPS receivers and the spatial and temporal resolution of the GOES-R observations allow us to form a large number of coincident GOES-R HES-GPS TPW pairs. The robust statistical comparison of GOES-R HES and GPS TPW pairs can be used to validate the GOES-R HES water vapor data and retrieval process. Experience in using GPS to validate AIRS water vapor data indicates that GPS is also sufficiently accurate (1 mm RMS) to act as an independent check on satellite water vapor channel radiances and derivatives. In addition, GPS water vapor products will be used to complement other GOES-R water vapor validation studies, including those based on match-ups to radiosonde, microwave water vapor radiometer, and lidar data.