Ocean and Sea Ice Retrievals From an End‐To‐End Simulation of the Copernicus Imaging Microwave Radiometer (CIMR) 1.4–36.5 GHz Measurements

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Jiménez, Carlos, Tenerelli, Joseph, Prigent, Catherine, Kilic, Lise, Lavergne, Thomas, Skarpalezos, Sotirios, Høyer, Jacob, Reul, Nicolas, Donlon, Craig
• Other Authors: Estellus, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), OceanDataLab, Norwegian Meteorological Institute Oslo (MET), Danish Meteorological Institute (DMI), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: microwave remote sensing; sea surface temperature; sea ice; salinity; brightness temperatures; polar regions; socio; info; Arctic; Sea ice
• Online Access: https://doi.org/10.1029/2021jc017610; https://hal.sorbonne-universite.fr/hal-03526209/file/JGR%20Oceans%20-%202021%20-%20Jim%20nez%20-%20Ocean%20and%20Sea%20Ice%20Retrievals%20From%20an%20End%25u2010To%25u2010End%20Simulation%20of%20the%20Copernicus%20Imaging.pdf; https://hal.sorbonne-universite.fr/hal-03526209

International audience The Copernicus Imaging Microwave Radiometer (CIMR) is currently being implemented by the European Space Agency (ESA) as a Copernicus Expansion Mission primarily designed to observe the Polar Regions in support of the Integrated European Policy for the Arctic. It is a conically scanning microwave radiometer with polarized channels centered at 1.414, 6.925, 10.65, 18.7, and 36.5 GHz and channel NEΔT between 0.2 and 0.7 K. A large rotating deployable mesh reflector will provide real-aperture resolutions ranging from urn:x-wiley:21699275:media:jgrc24799:jgrc24799-math-000160 (1.4 GHz) to urn:x-wiley:21699275:media:jgrc24799:jgrc24799-math-00025 km (36.5 GHz). To evaluate CIMR retrieval performance, a simplified end-to-end simulation of the mission has been carried out. The simulation includes important processes and input parameters, such as test geophysical datasets, forward models, an instrument simulator, and retrieval algorithms to derive the key mission geophysical products. The forward modeling is tested by producing Brightness Temperatures (TBs) from 4 global scenes. A comparison with current observations of the open ocean and sea ice at similar frequencies confirmed the realism of the simulations. The produced top-of-atmosphere TBs are converted to Antenna brightness Temperatures (TAs), taking into account the instrument design, and are then inverted to retrieve Sea Ice Concentration (SIC), Sea Surface Temperature (SST), and Sea Surface Salinity (SSS). Evaluating the retrieval performance showed that the simulated CIMR instrument can provide SST, SSS, and SIC measurements with precisions and spatial resolutions conforming with the mission requirements. The evaluation also highlighted the challenges of observing the Arctic environment and put in perspective CIMR capabilities compared with current instruments.