Search Results
You are looking at 1 - 2 of 2 items for :
- Author or Editor: Brian Cairns x
- Journal of Climate x
- Refine by Access: All Content x
Abstract
The effect of small spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. The cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) is exploited to 1) define and test different methods of representing cloud variation statistics; 2) investigate the range of spatial scales that should be included; 3) characterize cloud variations over a range of time- and space scales covering mesoscale (30–300 km, 3–12 h) into part of the lower part of the synoptic scale (300–3000 km, 1–30 days); 4) obtain a climatology of the optical thickness, emissivity, and cloud-top temperature variability of clouds that can be used in weather and climate GCMs, together with the parameterization proposed by Cairns et al., to account for the effects of small-scale cloud variations on radiative fluxes; and 5) evaluate the effect of observed cloud variations on the earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMs. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov.
Abstract
The effect of small spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. The cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) is exploited to 1) define and test different methods of representing cloud variation statistics; 2) investigate the range of spatial scales that should be included; 3) characterize cloud variations over a range of time- and space scales covering mesoscale (30–300 km, 3–12 h) into part of the lower part of the synoptic scale (300–3000 km, 1–30 days); 4) obtain a climatology of the optical thickness, emissivity, and cloud-top temperature variability of clouds that can be used in weather and climate GCMs, together with the parameterization proposed by Cairns et al., to account for the effects of small-scale cloud variations on radiative fluxes; and 5) evaluate the effect of observed cloud variations on the earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMs. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov.
Abstract
A full description of the ModelE version of the Goddard Institute for Space Studies (GISS) atmospheric general circulation model (GCM) and results are presented for present-day climate simulations (ca. 1979). This version is a complete rewrite of previous models incorporating numerous improvements in basic physics, the stratospheric circulation, and forcing fields. Notable changes include the following: the model top is now above the stratopause, the number of vertical layers has increased, a new cloud microphysical scheme is used, vegetation biophysics now incorporates a sensitivity to humidity, atmospheric turbulence is calculated over the whole column, and new land snow and lake schemes are introduced. The performance of the model using three configurations with different horizontal and vertical resolutions is compared to quality-controlled in situ data, remotely sensed and reanalysis products. Overall, significant improvements over previous models are seen, particularly in upper-atmosphere temperatures and winds, cloud heights, precipitation, and sea level pressure. Data–model comparisons continue, however, to highlight persistent problems in the marine stratocumulus regions.
Abstract
A full description of the ModelE version of the Goddard Institute for Space Studies (GISS) atmospheric general circulation model (GCM) and results are presented for present-day climate simulations (ca. 1979). This version is a complete rewrite of previous models incorporating numerous improvements in basic physics, the stratospheric circulation, and forcing fields. Notable changes include the following: the model top is now above the stratopause, the number of vertical layers has increased, a new cloud microphysical scheme is used, vegetation biophysics now incorporates a sensitivity to humidity, atmospheric turbulence is calculated over the whole column, and new land snow and lake schemes are introduced. The performance of the model using three configurations with different horizontal and vertical resolutions is compared to quality-controlled in situ data, remotely sensed and reanalysis products. Overall, significant improvements over previous models are seen, particularly in upper-atmosphere temperatures and winds, cloud heights, precipitation, and sea level pressure. Data–model comparisons continue, however, to highlight persistent problems in the marine stratocumulus regions.
