Cb-TRAM: Tracking and monitoring severe convection from onset over rapid development to mature phase using multi-channel Meteosat-8 SEVIRI data

Cb-TRAM is a new fully automated tracking and nowcasting algorithm. Intense convective cells are detected, tracked and discriminated with respect to onset, rapid development, and mature phase. Finally, short range forecasts are provided. The detection is based on Meteosat-8 SEVIRI (Spinning Enhanced Visible and Infra-Red Imager) data from the broad band high resolution visible, infra-red 6.2 micrometer (water vapour), and the infra-red 10.8 micrometer channels. Areas of convection initiation, of rapid vertical development, and mature thunderstorm cells (cumulonimbus Cb) are identified. For the latter, tropopause temperature data from ECMWF operational model analyses is utilised as an adaptive detection criterion. The tracking is based on geographical overlap between current detections and first guess patterns of cells detected in preceeding time steps. The first guess patterns as well as the short range forecasts are obtained with the aid of a new image matching algorithm providing complete fields of approximate differential cloud motion. Based on the so called pyramid matcher an interpolation and extrapolation technique is presented which can also be used to generate synthetic intermediate data fields between two known fields as well as nowcasts of motion and development of detected areas. Examples of application are presented for thunderstorm tracks over the Mediterranean

A fast method for the retrieval of integrated longwave and shortwave top-of-atmosphere upwelling irradiances from MSG/SEVIRI (RRUMS)

A new Rapid Retrieval of Upwelling irradiances from MSG/SEVIRI (RRUMS) is presented. It has been developed to observe the top-of-atmosphere irradiances of small scale and rapidly changing features that are not sufficiently resolved by specific Earth radiation budget sensors. Our retrieval takes advantage of the spatial and temporal resolution of MSG/SEVIRI and provides outgoing longwave and reflected shortwave radiation only by means of a combination of SEVIRI channels. The longwave retrieval is based on a simple linear combination of brightness temperatures from the SEVIRI infrared channels. The shortwave retrieval is based on a neural network that requires as input the visible and near-infrared SEVIRI channels

The Use of Meteorlogical Data to Improve Contrail Detection in Thermal Imagery over Ireland.

Aircraft induced contrails have been found to have a net warming influence on the climate system, with strong regional dependence. Persistent linear contrails are detectable in 1 Km thermal imagery and, using an automated Contrail Detection Algorithm (CDA), can be identified on the basis of their different properties at the 11 and 12 m w av.el enTgthshe algorithm s ability to distinguish contrails from other linear features depends on the sensitivity of its tuning parameters. In order to keep the number of false identifications low, the algorithm imposes strict limits on contrail size, linearity and intensity. This paper investigates whether including additional information (i.e. meteorological data) within the CDA may allow for these criteria to be less rigorous, thus increasing the contrail-detection rate, without increasing the false alarm rate

Umwetgerechte Flugroutenoptimierung

Die Klimawirkung des Luftverkehrs ist laut dem IPCC-Bericht "Aviation and the global at-mosphere" (Fahey et al., 1999) vor allem verursacht durch Emission von CO2 und NOx, durch die Entstehung von Kondensstreifen sowie durch die Emission von Aerosolen, die die natürlichen Bedingungen der Entstehung von Zirren ändern und deren Eigenschaften modifizieren. Abbildun

Umweltgerechte Flugroutenoptimierung

Ist es möglich, durch die gezielte Wahl der Flugrouten einzelner Flüge deren Klimawirkung zu verringern? Der Forschungsverbund „Verminderung von Kondensstreifen durch Flugrotenoptimierung“ bestehend aus der Deutschen Lufthansa AG, der Deutschen Flugsicherung, dem Deutschen Wetterdienst und dem Deutschen Zentrum für Luft- und Raumfahrt will diese Frage in einem vom BMBF geförderten Projekt beantworten. Durch geeignete Routenwahl könnten die Kondensstreifen, die auf das System Erde/Atmosphäre erwärmend wirken, vermieden werden. Die Klimawirkung des Luftverkehrs wird nicht nur durch die Emission von Kohlendioxid, Stickoxiden und Aerosolen bestimmt. Oft erzeugen Flugzeuge auch Kondensstreifen, die bei entsprechenden Bedingungen zu weit ausgedehnten Eiswolken anwachsen und über mehrere Stunden bestehen. Nach dem derzeitigen Stand des Wissens wirkt diese zusätzliche Bewölkung ähnlich erwärmend wie das emittierte Kohlendioxid. Im Projekt wird die gesamte Strahlungswirkung möglicher Kondensstreifen während ihrer Lebensdauer basierend auf Wetterprognosen abgeschätzt und mit der Strahlungswirkung der Kohlendioxid- und später auch Stickoxid-Emissionen verglichen, die bei unterschiedlichen Flugrouten entstehen. Dies ermöglicht, durch selektive Vermeidung derjenigen Kondensstreifen und Zirren, die einen stark erwärmenden Beitrag erwarten lassen, den Strahlungsantrieb des Flugverkehrs deutlich zu reduzieren. Bereits heute werden aus Zeit- und Kostengründen die Flugrouten so optimiert, dass Gegenwind vermieden und Rückenwind ausgenutzt wird. Aufbauend auf diesen bereits in der täglichen Praxis erprobten Optimierungsverfahren werden anhand der gegebenen meteorologischen Situation unter Berücksichtigung der Verkehrssituation, des zu erwartenden Strahlungsantriebes und des Kosten-Nutzen-Verhältnisses die günstigsten Flugprofile berechnet. Da der Nutzen einer solchen Optimierung entscheidend von der Zuverlässigkeit der Prognosen der Feuchte und der Bewölkung in den Flugniveaus abhängt, wird besondere Aufmerksamkeit der Messung und Modellierung dieser Parameter gewidmet. Zur Verifikation der Prognosen werden Satellitendaten genutzt

Messungen der Vulkanasche mit dem Forschungsflugzeug D-CMET (Falcon)

Am 14. April 2010 und in den darauf folgenden Tagen führten explosive Eruption des Vulkans am Eyjafalllajökull zu starker Belastung der Atmosphäre mit Vulkanasche. An den darauf folgenden Tagen musste in weiten Teilen Europas der Luftraum geschlossen werden. Seit dem 19. April wurden vom DLR Messflüge mit dem Forschungsflugzeug Falcon durchzgeführt

How to avoid contrail cirrus

The impact of air traffic on climate is dominated by the contribution of aircraft induced cirrus. Hence, any mitigation strategy has to consider the production of contrails and cirrus clouds. Here we use operational radiosonde data with high vertical resolution to estimate the effect of a small change in flight altitudes to avoid flight in ice supersaturated air, hence to suppress contrail and cirrus formation. It is shown that a substantial fraction of contrails and contrail induced cirrus can be avoided by relatively small changes in flight level, due to the shallowness of ice-supersaturation layers

METEOSAT Observations of the Daily Variation of Cirrus

Cirrus clouds have a substantial impact on net radiation and therefore also on climate, but the physical processes involved in cirrus formation and decay are not very well represented in climate and weather prediction models. In-situ formation of natural cirrus clouds is initiated when cooling moist air parcels reach a substantial supersaturation with respect to ice. This happens either due to dynamic lifting of the air or due to radiative cooling. But once ice crystals are formed, they grow until the ambient air becomes sub-saturated either by subsidence of the whole air-mass or sedimentation of the particles into drier air. Thus the pure diagnostic description of clouds, as it is still used in current climate and weather prediction models has to be tuned to match observations at least until a prognostic description of cirrus clouds will be introduced into these models. The decay of cirrus clouds is a process with a typical timescale of hours. Therefore geostationary satellites with their high temporal resolution are an ideal platform for cirrus observations. The data from these satellites offer the possibility to observe the life cycle either by tracking cirrus clouds or by observation of the typical daily and seasonal variation of cirrus coverage. In particular the infrared channels of the METEOSAT satellites, which are independent from day-light and not affected by the different scattering properties of the various ice particle habits are suitable for such observations. For the analysis we use a novel scheme to derive cirrus optical depth and height from the SEVIRI infrared channels. It is based on an artificial neural network trained with the data provided by CALIOP, the lidar system aboard of the CALIPSO satellite

COCS - Cirrus Optical properties derived from CALIOP and SEVIRI during day and night time

Significant progress in cirrus cloud observation has been achieved with spaceborne active remote sensing techniques, e.g. the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the polar-orbiting Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO). With its high vertical and horizontal resolution CALIOP provides high detailed profiles of optical properties especially of cirrus clouds. But to deliver information on the lifecycle of cirrus clouds high temporal resolution is needed. These observations are performed by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) aboard MSG every 5-15 minutes providing high detailed information (e.g. brightness temperatures of seven infrared channels) making a day and night time observation of clouds possible. In the following, the COCS algorithm (Cirrus Optical properties derived from CALIOP and SEVIRI) combining the advantages of both satellite instruments, some preliminary results, intercomparisons and examples of its application are presented. COCS provides the cloud optical thickness (COT) and the cloud top altitude (CTA) of cirrus clouds

How to avoid contrail cirrus

Aircraft induced cirrus clouds have a major effect on climate. These clouds are triggered by air-traffic, if the ambient air is super-saturated with respect to ice. Operational radiosonde data with high vertical resolution is used to estimate the effect of small changes in flight altitudes on contrail and cirrus formation. It is demonstrated that a substantial fraction of contrails and contrail induced cirrus could be avoided by relatively small changes in flight level,if the actual atmospheric conditions are known. Due to the shallowness of ice-super-saturation layers in most cases only small deviations from optimal flight profiles and routes are necessary, to avoid the formation of persistent contrails and contrail cirrus