A Comparison of the Brightness Temperatures and Water Vapor Path Delays Measured by the TOPEX,ERS-1,andERS-2Microwave Radiometers

Cross-Calibration and Long-Term Monitoring of the Microwave Radiometers of ERS, TOPEX, GFO, Jason, and Envisat

“…Stum (1998) first showed that the mean TOPEX-ERS-1 Downloaded by [University of Chicago Library] at 11:27 10 October 2014 wet tropospheric path delay difference was decreasing at a rate of about 1 mm/year. Ruf (2000) then detected a drift of 0.27 K/year in the calibration of the 18 GHz brightness temperatures, which translates directly to a decrease of path delay (and hence of apparent global sea level rise) by about 1.2 mm/year.…”

Combining all flying microwave radiometers to compute the water vapor path delay for altimeter missions

“…Table 2 gives for each cycle the ratio of the number of altimeter points with an OA-derived PD, relative to the number of altimeter points with a valid JMR PD, in percent. One factor explaining the disparity of the percentages is the difference in phasing of the sun-synchronous sensor orbits with the non sun-synchronous Jason-1 orbit ( [3], [4]). Some cycles have a more than 100% percentage, because altimeter points where JMR PD is locally not valid (e.g., due to rain contamination) are filled in with OA PD (which considers radiometer measurements around).…”

A GPS and Cold Ocean Brightness Temperature Calibration of the ERS-2 and TOPEX/Poseidon Microwave Radiometers

“…Subsequent studies using an upward looking water radiometer at Platform Harvest (Kubitschek et al 1997) by comparison with GPS derived wet path delays (Haines and Bar-Sever 1998) confirmed that the TMR was the source. A comparison of TOPEX and ERS-2 wet tropospheric path delay (Stum 1998) also revealed a divergence between the microwave radiometers close to 1 mm/yr. Detailed investigations into the TMR using the coldest brightness temperatures (Ruf 2000) and by comparison to the Special Sensor Microwave Imager (SSM/I) and radiosonde measurements (Keihm et al 2000) confirmed a drift in the 18 GHz channel as the source which translated into a path delay of about 1.2 mm/yr.…”