The uncertainty of the atmospheric integrated water vapour estimated from GNSS observations
Within the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) there is a need for an assessment of the uncertainty in the integrated water vapour (IWV) in the atmosphere estimated from ground-based global navigation satellite system (GNSS) observations. All relevant error sou...
Main Authors: | , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-01-01
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Series: | Atmospheric Measurement Techniques |
Online Access: | http://www.atmos-meas-tech.net/9/79/2016/amt-9-79-2016.pdf |
Summary: | Within the Global Climate Observing System (GCOS) Reference Upper-Air
Network (GRUAN) there is a need for an assessment of the
uncertainty in the integrated water vapour (IWV) in the atmosphere
estimated from ground-based global navigation
satellite system (GNSS) observations. All relevant error
sources in GNSS-derived IWV are therefore essential to be
investigated. We present two approaches, a statistical and a
theoretical analysis, for the assessment of the uncertainty of the
IWV. The method is valuable for all applications of GNSS IWV data in
atmospheric research and weather forecast. It will be implemented to
the GNSS IWV data stream for GRUAN in order to assign a specific
uncertainty to each data point. In addition, specific
recommendations are made to GRUAN on hardware, software, and data
processing practices to minimise the IWV uncertainty. By combining
the uncertainties associated with the input variables in the
estimations of the IWV, we calculated the IWV uncertainties for
several GRUAN sites with different weather conditions. The results
show a similar relative importance of all uncertainty contributions
where the uncertainties in the zenith total delay (ZTD) dominate the
error budget of the IWV, contributing over 75 % of the total
IWV uncertainty. The impact of the uncertainty associated with the
conversion factor between the IWV and the zenith wet delay (ZWD) is
proportional to the amount of water vapour and increases slightly
for moist weather conditions. The GRUAN GNSS IWV uncertainty data
will provide a quantified confidence to be used for the validation
of other measurement techniques. |
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ISSN: | 1867-1381 1867-8548 |