Multiscale Variations of Precipitable Water over China Based on 1999–2015 Ground-Based GPS Observations and Evaluations of Reanalysis Products

• DOI: 10.1175/jcli-d-17-0419.1
• Publication Date: 2017-11-21T18:00:37Z
• Authors: Weixing Zhang; Yidong Lou; Jinfang Huang; Fu Zheng; Yunchang Cao; Hong Liang; Chuang Shi; Jingnan Liu
• Keywords: Precipitable water

Abstract The dense ground-based GPS provides a good tool to study water vapor distribution and multiscale variations, especially for linear trends on the interannual scale short-term variations diurnal scale. It can also serve as an independent data source evaluate performances of reanalyses. In this study, 6-hourly precipitable (PW) products at more than 260 stations over China from 1999 2015 were analyzed eight commonly used reanalyses, including 20CR version 2 (20CRv2), CFSR, ERA-Interim, JRA-25, JRA-55, MERRA, NCEP–NCAR, NCEP–DOE AMIP-II, evaluated. climatological annual mean PW roughly shows decreasing trend southeast northwest, with largest semiannual amplitudes in lower reaches Yangtze River mideastern China, respectively, smallest values Tibetan Plateau southwestern China. All reanalyses (except 20CRv2) generally reproduce well (within 20%), 20% except tropical monsoon region), but they all show wet biases Plateau. Diurnal variation reproduced by reanalysis are smaller estimated observations whole, none capture phases correctly. most recent 16 years insignificant or absolute 0.10 mm yr−1. However, because assimilation unhomogenized radiosonde humidity data, artificial 20CRv2 CFSR).