Radar/radiometer retrievals of cloud liquid water and drizzle: Analysis using data from a three-dimensional large eddy simulation of marine stratocumulus clouds

Conference · Sat Apr 01 04:00:00 EST 1995

OSTI ID:83170

Feingold, G ^[1]; Frisch, A S ^[2]; Stevens, B; Cotton, W R ^[3]

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1. Univ. of Colorado, Boulder, CO (United States)
2. National Oceanic and Atmospheric Administration, Boulder, CO (United States)
3. Colorado State Univ., Fort Collins, CO (United States)

Marine stratocumulus clouds are believed to play an important role in the earth`s energy budget through their effect on the radiation budget. To evaluate the impact of stratocumulus clouds on climate, long-term cloud monitoring with extensive spatial coverage is imperative. Central to this problem are measurements of cloud liquid water and drizzle. This need prompted the National Oceanic and Atmospheric Administration`s (NOAA) Environmental Technology Laboratory to develop techniques for retrieving cloud liquid water content and drizzle characteristics using a K{sub {alpha}}-band Doppler radar and microwave radiometer. The instruments were deployed on the island of Porto Santo in the Madeiras during the recent Atlantic Stratocumulus Transition EXperiment (ASTEX), June 1992. Unfortunately, there were no useful overflights of the island, and there are no direct in situ measurements against which to compare the remote measurements. In this paper, we will use a data set generated by a three-dimensional (3-D) large eddy simulation (LES) model as a surrogate for real data. The model results presented do not represent an ASTEX case study; they are simply synthetic data of a marine stratocumulus capped boundary layer which are used to analyze the behavior of the remote sensing retrievals. The model is the Regional Atmospheric Modeling System (RAMS) developed at Colorado State University. The version used includes explicit treatment of cloud condensation nucleus and droplet size spectra. Because RAMS is able to resolve droplet size distributions, it is ideal for comparing various integrated moments of the distribution (e.g., LWC, Z, etc.) with similar parameters measured either in situ or by remote sensors. Model-derived information on droplet spectra and vertical velocities is used to calculate radar reflectivity factors, Doppler velocity spectra, and integrated liquid water paths (LWP). These parameters are then used as input to the retrieval method.

• Research Organization: USDOE Office of Energy Research, Washington, DC (United States). Environmental Sciences Div.
• OSTI ID: 83170
• Report Number(s): CONF-940277--; ON: DE95009951; CNN: Contract 164514-A-91
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CLIMATE MODELS
CLOUDS
COMPARATIVE EVALUATIONS
CONDENSATION NUCLEI
MOISTURE
RADAR
RADIANT HEAT TRANSFER
RADIOMETRIC ANALYSIS
REFLECTIVITY
REMOTE SENSING
SIMULATION
SPATIAL DISTRIBUTION