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Generation of real-time mode high-resolution water vapor fields from GPS observations

Lookup NU author(s): Chen YuORCiD, Dr Nigel Penna, Professor Zhenhong Li



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Pointwise GPS measurements of tropospheric zenith total delay can be interpolated to provide high resolution water vapor maps which may be used for correcting SAR images, for numeral weather prediction and for correcting Network Real-time Kinematic GPS observations. Several previous studies have addressed the importance of the elevation dependency of water vapor, but it is often a challenge to separate elevation-dependent tropospheric delays from turbulent components. In this paper, we present an iterative tropospheric decomposition interpolation model that decouples the elevation and turbulent tropospheric delay components. For a 150 km x 150 km California study region, we estimate real-time mode zenith total delays at 41 GPS stations over 1 year using the precise point positioning technique, and demonstrate that the decoupled interpolation model generates improved high resolution tropospheric delay maps compared with previous tropospheric turbulence and elevation dependent models. Cross validation of the GPS zenith total delays yields an RMS error of 4.6 mm with the decoupled interpolation model, compared with 8.4 mm with the previous model. On converting the GPS zenith wet delays to precipitable water vapor and interpolating to 1 km grid cells across the region, validations with the MODIS near-IR water vapor product show 1.7 mm RMS differences using the decoupled model, compared with 2.0 mm for the previous interpolation model. Such results are obtained without differencing the tropospheric delays or water vapor estimates in time or space, whilst the errors are similar over flat and mountainous terrain, as well as for both inland and coastal areas.

Publication metadata

Author(s): Yu C, Penna NT, Li Z

Publication type: Article

Publication status: Published

Journal: Journal of Geophysical Research: Atmospheres

Year: 2017

Volume: 122

Issue: 3

Pages: 2008-2025

Print publication date: 16/02/2017

Online publication date: 26/01/2017

Acceptance date: 22/01/2017

Date deposited: 30/01/2017

ISSN (print): 2169-897X

ISSN (electronic): 2169-8996

Publisher: Wiley-Blackwell Publishing, Inc.


DOI: 10.1002/2016JD025753


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Funder referenceFunder name
NE/N012151/1Natural Environment Research Council (NERC)
NE/K010794/1Natural Environment Research Council (NERC)