Vertical stratification of tropical cloud properties as determined from satellite

Sheu, Rong-Shyang; Curry, Judith A.; Liu, Guosheng

doi:10.1029/96jd02867

Cited by 28 publications

(22 citation statements)

References 27 publications

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“…Since each observed cloud layer is given equal weight in the histogram, many more thin than thick layers are identified. The high population of very thin cloud layers is consistent with the findings of previous studies (e.g., Warren et al 1985;Sheu et al 1997;Wang et al 2000), who find high frequencies of occurrence of often overlapping thin cloud layers in tropical cloud fields, mainly because cirrus clouds often overlay boundary layer clouds. However, as will be discussed in more detail below, this study reveals an additional layer of frequent occurrence of thin clouds located in the middle troposphere.…”

Section: B Cloud Characteristicssupporting

confidence: 81%

The Radiative, Cloud, and Thermodynamic Properties of the Major Tropical Western Pacific Cloud Regimes

Jakob¹,

Tselioudis

Hume³

2005

Journal of Climate

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This study investigates the radiative, cloud, and thermodynamic characteristics of the atmosphere separated into objectively defined cloud regimes in the tropical western Pacific (TWP). A cluster analysis is applied to 2 yr of daytime-only data from the International Satellite Cloud Climatology Project (ISCCP) to identify four major cloud regimes in the TWP region. A variety of data collected at the Department of Energy's Atmospheric Radiation Measurement Program (ARM) site on Manus Island is then used to identify the main characteristics of the regimes. Those include surface and top-of-the-atmosphere radiative fluxes and cloud properties derived from a suite of ground-based active remote sensors, as well as the temperature and water vapor distribution measured from radiosondes.The major cloud regimes identified in the TWP area are two suppressed regimes-one dominated by the occurrence of mostly shallow clouds, the other by thin cirrus-as well as two convectively active regimesone exhibiting a large coverage of optically thin cirrus clouds, the other characterized by a large coverage with optically thick clouds. All four of these TWP cloud regimes are shown to exist with varying frequency of occurrence at the ARM site at Manus. It is further shown that the detailed data available at that site can be used to characterize the radiative, cloud, and thermodynamic properties of each of the regimes, demonstrating the potential of the regime separation to facilitate the extrapolation of observations at one location to larger scales. A variety of other potential applications of the regime separation are discussed.

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Section: B Cloud Characteristicssupporting

confidence: 81%

The Radiative, Cloud, and Thermodynamic Properties of the Major Tropical Western Pacific Cloud Regimes

Jakob¹,

Tselioudis

Hume³

2005

Journal of Climate

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“…If the parameterization of IWP versus temperature obtained by Stephens et al [1990] is integrated from 500 to 200 hPa, the result is 190 g m-2; this assumes that the entire layer is always filled with cloud in any cloudy pixel, which makes it a rather distant upper limit. Sheu et al [ 1997] report that 60% of nonprecipitating stratiform cirrus clouds (their cloud class 8) have IWP < 50 g m -2 (though it is possible that some precipitating cirrus clouds were present in the cloudy scenes of Soden [1998], only a small fraction of their water content would be evaporated into levels above 500 hPa, since most would precipitate to lower levels or the surface.) Thus it appears that pumping ratios of 3-10 are required to reconcile the observations of ice content and moistening tendency.…”

Section: Observational Evidencementioning

confidence: 99%

On moistening of the tropical troposphere by cirrus clouds

Sherwood¹

1999

J. Geophys. Res.

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Abstract. Sublimation of ice crystals in cirrus clouds is often invoked as a moistening mechanism for the free troposphere, particularly in the tropics. An alternative mechanism is investigated here: "pumping" of water vapor into the cloudy atmospheric column from surrounding regions by diabatic transports resulting from the local radiative effects of the cloud. The effectiveness of this mechanism is computed for a variety of cirrus cloud types, using a simple model. For nonprecipitating cirrus clouds it is found that the pumping mechanism can import much more vapor mass into the cloudy column than the clouds contain as ice, especially as the clouds become optically thin. The advected vapor per unit ice mass (or "pumping ratio") also varies with cloud height, is proportional to cloud lifetime, and (for thin clouds) is approximately inversely proportional to effective particle radius. Thin cirrus above 300 hPa can pump vapor rapidly enough to sustain itself against dessication. The overall results are supported by the limited information available from observations and indicate that at sufficient distances from active convection, direct moistening of the environment by the sublimation of ice has significantly less impact on vapor distributions than cloud-radiative-dynamic effects.

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“…Some additional, but not complete, information on cloud vertical structure has been obtained from satellites using observations at more wavelengths than the two employed by ISCCP (e.g., Baum et al 1994;Jin and Rossow 1997;Sheu et al 1997;Lin et al 1998) or by using different viewing geometries, such as limb scanning by the Stratospheric Aerosol and Gas Experiment (SAGE) instrument (Liao et al 1995a,b;Wang et al 1996;Wylie and Wang 1997). A more promising approach uses active sensors, such as lidars (Sassen 1991;Platt et al 1994) and cloud radars (Kropfli et al 1995) or both (Uttal et al 1995;Wang et al 1999) to profile cloud layers from the surface; however, these instruments cannot provide coverage of whole synoptic systems or complete global coverage until they are deployed on satellites (Stephens et al 2002).…”

Section: Introductionmentioning

confidence: 99%

A Statistical Model of Cloud Vertical Structure Based on Reconciling Cloud Layer Amounts Inferred from Satellites and Radiosonde Humidity Profiles

2005

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To diagnose how cloud processes feed back on weather-and climate-scale variations of the atmosphere requires determining the changes that clouds produce in the atmospheric diabatic heating by radiation and precipitation at the same scales of variation. In particular, not only the magnitude of these changes must be quantified but also their correlation with atmospheric temperature variations; hence, the space-time resolution of the cloud perturbations must be sufficient to account for the majority of these variations. Although extensive new global cloud and radiative flux datasets have recently become available, the vertical profiles of clouds and consequent radiative flux divergence have not been systematically measured covering weather-scale variations from about 100 km, 3 h up to climate-scale variations of 10 000 km, decadal inclusive. By combining the statistics of cloud layer occurrence from the International Satellite Cloud Climatology Project (ISCCP) and an analysis of radiosonde humidity profiles, a statistical model has been developed that associates each cloud type, recognizable from satellite measurements, with a particular cloud vertical structure. Application of this model to the ISCCP cloud layer amounts produces estimates of low-level cloud amounts and average cloud-base pressures that are quantitatively closer to observations based on surface weather observations, capturing the variations with latitude and season and land and ocean (results are less good in the polar regions). The main advantage of this statistical model is that the correlations of cloud vertical structure with meteorology are qualitatively similar to "classical" information relating cloud properties to weather. These results can be evaluated and improved with the advent of satellites that can directly probe cloud vertical structures over the globe, providing statistics with changing meteorological conditions.

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Vertical stratification of tropical cloud properties as determined from satellite

Cited by 28 publications

References 27 publications

The Radiative, Cloud, and Thermodynamic Properties of the Major Tropical Western Pacific Cloud Regimes

The Radiative, Cloud, and Thermodynamic Properties of the Major Tropical Western Pacific Cloud Regimes

On moistening of the tropical troposphere by cirrus clouds

A Statistical Model of Cloud Vertical Structure Based on Reconciling Cloud Layer Amounts Inferred from Satellites and Radiosonde Humidity Profiles

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