Rainer Hollmann

REMO Cloud Modeling: Improvements and Validation with ISCCP DX Data

Abstract The grid-scale cloud properties of the Regional-Scale Model (REMO) are compared with the cloud retrievals derived from the International Satellite Cloud Climatology Project (ISCCP) “DX” datasets for the Baltic Sea Experiment region in March of 1994. For the uppermost cloud layer, the layer seen by a satellite instrument, the original REMO cloud scheme gives an ice cloud cover amount of about 90%, and the water cloud cover is close to zero. As compared with ISCCP, this result is an overestimation of ice clouds by up to 60% and underestimation of water clouds by up to 40%. To improve the REMO cloud results, a sensitivity study is carried out that shows that ice heterogeneous nucleation is the most influential process in the REMO cloud scheme. Cloud properties derived from the new REMO cloud scheme show that the amount of grid-scale ice clouds has decreased by about 40% and that of grid-scale water clouds has increased by about 20% in comparison with the old version. When compared with the ISCCP clo...

Study of aerosol impact on the earth radiation budget with satellite data

Abstract Preliminary to the launch of the first Meteosat Second Generation satellite and within support of the Geostationary Earth Radiation Budget experiment onboard of MSG, algorithms are tested to detect aerosol optical parameters and their possible signature on the Earth Radiation Budget using existing data from instruments on satellites in low earth orbit like NOAA/AVHRR and ScaRaB.

Satellite retrieved clouds and the radiation budget in support of BALTEX regional studies

Abstract We present in our paper two methods to use satellite data for a comparison with a regional scale model for the Baltic sea area. Two examples are given, first to derive the radiation budget from measurements with a scanning radiometer and second to make use of the cloud information from ISCCP. First results show good agreement and demonstrate their capability to improve regional scale models. The disadvantages are mainly the poor sampling (first method) and in the second case the coarse resolution. After an introduction and a brief discussion of the regional scale model and the instrument design of the Scanner for Radiation Budget, we present the comparison of ScaRaB and the model calculated radiation. After that we discuss a comparison of the ISCCP cloud data with the model.

The surface shortwave net flux from the scanner for radiation budget (SCARAB)

Abstract Shortwave surface net radiation is usually determined by combining the measurement of insolation with an independent estimate of surface albedo. However, uncertainties associated with each of these quantities may lead to large errors in the value of net surface solar radiation. An alternative approach is to deduce the net solar flux (the term flux is used here as the radiometric quantity flux density) at the surface directly from the budget at the top of the atmosphere, without explicit knowledge of surface albedo. The Satellite Application Facility on Climate Monitoring is a joint project of the German Meteorological Service and other European Meteorological Services dedicated to produce climate data sets using data from instruments onboard of METEOSAT Second Generation and polar orbiting satellites NOAA and METOP. In this context, it is planned to use the Li-Leighton algorithm as a validation tool for the independently derived solar incoming radiation at teh surface and the surface albedo. In the framework of the current development phase of the Satellite Application Facility on Climate Monitoring project, data from the well calibrated Scanner for Radiation Budget are used to apply the Li and Leighton algorithm to compute the shortwave surface net radiation.

Aerosol impact on the earth radiation budget with satellite data

Preliminary to the launch of the first Meteosat Second Generation satellite (MSG) and within support of the Geostationary Earth Radiation Budget (GERB) instrument onboard of MSG, algorithms are tested to detect aerosol optical parameters and their possible signature on the Earth Radiation Budget (ERB) using existing data from instruments on satellites in low earth orbit like NOAA/AVHRR and ScaRaB.

ScaRaB as a valuable tool for BALTEX and MAGS

Abstract A study is presented to derive regional earth radiation budget product with high spatial and temporal resolution by synergy of the well calibrated scanner for radiation budget (ScaRaB) data with auxiliary data from the operational meteorological satellites. The topic of a narrow-broadband conversion from NOAA 11 AVHRR channel 1 to the broadband shortwave channel of ScaRaB is addressed. This splits up into a narrow-to-narrowband conversion to go from NOAA AVHRR to ScaRaB visible radiances and into a narrow-to-broadband conversion for ScaRaB. As a preliminary result for the BALTEX area, a simultaneous overpass of ScaRaB and NOAA 11 over the Baltic Sea area is analysed. The errors due to the narrow-to-broadband conversion are in the order of 25 W/m 2 on an instantaneous basis.

A regional earth radiation budget derived with ScaRaB for validation purposes in BALTEX

Abstract From February 1994 to February 1995 the well calibrated Scanner for Radiaton Budget (ScaRaB) was in orbit on the Russian METEOR 3–7 satellite. First products consist of longwave and shortwave fluxes on a spatial scale of 60 x 60 km2 at nadir. Due to the very good calibration of the instrument it is very well suited for comparison of the earth radiation components with those computed by mesoscale atmosperic models. This is done here for the regional scale model REMO which is in use for modelling activities within the BALTEX programmes. Results of this comparison for the outgoing longwave radiation for March 1994 are shown. Additionaly the mean clear sky longwave cloud forcing for March 1994 is investigated. The difference between the measurement and the model are very small and in the order of 5 to 10 WW, which is well within the uncertainty of the measurements from ScaRaB. Together with a method developed to derive a high spatial and temporal earth radiation budget product from the ScaRaB measurements it is expected to extend the investigation to the shortwave flux. A comparison of instantaneous measurements of the albedo derived from NOAA-AVHR with model results are shown

Comparison of ScaRaB narrowband visible channel with other satellite instruments

Abstract A comparison of co-aligned, simultaneous measurements of METEOSAT 5 visible channel and ScaRaB/Meteor visible channel is presented. The METEOSAT data is calibrated using the ISCCP calibration in two steps: (1) nominal calibration, the best information available at the begin of data processing, and (2) absolute calibration, derived from comparison with the calibrated reference instrument (NOAA11, AVHRR). The comparison with the METEOSAT nominal calibration shows a good agreement between ScaRaB and METEOSAT for the entire duration of the ScaRaB mission. Absolutely calibrated data show a less good agreement and significant change in time. The ScaRaB and METEOSAT 5 instrument seem to be subject of the same degradation, if any. With respect to the NOAA11 standard, ScaRaB (and METEOSAT) seem to increase its sensitivity with time.

Aerosol impact on the Earth radiation budget in support of the Geostationary Earth Radiation Budget (GERB) experiment

Preliminary to the launch of the first Meteosat Second Generation (MSG) satellite and within support of the Geostationary Earth Radiation Budget experiment onboard of MSG, algorithms are tested to retrieve aerosol optical parameters and their possible signature on the Earth Radiation Budget (ERB). For this existing data from instruments on satellites in low earth orbit is used like NOAA/AVHRR and ScaRaB. In particular AVHRR data are used for retrieving aerosol optical parameters which then will be related to ERB measurements from ScaRaB.

Aerosol impact on the Earth radiation budget-a study in support of the Geostationary Earth Radiation Budget experiment

Preliminary to the launch of the first Meteosat Second Generation satellite (MSG) and within support of the Geostationary Earth Radiation (GERB) instrument onboard MSG, algorithms are tested to detect aerosol optical parameters and their possible signature on the Earth Radiation Budget (ERB) using existing data from instruments on satellites in low Earth orbit like NOAA/AVHRR and ScaRaB.