Assimilation of GPSRO Bending Angle Profiles into the Brazilian Global Atmospheric Model

Abstract

The Global Positioning System (GPS) Radio Occultation (RO) technique allows valuable information to be obtained about the state of the atmosphere through vertical profiles obtained at various processing levels. From the point of view of data assimilation, there is a consensus that less processed data are preferable because of their lowest addition of uncertainties in the process. In the GPSRO context, bending angle data are better to assimilate than refractivity or atmospheric profiles; however, these data have not been properly explored by data assimilation at the CPTEC (acronym in Portuguese for Center for Weather Forecast and Climate Studies). In this study, the benefits and possible deficiencies of the CPTEC modeling system for this data source are investigated. Three numerical experiments were conducted, assimilating bending angles and refractivity profiles in the Gridpoint Statistical Interpolation (GSI) system coupled with the Brazilian Global Atmospheric Model (BAM). The results highlighted the need for further studies to explore the representation of meteorological systems at the higher levels of the BAM model. Nevertheless, more benefits were achieved using bending angle data compared with the results obtained assimilating refractivity profiles. The highest gain was in the data usage exploring 73.4% of the potential of the RO technique when bending angles are assimilated. Additionally, gains of 3.5% and 2.5% were found in the root mean square error values in the zonal and meridional wind components and geopotencial height at 250 hPa, respectively.

Comparison of Desroziers and Three-Cornered Hat Methods for Estimating COSMIC-2 Bending Angle Uncertainties

“…The RO observations contain information on temperature and water vapor, have high vertical resolution (∼200 m) and corresponding small vertical footprints, are relatively unbiased and unaffected by clouds and precipitation, and have high accuracy and precision (Kursinski et al 1997;Anthes 2011). They have had a significant positive impact on operational NWP models and reanalyses in many centers, e.g., ECMWF (Healy 2008;Healy and Thépaut 2006), NCEP (Cucurull et al 2007), the Met Office (Rennie 2010), Environment and Climate Change Canada (Aparicio and Deblonde 2008), Météo-France (Poli et al 2009(Poli et al , 2010, Center for Weather Forecasts and Climate Brazil (Banos et al 2019), and the U.S. Naval Research Laboratory (Ruston and Healy 2020).…”

50 anos de sinergia entre Geodésia Espacial e Meteorologia: do erro no posicionamento GNSS a aplicações de previsão de precipitação de curtíssimo prazo

“…Mais detalhes sobre a metodologia utilizada podem ser encontrados com bastante riqueza de informações em Sapucci (2001). Em Sapucci et al, (2019) foi reportando uma aplicação inovadora dos dados do PWV advindos de receptores GNSS, que é a sua utilização para prever eventos extremos de precipitação em atividades em previsão imediata (nowcasting), tendo como principal finalidade a emissão de alertas sobre a ocorrência iminente de uma tempestade. O foco é a população vulnerável aos riscos de perda da vida e de prejuízos materiais, induzindo ações efetivas e antecipadas de prevenção e redução dos danos na ocorrência desses fenômenos.…”

“…Na técnica denominada Rádio Ocultação GNSS (RO-GNSS), os receptores GNSS são embarcados em bases espaciais, e com eles pode-se obter perfis da concentração os constituintes atmosféricos com alta resolução vertical (SAPUCCI et al, 2014b;BONAFONI et al, 2020). Os perfis de RO-GNSS têm apresentado um forte impacto na qualidade dos produtos de PNT dentro do processo de assimilação de dados, sendo o segundo sistema de observação em ordem de importância (BANOS et al, 2019). Como a abordagem na obtenção das medidas de receptores em bases terrestres é bastante diferente dos receptores em bases espaciais, apenas a primeira será detalhada nesse artigo, enquanto que a segunda trabalhos já publicados serão referenciados, a fim de simplificação.…”

Editorial for the Special Issue “Assimilation of Remote Sensing Data into Earth System Models”

“…In this Special Issue, state-of-the-art developments in operational coupled ocean-atmosphere developments are presented by Browne et al [10]. Recent advances in Earth system components assimilation are presented, including (1) assimilation of Global Positioning System (GPS) radio occultation (RO) in atmospheric models (Banos et al [11]) as well as (2) sea level interpolation using an analog data assimilation approach to improve high resolution current representation in ocean general circulation models (Lguensat et al [12]). Assimilation of observations from the Tropical Rainfall Measuring Mission (TRMM) and the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM IMERG) is also investigated by Yi et al [13].…”