[1] In this study we prove the feasibility of the advanced very high resolution radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer sea surface temperature algorithms to derive operational lake surface water temperature (LSWT). A validation study covering 2 years was done using data from the AVHRR on NOAA 12, 15, 16, and 17, the MODIS on TERRA, and AQUA and with different method-ingested in situ data from different sized lakes. Best results were found for NOAA 16 nighttime data at Lake Geneva (bias of 0.18 K and standard deviation of 0.73 K) and TERRA nighttime data at Lake Constance (satellite-buoy bias of À0.08 K and standard deviation of 0.92 K). For all sensor families an overall scatter ranging from 0.9 to 1.6 K was found. Bias of MODIS is larger, À1.73 to 1.9 K, than the one of the AVHRR (À0.28 to 1.5 K). The current orbital configuration of the platforms used revealed the diurnal evolution of the lake surface temperature amplitude from space. The damped mixing found for a typical calm and clear-sky regime is different from open ocean conditions. As the main error source, we found undetected cloudy pixel. Furthermore, the physical difference between skin and bulk temperature, especially its relation to the diurnal thermocline, solar insolation, and wind stress contributes to the bias and scatter within the match-up data set. The data sets have been validated to allow further application for LSWT climatology and assimilation into numerical weather prediction models.Citation: Oesch, D. C., J.-M. Jaquet, A. Hauser, and S. Wunderle (2005), Lake surface water temperature retrieval using advanced very high resolution radiometer and Moderate Resolution Imaging Spectroradiometer data: Validation and feasibility study,

[1] Aerosol optical depth was retrieved from a time series of NOAA-16 AVHRR data from May 2001 through December 2002 for Central Europe (40.5°N-50.0°N, 0°E-17°E). In contrast to classical methods, no a priori knowledge of the surface reflectance is necessary, but instead the surface reflectance is estimated from a time series including the previous 44 days. Additionally, the area where aerosol optical depth can be retrieved is no longer limited to certain land cover types. Only bright surface targets are excluded in the retrieval. To retrieve the aerosol optical depth, the radiative transfer code SMAC is used. Afterwards the data are averaged within a 25 Â 25 pixel region to increase the retrieval precision. The resulting standard deviation of the aerosol optical depth within this region is used as a quality control parameter and suitable for a post-processing of the initial aerosol retrieval. This post-processing leads to a substantial increase in the retrieval accuracy when compared to ground-based AERONET measurements. Over 650 co-incident AVHRR retrievals and AERONET measurements were compared, and a correlation coefficient of 0.70 was found. Altogether, the proposed method offers the potential to generate an aerosol climatology based on NOAA AVHRR data, which dates back to the early 1980s.

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f-element sandwich complexes bearing a η5-plumbole ligand are reported. Quantum chemical calculations suggest that this ligand retains its aromaticity upon coordination. The Er complexes show SMM behavior including magnetic hysteresis.

Novel lanthanide multi-decker complexes were established utilizing dianionic group 14 metallole ligands. The dimensionality of the multidecker species increases from a dimeric structure to 2D depending on the lanthanide ion and the metallole ligand.

[1] In this study, the remote sensing of aerosol optical depth (t a ) from the geostationary Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) is demonstrated. The proposed method is based on the analysis of a time series of SEVIRI's 0.6 mm channel images. Top-of-atmosphere reflectance is precorrected for the effect of atmospheric gases and a background aerosol amount. Subsequently, surface reflectance for each pixel is estimated by determining its lowest precorrected reflectance within the observed time period for each satellite observation time of the day. The resulting diurnal surface reflectance curve in combination with the radiative transfer code SMAC are finally used to derive t a . This approach is applied to SEVIRI subscenes of central Europe (40.8-51.3°N, 0.3°W-19.9°E) from August 2004, daily acquired between 0612 and 1712 UTC in intervals of 15 min. SEVIRI t a are related to Aerosol Robotic Network (AERONET) Sun photometer measurements from nine sites. About 3200 instantaneous SEVIRI and Sun photometer t a are compared. An overall correlation of 0.9 and a root mean square error of 0.08 are obtained. Further, the spatial distribution of SEVIRI t a maps for August 2004 represent expectable features like higher concentrations in industrialized regions or lower loading in higher altitudes. It is concluded that the described method is able to provide an estimate of t a from MSG-SEVIRI data. Such aerosol maps of high temporal frequency could be of interest to atmospheric related sciences, e.g., to track aerosol particle transport.Citation: Popp, C., A. Hauser, N. Foppa, and S. Wunderle (2007), Remote sensing of aerosol optical depth over central Europe from MSG-SEVIRI data and accuracy assessment with ground-based AERONET measurements,

Abstract. The Advanced Very High Resolution Radiometer (AVHRR) carried on board the National Oceanic and Atmospheric Administration (NOAA) and the Meteorological Operational Satellite (MetOp) polar orbiting satellites is the only instrument offering more than 25 years of satellite data to analyse aerosols on a daily basis. The present study assessed a modified AVHRR aerosol optical depth τ a retrieval over land for Europe. The algorithm might also be applied to other parts of the world with similar surface characteristics like Europe, only the aerosol properties would have to be adapted to a new region. The initial approach used a relationship between Sun photometer measurements from the Aerosol Robotic Network (AERONET) and the satellite data to post-process the retrieved τ a . Herein a quasistand-alone procedure, which is more suitable for the pre-AERONET era, is presented. In addition, the estimation of surface reflectance, the aerosol model, and other processing steps have been adapted. The method's cross-platform applicability was tested by validating τ a from NOAA-17 and NOAA-18 AVHRR at 15 AERONET sites in Central Europe (40.5 • N-50 • N, 0 • E-17 • E) from August 2005 to December 2007. Furthermore, the accuracy of the AVHRR retrieval was related to products from two newer instruments, the Medium Resolution Imaging Spectrometer (MERIS) on board the Environmental Satellite (ENVISAT) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Aqua/Terra. Considering the linear correlation coefficient R, the AVHRR results were similar to those of MERIS with even lower root mean square error RMSE. Not surprisingly, MODIS, with its high spectral coverage, gave the Correspondence to: M. Riffler (riffler@giub.unibe.ch) highest R and lowest RMSE. Regarding monthly averaged τ a , the results were ambiguous. Focusing on small-scale structures, R was reduced for all sensors, whereas the RMSE solely for MERIS substantially increased. Regarding larger areas like Central Europe, the error statistics were similar to the individual match-ups. This was mainly explained with sampling issues. With the successful validation of AVHRR we are now able to concentrate on our large data archive dating back to 1985. This is a unique opportunity for both climate and air pollution studies over land surfaces.

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