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Title: Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?

Abstract

Aerosol measurements over the Southern Great Plains (SGP) Cloud And Radiation Test bed (CART) site under Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program characterize the temporal variability, vertical distribution, and optical properties of aerosols in the region. They were made by the Cimel sunphotometer and Multifilter Rotating Shadow-band Radiometer (MFRSR), Raman Lidar, In situ Aerosol Profiling (IAP) flights, and the Aerosol Observing System (AOS). The spatial variability of aerosols relies a network of MFRSR at the Central Facility (CF) and Extended Facilities (EF), together with satellite remote sensing. The current state-of-art satellite-based estimates over land--e.g., MODerate resolution Imaging Scanner (MODIS) aerosol optical thickness--still suffer from large uncertainties. Contamination due to sub-pixel and/or thin cirrus clouds is believed to be one of the major sources of uncertainties. Retrievals near clouds are discouraged to use, which reduces considerably the amount of useful data. In this regard, cloud is considered as an artifact. However, cloud could have a real impact on AOT by changing humidity, which affects aerosol through the aerosol swelling effect. As a preliminary study, we first investigate the effects of cloud cover and humidity on the retrievals of AOT from ground-based Cimel sunphotometer measurements, in order to helpmore » us sort out the real influence and artifact. In general, it is very difficult to verify and quantify the effects of cloud on satellite retrieval of aerosol quantities. Speculation and warning of cloud contamination have been made whenever there is a correlation between the retrieved AOT and cloud fraction or their spatial variabilities, while it has also been argued that aerosol humidification effect (AHE) might be at work. The ample measurements available from ARM over the SGP region may allow us to unravel this complex issue. Our ultimate goals are to (1) evaluate various effects on the retrievals of AOT from both satellite and ground sensors; (2) separate artifact from real effect; (3) create ''clean'' aerosol products for studying their direct and indirect effect. Presented are some very preliminary findings.« less

Authors:
;
Publication Date:
Research Org.:
University of Maryland, College Park, Maryland (US)
Sponsoring Org.:
USDOE Office of Science (SC) (US)
OSTI Identifier:
841617
DOE Contract Number:  
FG02-01ER63166
Resource Type:
Conference
Resource Relation:
Conference: Fifteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting, Daytona Beach, FL (US), 03/14/2005--03/18/2005; Other Information: PBD: 18 Mar 2005
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AEROSOLS; CLOUD COVER; CLOUDS; CONTAMINATION; DISTRIBUTION; HUMIDITY; OPTICAL PROPERTIES; OPTICAL RADAR; RADIATIONS; RADIOMETERS; REMOTE SENSING; RESOLUTION; SATELLITES; SWELLING; THICKNESS

Citation Formats

Jeong, M-J, and Li, Z. Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?. United States: N. p., 2005. Web.
Jeong, M-J, & Li, Z. Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?. United States.
Jeong, M-J, and Li, Z. 2005. "Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?". United States. https://www.osti.gov/servlets/purl/841617.
@article{osti_841617,
title = {Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?},
author = {Jeong, M-J and Li, Z},
abstractNote = {Aerosol measurements over the Southern Great Plains (SGP) Cloud And Radiation Test bed (CART) site under Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program characterize the temporal variability, vertical distribution, and optical properties of aerosols in the region. They were made by the Cimel sunphotometer and Multifilter Rotating Shadow-band Radiometer (MFRSR), Raman Lidar, In situ Aerosol Profiling (IAP) flights, and the Aerosol Observing System (AOS). The spatial variability of aerosols relies a network of MFRSR at the Central Facility (CF) and Extended Facilities (EF), together with satellite remote sensing. The current state-of-art satellite-based estimates over land--e.g., MODerate resolution Imaging Scanner (MODIS) aerosol optical thickness--still suffer from large uncertainties. Contamination due to sub-pixel and/or thin cirrus clouds is believed to be one of the major sources of uncertainties. Retrievals near clouds are discouraged to use, which reduces considerably the amount of useful data. In this regard, cloud is considered as an artifact. However, cloud could have a real impact on AOT by changing humidity, which affects aerosol through the aerosol swelling effect. As a preliminary study, we first investigate the effects of cloud cover and humidity on the retrievals of AOT from ground-based Cimel sunphotometer measurements, in order to help us sort out the real influence and artifact. In general, it is very difficult to verify and quantify the effects of cloud on satellite retrieval of aerosol quantities. Speculation and warning of cloud contamination have been made whenever there is a correlation between the retrieved AOT and cloud fraction or their spatial variabilities, while it has also been argued that aerosol humidification effect (AHE) might be at work. The ample measurements available from ARM over the SGP region may allow us to unravel this complex issue. Our ultimate goals are to (1) evaluate various effects on the retrievals of AOT from both satellite and ground sensors; (2) separate artifact from real effect; (3) create ''clean'' aerosol products for studying their direct and indirect effect. Presented are some very preliminary findings.},
doi = {},
url = {https://www.osti.gov/biblio/841617}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Mar 18 00:00:00 EST 2005},
month = {Fri Mar 18 00:00:00 EST 2005}
}

Conference:
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