Alain Lefebvre

GOME-2 -- the ozone instrument onboard the European METOP satellites

Since 1995 the Global Ozone Monitoring Experiment (GOME) is measuring ozone (total column and profile), nitrogen dioxide and other minor trace gases on-board of the European Space Agency (ESA) ERS-2 satellite. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and ESA decided to fly an advanced GOME-2 instrument on the METOP satellites. Within the EUMETSAT Polar System (EPS), the GOME-2 measurements will provide the input for the ozone data record in the timeframe 2005 to 2020. The radiometric calibration of the polarisation sensitive GOME-2 instrument is significantly improved by the simultaneous measurement of s- and p-polarised light at moderate resolution and high temporal resolution. The Polarisation Monitoring Unit (PU) measures the spectral range between 312 and 790 nm in 15 narrow bands. The ground pixel size in the 960 km swath is 40 * 5km2. The paper describes in detail the polarization measurement devices and their technical capabilities.

The EarthCARE mission: Mission concept and lidar instrument pre-development

The earth clouds, aerosols, and radiation explorer mission has been selected as the 6th earth explorer mission of ESAs living planet programme [1]. A suite of four instruments, active and passive, will be embarked on the same satellite to measure cloud and aerosol properties simultaneously with TOA radiances in order to derive TOA fluxes in relation to clouds and aerosols.

Development status of the EarthCARE Mission and its atmospheric Lidar

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop as part of ESA’s Living Planet Programme, the third Earth Explorer Core Mission, EarthCARE, with the fundamental objective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth’s atmosphere. EarthCARE payload consists of two active and two passive instruments: an ATmospheric LIDar (ATLID), a Cloud Profiling Radar (CPR), a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer (BBR). The four instruments data are processed individually and in a synergetic manner to produce a large range of products, which include vertical profiles of aerosols, liquid water and ice, observations of cloud distribution and vertical motion within clouds, and will allow the retrieval of profiles of atmospheric radiative heating and cooling. Operating in the UV range at 355 nm, ATLID provides atmospheric echoes with a vertical resolution up to 100 m from ground to an altitude of 40 km. Thanks to a high spectral resolution filtering, the lidar is able to separate the relative contribution of aerosol (Mie) and molecular (Rayleigh) scattering, which gives access to aerosol optical depth. Co-polarised and cross-polarised components of the Mie scattering contribution are also separated and measured on dedicated channels. This paper gives an overview of the mission science objective, the satellite configuration with its four instruments and details more specifically the implementation and development status of the Atmospheric Lidar. Manufacturing status and first equipment qualification test results, in particular for what concerns the laser transmitter development are presented.

GOME-2 ozone instrument onboard the European METOP satellites

Since 1995 the Global Ozone Monitoring Experiment (GOME) is measuring ozone (total column and profile), nitrogen dioxide and other minor trace gases on-board of the European Space Agency (ESA) ERS-2 satellite. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and ESA decided to fly an advanced GOME-2 instrument on the METOP satellites. Within the EUMETSAT Polar System (EPS), the GOME-2 measurements will provide the input for the ozone data record in the timeframe 2005 to 2020. The radiometric calibration of the polarisation sensitive GOME-2 instrument is significantly improved by the simultaneous measurement of s- and p-polarised light at moderate resolution and high temporal resolution. The Polarisation Monitoring Unit (PU) measures the spectral range between 312 and 790 nm in 15 narrow bands. The ground pixel size in the 960 km swath is 40 * 5km2. The paper describes in detail the polarisation measurement devices and their technical capabilities.

The multi-spectral imager on board the EarthCARE spacecraft

Clouds and aerosols are important atmospheric elements that strongly influence the weather and climate on planet Earth. The European Space Agency (ESA) is currently developing, in co-operation with the Japan Aerospace Exploration Agency (JAXA) the EarthCARE satellite mission with the objective of improving the understanding of the cloudaerosols- radiation interactions within the Earths atmosphere. It is foreseen that the data provided by the EarthCARE satellite will allow the improvement of the currently available numerical prediction models, and therefore the quality of the weather forecast and climate evolution predictions. The payload of the EarthCARE satellite consists of a Cloud Profiling Radar (CPR), a Backscatter Lidar (ATLID), a Broadband Radiometer (BBR), and a Multi-spectral Imager (MSI). The MSI instrument will provide images of the earth in 7 spectral bands in the visible and infrared parts of the spectrum, with a spatial ground resolution of 500 m and an image width on the ground of 150 km. This paper provides a description of the MSI instrument and its expected performance.

An overview of the EarthCARE mission and end-to-end simulator

The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission aims at improving the representation and understanding of the Earths radiative balance in climate and numerical weather forecast models by acquiring vertical profiles of clouds - including vertical motion within clouds - and aerosols, as well as measuring the broadband radiances at the top of the atmosphere for flux estimates in relation of the observed clouds and aerosols fields. The EarthCARE payload comprises an High Spectral Resolution (HSR) Lidar (ATLID) operating at 355 nm and equipped with a high-spectral resolution (HSR) receiver and the Cloud Profiling Radar (CPR), a highly sensitive 94GHz cloud radar with Doppler capability. A Multi-Spectral Imager (MSI) supporting the active instruments consists of a push-broom imager with 7 channels in the visible, near infrared, short-wave infrared and thermal infrared. Finally, a Broad-Band Radiometer (BBR) measures the outgoing top-of-atmosphere radiances in a short wave channel and a total wave channel, from which the long wave contribution can be deduced. The EarthCARE end-to-end Simulator (ECSIM) encompasses the full EarthCARE observation chain from scene definition to single-instrument and synergistically derived multi-instrument Level 2 products. Level 2 retrieval algorithms can be tested in the full chain (provision of input data, algorithm performance tests by comparison of outputs with known inputs) by using a single framework with well-defined interfaces helping to harmonise algorithm developments. The CPR is developed and procured by JAXA (Japanese Aerospace Exploration Agency) and NiCT (National Institute of Information and Communications Technology) and will be embarked as an integral part of the EarthCARE satellite in the context of the ESA/JAXA cooperation for EarthCARE.

EarthCARE mission, overview, implementation approach, and development status

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop the EarthCARE satellite mission with the fundamental objective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earths atmosphere in order to include them correctly and reliably in climate and numerical weather prediction models. The satellite will be placed in a Sun-Synchronous Orbit at about 400 Km altitude and14h00 mean local solar time. The payload consisting of a High Spectral Resolution UV Atmospheric LIDar (ATLID), a 94GHz Cloud Profiling Radar (CPR) with Doppler capability, a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer will provide information on cloud and aerosol vertical structure of the atmosphere along the satellite track as well as information about the horizontal structures of clouds and radiant flux from sub-satellite cells. The presentation will cover the configuration of the satellite with its four instruments, the mission implementation approach, an overview of the ground segment and the overall mission development status.

The engineering model for the multispectral imager of the EarthCARE spacecraft

The Multi-Spectral Imager (MSI) will be flown on board the EarthCARE spacecraft, under development by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The fundamental objective of the EarthCARE mission is improving the understanding of the processes involving clouds, aerosols and radiation in the Earth’s atmosphere. In addition to the MSI instrument, a Cloud Profiling Radar (CPR), an Atmospheric Lidar (ATLID), and a Broadband Radiometer (BBR) complete the payload of the EarthCARE satellite. By acquiring images of the clouds and aerosol distribution, the MSI instrument will provide important contextual information in support of the radar and lidar geophysical retrievals. The MSI development philosophy is based on the early development of an Engineering Confidence Model (ECM) and the subsequent development of a Proto-flight Model, the model to be launched on-board the EarthCARE satellite. This paper provides an overview of the MSI instrument and its development approach. A description of the ECM and its verification program is also provided.

The calibration of the multi-spectral imager on-board the EarthCARE spacecraft

The European Space Agency (ESA) is currently developing, in co-operation with the Japan Aerospace Exploration Agency (JAXA) the EarthCARE satellite mission with the basic objective of improving the understanding of the cloudaerosols- radiation interactions within the Earths atmosphere. As part of the EarthCARE payload, the MSI instrument will provide images of the earth in 7 spectral bands in the visible and infrared parts of the spectrum, with a spatial ground resolution of 500 m and an image width on the ground of 150 km. The radiometric accuracy of the MSI instrument is of paramount importance to accurately retrieve the physical properties of clouds and aerosols from the radiometric measurements in the different MSI spectral channels. The prelaunch calibration campaign together with the in-flight calibration facilities that the MSI instrument incorporates will ensure the fulfilment of the radiometric requirements of the mission. The overall calibration approach for the MSI instrument is described in this paper, including the pre-launch and in-flight calibration activities.

Calibration of GOME-2 data

The GOME-2 spaceborne spectrometers will provide data for the ozone product chain of the EUMETSAT Polar System (EPS), in charge of the monitoring of atmospheric ozone. The accuracy of any geophysical parameter retrieved from the GOME-2 measurements will ultimately be limited by the accuracy of the spectral and radiometric calibration of instrument data. This imposes strong accuracy and stability requirements on the instrument, the calibration activities and the ground processing. In this paper, the processing scheme for the spectral and radiometric calibration of GOME-2 data is presented.