Publication Date:
2016-09-26
Description:
The variability and trend in global precipitable water vapor (PWV) from 1979 to 2014 are analyzed using the PWV datasets from the ERA-Interim reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF), reanalysis of the National Centers for Environmental Prediction (NCEP), radiosonde, global positioning system (GPS) and microwave satellite observations. PWV data from the ECMWF and NCEP have been evaluated by radiosonde, GPS and microwave satellite observations, showing that ECMWF has higher accuracy than NCEP. Over the oceans, ECMWF has a much better agreement with the microwave satellite than NCEP. An upward trend in the global PWV is evident in all the five PWV datasets over three study periods: 1979-2014, 1992-2014 and 2000-2014. Positive global PWV trends, defined as percentage normalized by annual average, of 0.61 ± 0.33% decade -1 , 0.57 ± 0.28% decade -1 and 0.17 ± 0.35% decade -1 have been derived from the NCEP, radiosonde and ECMWF respectively for the period 1979-2014. It is found that ECMWF overestimates the PWV over the ocean prior to 1992. Thus two more periods 1992-2014 and 2000-2014 are studied. Increasing PWV trends are observed from all the five datasets in the two periods: 1992-2014 and 2000-2014. The linear relationship between PWV and surface temperature is positive over most oceans and the polar region. Steep positive/negative regression slopes are generally found in regions where large regional moisture flux divergence/convergence occurs.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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