Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm Boundary Layer Clouds: An Observational Study

Journal Article · Mon Sep 15 04:00:00 EDT 2003 · Journal of Climate, 16(18):2997-3009

DOI:https://doi.org/10.1175/1520-0442(2003)016<2997:IOALWP>2.0.CO;2· OSTI ID:15010334

Sengupta, Manajit; Clothiaux, Eugene E; Ackerman, Thomas P; Kato, Seiji; Min, Qilong

A one-year observational study of overcast boundary layer stratus at the U.S. Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site illustrates that surface radiation is primarily sensitive to cloud liquid water path, with cloud drop effective radius having a secondary influence. The mean, median and standard deviation of cloud liquid water path and cloud drop effective radius for the dataset are 0.120 mm, 0.101 mm, 0.108 mm, and 7.38 {micro}m, 7.13 {micro}m, 2.39 {micro}m, respectively. Radiative transfer calculations demonstrate that cloud optical depth and cloud normalized forcing are respectively three and six times as sensitive to liquid water path variations as they are to effective radius variations, when the observed ranges of each of those variables is considered. Overall, there is a 79% correlation between observed and computed surface fluxes when using a fixed effective radius of 7.5 {micro}m and observed liquid water paths in the calculations. One conclusion from this study is that measurement of the indirect aerosol effect will be problematic at the site, as variations in cloud liquid water path will most likely mask effects of variations in particle size.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15010334
• Report Number(s): PNNL-SA-37196; KP1201030
• Journal Information: Journal of Climate, 16(18):2997-3009, Journal Name: Journal of Climate, 16(18):2997-3009
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Southern Great Plains
optical depth
stratocumulus clouds
marine stratocumulus
size distributions
effective radius
scattering
climate
parameterization
atmospheres