An Analysis of Total Water Storage Changes Obtained from GRACE FO Observations over the Venezia Islands Area Supported with Additional Data

Monika Biryło,Zofia Rzepecka

doi:10.7494/geom.2021.15.2.17

Abstract

The Venezia Islands are a very special area from the hydrological point of view due to its water mass changes. Regular floods results in the need for the regular monitoring of water mass changes. For this purpose, a Gravity Recovery and Climate Experiment mission (GRACE) can be used as a source of data. The aim of the paper is to compare the latest results of the new GRACE FO observations. The comparisons were carried out all over Venezia Island using the L3 level, RL06 release data obtained with spherical harmonics degree and order extension of up to 120, by the three most important computational centres: JPL, GFZ, CSR. Results are compared to an average month values of precipitation and evapotranspiration and tide gauge data in the nearby area. Based on the research, no dependence between TWS and evapotranspiration and evapotranspiration change were found.

Highlights

The research focuses on the analysis of the total water storage determined on the basis of the new Gravity Recovery and Climate Experiment mission (GRACE) FO (Gravity Recovery and Climate Experiment Follow‐On) observation and comparing it with precipitation and evapotranspiration from the MERRA 2 model (The Second Modern‐Era Retrospective analysis for Research and Applications), and with tide gauge data
Gridded surface Total water storage (TWS) variations over the Venezia Island area were derived from spherical harmon‐ ic coefficients that represent the Earth’s mean gravity field estimations during the specified one‐month timespan
GRACE data with a spatial resolution of approximately 100 km is character‐ ized with a significant noise ratio

Summary

Introduction

The research focuses on the analysis of the total water storage determined on the basis of the new GRACE FO (Gravity Recovery and Climate Experiment Follow‐On) observation and comparing it with precipitation and evapotranspiration from the MERRA 2 model (The Second Modern‐Era Retrospective analysis for Research and Applications), and with tide gauge data. The research undertaken in the paper is to look for a possible relation between climatic parameters and TWS (total water storage). Having ana‐ lysed and processed the values of monthly precipitation and evapotranspiration, an atmospheric budget was estimated. TWS was and is used in many applications, like computing TWS for big river basins, like e.g. the Amazon or Mekong [3], for the improvement of hydrological models [4], correct assimilation model outputs [5], computing water budget in combination with other products [6], estimating groundwater storage [1, 7], finding TWS relationship with climate variability and human activities [8]

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