HR: 10:35h
AN: B32A-02    [Abstracts]
TI: How Well Can We Simulate the Effect of Clouds on Surface Radiative Fluxes?
AU: * Ackerman, T P
EM: ackerman@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352
AU: McFarlane, S A
EM: sally.mcfarlane@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352
AU: Mather, J H
EM: jim.mather@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352
AU: Long, C N
EM: chuck.long@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352
AB: We now have available accurate records of surface radiative fluxes that extend for more than a decade. The accuracy of these measurements is generally better than 10 W/m2. Analysis techniques have been developed that allow us to determine the impact of clouds on both shortwave and longwave radiation directly from these time series. We have carried out such analyses for data from the Atmospheric Radiation Measurement (ARM) sites for periods of at least five years. Here, we show frequency plots of surface radiative fluxes and cloud effect for these sites, where cloud effect is defined as the difference between the observed flux and the clear (non-cloudy) sky flux. The next step is to ask how well can we simulate surface fluxes and cloud effect. We approach this from two perspectives. In the first, we use observations of atmospheric and cloud profiles from the ARM sites to provide inputs to a radiative transfer code. We then compute the fluxes and compare to observations. The calculated fluxes agree very well with the observations with respect to bias and somewhat less well with respect to rms error. Secondly, we compare our results with those obtained from global climate models. The results here are somewhat mixed.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0321 Cloud/radiation interaction
SC: Biogeosciences [B]
MN: Fall Meeting 2005