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...
The Earth Radiation Budget Experiment (ERBE) uses Angular Dependence Models
(ADMs) to convert satellite observed radiances to radiative fluxes at the top of the
atmosphere. Owing to errors in scene identification and to the relationship between
the spatial scales of cloud systems and the spatial resolution of the ERBE scanner,...
Improvements have been made to the spatial coherence method for automatically determining cloud-free ocean radiances in satellite imagery by incorporating the spectral signatures of reflecting surfaces. The spatial coherence method relies on the fact that small-scale cloud-free regions typically exhibit uniform emission and uniform reflection. While small-scale overcast regions typically...
The accurate determination of cloud cover amount is important for characterizing the role of cloud feedbacks in the climate system. Clouds have a large influence on the climate system through their effect on the earth's radiation budget. As indicated by the NASA Earth Radiation Budget Experiment (ERBE), the change in...
Satellite technology represents the only technique for measuring sea surface temperatures (SSTs) on a global scale. SSTs are important as boundary conditions for climate and atmospheric boundary layer models which attempt to describe phenomena of all scales, ranging from local forecasts to predictions of global warming. Historical use of infrared...
Cloud reflectivity is a function of cloud liquid water content and droplet number concentration. Since cloud droplets form around pre-existing aerosol particles, cloud droplet number concentration depends on the availability of particles that can serve as cloud condensation nuclei. Given constant liquid water amount, increased availability of cloud condensation nuclei...
The atmospheric radiative transfer model MOCARAT was developed and is presented in this thesis. MOCARAT employs a Monte Carlo Technique for the accurate modeling of band radiances and reflectances in an atmospheric system with a ruffled ocean surface as a lower boundary. The atmospheric radiative transfer is modeled with consideration...
One method of estimating the longwave radiative heating of the atmosphere is to combine satellite observations of emitted radiances with those computed from synoptic temperature and humidity profiles. Modeled and observed radiances are brought into agreement by altering cloud properties or even by adjusting the temperature and water vapor profiles....
The Indian Ocean Experiment (INDOEX) had as a primary objective
determining the radiative forcing due to anthropogenic aerosols over
climatologically significant space and time scales: the Indian Ocean during the
winter monsoon, January-March. During the winter monsoon, polluted, low-level
air from the Asian subcontinent blows over the Arabian Sea and...
Realistic assessment of the vertical distribution of clouds, particularly the occurrence of multi-layered systems, is critical for accurate calculations of radiative transfer in general circulation models. Such information is also useful in the design and improvement of satellite retrieval techniques. Current methods for retrieving cloud properties from satellite data assume...
A multispectral retrieval method is developed on the 100 km regional scale to extract
the temperature, particle size, fractional cover and 11-μm emissivity of clouds which
may be semitransparent in the infrared based on emitted radiances. The scheme utilizes
the nonlinear relationship between emitted radiances when clouds are semitransparent and...
The 2007 Intergovernmental Panel on Climate Change assessment established that the effect of clouds on climate contributes the largest uncertainty in predicting the future climate. Satellite observations provide an opportunity for learning about the behavior of clouds. This thesis seeks to assess the accuracy of cloud properties retrieved from multispectral...
One kilometer Moderate Resolution Imaging Spectroradiometer (MODIS) observations for Terra (morning) and Aqua (afternoon) satellites were used to follow the morning to afternoon evolution of marine stratocumulus clouds that were affected by ship stack exhaust. The observations covered the summer months of 2002-2003 and August 2007 for marine layers off...
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James A. Coakley, Jr.
One kilometer Moderate Resolution Imaging Spectroradiometer (MODIS
The operational processing of MODIS imagery to produce the MOD06 cloud product is based on the assumption that cloudy 1-km pixels are overcast. This assumption is examined using a partly cloudy pixel retrieval scheme, which allows for fractional cloud cover within the 1-km pixels. Cloud flags attached to 250-m MODIS...
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James A. Coakley, Jr.
The operational processing of MODIS imagery to produce the MOD06
Adiabatic parcel models suggest specific relationships between cloud thickness and cloud properties. Such relationships govern cloud radiative forcing and thus cloud feedbacks in the climate system. Current remote sensing techniques work well at measuring these properties in low-level cloud systems that are overcast. Significant biases exist, however, when measuring cloud...
1-km MODIS observations of ship tracks off the west coast of the U.S. are used to characterize changes in cloud visible optical depths, cloud droplet radii, cloud cover fraction, and column cloud liquid water amount as low-level marine clouds respond to particle pollution from underlying ships. This study re-examines the...
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James A. Coakley, Jr.
1-km MODIS observations of ship tracks off the west coast of the U.S
Advanced Very-High Resolution Radiometer 4-km data were collected over the northeast Atlantic for May-August, 1995-1999. Aerosol optical depth was retrieved in cloud-free pixels. In pixels containing clouds from only single-layered, low-level systems, a retrieval scheme that accounts for partly-cloudy pixels was used to retrieve: cloud optical depth, droplet effective radius,...
Ship tracks have proven to be an ideal laboratory for studying the response of marine
stratocumulus to an increase in aerosol pollution. Here the response of already
polluted marine stratocumulus to further pollution was examined by studying the
clouds where two ship tracks cross. 78 crossings of ship tracks were...
Aerosols are tiny particles that serve as nuclei for cloud droplet and ice crystal formation. Increases in aerosol concentration lead to clouds with smaller but more numerous droplets. Some recent studies have found evidence that ice crystal size in deep convective clouds is also reduced by elevated aerosol concentrations. In...