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Daniel F. Steinhoff, Saptarshi Chaudhuri, and David H. Bromwich

feature in the 2001–05 wind speed climatology of Seefeldt and Cassano (2008) . The predominance of moisture transport and the lifting mechanism in the climatology of West Antarctica and the Ross Ice Shelf means that cloud formation similar to that studied here is likely to be a common feature. Consistent with wind speed forcing from previous studies, synoptic-scale processes are important for cloud formation in this case. The cyclone over the Marie Byrd Land coast draws moisture across West

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C. Warner, J. Simpson, D. W. Martin, D. Suchman, F. R. Mosher, and R. F. Reinking

cloud patterns of the moist layer appeared to play a primary role in heat transfer upwardwithin this layer, and contributed to the forcing of showering midtropospheric clouds.1. Introduction The Atlantic Tropical Experiment of the GlobalAtmospheric Research Program (GATE) wascentered on an area near 8.5-N, 22.5-W duringsummer 1974. On 18 September 1974 (day 261) agrowing cloud cluster was monitored using thesatellite SMS-1, ships and aircraft. A preliminarysynthesis of observations of this

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Brian F. Jewett and Robert B. Wilhelmson

front propagation ( Weaver and Nelson 1982 ); and vertical perturbation pressure gradients related to storm rotation and to the mean shear acting upon the updraft ( Rotunno and Klemp 1982 ). We find that boundary forcing here plays an important role in storm propagation and cell behavior, due to (a) changes in the mean wind across the boundary, (b) changes in storm intensification with the boundary present, and thus storm height and cloud-bearing wind, and (c) subsequent changes in split

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Richard H. Johnson and David L. Priegnitz

of convection persists in the region whetherthe synoptic-scale forcing is weak or strong. Convection over water to the north of Borneo regularlyevolves on a diurnal basis from a small group of cumulonimbus clouds into a uniform mesoscale precipitation area having the characteristic structure of those observed in recent years over the tropical easternPacific and Atlantic oceans. In their mature stage the precipitation systems contain mesoscale anvil cloudscommonly extending from near 500 mb to the

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Bjorn Stevens, Robert L. Walko, William R. Cotton, and Graham Feingold

advection, this note demonstrates more generally that the cloud-edge supersaturation problemis a fundamental problem associated with the ubiquitous assumption that the forcings on the droplet spectra arewell represented by the mean thermodynamic fields- In certain respects, this assumption is equivalent to failingto represent fractional cloudiness within a grid. Although well-known consequences of this problem are theunderprediction of temperature and the erroneous representation of the mean buoyancy

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J. A. Curry and G. F. Herman

Force Three-DimensionalNephanalysis ("3DNEPH") and visible and infraredimages from the Defense Meteorological Satellite Program (DMSP) satellite for cloud' observations. Thelarge-scale heat and moisture budgets for this regionare calculated with the atmospheric parameters obtained from the operational objective analysis producedby the European Centre for Medium-Range WeatherForecasts (ECMWF). The heat and moisture budgetsare also combined to describe relative humiditychanges, thus providing insight

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M. Tiedtke

in large-scale models, but this approach, through the introduction of a spectral cloud ensemble,leads normally to rather complex schemes. In this paper the question is addressed whether much simplerschemes can already provide realistic values of the thermal forcing by convection under various synoptic conditions. This is done through verifying such a scheme first on data from field experiments for periods of tropicalpenetrative convection (GATE, Marshall Islands), tradewind cumuli (ATEX, BOMEX

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David O'C. Starr and Donald P. Wylie

purpose: 1 ) to provide a meteorological overview including synoptic(section 3 ) and regional (sections 4a and 5a) perspectives, 2) to document the rawinsonde-resolved atmospheric structure (sections 4b and 5b) and large-scale Corresponding author address: Dr. David O'C. Starr, NASA Goddard Space Flight Center, Code 913, Greenbelt, MD 20771.forcing (sections 4c and 5c) associated with the observed cloud systems, and 3) to provide understandingof the relationship between atmospheric structure andthe

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Jason A. Otkin

, possibly due to the less accurate moisture, temperature, and wind analyses at end of the assimilation period ( Fig. 9 ) and the subsequently larger errors during the forecast period ( Fig. 10 ). If the moisture and thermodynamic forcing controlling the cloud evolution are not improved, then it is difficult to maintain the beneficial changes made to the final cloud analysis. Last, comparison of the brightness temperature assimilation cases shows that the RMSE tended to decrease for these cloud

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John Turner, Thomas A. Lachlan-Cope, David E. Warren, and Charles N. Duncan

evolution and structure of a mesoscale vortex and associated cloud comma thatdeveloped at the eastern edge of the Weddell Sea, Antarctica, during the early part of January 1986 is presented.The system remained quasi-stationary for over three days close to the British research station Halley (75 - 36'S,26 -42'W) and gave severe weather with gale-force winds and prolonged snow. The formation and development of the system were investigated using conventional surface and upper

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