Rolf Stuhlmann

Dry Bias in Satellite-Derived Clear-Sky Water Vapor and Its Contribution to Longwave Cloud Radiative Forcing

Abstract In this paper, the amount of satellite-derived longwave cloud radiative forcing (CRF) that is due to an increase in upper-tropospheric water vapor associated with the evolution from clear-sky to the observed all-sky conditions is assessed. This is important because the satellite-derived clear-sky outgoing radiative fluxes needed for the CRF determination are from cloud-free areas away from the cloudy regions in order to avoid cloud contamination of the clear-sky fluxes. However, avoidance of cloud contamination implies a sampling problem as the clear-sky fluxes represent an area drier than the hypothetical clear-sky humidity in cloudy regions. While this issue has been recognized in earlier works this study makes an attempt to quantitatively estimate the bias in the clear-sky longwave CRF. Water vapor amounts in the 200–500-mb layer corresponding to all-sky condition are derived from microwave measurements with the Special Sensor Microwave Temperature-2 Profiler and are used in combination with c...

Infrared atmospheric sounder interferometer radiometric noise assessment from spectral residuals

The problem of characterizing and estimating the radiometric noise of satellite high spectral resolution infrared spectrometers from Earth views is addressed in this paper. A methodology has been devised which is based on the common concept of spectral residuals (Observations-Calculations) obtained after spectral radiance inversion for atmospheric and surface parameters. An in-depth analytical assessment of the statistical covariance matrix of the spectral residuals has been performed which is based on the optimal estimation theory. It has been mathematically demonstrated that the use of spectral residuals to assess instrument noise leads to an effective estimator, which is largely independent of possible departures of the observational covariance matrix from the true covariances. Application to the Infrared Atmospheric Sounder Interferometer has been considered. It is shown that Earth-view-derived observation errors agree with blackbody in-flight calibration. The spectral residuals approach also proved to be effective in characterizing noise features due to mechanical microvibrations of the beam splitter of the IASI instrument.

Meteosat Third Generation: progress on space segment system feasibility studies: payload aspects

ESA and EUMETSAT have initiated joint preparatory activities for the formulation and definition of the Meteosat Third Generation (MTG) geostationary system to ensure the continuity and improvement of the Meteosat Second Generation (MSG) system. The MTG will become the new system to be the backbone of the European operational meteorological services from 2015, in particular, will ensure the continuation of the imagery missions. The first phases were devoted to the definition and consolidation of end user requirements and priorities in the field of Nowcasting and Very Short Term Weather Forecasting (NWC), Medium/Short Range global and regional Numerical Weather Prediction (NWP), Climate and Air Composition Monitoring and to the definition of the relevant observation techniques. The following missions have been analysed and preliminary concepts studied: The Flexible Combined Imager, an improvement of the actual MSG-SEVIRI Imager Lightning Imagery Mission IR Sounding Mission UV-VIS-NIR Sounding Mission as a payload complement from GMES. After pre-phase A mission studies (2003-2006), where preliminary instrument concepts were investigated allowing in the same time to consolidate the technical requirements for the overall system study, a phase A study on MTG has been launched at the beginning of February 2007 for the space segment system feasibility and programmatic aspects to be accomplished during 2007-2008 time frame. The space segment phase A study will cover all elements to the level of details allowing to conclude on the feasibility of the system and to produce cost estimates with a good level of confidence. This paper provides an overview of the outcome of the MTG space segment at the end of phase A, addressing the progress accomplished for the various payloads in terms of achievable performances including Radiometry and Image Navigation and Registration aspects. It namely focuses onto the Imaging and IR Sounding, Lightning Missions, introduces the UV-VIS-NIR Sounding mission concept status, establishes the critical technologies and introduces the way forward to the implementation of the MTG development programme.

Meteosat third generation: user requirements and sensors concept

Following the successful commissioning of the first Meteosat Second Generation (MSG) series, EUMETSAT and the European Space Agency (ESA) are actively preparing the Meteosat Third Generation (MTG) mission to plan for a future operational geostationary meteorological satellite system in the post 2015 time frame. Early user consultation activities of EUMETSAT and ESA for the MTG mission culminated with a user consultation workshop held in November 2001. The User Consultation Process was devoted to the definition and consolidation of end user requirements and priorities in the field of Medium/Short Range global and regional Numerical Weather Prediction (NWP), Nowcasting and Very Short Term Weather Forecasting (NWC) and to the definition of the relevant observation techniques. Studies on potential observation techniques and sensor concepts have been initiated, covering three distinct imagery missions dedicated to operational meteorology, with emphasis on nowcasting and very short term forecasting and two sounding missions: - The high resolution fast imagery mission aiming at 5 minutes revisit time with 0.5 km resolution - The full disk high spectral resolution imagery mission with a large number of spectral channels and with high radiometric performance - The lighting imagery mission, capable of detecting very low energy events with high reliability - The infrared sounding mission supporting NWP through the provision of atmospheric motion vectors and temperature and water vapour profiles - The UV/VIS/SWIR sounding mission dedicated to atmospheric chemistry The paper describes the MTG user requirements and the preliminary instruments concept, with emphasis on the observation missions.

Meteosat Third Generation (MTG) status of space segment definition

ESA and EUMETSAT have initiated joint preparatory activities for the formulation and definition of the Meteosat Third Generation (MTG) geostationary system to ensure the future continuity, and enhancement, of the current Meteosat Second Generation (MSG) system. The MTG programmatics are being established to ensure a seamless transition between the conclusion of the successful MSG operational system and the start of the new MTG operational system, with particular emphasis on continuity of the imagery missions. The MTG phase A studies were successfully concluded in December 2008 an re-consolidation phase B1 activities continued from January to July 2009. They were devoted to the MTG concept definition and requirements consolidation for meeting the User needs in the field of Nowcasting and Very Short Term Weather Forecasting (NWC), Medium/Short Range global and regional Numerical Weather Prediction (NWP), Climate, Air Quality and Composition Monitoring. The following missions have been analysed, measurement techniques studied and preliminary concepts established: - High Resolution Fast Imagery Mission (improved successor to MSG SEVIRI HRV mission) - Full Disk High Spectral Resolution Imagery Mission (improved successor to SEVIRI) - Lightning Imagery Mission - IR Sounding Mission - UV-VIS-NIR Sounding Mission Both space segment architecture and preliminary satellite and instrument concepts were investigated in the course of these studies, and a dual satellite configuration established comprising the Imaging satellite (MTG-I) and the sounding satellite (MTG-S). The study covered all elements to a level of detail allowing to establish a technical baseline, conclude on the feasibility of the system requirements and undertake preliminary programmatic evaluation. Riders to the Phase A studies (Phase B1 work) have been placed to further consolidate the satellite and payload definition and development, prior to the release of the Invitation To Tender (ITT) for the full space segment implementation in July 2009. This paper provides an overview of the conclusions of those MTG space segment studies. It summarises the conclusions reached for the satellites, and associated instruments relating to Imaging, IR Sounding and Lightning missions, with respect to achievable performances, including Radiometry and Image Navigation and Registration aspects.

Meteosat third generation: preliminary design of the imaging radiometers and sounding instruments

The operational deployment of MSG-1 at the beginning of 2004, the first of a series of four Meteosat Second Generation (MSG) satellites, marks the start of a new era in Europe for the meteorological observations from the geostationary orbit. The new system shall be the backbone of the European operational meteorological services up to at least 2015. The time required for the definition and the development of new space systems as well as the approval process of such complex programs implies anyhow to plan well ahead for the future missions. EUMETSAT have initiated in 2001, with ESA support, a User Consultation Process aiming at preparing for a future operational geostationary meteorological satellite system in the post-MSG era, named Meteosat Third Generation (MTG). The first phase of the User Consultation Process was devoted to the definition and consolidation of end user requirements and priorities in the field of Nowcasting and Very Short Term Weather Forecasting (NWC), Medium/Short Range global and regional Numerical Weather Prediction (NWP), Climate and Air Composition Monitoring and to the definition of the relevant observation techniques. The intermediate results of this first phase were presented to and discussed with the user community at the first Post-MSG User Consultation Workshop convened by EUMETSAT in November 2001 and further consolidated with the support of ESA in the area of potential observation techniques and sensor concepts via dedicated studies conducted in the 2003/2004 time frame. The following missions have been analysed and preliminary concepts studied: -High Resolution Fast Imagery Mission (successor to MSG SEVIRI HRV mission) -Full Disk High Spectral Resolution Imagery Mission (successor to the mission of other MSG-SEVIRI channels) -Lightning Imagery Mission -IR Sounding Mission -UV-VIS-NIR-SWIR Sounding Mission In March 2003, ESA and EUMETSAT derived technical requirements applicable to the MTG mission study where preliminary instrument concepts were investigated allowing in the same time to consolidate the technical requirements for the overall system study. This paper provides an overview of the outcome of the MTG observation techniques and sensor concept studies conducted in 2003-2004. It namely focuses onto the Imaging and Sounding Missions, highlights the resulting instrument concepts and introduces the study steps towards the implementation of the MTG development programme.

Potential of the MTG‐IRS mission to resolve small scale variability of atmospheric humidity

This paper describes the assessment analysis for the spatial scales relevant to humidity fields, which can be resolved with the infrared sounder planned for the Meteosat Third Generation. Our findings show that the current design of the infrared sounder should be able to achieve a vertical resolution of ≈1 km in the vertical. As far as the horizontal length scales are concerned, the analysis has shown the need of a Field of View of size less than 10 km.

Meteosat Third Generation: mission and system concepts

EUMETSAT and ESA initiated in 2000 joint preparatory activities for the formulation and definition of the Meteosat Third Generation (MTG) geostationary system, to ensure continuity and improvement of current Meteosat Second Generation (MSG) services. MTG will become the backbone of the European operational meteorological applications taking the relay from MSG by 2017, and warranting the continuation of the earth imagery mission supported by the Spin Enhanced Visible and Infrared Imager (SEVIRI). The early program definition phases were devoted to the discussion and consolidation of end user requirements and their priorities in meteorology fields as Nowcasting and Very Short Term Weather Forecasting (NWC), Medium/Short Range global and regional Numerical Weather Prediction (NWP), Climate and Air Composition Monitoring and the identification of the relevant observation techniques. In the system conceptualization process, the following missions have been analyzed: • Full Disc High Spectral resolution Imagery (FDHSI) • High Resolution and Fast Imagery (HRFI) • Lightning detection Mission (LI) • IR Sounding Mission (IRS) • UV-VIS-NIR Sounding Mission as a payload complement (UVN). After pre-phase A mission studies (2003-2006), where preliminary instrument concepts were investigated allowing the consolidation of the most critical and demanding technical requirements, phase A studies were launched at the beginning of February (2007-2008) addressing both the space segment system feasibility and ground and operations programmatic aspects. The space segment, phase A level, studies covered the entire suite of optical instruments identified in the preliminary assessments including: 1) a flexible combined imager for both FDHSI and HRFI missions; 2) a Fourier Transform Spectrometer for IRS observations; and 3) a lightning detector sensor. The study of concepts and implementation of the UVN mission are covered by the efforts of ESA and the European Union (EU) in the framework of the Global Monitoring for Environment and Security (GMES) Sentinel 4 program. This paper provides an overview of the outcome of the MTG System analyses at the end of phase A confirming its technical feasibility, the key characteristics of the intended missions, and the progress accomplished in the definition of the satellite optical payloads.

MTG-IRS: Status, Specifications and Technical Concept

A special EUMETSAT Council approved on 9 October 2008 the payload complement for the Meteosat Third Generation (MTG) satellites. MTG will for the first time carry a hyperspectral InfraRed Sounder (IRS) into a geo-stationary orbit. The IRS concept is that of a Fourier Transform Spectrometer covering two bands (700-1210 and 1600-2175 cm−1) with a spectral sampling of 0.625 cm−1. The IRS will be capable of observing the full disc with a repeat cycle of 60 min and a spatial sampling of 4 km. The launch of the IRS into the geostationary orbit is anticipated by early 2018.

Regional Retrieval Processor for Direct Broadcast High-Resolution Infrared Data

AbstractThe Space Science Engineering Center, in collaboration with the Mauna Kea Weather Center at the University of Hawai’i at Mānoa, has developed a regional retrieval processor for high-spectral-resolution infrared data. The core of the processor makes use of an inversion system, referred to as Mirto, which combines, in a Bayesian way, the a priori knowledge of the atmospheric state, based on available numerical weather prediction forecasts, with the physical information embedded in satellite observations. Forecast temperature and water vapor mixing ratio fields over the central North Pacific Ocean are adjusted to produce synthetic radiances closer and closer to the Suomi NPP Cross-track Infrared Sounder (CrIS) observations taken in clear-sky conditions. The paucity of synoptic observations over this area and the highly homogeneous background represented by the ocean provide a good framework for the implementation of this hyperspectral data inversion system. Nearly real-time (less than 60 min from ove...