Interferometric measurements of sea surface temperature and emissivity

A new multispectral method to derive sea surface emissivity and temperature (SST) by using interferometer measurements of the near surface upwelling radiation in the infrared window region is presented. As reflected sky radiation adds substantial spectral variability to the otherwise spectrally smooth surface radiation an appropriate estimate of surface emissivity allows to correct the measured upwelling radiation for the reflected sky component. The remaining radiation together with the estimated surface emissivity, yields an estimate of the sea surface temperature. Measurements from an ocean pier at the Baltic Sea in October 1995 indicate an accuracy of about 0.1 K for the so derived sea surface temperature. A strong sea surface skin effect of about 0.6 K is found in that special case. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Improvements of cloud particle sizing with a 2D-Grey probe

The potential of the OAP-2D-Grey probe for the determination of cloud microphysical properties is studied. Through systematic test measurements with a spinning glass disk with sample spots of various sizes it is shown, that the particle image diameter increases considerably if the particle crosses the illuminating laser beam out-of-focus. A method is proposed to estimate the nominal particle size by exploiting the available four shadow grey levels which improves results especially for particle sizes <100 #mu#m. The use of grey levels also allows a consistent definition of a depth-of-field, which turns out to be by a factor of 3.02 larger than conventionally assumed. Finally, the impact of these findings on particle sizing for in situ measurements is discussed. (orig.)12 refs.Available from TIB Hannover: RR 1347(182) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

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 transatlantic flight corridor around 50 N (of almost 2%) and over western Europe resulting 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 western 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 during 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. (orig.)SIGLEAvailable from TIB Hannover: RR 1347(118) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Atmospheric corrections of colour images of case I waters - a review. Of case II waters - a review

Discussed are the basic approaches reported in literature for atmospheric correction of airborne/spaceborne multispectral (visible to near infrared) images of clear waters pertaining to open ocean conditions, i.e. case I waters according to Morel's classification. The extent of applicability and inherent limitations of such approaches are analyzed and the persisting problems identified. (orig.)93 refs.SIGLEAvailable from TIB Hannover: RR 1347(308) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Passive remote sensing of columnar water vapour content above land surfaces. Pt. 1 and 2 Theoretical algorithm development. - Comparison of OVID measurements with radiosonde and dial measurements

A method is presented to retrieve the total atmospheric water vapour content above land surfaces with the aid of airborne or satellite spectral measurements of backscattered solar radiation. During algorithm development, special emphasis is given to proper description of the global variety of temperature, pressure, and water vapour profiles, as well as optical parameters of aerosols and spectral surface reflectivity values. Sensitivity studies show that the variability of spectral surface reflectivity has the greatest impact on the errors of the derived water vapour contents. The number and location of necessary channels is therefore optimized with respect to the influence of surface reflectance. Finally the water vapour algorithm for the spectrometer MERIS on board ESA's environmental satellite ENVISAT is defined. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Spektral hochaufloesende Messungen rueckgestreuter Strahlung ueber Wolken im Spektralbereich #DELTA##lambda# = 0.2 - 4.5 #mu#m Endbericht

The following five problems were to be investigated: 1. Explanation of the discrepancies between measured and calculated data for the absorption of solar radiation by clouds. 2. Verification and application of remote measuring methods for determining cloud height and optical density, droplet size distribution and liquid water concentrations within clouds, and cloud phases. 3. Derivation and verification of a remote measuring method for determining the total atmospheric vapour concentration. 4. Remote measuring of aerosol type and optical density. 5. Remote measurement of the total concentration of atmospheric trace gases (O_3, CO, SO_2, NO_2). (orig./KW)Es sollten fuenf Teilziele untersucht werden: 1. Erklaerung der Diskrepanzen bei der Absorption der Sonnenstrahlung in Wolken, die im Vergleich von Messung und Strahlungstransportrechnung auftreten. 2. Verifizierung und Anwendung von Fernerkundungsverfahren zur Bestimmung von: - Wolkenhoehe und optischer Dicke der Wolken - Troepfchengroessenverteilung und Fluessigwassergehalt von Wolken -Wolkenphase. 3. Herleitung und Verifizierung eines Fernerkundungsverfahrens zur Bestimmung des Gesamtwasserdampfgehalts der Atmosphaere. 4. Fernerkundung von Aerosoltyp und optischer Dicke der Aerosole. 5. Fernerkundung des Gesamtgehalts atmosphaerischer Spurengase (O_3, CO, SO_2 und NO_2). (orig./KW)Available from TIB Hannover: F96B376+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman