Comparison of satellite derived ocean surface wind speeds and their error due to precipitation

The combination of passive and active microwave satellite data products should give new and improved insight into the structure and development of sub-synoptic scale circulation systems in the Earth's atmosphere, as e.g. polar lows, comma clouds and tropical cyclones. The present study focuses on wind speeds in severe storm systems derived from microwave radiometers and altimeters in comparison with related products from the Envisat mission. Especially, the influence of precipitation on the accuracy of wind speed estimates is analysed through this combination technique. Preliminary results suggest only minor errors through undetected signal contamination by precipitation

Impact of ship emissions on cloud properties over coastal areas

Although land based emissions in Europe are decreasing, ship emissions continue to grow. The main emissions from ships can modulate cloud properties of coastal areas and are of direct relevance to the earth radiation budget. In this context, satellite data from AVHRR onboard NOAA-14 are evaluated for six years (1997–02) in order to assess impact of ship emissions on cloud properties over coastal areas. Study area was chosen in such a way that it includes the English Channel and top three polluting harbours in Europe. Results present first evidence of possible impact of ship emissions on both cloud albedo and cloud top temperature over coastal areas using long-term satellite measurements. Increase in cloud albedo (with corresponding decrease in cloud top temperature) and higher variability are observed over coastal areas. This effect is more pronounced for areas over and around harbours and the English Channel. It also confirms indirect aerosol effects

The impact of the spacecraft system SÄNGER on the composition of the middle atmosphere

A two-dimensional chemical model and physical considerations are used to estimate the impact of the spacecraft system SÄNGER on stratospheric and mesospheric ozone in relation to other spacecraft and other anthropogenic perturbations. Perturbations of middle atmospheric NOy H2O and H2 concentrations, and their impact on the radiative balance of the atmosphere, including contrail formation, are discussed. It is found, that in case of about 24 launches per year the perturbations due to SÄGER are about negligible on a global scale. However, if a SÄGER version would be used for a hypersonic fleet of commercial aircraft a serious ozone depletion is predicted. © 1992 by Wax Planck Society

Towards a contrail climatology from NOAA—satellite images over Europe

Contrail cloudiness over Europe and the eastern part of the North Atlantic Ocean was analyzed for the two periods Sept. 1979-Dec. 1981 and Sept. 1989-Aug. 1992 by visual inspection of quicklook photographic prints of NOAA/AVHRR infrared images. The averaged contrail cover exhibits maximum values along the transat- lantic flight corridor around 50°N (of almost 2%) and over western Europe resillting in 0.5% contrail cloudiness on the average. A strong yearly cycle appears with a maximum (< 2%) in spring and summer over the Atlantic and a smaller maximum (< 1%) in winter over southwestern Europe. Comparing the two time periods of one decade separation there is a significant decrease in contrail cloudiness over west- ern Europe and a significant increase over the North Atlantic observable between March and July. Contrail cloud cover during daytime is about twice as high as dur- ing nighttime. Contrails are preferably found in larger fields of 1000 km diameter which last usually for more than one day. Causes, possible errors and consequences are discussed