Assessment of Sampling Effects on Various Satellite-Derived Integrated Water Vapor Datasets Using GPS Measurements in Germany as Reference

Passive imagers on polar-orbiting satellites provide long-term, accurate integrated water vapor (IWV) data sets. However, these climatologies are affected by sampling biases. In Germany, a dense Global Navigation Satellite System network provides accurate IWV measurements not limited by weather cond...

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Bibliographic Details
Published in:Remote sensing (Basel, Switzerland) Switzerland), 2020-04, Vol.12 (7), p.1170
Main Authors: Carbajal Henken, Cintia, Dirks, Lisa, Steinke, Sandra, Diedrich, Hannes, August, Thomas, Crewell, Susanne
Format: Article
Language:English
Subjects:
Clouds
Datasets
Global navigation satellite system
Global positioning systems
GPS
IASI
Meteorological satellites
MIRS
MODIS
Polar orbiting satellites
Precipitation
Quality assessment
Remote sensing
Sampling
sampling effects
Satellite instruments
Satellite navigation systems
Satellite-borne instruments
Studies
Temporal resolution
validation
Water vapor
water vapor retrievals
Weather
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Summary:Passive imagers on polar-orbiting satellites provide long-term, accurate integrated water vapor (IWV) data sets. However, these climatologies are affected by sampling biases. In Germany, a dense Global Navigation Satellite System network provides accurate IWV measurements not limited by weather conditions and with high temporal resolution. Therefore, they serve as a reference to assess the quality and sampling issues of IWV products from multiple satellite instruments that show different orbital and instrument characteristics. A direct pairwise comparison between one year of IWV data from GPS and satellite instruments reveals overall biases (in kg/m 2 ) of 1.77, 1.36, 1.11, and −0.31 for IASI, MIRS, MODIS, and MODIS-FUB, respectively. Computed monthly means show similar behaviors. No significant impact of averaging time and the low temporal sampling on aggregated satellite IWV data is found, mostly related to the noisy weather conditions in the German domain. In combination with SEVIRI cloud coverage, a change of shape of IWV frequency distributions towards a bi-modal distribution and loss of high IWV values are observed when limiting cases to daytime and clear sky. Overall, sampling affects mean IWV values only marginally, which are rather dominated by the overall retrieval bias, but can lead to significant changes in IWV frequency distributions.
ISSN:2072-4292
2072-4292
DOI:10.3390/rs12071170