Validation activities for the level 2 geophysical products of the EUMETSAT Polar System-Second Generation (EPS-SG) visible/infrared imager (METimage)

Spezzi, L.; Borde, Régis; Phillips, P. L.; Schlüssel, Peter; Watts, P. D.

doi:10.1117/12.2325586

Cited by 2 publications

(2 citation statements)

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“…• exploitation of the extended spectral capabilities; • improvement in the inversion scheme by introducing a complete optimal estimation scheme including linear error characterisation; • set-up designed for flexible forward operator use and application to similar types of observations, certainly from OLCI on future Sentinel-3 satellites, but also, e.g., from future Flexible Combined Imager (FCI) on Meteosat Third Generation (MTG; [67]) and METimage on Metop -Second Generation (Metop-SG; [68]).…”

Section: Discussionmentioning

confidence: 99%

Retrieval of Daytime Total Column Water Vapour from OLCI Measurements over Land Surfaces

2021

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A new retrieval of total column water vapour (TCWV) from daytime measurements over land of the Ocean and Land Colour Instrument (OLCI) on-board the Copernicus Sentinel-3 missions is presented. The Copernicus Sentinel-3 OLCI Water Vapour product (COWa) retrieval algorithm is based on the differential absorption technique, relating TCWV to the radiance ratio of non-absorbing band and nearby water vapour absorbing band and was previously also successfully applied to other passive imagers Medium Resolution Imaging Spectrometer (MERIS) and Moderate Resolution Imaging Spectroradiometer (MODIS). One of the main advantages of the OLCI instrument regarding improved TCWV retrievals lies in the use of more than one absorbing band. Furthermore, the COWa retrieval algorithm is based on the full Optimal Estimation (OE) method, providing pixel-based uncertainty estimates, and transferable to other Near-Infrared (NIR) based TCWV observations. Three independent global TCWV data sets, i.e., Aerosol Robotic Network (AERONET), Atmospheric Radiation Measurement (ARM) and U.S. SuomiNet, and a German Global Navigation Satellite System (GNSS) TCWV data set, all obtained from ground-based observations, serve as reference data sets for the validation. Comparisons show an overall good agreement, with absolute biases between 0.07 and 1.31kg/m2 and root mean square errors (RMSE) between 1.35 and 3.26kg/m2. This is a clear improvement in comparison to the operational OLCI TCWV Level 2 product, for which the bias and RMSEs range between 1.10 and 2.55kg/m2 and 2.08 and 3.70kg/m2, respectively. A first evaluation of pixel-based uncertainties indicates good estimated uncertainties for lower retrieval errors, while the uncertainties seem to be overestimated for higher retrieval errors.

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Section: Discussionmentioning

confidence: 99%

Retrieval of Daytime Total Column Water Vapour from OLCI Measurements over Land Surfaces

2021

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“…Thus, the reference datasets include ground-based measurements from networks of stations, radiosondes, space-born lidars/radars measurements, cross-comparison with other satellite products already validated, etc. For a detailed description of the EUMETSAT validation strategy for cloud and WV products, we defer the reader to, e.g., [11][18][20].…”

Section: Tools For Product's Tuning Validation and Monitoringmentioning

confidence: 99%

An overview of the enhanced cloud and water vapour products from EUMETSAT new generation imagers

Spezzi,

Bozzo,

Jackson

et al. 2023

Remote Sensing of Clouds and the Atmosphere XXVIII

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The EUMETSAT Central Facility retrieves and disseminates several near-real time geophysical products from both geostationary and polar VIS/IR imagers. The primary scope of these missions is to serve numerical weather prediction (NWP), nowcasting and climate monitoring. In this contribution, we focus on the cloud and water vapour (WV) imaging products from the new generation EUMETSAT imagers i.e., the Flexible Combined Imager (FCI) on board of Meteosat Third Generation (MTG-I, launched in Dec 2022) and METimage on board EUMETSAT Polar System Second Generation (EPS-SG, expected 2024+). These instruments provide unprecedented spatial resolution (down to 500m at Nadir), temporal sampling (10min for the geostationary FCI), and wider spectral range (approximately 0.4-13µm) including WV (~0.9µm, 1.38µm, ~6.7µm, ~7.3µm), O2 A-band (0.762µm), and CO2 (~13.3µm) absorption channels. We present the retrieval and validation approach chosen for these products and the challenges presented by the near-real time operational processing. We explore, in particular, the expected improvements based on the enhanced instrument's capabilities (i.e., more accurate cloud detection, layering, altitude and spatial inhomogeneity), while maintaining continuity with the legacy products from their predecessor satellites. In particular, the new ~0.9µm channel allows improved daytime estimates of WV amount near the surface. We show preliminary cloud and WV products retrieved from early FCI measurements, including their validation strategy against independent cloud observations from the ground-based ACTRIS network and humidly measurements from IGRA radiosondes.

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Validation activities for the level 2 geophysical products of the EUMETSAT Polar System-Second Generation (EPS-SG) visible/infrared imager (METimage)

Cited by 2 publications

References 10 publications

Retrieval of Daytime Total Column Water Vapour from OLCI Measurements over Land Surfaces

Retrieval of Daytime Total Column Water Vapour from OLCI Measurements over Land Surfaces

An overview of the enhanced cloud and water vapour products from EUMETSAT new generation imagers

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