Determination of Bulk Properties of Tropical Cloud Clusters from Large-Scale Heat and Moisture Budgets

Yanai, Michio; Esbensen, Steven K.; Chu, Jan-Hwa

doi:10.1175/1520-0469(1973)030<0611:dobpot>2.0.co;2

Cited by 1,547 publications

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“…These vertical profiles of Q1 and Q2 are quite similar to those obtained over the tropical oceanic area having strong convective activity (ex. Yanai et al, 1973 andNitta, 1977). These results indicate that the large amount of the heat source found in the southeastern part of the Tibetan Plateau (Area-S) would be largely due to the condensation heating by deep active convective clouds.…”

Section: Data and Methods Of Analysismentioning

confidence: 76%

“…Fig. 1 represents a Similar budget equations to those commonly used for the analyses over the tropical oceanic areas (for example, Yanai et al, 1973 andNitta andEsbensen, 1974) are adopted in this study. (1)- (3) is the area ratio occupied by the atmosphere in the analyzed area at each constant pressure level with a function of height (or pressure).…”

Section: Data and Methods Of Analysismentioning

confidence: 99%

“…Yanai et al, 1973) showed that the heating in the middle and upper troposphere is mainly due to the condensation heating and that effects of convective heat transport are quite small. However, since the plateau surface is strongly heated by the solar radiation, Table 1 shows all terms in total heat and moisture balances including the amount of condensation heating for each subarea.…”

Section: Data and Methods Of Analysismentioning

confidence: 99%

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Observational Study of Heat Sources Over the Eastern Tibetan Plateau during the Summer Monsoon

Nitta

1983

Journal of the Meteorological Society of Japan

103

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Spatial and temporal variations of the heat source over the eastern Tibetan Plateau are analyzed based on the FGGE Level II-b upper-air observation data during the Summer MONEX in 1979. The budget results of mass, heat and moisture obtained over the four divided subareas show that the upward mass circulation, large-scale apparent heat source and moisture sink predominate in the eastern Plateau as a whole, but there exist considerable spatial and temporal variations.Over the Plateau region higher than 3000m surface elevation, the maximum heating of about 4* d-1 exists around 400mb and both the effects by the heat supply from the elevated surface and the latent heat release contribute nearly equally to the net total heating. It is suggested from the moisture budget analysis that the water vapor lost by the condensation over the Plateau is generally balanced by the surface evaporation and that the effect of moisture convergence by large-scale motions is rather small. On the contrary, the low-level southwesterly monsoon flow brings a lot of water vapor and heavy precipitation occurs over the southern part of the Plateau including the Assam region. Large amounts of the condensation heating are liberated in the whole troposphere with the maximum near 400mb.Small amounts of heating and relatively large amounts of heating are observed over the northern and eastern slopes of the Plateau, respectively.It is found that there exist large diurnal variations of the upward motion and the heat source over the eastern Tibetan Plateau except in its northern part. Larger upward motion and heat source are found at 1200GMT (*1800LT) than at 0000GMT (*0600LT). Amplitudes of the diurnal variations are 1mb h-1*2mb h-1 for the vertical p-velocity and 1* d-1*2* d-1 for the heat source, respectively. These diurnal variations over the Plateau might be generated by the intense convective activity enhanced by the solar heating absorbed on the elevated Plateau surface during the daytime.Total heating, precipitation and relative vorticity in the upper troposphere averaged over the eastern Plateau have long-period fluctuations with the periods of 10*15 days and * 30 days. Large heating corresponds to large amounts of precipitation and strong upperlevel anticyclonic circulation. Time variations of the heat source and precipitation over the eastern Plateau show general out of phase relationships with the precipitation over the central India. The long-period fluctuations of the heat source over the Tibetan Plateau appear to be a part of the oscillation of the whole summer monsoon activity.

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Section: Data and Methods Of Analysismentioning

confidence: 76%

Section: Data and Methods Of Analysismentioning

confidence: 99%

Section: Data and Methods Of Analysismentioning

confidence: 99%

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Observational Study of Heat Sources Over the Eastern Tibetan Plateau during the Summer Monsoon

Nitta

1983

Journal of the Meteorological Society of Japan

103

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“…The form of the warming caused by convective heating is a non-steady expanding pattern of downwelling wavefronts in the stratified environment (Bretherton and Smolarkiewicz 1989, Nicholls et al 1992, Bretherton 1993, Mapes 1997). Unfortunately, the terms 'compensating subsidence' and 'cloud-induced subsidence,' which might appear to describe this response, were taken long ago to describe a mathematical term that arose as a definitional artifact in literature on the interaction of convection with large scales (Ooyama 1971, Yanai et al 1973. This section examines the conceptual roots of this term, in the tacit 'externalization' of largescale vertical velocity from convection.…”

Section: Do Clouds Modify Their Environment Through 'Compensating Submentioning

confidence: 99%

Equilibrium Vs. Activation Control of Large-Scale Variations of Tropical Deep Convection

Mapes

1997

The Physics and Parameterization of Moist Atmospheric Convection

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What processes control large-scale variations of deep convection (LSVDC) in the tropics? Here 'large-scale' is taken to mean any coherent variations, in either space or time, comprised of statistical populations of separate convective cloud systems. This essay highlights the distinction between processes which supply moisture or available energy over the depth of the convecting layer (equilibrium control), versus inhibition and initiation processes at low levels (activation control), as hypotheses for explaining LSVDC.Conceptual separations of the LSVDC problem are reviewed. Scale separation, though rigorous, is artificial, since net heating makes deep convective clouds multiscale, or spectrally red. Moist-dry, or diabatic-adiabatic, separation is more useful. An ill-posed hybrid separation -'the interaction of moist convection with large scales' -has spawned confusion. Correlations between deep convection and its own large-scale components (suggestively labeled 'forcing') have been misinterpreted as evidence for equilibrium control. This externalization of large-scale vertical velocity also encourages overinterpretation of a fictitious 'compensating subsidence' term.Published evidence for equilibrium control theories is critically re-examined. The deep-cloud quasi-equilibrium observations of Arakawa and Schubert would hold for arbitrarily determined variations of convection, because stratified fluid dynamics efficiently redistributes localized heating, not because convection is controlled by slow deep large-scale 'forcing.' A more sensitive test indicates that most tropical LSVDC are not forced by preexisting deep upward motions.Activation-control processes can operate on the large space scales and long time scales that define LSVDC. Modulation of convection by easterly waves and upper-tropospheric troughs, and the climatological distribution of convective cloudiness, are examined as examples. Lower boundary flux enhancements and deep lifting exert both equilibrium and activation influences on convection. The hypothesis that activation control may prevail on all scales short of globally-averaged climate is difficult to refute.Systematic study of convective cloud-ensemble sensitivities is badly needed. Unfortunately, current cloud ensemble modeling strategies, based on unnatural equilibriumcontrol assumptions, render the results merely diagnostic.To represent activation controls, large-scale models need multiple levels, and some prognostic representation of the subgridscale inhomogeneity of low-level fields.

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“…Over the equatorial eastern Pacific and Atlantic oceans (Figure 2a) latent heating is not observed. It is related to the absence of deep convective processes, which are the main causes of latent heating release (Yanai et al, 1973).…”

Section: Heat Balance For the Tropics And The Walker Circulationmentioning

confidence: 99%

Annual mean analysis of the tropical heat balance and associations with the Walker circulation

Augusto

Veiga

Brahamananda

2011

Rev. bras. meteorol.

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The present study presents an analysis of the annual mean tropical heat balance and its association with the Walker circulation (WC) using NCEP/NCAR Reanalysis data. This study shows the relative importance of diabatic data to produce vertical motion in the tropics and for the WC region. It is shown that ascending motion in the WC's upward branch is determined by the joint effect of latent heating and radiative cooling processes while infrared radiation loss is associated to sink motions on the WC's descending branch. In ascending branches of the WC vertical velocity from reanalysis is overestimated when latent heat is taken into account to drive motions. Radiative cooling is indentified as the main physical process yielding sinking motion in the WC's downward branches. In upward branches of the WC, resulting diabatic processes (latent heat release) are balanced by adiabatic expansion (due rising motions). In descending branches of the WC, there is a near balance between radiative cooling (due to longwave emission) and heating (due to sinking motions). Keywords: Walker Circulation, Heat Balance, Tropical Circulation RESUMO: ANÁLISE MÉDIA ANUAL DO BALANÇO DE CALOR TROPICAL E ASSOCIAÇÕES COM A CIRCULAÇÃO DE WALKER Este estudo apresenta uma análise do balanço de calor anual médio da região tropical e sua associação com a Circulação de Walker (CW), a partir das reanálises do NCEP/NCAR. Este estudo mostra a importância relativa do aquecimento diabático para gerar movimentos verticais nos trópicos e na região de atuação da CW. Os resultados mostram que o movimento ascendente nos ramos principais da CW é governado pelo efeito conjunto dos processos de aquecimento latente e resfriamento radiativo, enquanto que a perda de radiação infravermelha produz movimento descendente nos ramos secundários da CW. Mostra-se que o aquecimento latente força movimentos ascendentes sobre os ramos principais da CW, todavia, a velocidade vertical observada é superestimada, se apenas o calor latente é levado em consideração para forçar os movimentos. Além disso, o resfriamento radiativo foi identificado como o principal processo físico que produz movimentos subsidentes nos ramos secundários da CW. Nos ramos ascendentes da CW, o aquecimento resultante entre os processos de liberação de calor latente e de resfriamento radiativo é balanceado pela expansão adiabática, enquanto que em regiões de fraca convecção (ramos secundários da CW) existe um balanço aproximado entre o resfriamento radiativo (devido a emissão de ondas longas) e o aquecimento devido à compressão associado aos movimentos descendentes. Palavras Chaves: Circulação de Walker, Balanço de Calor, Circulação Tropical 2 Veiga et al.Volume 26(1)

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Determination of Bulk Properties of Tropical Cloud Clusters from Large-Scale Heat and Moisture Budgets

Cited by 1,547 publications

References 48 publications

Observational Study of Heat Sources Over the Eastern Tibetan Plateau during the Summer Monsoon

Observational Study of Heat Sources Over the Eastern Tibetan Plateau during the Summer Monsoon

Equilibrium Vs. Activation Control of Large-Scale Variations of Tropical Deep Convection

Annual mean analysis of the tropical heat balance and associations with the Walker circulation

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