Generation Geostationary Satellite Research Articles

Quality assessment of heterogeneous surface radiation network data

Abstract. The DWD national radiation measurement network comprises 82 automatic sites, 29 manned sites with shaded and unshaded pyranometer and the BSRN station at Lindenberg. The quality assessment routinely applied takes into account the basic astronomical and empirical considerations as well as some interdependencies like total to diffuse flux relation and cross checking with sunshine duration. A more advanced quality assessment approach attempts to routinely utilise timeseries of clear sky radiative transfer simulations for every site. For that purpose a link to cloud coverage obtained from Meteosat second generation geostationary satellite data, highly resolved in time and space, was established. There is a predefined calibration cycle of 30 month for automatic stations. Data analysis on this timescale allows for the detection of sensor degradation, wrong calibration or configuration and other possible local disturbances. Furthermore using satellite cloud mask enables the identification of larger clear sky regions characterized by similar atmospheric conditions. Thus, in a regionalization step correction or recalibration of moderate quality data to a higher level can be considered. The paper provides an overview of DWD surface radiation network and the current activities to improve automatic quality assessment using remotely sensed data and clear sky modeling for the upgrading of radiation data.

Incoming Solar and Infrared Radiation Derived from METEOSAT: Impact on the Modeled Land Water and Energy Budget over France

Abstract The Land Surface Analysis Satellite Applications Facility (LSA SAF) project radiation fluxes, derived from the Meteosat Second Generation (MSG) geostationary satellite, were used in the Interactions between Soil, Biosphere, and Atmosphere (ISBA) land surface model (LSM), which is a component of the Surface Externalisée (SURFEX) modeling platform. The Système d’Analyze Fournissant des Renseignements Atmosphériques à la Neige (SAFRAN) atmospheric analysis provides high-resolution atmospheric variables used to drive LSMs over France. The impact of using the incoming solar and infrared radiation fluxes [downwelling surface shortwave (DSSF) and longwave (DSLF), respectively] from either SAFRAN or LSA SAF, in ISBA, was investigated over France for 2006. In situ observations from the Flux Network (FLUXNET) were used for the verification. Daily differences between SAFRAN and LSA SAF radiation fluxes averaged over the whole year 2006 were 3.75 and 2.61 W m−2 for DSSF and DSLF, respectively, representing 2.5% and 0.8% of their average values. The LSA SAF incoming solar radiation presented a better agreement with in situ measurements at six FLUXNET stations than the SAFRAN analysis. The bias and standard deviation of differences were reduced by almost 50%. The added value of the LSA SAF products was assessed with the simulated surface temperature, soil moisture, and the water and energy fluxes. The latter quantities were improved by the use of LSA SAF satellite estimates. As many areas lack a high-resolution meteorological analysis, the LSA SAF radiative products provide new and valuable information.

An example of the use of synthetic 3.9 μm GOES-12 imagery for two-moment microphysical evaluation

In preparation for the launch of the next generation of geostationary satellites, considerable effort has been placed on developing new products and algorithms for operational purposes. In addition to satellite-based products and algorithms, satellite imagery can be used to evaluate numerical weather prediction models. Important first steps have already been undertaken to produce synthetic satellite imagery from numerical model output. By comparing synthetic imagery with observed imagery, model performance can be evaluated with a relatively new metric. In this paper, synthetic Geostationary Operational Environmental Satellite (GOES)-12 imagery was used to improve the two-moment prediction of pristine ice in the RAMS (Regional Atmospheric Modeling System) mesoscale model. A thunderstorm event that occurred on 27 June 2005 over the central plains of the USA was chosen for study. Synthetic GOES-12 3.9 μm imagery of RAMS output was compared with observed GOES-12 3.9 μm imagery. A discrepancy between brightness temperatures of two anvils of thunderstorms led to an improvement in the prediction of pristine ice number concentrations. After the model was re-run, subsequent synthetic GOES-12 3.9 μm imagery of one anvil exhibited an improvement compared with observed imagery. Brightness temperatures of the second anvil became too warm, an issue that may be related to model-specified cloud condensation nuclei (CCN) concentrations. This example highlights the potential importance of using synthetic imagery to evaluate numerical weather prediction models.

Wildfire Detection and Tracking over Greece Using MSG‑SEVIRI Satellite Data

Greece is a high risk Mediterranean country with respect to wildfires. This risk has been increasing under the impact of climate change, and in summer 2007 approximately 200,000 ha of vegetated land were burnt. The SEVIRI sensor, on board the Meteosat Second Generation (MSG) geostationary satellite, is the only spaceborne sensor providing five and 15-minute observations of Europe in 12 spectral channels, including a short-wave infrared band sensitive to fire radiative temperature. In August 2007, when the bulk of the destructive wildfires started in Greece, the receiving station, operated by the Institute for Space Applications and Remote Sensing, provided us with a time series of MSG-SEVIRI images. These images were processed in order to test the reliability of a real‑time detection and tracking system and its complementarity to conventional means provided by the Fire Brigade. EUMETSAT’s Active Fire Monitoring (FIR) image processing algorithm for fire detection and monitoring was applied to SEVIRI data, then fine-tuned according to Greek conditions, and evaluated. Alarm announcements from the Fire Brigade’s archives were used as ground truthing data in order to assess detection reliability and system performance. During the examined period, MSG-SEVIRI data successfully detected 82% of the fire events in Greek territory with less than 1% false alarms.

Comparing Operational MSG/SEVIRI Land Surface Albedo Products From Land SAF With Ground Measurements and MODIS

This study is devoted to an assessment of the quality performance of the Satellite Application Facility on Land Surface Analysis (LSA-SAF) albedo products, which are generated from the high frequency of observations now offered by the Meteosat Second Generation (MSG) geostationary satellite series. Land surface albedo products are compared against in situ measurements and the analogous products from the Collection 4 of Moderate Resolution Imaging Spectroradiometer (MODIS) in domains in European and Northern African regions. We find a good consistency with MODIS broadband shortwave and near-infrared directional-hemispherical reflectance (DHR) over midlatitude regions. Comparative statistics indicate biases below 0.01 in absolute and 5% in relative terms, and an average root-mean-square error (RMSE) around 0.03 for all situations, including in snow cases. The comparison for shortwave bihemispherical reflectance (BHR) shows an even better match over herbaceous cover with respective values for bias and RMSE of 0.007 and 0.012. Broadband visible BHR from LSA-SAF overestimates MODIS equivalent albedo product by 20%, which seems to be caused by remaining uncertainties in narrowband-to-broadband conversion, residual aerosol signals, and the use of a different bidirectional reflectance distribution function (BRDF) model. The commendable statistical results obtained over bright desert targets such as Northern Africa are worth noticing. Assuming that the MODIS product is a good reference, a relative bias of 10% can be judged satisfactory for the LSA-SAF snow-free broadband DHR values. In addition, quarter-hourly MSG observations better capture snow episodes, although some discrepancies appear for areas with high vegetation cover.

Towards Multidecadal Consistent Meteosat Surface Albedo Time Series

Monitoring of land surface albedo dynamics is important for the understanding of observed climate trends. Recently developed multidecadal surface albedo data products, derived from a series of geostationary satellite data, provide the opportunity to study long term surface albedo dynamics at the regional to global scale. Reliable estimates of temporal trends in surface albedo require carefully calibrated and homogenized long term satellite data records and derived products. The present paper investigates the long term consistency of a new surface albedo product derived from Meteosat First Generation (MFG) geostationary satellites for the time period 1982–2006. The temporal consistency of the data set is characterized. The analysis of the long term homogeneity reveals some discrepancies in the time series related to uncertainties in the characterization of the sensor spectral response of some of the MFG satellites. A method to compensate for uncertainties in the current data product is proposed and evaluated.

Utilizing Total Lightning Information to Diagnose Convective Trends

suMMArY And Con-Clusions. The use of real-time output from the NALMA has proven benefi-cial to NWS forecasting and warning decision-making. Beyond the standard analysis of cloud-to-ground lightning information, the ability to visualize three-dimensional total lightning within thun-derstorms has provided fore -casters with greater knowl-edge of storm-scale processes and enhanced warning oper -ations. This has led to greater confidence when issuing severe thunderstorm and tornado warnings.Preliminary studies and forecaster surveys suggest that the inclusion of total lightning information pro-vides a unique insight into storm-scale structures that may be crucial to increasing warning lead times and severe storm discernment, especially in situations where radar and other obser-vational datasets provide conflicting signals or partial information. However, further research is certainly needed to develop a more quantifiable measure of the “added value” of total lightning information. To date, over 150 specific cases have been archived for collab-orative post-storm analyses, training, and research purposes. A further emphasis should also be placed on null cases (e.g., when lightning jumps are observed with no associated reports of severe weather) to gain a better understanding of the false-alarm potential of perceived lightning jumps. Likewise, greater em-phasis should be placed on the detection efficiency of ground-based networks so forecasters can recognize when artificial trends in lightning data are strictly related to efficiency or range issues.Building upon the knowledge and lessons learned from the NWS Huntsville and NASA/SpoRT expe-rience in transferring total lightning observations into operations, other offices with nearby total lightning networks have been able to utilize total lightning products in their forecast operations. One outgrowth of this collaboration is Southern Thunder, which brings together total lightning data and product producers and decision-making consumers for periodic workshops to advance the scientific understanding of thunderstorm processes and help develop nowcasting and warning decision-making applications that use total lightning in an operational environment. Presentations from the July 2009 Southern Thunder Workshop can be found at http://weather.msfc.nasa.gov/sport/southern-thunder/presentations.html.Finally, related training and operational experience associated with the NALMA project have aided similar initiatives across the country. Moreover, when the next generation of geostationary satellites are launched

Aerosol remote sensing over the ocean using MSG‐SEVIRI visible images

With its observational frequency of 15 minutes, the Meteosat Second Generation (MSG) geostationary satellite offers a great potential to monitor aerosol transport using Spinning Enhanced Visible and Infra‐Red Imager (SEVIRI) data. To explore this potential, an algorithm for the retrieval of aerosol optical properties has been developed for use over the ocean. It is a multispectral algorithm based on the single‐view algorithm for the Along Track Scanning Radiometer (ATSR‐2) (Veefkind and de Leeuw, 1998) which has been adapted to the corresponding channels of SEVIRI (635 nm, 810 nm and 1640 nm). The SEVIRI Aerosol Retrieval Algorithm (SARA) provides the Aerosol Optical Depth (AOD) for these channels. To illustrate its capabilities, the application of this algorithm to two cases is presented: (1) a forest‐fire smoke plume advected from Spain and Portugal over the Atlantic Ocean in August 2006, and (2) an outbreak of Saharan dust over the Western Mediterranean Sea in February 2006. The results obtained are validated with AERONET ground‐based measurements for two coastal stations, and compared with the retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites. The diurnal variations of the aerosol optical depth observed at the AERONET sites are well reproduced, and the spatial patterns retrieved using the SARA algorithm are in reasonable agreement with those observed by MODIS.

Sensible and latent heat flux from radiometric surface temperatures at the regional scale: methodology and evaluation

Abstract. The CarboEurope Regional Experiment Strategy (CERES) was designed to develop and test a range of methodologies to assess regional surface energy and mass exchange of a large study area in the South-Western part of France. This paper describes a methodology to estimate sensible and latent heat fluxes on the basis of net radiation, surface radiometric temperature measurements and information obtained from available products derived from the Meteosat Second Generation (MSG) geostationary meteorological satellite, weather stations and ground-based eddy covariance towers. It is based on a simplified bulk formulation of sensible heat flux that considers the degree of coupling between the vegetation and the atmosphere and estimates latent heat as the residual term of net radiation. Estimates of regional energy fluxes obtained in this way are validated at the regional scale by means of a comparison with direct flux measurements made by airborne eddy-covariance. The results show an overall good matching between airborne fluxes and estimates of sensible and latent heat flux obtained from radiometric surface temperatures that holds for different weather conditions and different land use types. The overall applicability of the proposed methodology to regional studies is discussed.

EUMETSAT Geostationary Satellite Monitors the Sea Surface Temperatures of the Atlantic and Indian Oceans since 2004

The atmosphere and oceans have been monitored by a EUMETSAT Meteosat Second Generation Geostationary Satellite in the Eastern Atlantic and Western Indian Oceans and adjacent Seas since 2004. This satellite provides daily atmospheric weather conditions and is a valuable climate research tool. We demonstrate that it is also useful for monitoring ocean surface temperatures and oceanic patterns associated with currents, eddies and upwelling. Meteo-France provides an hourly, cloud cleared, validated sea surface temperature product at intervals of 5 km with an accuracy of about 0.5° C relative to in-situ values. Image composites are used to reduce cloud cover at daily and seasonal time scales. Several examples of surface ocean patterns and temperature profiles are used to illustrate the advantages and limitations of the composites and include: Atlantic Tropical Instability Waves, cold core eddies in the lee of the Canary Islands, meanders of the Agulhas Current off South Africa, coastal upwelling along southwestern Spain and temperatures between Gotland Island and the shallow Curonian Lagoon on the coast of Lithuania.

Clouds-Aerosols-Precipitation Satellite Analysis Tool (CAPSAT)

Abstract. A methodology for representing much of the physical information content of the METEOSAT Second Generation (MSG) geostationary satellite using red-green-blue (RGB) composites of the computed physical values of the picture elements is presented. The physical values are the solar reflectance in the solar channels and brightness temperature in the thermal channels. The main RGB compositions are (1) "Day Natural Colors", presenting vegetation in green, bare surface in brown, sea surface in black, water clouds as white, ice as magenta; (2) "Day Microphysical", presenting cloud microstructure using the solar reflectance component of the 3.9 μm, visible and thermal IR channels; (3) "Night Microphysical", also presenting clouds microstructure using the brightness temperature differences between 10.8 and 3.9 μm; (4) "Day and Night", using only thermal channels for presenting surface and cloud properties, desert dust and volcanic emissions; (5) "Air Mass", presenting mid and upper tropospheric features using thermal water vapor and ozone channels. The scientific basis for these rendering schemes is provided, with examples for the applications. The expanding use of these rendering schemes requires their proper documentation and setting as standards, which is the main objective of this publication.

A dynamic cloud masking and filtering algorithm for MSG retrieval of land surface temperature

A dynamic cloud masking and filtering algorithm is proposed for the Land Surface Temperature (LST) retrieval from infrared imagery of geostationary satellites. The algorithm uses a modified Kalman Filter (KF) to separate the non‐Gaussian error due to clouds from the reference cloud‐free LST retrieval error, in order to discriminate and possibly correct for different levels of cloud contamination. This approach was intended to make better use of the important features of the new generation of geostationary satellites, such as the Meteosat Second Generation (MSG) satellites, including their high sampling frequency and the extensive real‐time availability of images. The reference surface energy balance model on which the KF is based was simplified to the extent that no information other than top‐of‐atmosphere solar radiation was required to force the system together with LST measurements. The overall accuracy of the new algorithm, named Cloud Masking with Kalman Filter (CMKF), was tested on the LST retrievals over the Italian peninsula for a 15‐day summer period from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) sensor onboard the MSG satellite. As a verification dataset, analogous retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used. The higher spatial resolution of the MODIS LST maps and accompanying cloud masks also allowed us to analyse the results in terms of different levels of fractional cloud cover. The results of these first verification experiments show that the application of the proposed dynamic algorithm improves the LST retrieval, with respect to cloud masking with a classical static algorithm, in two different ways: first, there is a more consistent identification of cloud‐free LST data; and second, and more importantly, there is a substantial increase in the quantity of final LST estimates, up to four times more in very cloudy conditions, with the use of prior model predictions at a cost of a very modest increase in the LST root mean squared error (RMSE). Moreover, the higher coefficient of determination in both cases indicates that the algorithm provides LST estimates over a wider range, as it is capable of reconstructing with some accuracy certain lower LST values under cloud cover.

The time-space exchangeability of satellite retrieved relations between cloud top temperature and particle effective radius

Abstract. A 3-minute 3-km rapid scan of the METEOSAT Second Generation geostationary satellite over southern Africa was applied to tracking the evolution of cloud top temperature (T) and particle effective radius (re) of convective elements. The evolution of T-re relations showed little dependence on time, leaving re to depend almost exclusively on T. Furthermore, cloud elements that fully grew to large cumulonimbus stature had the same T-re relations as other clouds in the same area with limited development that decayed without ever becoming a cumulonimbus. Therefore, a snap shot of T-re relations over a cloud field provides the same relations as composed from tracking the time evolution of T and re of individual clouds, and then compositing them. This is the essence of exchangeability of time and space scales, i.e., ergodicity, of the T-re relations for convective clouds. This property has allowed inference of the microphysical evolution of convective clouds with a snap shot from a polar orbiter. The fundamental causes for the ergodicity are suggested to be the observed stability of re for a given height above cloud base in a convective cloud, and the constant renewal of growing cloud tops with cloud bubbles that replace the cloud tops with fresh cloud matter from below.

Next generation GOES satellite power subsystem

Hughes space and communications was awarded a contract in January 1998 from NASA's Goddard Space Flight Center for the design, manufacture, integration and launch of two next generation geostationary operational environmental satellites (GOES) and options for two additional satellites. The satellites measure weather phenomena as the primary mission and X-rays and charged particles as the secondary missions. This paper describes the GOES electrical power subsystem (EPS) requirements, architecture, hardware and energy balance analysis. As of this writing, the design of the EPS has completed the critical design review phase and the hardware has entered the manufacturing phase.

Radiometric calibration of the GERB instrument

The balance between the incoming solar radiation from the Sun and the outgoing reflected and scattered solar radiation and thermal-infrared emission from the Earth, the so-called Earth Radiation Budget (ERB), provides information on the fundamental energy source of the climate system [1]. To fulfil global coverage and sampling requirements, the ERB measurements have to be made from space. Broadband measurements are necessary because all spectral regions in both the solar and infrared contribute to the Earth's radiative fluxes. The Geostationary Earth Radiation Budget instrument (GERB) will be launched on the Meteosat Second Generation (MSG) geostationary satellite in the year 2000. Both short-wave (0.32 µm to 4 µm) and total (0.32 µm to 30 µm) radiance measurements will be made, with long-wave (4 µm to 30 µm) data obtained by subtraction. The accuracy requirements, 1% short-wave and 0.5% long-wave, are challenging but consistent with previous radiation-budget measurements. The instrument will be characterized and calibrated on the ground prior to launch. The radiometric calibration is performed using two black bodies and a lamp-illuminated, integrating-sphere source in the near field. In this paper we describe the calibration algorithm and procedure.

Radar rift

A series of record‐setting weather‐related disasters has brought the issue of modernizing the U.S. National Weather System (NWS) once again to the fore. The modernization, which includes implementing 160 Doppler weather surveillance radars, or the Next Generation of Weather Radar (NEXRAD), hundreds of Automated Surface Observing Systems, next generation Geostationary Operational Environmental Satellites, and supercomputers, has proceeded more slowly than planned. To date, about half of the NEXRAD units have been installed, and only 12 of these 80 are operational. Concern remains about local limitations of the system, especially now that the Defense Department and National Oceanic and Atmospheric Administration will be sharing facilities under a new administration initiative. At a recent space subcommittee hearing, Rep. Bud Cramer (D‐Ala.) said he plans to introduce legislation to allow geographic areas, such as northern Alabama and the Tenessee Valley, that fall between the range of the new radars to request a scientific evaluation as to whether the NWS plan will meet the community's needs.

Introducing GOES-I: The First of a New Generation of Geostationary Operational Environmental Satellites

Abstract In the spring of 1994, the first of the National Oceanic and Atmospheric Administration's (NOAA's) next generation of geostationary satellites, GOES-I, is scheduled for launch. The introduction of this major component of NOAA's modernization represents a significant advance in geostationary remote sensing. All major components of the GOES-1 system are new or greatly improved: 1) the satellite is earth oriented to improve instrument performance; 2) sounding and imaging operations are now performed by different and separate instruments; 3) a five-band multispectral radiometer with higher spatial resolution improves imaging capabilities; 4) a sounder with higher radiometric sensitivity enables operational temperature and moisture profile retrieval from geostationary altitude for the first time; 5) a different data format is used to retransmit raw data to direct receive users; and 6) a new ground data processing system handles the high data volume and distributes advanced products to a variety of use...