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Han, W, Stamnes K, Lubin D.  1999.  Remote sensing of surface and cloud properties in the Arctic from AVHRR measurements. Journal of Applied Meteorology. 38:989-1012.   10.1175/1520-0450(1999)038<0989:rsosac>;2   AbstractWebsite

Algorithms to retrieve cloud optical depth and effective radius in the Arctic using Advanced Very High Resolution Radiometer (AVHRR) data are developed, using a comprehensive radiative transfer model in which the atmosphere is coupled to the snowpack. For dark surfaces AVHRR channel 1 is used to derive visible cloud optical depth, while for bright surfaces AVHRR channel 2 is used. Independent inference of cloud effective radius from AVHRR channel 3 (3.75 mu m) allows for derivation cloud liquid water path (proportional to the product of optical depth and effective radius). which is a fundamental parameter of the climate system. The algorithms are based on the recognition that the reflection function of clouds at a nonabsorbing wavelength (such as AVHRR channel 1) in the solar spectrum is primarily a function of cloud optical thickness, whereas the reflection function at a liquid water absorbing wavelength (such as AVHRR channel 3) is primarily a function of cloud particle size. For water clouds over highly reflecting surfaces (snow and ice), the reflectance in AVHRR channel 1 is insensitive to cloud optical depth due to the multiple reflections between cloud base and the underlying surface; channel 2 (0.85 mu m) must be used instead for optical depth retrieval. Water clouds over tundra or ocean are more straightforward cases similar to those found at lower latitudes, and in these cases a comprehensive atmospheric radiative transfer model with a Lambertian surface under cloud is used. Thus, for water cloud over tundra and ocean, channel 1 is used for cloud optical depth retrieval. In all cases, channel 3 is used for independent retrieval of cloud droplet effective radius. The thermal component of channel 3 is estimated by making use of channel 4 (11 mu m) and is subtracted from the total channel 3 radiance. Over clear-sky scenes, the bidirectional reflectance properties of snow are calculated directly by the coupled snowpack-atmosphere model. This results in greater overall accuracy in retrieved surface properties as compared with the simplified approach that uses a Lambertian approximation for the surface albedo. To test the physical soundness of the algorithms the authors have applied them to AVHRR data over Barrow, Alaska, from April to August 1992. Downwelling irradiances at the surface calculated using the retrieved cloud optical depth and effective radius are compared with field irradiance measurements, and encouraging agreement is found. The algorithms are also applied to three areas of about 100-km dimension around Barrow, each having a different underlying surface (ocean, tundra, snow).

Holm-Hansen, O, Lubin D.  1994.  Solar ultraviolet radiation: effect on rates of CO2 fixation in marine phytoplankton. Regulation of atmospheric CO2 and O2 by photosynthetic carbon metabolism. ( Tolbert NE, Preiss J, Eds.).:55-74., New York; Oxford: Oxford University Press Abstract
Holmhansen, O, Helbling EW, Lubin D.  1993.  Ultraviolet-Radiation in Antarctica - Inhibition of Primary Production. Photochemistry and Photobiology. 58:567-570.   10.1111/j.1751-1097.1993.tb04933.x   AbstractWebsite

With the seasonal formation of the ozone hole over Antarctica, there is much concern regarding the effects of increased solar UV-B radiation (280-320 nm) on the marine ecosystem in the Southern Ocean. In situ incubations of natural phytoplankton assemblages in antarctic waters indicate that under normal ozone conditions UV-B radiation is responsible for a loss of approximately 4.9% of primary production in the euphotic zone, whereas UV radiation with wavelengths between 320 and 360 nm causes a loss of approximately 6.2%. When combined with data on the action spectrum for photoinhibition by UV radiation, our data suggest that the enhanced fluence of UV-B radiation under a well-developed ozone hole (1 50 Dobson units) would decrease daily primary productivity by an additional amount of less-than-or-equal-to 53.8%. Calculations that take into consideration the extent and duration of low stratospheric ozone concentrations during September to November indicate that the decrease in total annual primary production in antarctic waters due to enhanced UV-B radiation would be less-than-or-equal-to 0.20%.