Processing, geocoding and mosaicking of MiSAR data

EADS MiSAR ist ein Miniatur FM-CW Ka-Band SAR-System, entwickelt für UAVPlattformen wie dem Deutschen LUNA-System. MiSAR kann Echtzeit ("Video-ähnliche") SAR-Bilder liefern. In diesem Modus werden SAR-Bilder mit einer Rate von ~1 Hz erzeugt, mit einem Überlappungsbereich von ~90% zwischen aufeinander folgenden Bildern. Im vorliegenden Artikel wird ein Ansatz präsentiert, wie aufeinander foldende Bilder sequenziell, mit Hilfe von Flugzeug-Navigationsdaten, einem Geländemodell sowie den Range-Doppler Gleichungen geokodiert werden. Das Resultat der anschliessenden Mosaikierung ist ein Bildstreifen beliebiger Länge. Um eine optimale Grundlage für Geokodierung bereitzustellen wurde eigens ein neues, SPECAN-basiertes Fokussierungsverfahren implementiert, welches aus den "range-komprimierten" Daten die benötigten Einzelbilder samt geometrischen Parametern liefert. Die Ergebnisse zeigen eine gute Fokussierungsqualität sowie eine sehr hohe Geokodierungs-Genauigkeit. Die Implementierung erlaubt eine Geokodierung/Mosaikierung auf beliebige geodätische und kartographische Referenzsysteme

Regional Aerosol Optical Properties and Radiative Impact of the Extreme Smoke Event in the European Arctic in Spring 2006

In spring 2006 a special meteorological situation occurred in the European Arctic region giving record high levels of air pollution. The synoptic situation resulted in extensive transport of pollution predominantly from agricultural fires in Eastern Europe into the Arctic region and record high air-pollution levels were measured at the Zeppelin observatory at Ni-Alesun(78deg 54'N, 11deg 53'E) in the period from 25 April to 12 May. In the present study we investigate the optical properties of the aerosols from this extreme event and we estimate the radiative forcing of this episode. We examine the aerosol optical properties from the source region and into the European Arctic and explore the evolution of the episode and the changes in the optical properties. A number of sites in Eastern Europe, Northern Scandinavia and Svalbard are included in the study. In addition to AOD measurements, we explored lidar measurements from Minsk, ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research at Andenes) and Ny-Alesund. For the AERONET sites included (Minsk, Toravere, Hornsund) we have further studied the evolution of the aerosol size. Importantly, at Svalbard it is consistency between the AERONET measurements and calculations of single scattering albedo based on aerosol chemical composition. We have found strong agreement between the satellite dally MODIS AOD and the ground-based AOD observations. This agreement is crucial for the radiative forcing calculations. We calculate a strong negative radiative forcing for the most polluted days employing the analysed ground based data, MODIS AOD and a multi-stream model for radiative transfer of solar radiation

Earlinet - lidar algorithm intercomparison

Postprint (published version

SAR AND OBLIQUE AERIAL OPTICAL IMAGE FUSION FOR URBAN AREA IMAGE SEGMENTATION

The fusion of synthetic aperture radar (SAR) and optical data is a dynamic research area, but image segmentation is rarely treated. While a few studies use low-resolution nadir-view optical images, we approached the segmentation of SAR and optical images acquired from the same airborne platform – leading to an oblique view with high resolution and thus increased complexity. To overcome the geometric differences, we generated a digital surface model (DSM) from adjacent optical images and used it to project both the DSM and SAR data into the optical camera frame, followed by segmentation with each channel. The fused segmentation algorithm was found to out-perform the single-channel version

Multi-Channel Radar at 35 GHz for Airborne SAR-Applications

In this paper, we present the upgraded MIRANDA-35 SAR system, which has been extended by three additional receiving channels. The adapted antenna configuration enables simultaneous interferometric and polarimetric SAR measurements. We describe the improved frontend setup and the new data acquisition including the chirp generation board. The first results from an airborne campaign in Switzerland conclude the paper and demonstrate the capabilities of the four-channel Ka-band sensor

Aerosol lidar intercomparison in the framework of the EARLINET project. 3. Raman lidar algorithm for aerosol extinction, backscatter, and lidar ratio

An intercomparison of the algorithms used to retrieve aerosol extinction and backscatter starting from Raman lidar signals has been performed by 11 groups of lidar scientists involved in the European Aerosol Research Lidar Network (EARLINET). This intercomparison is part of an extended quality assurance program performed on aerosol lidars in the EARLINET. Lidar instruments and aerosol backscatter algorithms were tested separately. The Raman lidar algorithms were tested by use of synthetic lidar data, simulated at 355, 532, 386, and 607 nm, with realistic experimental and atmospheric conditions taken into account. The intercomparison demonstrates that the data-handling procedures used by all the lidar groups provide satisfactory results. Extinction profiles show mean deviations from the correct solution within 10% in the planetary boundary layer (PBL), and backscatter profiles, retrieved by use of algorithms based on the combined Raman elastic-backscatter lidar technique, show mean deviations from solutions within 20% up to 2 km. The intercomparison was also carried out for the lidar ratio and produced profiles that show a mean deviation from the solution within 20% in the PBL. The mean value of this parameter was also calculated within a lofted aerosol layer at higher altitudes that is representative of typical layers related to special events such as Saharan dust outbreaks, forest fires, and volcanic eruptions. Here deviations were within 15%. (C) 2004 Optical Society of America

Theatre Royal William Anderson's Season 1906

An intercomparison of the algorithms used to retrieve aerosol extinction and backscatter starting from Raman lidar signals has been performed by 11 groups of lidar scientists involved in the European Aerosol Research Lidar Network (EARLINET). This intercomparison is part of an extended quality assurance program performed on aerosol lidars in the EARLINET. Lidar instruments and aerosol backscatter algorithms were tested separately. The Raman lidar algorithms were tested by use of synthetic lidar data, simulated at 355, 532, 386, and 607 nm, with realistic experimental and atmospheric conditions taken into account. The intercomparison demonstrates that the data-handling procedures used by all the lidar groups provide satisfactory results. Extinction profiles show mean deviations from the correct solution within 10% in the planetary boundary layer (PBL), and backscatter profiles, retrieved by use of algorithms based on the combined Raman elastic-backscatter lidar technique, show mean deviations from solutions within 20% up to 2 km. The intercomparison was also carried out for the lidar ratio and produced profiles that show a mean deviation from the solution within 20% in the PBL. The mean value of this parameter was also calculated within a lofted aerosol layer at higher altitudes that is representative of typical layers related to special events such as Saharan dust outbreaks, forest fires, and volcanic eruptions. Here deviations were within 15%. (C) 2004 Optical Society of America

Föohn/cold-pool interactions in the Rhine valley during MAP IOP 15

The föhn/cold-pool interactions in the lower Alpine Rhine valley documented in the framework of the Intensive Observing Period (IOP) 15 of the Mesoscale Alpine Programme (MAP) on 5 November 1999 are analysed. The present study focuses on the water vapour mixing ratio measurements acquired with the airborne differential absorption lidar LEANDRE 2 which enabled detailed documentation of the along-valley structure of the cold pool. LEANDRE 2 and microbarograph measurements revealed the presence of Kelvin-Helmholtz waves (KHW) at the top of the cold pool. The characteristics of the waves were different in the region of the cold- pool leading edge (the southernmost part of the cold pool) and in the vicinity of the Bodensee (Lake Constance), further to the north. Gravity waves were also observed above the cold pool in the in situ aircraft data acquired in the vicinity of the Bodensee. The gravity waves are suspected to be triggered by the KHW at the top of the cold pool. We also investigate the respective role of the three known processes likely to control the structure of the cold pool and its erosion along the Rhine valley, namely (i) convection within the cold pool, (ii) turbulent erosion at the top of the cold pool due to the presence of KHW, and (iii) dynamic displacement of the cold pool by föhn air. The former two processes are likely not to play a role in the erosion of the cold pool observed in the course of this IOP. Finally, the temporal evolution of the heat budget advection term in the lower Rhine valley was investigated using temperature profiles derived from balloon soundings acquired at two sites which were overpassed by the cold-pool edge in the course of its displacement northwards during the early afternoon as the result of the action of the föhn, and then southwards in the late afternoon as the föhn weakened and cold air from the Bodensee area was filling the lower Rhine Valley. Copyright © 2006 Royal Meteorological Societ