Comprehensive Study on the Tropospheric Wet Delay and Horizontal Gradients during a Severe Weather Event

Francisco Azpilicueta,Mauricio Gende,Victoria Graffigna,Manuel Hernández-Pajares

doi:10.3390/rs14040888

Abstract

GNSS meteorology is today one of the most growing technologies to monitor severe weather events. In this paper, we present the usage of 160 GPS reference stations over the period of 14 days to monitor and track Hurricane Harvey, which struck Texas in August 2017. We estimate the Zenith Wet Delay (ZWD) and the tropospheric gradients with 30 s interval using TOMION v2 software and carry out the processing in Precise Point Positioning (PPP) mode. We study the relationship of these parameters with atmospheric variables extracted from Tropical Rainfall Measuring Mission (TRMM) satellite mission and climate reanalysis model ERA5. This research finds that the ZWD shows patterns related to the rainfall rate and to the location of the hurricane. We also find that the tropospheric gradients are correlated with water vapor gradients before and after the hurricane, and with the wind and the pressure gradients only after the hurricane. This study also shows a new finding regarding the spectral distribution of the gradients, with a clear diurnal period present, which is also found on the ZWD itself. This kind of study approaches the GNSS meteorology to the increasing requirements of meteorologist in terms of monitoring severe weather events.

Highlights

Academic Editors: Weizeng Shao, Marine disasters have rapidly increased since 2000, and the ability of monitoring them today relies on the satellite methods available to track such disastrous phenomena
We will show the results obtained regarding the comparison between the Zenith Wet Delay (ZWD) and the rain rate from the Tropical Rainfall Measuring Mission (TRMM) satellite mission, followed by a description of the periods found on the Zenith Tropospheric Delay (ZTD) and gradients’ spectral analysis
We will study the correlation between the gradients and atmospheric variables from ERA5, namely the atmospheric pressure gradients, water vapor gradients, and wind field components

Summary

Introduction

Academic Editors: Weizeng Shao, Marine disasters have rapidly increased since 2000, and the ability of monitoring them today relies on the satellite methods available to track such disastrous phenomena. In this sense, GNSS (Global Navigation Satellite System) meteorology has become a very useful technique considering the remote sensing of the atmosphere in the last 20 years. The water vapor fields are highly heterogeneous fields that vary rapidly, which has encouraged, among other improvements, the development and implementation of low cost, and with high temporal resolution technologies to track them This is where GNSS extensive, all weather, and low cost operational foundation becomes of great importance. Compared with other available techniques, which have calibration problems, Global Positioning Systems (GPSs) have long-term stability

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