Open AccessValidation of the Moderate‐Resolution Imaging Spectroradiometer precipitable water vapor product using measurements from GPS on the Tibetan Plateau
Author(s) -
Liu Jingmiao,
Liang Hong,
Sun Zhian,
Zhou Xiuji
Publication year - 2006
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd007028
Subject(s) - moderate resolution imaging spectroradiometer , environmental science , water vapor , precipitable water , global positioning system , remote sensing , spectroradiometer , plateau (mathematics) , meteorology , atmospheric sciences , satellite , geology , mathematics , reflectivity , geography , physics , telecommunications , mathematical analysis , astronomy , computer science , optics
Moderate‐Resolution Imaging Spectroradiometer (MODIS) Global atmospheric column water vapor amount product (MOD05_L2) released by NASA Goddard DAAC was evaluated using 1 year of observations obtained by the Global Positioning System (GPS) installed at Gaize (32.3°N, 84.06°E, 4420 m) and Naqu (30.48°N, 92.06°E, 4518 m) on the Tibetan Plateau. It was found that the MODIS retrieved atmospheric column water vapor amount is much lower than that retrieved by GPS at the two sites. The results show that there is a systematic bias in precipitable water between MODIS and GPS, with root‐mean‐square errors (rms) of 2.93 mm at Naqu and 3.48 mm at Gaize. Mean relative differences in PW between GPS and MODIS at Naqu and Gaize are 57.1% and 51.1%, respectively. The reason for the bias is found to be an error in the coding of operational water vapor retrievals at the NASA Goddard DAAC for data processing. After correction for the MODIS water vapor product (MOD05_L2), the RMS difference between GPS‐PW and MODIS‐PW drops to 1.9 mm at Naqu and 1.68 mm at Gaize.