Diurnal and Semidiurnal Variations in the Time Series of 3-Hourly Assimilated Precipitation by NASA GEOS-1

Lim, Gyu-Ho; Suh, Ae-Sook

doi:10.1175/1520-0442(2000)013<2923:dasvit>2.0.co;2

Cited by 12 publications

(6 citation statements)

References 23 publications

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“…These mechanisms can be classified into three categories, according to their horizontal scale: 1) local convective instability induced by boundary heating (Machado et al 2002); 2) regional controls from differential heating such as landsea circulations, topography, surface vegetation type (Machado et al 2004), and mesoscale convective systems (Maddox 1980;Riley et al 1987;Arritt and Mitchell 1994;Carbone et al 2002); and 3) large-scale or subcontinental controls such as the nocturnal low-level jet (Rasmusson 1967;Helfand and Schubert 1995;Higgins et al 1997;Schubert et al 1998), atmospheric tides (Dai and Deser 1999;Dai et al 1999;Lim and Suh 2000), thermally driven large-scale land-ocean circulation and regional subsidence (Silva Dias et al 1987;Figueroa et al 1995;Gandu and Silva Dias 1998;Dai and Deser 1999;Dai 2001), and the seasonal march of the summer monsoon and basic-state changes (Machado et al 2004). All these forcing mechanisms can potentially contribute to a complicated and localized response in the diurnal cycle of precipitation.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity to Horizontal Resolution in the AGCM Simulations of Warm Season Diurnal Cycle of Precipitation over the United States and Northern Mexico

et al. 2007

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This study examines the sensitivity of the North American warm season diurnal cycle of precipitation to changes in horizontal resolution in three atmospheric general circulation models, with a primary focus on how the parameterized moist processes respond to improved resolution of topography and associated local/regional circulations on the diurnal time scale. It is found that increasing resolution (from approximately 2°to 1 ⁄2°in latitude-longitude) has a mixed impact on the simulated diurnal cycle of precipitation. Higher resolution generally improves the initiation and downslope propagation of moist convection over the Rockies and the adjacent Great Plains. The propagating signals, however, do not extend beyond the slope region, thereby likely contributing to a dry bias in the Great Plains. Similar improvements in the propagating signals are also found in the diurnal cycle over the North American monsoon region as the models begin to resolve the Gulf of California and the surrounding steep terrain. In general, the phase of the diurnal cycle of precipitation improves with increasing resolution, though not always monotonically. Nevertheless, large errors in both the phase and amplitude of the diurnal cycle in precipitation remain even at the highest resolution considered here. These errors tend to be associated with unrealistically strong coupling of the convection to the surface heating and suggest that improved simulations of the diurnal cycle of precipitation require further improvements in the parameterizations of moist convection processes.

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Section: Introductionmentioning

confidence: 99%

Sensitivity to Horizontal Resolution in the AGCM Simulations of Warm Season Diurnal Cycle of Precipitation over the United States and Northern Mexico

et al. 2007

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“…In the Gulf of California, the GCLLJ contributes to the flux of moisture into the southwest, though the spatial scale of the jet is smaller than in the GP, and the relative contribution of the jet to the diurnal cycle is less well known, in large part due to the lack of adequate observations (Higgins et al 2006). Large-scale thermally driven atmospheric tides also contribute to diurnal variations (Dai and Deser 1999;Dai et al 1999;Lim and Suh 2000). Other factors impacting the diurnal cycle include interactions with clouds (Wilson and Mitchell 1986;Randall et al 1991;Bergman 1997;Soden 2000), interactions with the land surface (Betts and Ball 1995;Chang et al 2000;Schulz et al 2001), landscape changes (Markowski and Stensrud 1998), and radiative heating over deserts (Douglas and Li 1996).…”

Section: Introductionmentioning

confidence: 99%

An Analysis of the Warm-Season Diurnal Cycle over the Continental United States and Northern Mexico in General Circulation Models

Lee

Schubert

Suárez

et al. 2007

Journal of Hydrometeorology

100

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The diurnal cycle of warm-season rainfall over the continental United States and northern Mexico is analyzed in three global atmospheric general circulation models (AGCMs) from NCEP, GFDL, and the NASA Global Modeling Assimilation Office (GMAO). The results for each model are based on an ensemble of five summer simulations forced with climatological sea surface temperatures.Although the overall patterns of time-mean (summer) rainfall and low-level winds are reasonably well simulated, all three models exhibit substantial regional deficiencies that appear to be related to problems with the diurnal cycle. Especially prominent are the discrepancies in the diurnal cycle of precipitation over the eastern slopes of the Rocky Mountains and adjacent Great Plains, including the failure to adequately capture the observed nocturnal peak. Moreover, the observed late afternoon-early evening eastward propagation of convection from the mountains into the Great Plains is not adequately simulated, contributing to the deficiencies in the diurnal cycle in the Great Plains. In the southeast United States, the models show a general tendency to rain in the early afternoon-several hours earlier than observed. Over the North American monsoon region in the southwest United States and northern Mexico, the phase of the broadscale diurnal convection appears to be reasonably well simulated, though the coarse resolution of the runs precludes the simulation of key regional phenomena.All three models employ deep convection schemes that assume fundamentally the same buoyancy closure based on simplified versions of the Arakawa-Schubert scheme. Nevertheless, substantial differences between the models in the diurnal cycle of convection highlight the important differences in their implementations and interactions with the boundary layer scheme. An analysis of local diurnal variations of convective available potential energy (CAPE) shows an overall tendency for an afternoon peak-a feature well simulated by the models. The simulated diurnal cycle of rainfall is in phase with the local CAPE variation over the southeast United States and the Rocky Mountains where the local surface boundary forcing is important in regulating the diurnal cycle of convection. On the other hand, the simulated diurnal cycle of rainfall tends to be too strongly tied to CAPE over the Great Plains, where the observed precipitation and CAPE are out of phase, implying that free atmospheric large-scale forcing plays a more important role than surface heat fluxes in initiating or inhibiting convection. *

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“…Their simulation produced a broad afternoon maximum over land during rainy seasons, as well as an early morning maximum over the oceans. Data assimilation models (e.g., Lim and Suh 2000) have also shown similar patterns over a global domain. In addition, the monsoonal precipitation amounts in Randall et al (1991) were reduced when the diurnal cycle was omitted.…”

Section: Introductionmentioning

confidence: 82%

The Diurnal Cycle of Water and Energy over the Continental United States from Three Reanalyses

Ruane

Roads

2007

Journal of the Meteorological Society of Japan

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The Continental United States summertime diurnal surface and column-integrated atmospheric water and energy components are compared among three reanalyses. The strength of the diurnal solar forcing leads to consistent phases among surface energy components across the continent and all reanalyses, but the amplitudes vary widely. This forcing has a particularly strong and direct impact on the surface energy cycle, but interacts with many aspects of the surface and column-integrated water and energy cycles through dynamical convergence, leading to large diurnal fluctuations in the atmospheric reservoir of water vapor and total dry energy. Although they are negligible on timescales greater than a year, the tendency terms of the water and energy budgets at the surface and in the atmosphere are important on the diurnal scale. The North American Regional Reanalysis (NARR) displays a diurnal circulation pattern centered over Northern Texas that links together regional patterns in the diurnal cycles of assimilated precipitation. Constructed vapor flux convergences from the National Centers for Environmental Prediction/Department of Energy (NCEP/DOE) Reanalysis-2 Global Spectral Model and the Experimental Climate Prediction Center's reanalysis using an updated Seasonal Forecast Model reproduce many of the observed regional circulation and convergence patterns, but fail to generate the appropriate diurnal precipitation, presumably due to inadequate convective parameterizations. Diurnal variations in atmospheric energy respond not only to the direct solar forcing, but also to the resulting dynamically-forced semidiurnal thermal tide.

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Diurnal and Semidiurnal Variations in the Time Series of 3-Hourly Assimilated Precipitation by NASA GEOS-1

Cited by 12 publications

References 23 publications

Sensitivity to Horizontal Resolution in the AGCM Simulations of Warm Season Diurnal Cycle of Precipitation over the United States and Northern Mexico

Sensitivity to Horizontal Resolution in the AGCM Simulations of Warm Season Diurnal Cycle of Precipitation over the United States and Northern Mexico

An Analysis of the Warm-Season Diurnal Cycle over the Continental United States and Northern Mexico in General Circulation Models

The Diurnal Cycle of Water and Energy over the Continental United States from Three Reanalyses

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