Record Details
Properties of low-level marine clouds as deduced from advanced very high resolution radiometer satellite observations
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Properties of low-level marine clouds as deduced from advanced very high resolution radiometer satellite observations |
| Names |
Chang, Fu-Lung
(creator) Coakley, James A. Jr (advisor) |
| Date Issued | 1997-08-05 (iso8601) |
| Note | Graduation date: 1998 |
| Abstract | A radiation model was developed for retrieving cloud visible optical depth, droplet effective radius, and cloud top emission temperature using AVHRR satellite observations at 0.63, 3.7, and 11 μm. The model was used to determine the sensitivity of the retrieved properties to various approximations often employed in such retrievals. Droplet effective radius appears to be the most sensitive to the commonly used approximations. Cloud properties retrieved using a 16-stream scheme were within ±5% of those retrieved using a 148-stream scheme. Cloud properties retrieved using double Henyey-Greenstein phase functions were within ±10% of those retrieved using Mie scattering. The retrieved cloud properties were used to investigate biases that arise when partly cloudy pixels were assumed to be overcast and biases that arise due to oblique satellite view angles. On average, cloud visible optical depths retrieved for partly cloudy pixels were 40-60% of those retrieved for overcast pixels. Likewise, cloud liquid water paths were 30-50%, droplet effective radii were 1-3 μm smaller, and cloud top emission temperatures were 2-4K larger. Cloud visible optical depths retrieved at 60° satellite zenith angles were 60-70% of those retrieved at nadir. The retrieved droplet effective radii and cloud top emission temperatures varied little with changing satellite zenith angle. For March 1989, cloud optical depths and cloud emission temperatures retrieved for pixels overcast by single-layer, low-level clouds were negatively correlated. Cloud optical depth, liquid water path, and droplet effective radius were positively correlated with the sea surface-cloud top temperature difference. The retrieved cloud properties were also compared for the spatial coherence, CLAVR (Clouds from AVHRR), and a threshold method based on International Satellite Cloud Climatology Project procedures. For regions containing single-layered cloud systems, fractional cloud cover and cloud brightness temperatures derived by the ISCCP-like threshold method were systematically larger than those derived by the spatial coherence method, whereas cloud reflectivities were systematically smaller. Cloud reflectivities and brightness temperatures derived by CLAVR and the spatial coherence method were in better agreement. |
| Genre | Thesis/Dissertation |
| Topic | Clouds -- Pacific Ocean -- Remote sensing |
| Identifier | http://hdl.handle.net/1957/31695 |
