Observation operator and observation processing for cloud radar. Support-to-Science-Element (STSE) Study EarthCARE Assimilation

TitleObservation operator and observation processing for cloud radar. Support-to-Science-Element (STSE) Study EarthCARE Assimilation
Publication TypeReport
Date Published01/2014
Series/CollectionWP-1100 Report: ESA ESTEC Contract AO/I-6441/10/NL/CB
Document Number2014:WP-1100
AuthorsDi Michele, S, Martins, E, Janiskova, M
Event Series/CollectionESA Contract Report
InstitutionECMWF
Place of publicationShinfield Park, Reading
Abstract

This report summarizes the work done to prepare for the inclusion of the EarthCARE radar data in the ECMWF monitoring/assimilation system using CloudSat observations as testing data. The first part of the study describes the refinements brought to the radar forward operator. Improvements to the definition of the optical properties of frozen precipitation has led to a better agreement between simulated and CloudSat reflectvities. The impact of multiple scattering on the radar signal has been also investigated. Simulations show that this phenomenon affects all precipitation regimes, degrading the signal in conditions of heavy precipitation. The second part of the study focuses on the characterization of the observation errors, needed for data assimilation. Uncertainties due to the observation operator have been estimated perturbating some of the microphysical assumptions there made. In case of space-borne radar observations as the ones from CloudSat/EarthCARE, an important component of the observation error is the representativity one. In this work a flow-dependent estimate has been implemented following a previously-developed statistical approach. The final part of the study describes the quality control and bias correction schemes developed in order to have departures between CloudSat observations and model first guess suitable for assimilation. ESA

URLhttps://www.ecmwf.int/node/9043
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