Ocean water vapor and cloud liquid water trends from 1992 to 2005 TOPEX Microwave Radiometer data

The continuous 1992–2005 data set of the TOPEX Microwave Radiometer (TMR) has been reprocessed to provide global, zonal, and regional scale histories of overocean integrated water vapor (IWV) and cloud liquid water (CLW). Results indicate well-defined trends in IWV on global and hemisphere scales, with values of 1.8 ± 0.4%/decade (60°S–60°N), 2.4 ± 0.4%/decade (0–60°N), and 1.0 ± 0.5%/decade (0–60°S). The uncertainties represent 1 standard deviation of the regressed slope parameter adjusted for lag 1 autocorrelation. These results are comparable to earlier results based on analyses of the multiinstrument SSM/I ocean measurements beginning in 1988. For the 1992–2005 interval, comparisons between SSM/I- and TMR-derived IWV trends show remarkable agreement, with global trends differing by less than 0.3%/decade, comparable to the statistical uncertainty level and about one-sixth of the global TMR-derived trend. Latitudinal and regional analyses of IWV trends show large variability about the global mean, with synoptic scale variations of IWV trends ranging from ∼−8 to +8%/decade. Averaged over 5° latitude bands the IWV trends reveal a near zero minimum in the Southern Tropical Pacific and maximum values of ∼4%/decade over the 30–40N latitude band. Comparisons with band latitude averaged SST data over the same 1992–2005 interval roughly match a delta_IWV/delta_SST trend scaling of ∼11%/K, consistent with previously observed tropical and midlatitude seasonal variability. TMR-derived CLW trends are fractionally comparable to the IWV trends. The CLW values are 1.5 ± 0.6%/decade (60°S–60°N), 2.0 ± 0.8%/decade (0–60°N), and 1.1 ± 0.8%/decade (0–60°S). When scaled to global mean CLW derived from SSM/I and compared seasonally, the TMR CLW variations exhibit excellent tracking with the SSM/I results. Unlike IWV, however, the CLW statistical uncertainties do not likely reflect the dominant error component in the retrieved trends. The 1992–2005 CLW trend estimates were particularly sensitive to short-term trends in the first and last 2 years of the TMR archive. Additional errors difficult to quantify include strong aliasing effects from precipitation cells and uncertainties in the radiative transfer models utilized in the generation of the TMR CLW algorithm

An assessment of Jason-1 microwave radiometer measurements and products

http://taylorandfrancis.metapress.com/content/3q9dunmn5442x9um/fulltext.htm

A comparison of ocean emissivity models using the Advanced Microwave Sounding Unit, the Special Sensor Microwave Imager, the TRMM Microwave Imager, and airborne radiometer observations

[1] New measurements of the permittivity of saline water at millimeter wavelengths have the potential to improve the accuracy of ocean surface emissivity models for use with microwave and millimeter-wave imaging and sounding instruments. Recent radiative transfer models employing a range of different treatments of surface ocean emissivity are compared with observations from the following microwave radiometers: Advanced Microwave Sounding Unit, Special Sensor Microwave Imager, TRMM Microwave Imager, Microwave Airborne Radiometer Scanning System, and Deimos. Emissivity models using the new permittivity model fit these observations more closely than those models which use the Klein and Swift extrapolation model. INDEX TERMS: 333

A comparison of ocean emissivity models using the Advanced Microwave Sounding Unit, the Special Sensor Microwave Imager, the TRMM Microwave Imager, and airborne radiometer observations

International audienceNew measurements of the permittivity of saline water at millimeter wavelengths have the potential to improve the accuracy of ocean surface emissivity models for use with microwave and millimeter-wave imaging and sounding instruments. Recent radiative transfer models employing a range of different treatments of surface ocean emissivity are compared with observations from the following microwave radiometers: Advanced Microwave Sounding Unit, Special Sensor Microwave Imager, TRMM Microwave Imager, Microwave Airborne Radiometer Scanning System, and Deimos. Emissivity models using the new permittivity model fit these observations more closely than those models which use the Klein and Swift extrapolation model