Graeme Stephens

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DECEMBER 2002 AMERICAN METEOROLOGICAL SOCIETY | O ne of the more stunning features of the images of earth from space are the clouds that move around our planet in quasi-organized largescale systems (e.g., Rossow and Cairns 1995). The character and movement of these coherent cloud features are primarily governed by the large-scale atmospheric circulation(More)
In late April 2006, NASA launched Cloudsat, an earth-observing satellite that uses a near-nadir-pointing millimeter-wavelength radar to probe the vertical structure of clouds and precipitation. The first step in using Cloudsat measurements is to distinguish clouds and other hydrometeors from radar noise. In this article the operational Cloudsat hydrometeor(More)
From the analysis of surface, upper-air, and satellite observations it is suggested that the hydrological cycle associated with the Madden–Julian oscillation acts in the mode of a self-regulating oscillator. The regulation occurs as a feedback between hydrological processes in the atmosphere; radiation processes; and the dynamical movement of air over the(More)
[1] The occurrence statistics of hydrometeor layers covering the Earth’s surface is described using the first year of millimeter radar data collected by Cloudsat merged with lidar data collected by CALIPSO (July 2006 to June 2007). These satellites are flown in a tight orbital configuration so that they probe nearly the same volumes of the atmosphere within(More)
Aerosols are known to have both direct and indirect effects on clouds through their role as cloud condensation nuclei. This study examines the effects of differing aerosol concentrations on convective storms developing under different environments. The Regional Atmospheric Modeling System (RAMS), a cloudresolving model with sophisticated microphysical and(More)
691 Earth’s climate is determined by the flows of energy into and out of the planet and to and from Earth’s surface. Geographical distributions of these energy flows at the surface are particularly important as they drive ocean circulations, fuel the evaporation of water from Earth’s surface and govern the planetary hydrological cycle. Changes to the(More)
[1] Measurements of global hydrometeor coverage and occurrence frequencies as observed by the cloud radar on CloudSat are summarized using data collected during Summer 2006. CloudSat was launched on 28 April 2006 and began collecting data routinely on 7 June 2006. In this article we document the distribution of cloudiness from the ITCZ to the Polar regions(More)
[1] While cumulus congestus as an important mode of tropical convection has been established, many of the previous studies that rely on radar observations usually capture them as snapshots. A logical question to consider is: are the statistics gathered from snapshot observations of cumulus congestus really reflective of this mode of convection that ceases(More)
This paper describes radiative transfer through a single cloud layer that is horizontally uniform but statistically distributed in the vertical and compares the radiative transfer in such a statistical cloud to its deterministic counterpart. Specific examples of the derivation of the probability density functions of cloud reflection and transmission by(More)