Export 2 results:
Sort by: Author Title Type [ Year  (Desc)]
Lubin, D, Vogelmann AM.  2010.  Observational quantification of a total aerosol indirect effect in the Arctic. Tellus Series B-Chemical and Physical Meteorology. 62:181-189.   10.1111/j.1600-0889.2010.00460.x   AbstractWebsite

We use 6 yr of multisensor radiometric data (1998-2003) from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program to provide an observational quantification of the short-wave aerosol first indirect effect in the Arctic. Combined with the previously determined long-wave indirect effect, the total (short-wave and long-wave) first indirect effect in the high Arctic is found to yield a transition from surface warming of +3 W m(-2) during March to a cooling of -11 W m(-2) during May, therefore altering the seasonal cycle of energy input to the Arctic Earth atmosphere system. These data also reveal evidence of a first indirect effect that affects optically thinner clouds during summer. which may represent an additional negative climate feedback that responds to a warming Arctic Ocean with retreating sea ice.

Lubin, D, Morrow E.  2001.  Ultraviolet radiation environment of Antarctica 1. Effect of sea ice on top-of-atmosphere albedo and on satellite retrievals. Journal of Geophysical Research-Atmospheres. 106:33453-33461.   10.1029/2001jd000687   AbstractWebsite

The backscattered ultraviolet radiance measured by the Total Ozone Mapping Spectrometer (TOMS) over the Southern Ocean is influenced by both cloud cover and sea ice concentration. In TOMS data alone, these influences cannot be separated. To assess the relative importance of cloud opacity and sea ice concentration, TOMS level 2 data are colocated with AVHRR and SSM/I data. AVHRR provides independent cloud identification at a spatial resolution sufficient to estimate cloud fraction within a TOMS level 2 footprint, while the SSM/I provides useful estimates of sea ice concentration over clear and cloudy scenes. The sea ice cover is shown to have a stronger influence than cloud cover on the backscattered ultraviolet radiance at the top of the atmosphere. Over overcast scenes the mean TOMS reflectivity increases from 45 to 84% as the underlying sea ice concentration increases from 0 to 1. Over scenes containing sea ice concentrations greater than 0.5, the increase in TOMS-measured radiance with increasing cloud amount (0-1) is generally less than 30% and is negligible over high sea ice concentrations. Over clear-sky scenes the characteristic UV-A albedos of the sea ice components of the scenes are retrieved from the TOMS data. These albedos range from 0.19 +/- 0.14 for sea ice concentration 0.1, increasing rapidly to 0.53 +/- 0.15 for sea ice concentration 0.3, and then approximately linearly to 0.80 +/- 0.11 for sea ice concentration 1.0. There is the potential to develop a climatology of surface ultraviolet and photosynthetically active radiation for southern high latitudes, which utilizes a combination of TOMS and SSM/I data. Such a climatology could cover the entire Southern Ocean throughout the duration of the modern springtime ozone depletion phenomenon. Analysis of uncertainties related to sea ice concentration retrieval from SSM/I, and related uncertainties in surface albedo identification and their influence on the estimated surface radiative flux, shows that such a climatology would have the most quantitative value for sea ice concentrations less than 0.5.