Effect of the ingestion in the WRF model of different Sentinel-derived and GNSS-derived products: analysis of the forecasts of a high impact weather event

Abstract

This paper presents the first experimental results of a study on the ingestion in the Weather Research and Forecasting (WRF) model, of Sentinel satellites and Global Navigation Satellite Systems (GNSS) derived products. The experiments concern a flash-floodevent occurred in Tuscany (Central Italy) in September 2017. The rationale is that numerical weather prediction (NWP) models are presently able to produce forecasts with a km scale spatial resolution, but the poor knowledge of the initial state of the atmosphere may imply an inaccurate simulation of the weather phenomena. Hence, to fully exploit the advances in numerical weather modelling, it is necessary to feed them with high spatiotemporal resolution information over the surface boundary and the atmospheric column. In this context, the Copernicus Sentinel satellites represent an important source of data, because they can provide a set of high-resolution observations of physical variables (e.g. soil moisture, land/sea surface temperature, wind speed) used in NWP models runs. The possible availability of a spatially dense network of GNSS stations is also exploited to assimilate water vapour content. Results show that the assimilation of Sentinel-1 derived wind field and GNSS-derivedwater vapour data produce the most positive effects on the performance of the forecast.

A Synergistic Use of a High-Resolution Numerical Weather Prediction Model and High-Resolution Earth Observation Products to Improve Precipitation Forecast

“…This is done because, in its original formulation, MODE makes use of an interest function that depends on a certain number of parameters that are not simple to define. Thus, to avoid extracting partial or wrong information, we decided to follow our simple and physically-oriented approach, as in References [12,24]. Figures 8 and 9 summarize the QPF values provided by the different modelling experiments for the 12 h time period from 18UTC on 9 September 2017 to 06UTC on 10 September 2017.…”

“…For a detailed description of the reasoning behind the selection of the EO variables to be ingested into the WRF model, that was based on the Observing Systems Capability Analysis and Review (OSCAR) tool, the reader is referred to Reference [12]. Through OSCAR, which is a resource developed by World Meteorological Organization (WMO) in support of Earth Observation applications, studies and global coordination (https://www.wmo-sat.info/oscar/), a set of requirements for observation of physical variables in support of WMO programs is available.…”

“…An inverse square distance weighting interpolation of the Sentinel data on the WRF domains computational grids allowed obtaining the Sentinel maps into to the resolution of the innermost domain (1.5 km) before the assimilation. As mentioned in Section 2.3, the SM maps are also propagated in all the model soil layers (refer to Figure 3 in Reference [12]). Concerning ZTD measurements, for the Livorno test case the ZTD from InSAR was not available, thus only GNSS data were assimilated.…”

“…The scientific questions at the base of the "SaTellite Earth observation for Atmospheric Modelling" (STEAM) project (awarded in 2017 by the European Space Agency (ESA)) concern the synergistic use of high-resolution numerical atmosphere models with space-borne systems. A subset of experiments were presented in Reference [12] with a focus on operational issues, while in this study the complete outcomes of the STEAM project are presented. This paper introduces and discusses the results of a set of experiments on the assimilation in the Weather Research and Forecasting (WRF) model [13], of surface information derived from Sentinel products and information about the atmospheric water vapour content derived from both Sentinel-1 data and GNSS measurements.…”

Joint Exploitation of SAR and GNSS for Atmospheric Phase Screens Retrieval Aimed at Numerical Weather Prediction Model Ingestion

“…The Observing Systems Capability Analysis and Review (OSCAR) tool, developed by the World Meteorological Organization (WMO) set the minimum horizontal resolution for Integrated Water Vapor (IWV) maps in high-resolution NWPMs at 20 km with a goal, over which further improvements are not necessary, of 0.5 km [22].…”