scholarly journals Quality Control Aerosol Optical Depth Value-Added Product Report

2021 ◽  
Author(s):  
Evgueni Kassianov ◽  
◽  
Erol Cromwell ◽  
Yan Shi ◽  
Justin Monroe ◽  
...  
Keyword(s):  
Quality Control ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Value Added ◽  
Product Report

scholarly journals Aerosol Optical Depth Value-Added Product Report

2013 ◽  
Author(s):  
A Koontz ◽  
G Hodges ◽  
J Barnard ◽  
C Flynn ◽  
J Michalsky
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Value Added ◽  
Product Report

scholarly journals The relevance of aerosol optical depth to cumulus fraction changes: a five-year climatology at the ACRF SGP site

2007 ◽  
Vol 7 (4) ◽  
pp. 11797-11837 ◽  
Author(s):  
E. I. Kassianov ◽  
L. K. Berg ◽  
C. Flynn ◽  
S. McFarlane
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Great Plains ◽  
Value Added ◽  
Cloud Fraction ◽  
Satellite Observations ◽  
Time Dependent ◽  
Size Dependent ◽  
Cloud Properties ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. The objective of this study is to investigate, by observational means, the magnitude and sign of the actively discussed relationship between cloud fraction N and aerosol optical depth τa. Collocated and coincident ground-based measurements and Terra/Aqua satellite observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site form the basis of this study. The N–τa relationship occurred in a specific 5-year dataset of fair-weather cumulus (FWC) clouds and mostly non-absorbing aerosols. To reduce possible contamination of the aerosols on the cloud properties estimation (and vice versa), we use independent datasets of τa and N obtained from the Multi-filter Rotating Shadowband Radiometer (MFRSR) measurements and from the ARM Active Remotely Sensed Clouds Locations (ARSCL) value-added product, respectively. Optical depth of the FWC clouds τcld and effective radius of cloud droplets re are obtained from the MODerate resolution Imaging Spectroradiometer (MODIS) data. We found that relationships between cloud properties (N,τcld, re) and aerosol optical depth are time-dependent (morning versus afternoon). Observed time-dependent changes of cloud properties, associated with aerosol loading, control the variability of surface radiative fluxes. In comparison with pristine clouds, the polluted clouds are more transparent in the afternoon due to smaller cloud fraction, smaller optical depth and larger droplets. As a result, the corresponding correlation between the surface radiative flux and τa is positive (warming effect of aerosol). Also we found that relationship between cloud fraction and aerosol optical depth is cloud size dependent. The cloud fraction of large clouds (larger than 1 km) is relatively insensitive to the aerosol amount. In contrast, cloud fraction of small clouds (smaller than 1 km) is strongly positively correlated with τa. This suggests that an ensemble of polluted clouds tends to be composed of smaller clouds than a similar one in a pristine environment. One should be aware of these time- and size-dependent features when qualitatively comparing N–τa relationships obtained from the satellite observations, surface measurements, and model simulations.

scholarly journals Daytime and nighttime aerosol optical depth implementation in CÆLIS

2020 ◽  
Vol 9 (2) ◽  
pp. 417-433 ◽  
Author(s):  
Ramiro González ◽  
Carlos Toledano ◽  
Roberto Román ◽  
David Fuertes ◽  
Alberto Berjón ◽  
...  
Keyword(s):  
Quality Control ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Processing System ◽  
Software Tool ◽  
Mean Differences ◽  
The University ◽  
Phase Angles ◽  
Climate Studies ◽  
Cloud Screening

Abstract. The University of Valladolid (UVa, Spain) has managed a calibration center of the AErosol RObotic NETwork (AERONET) since 2006. The CÆLIS software tool, developed by UVa, was created to manage the data generated by AERONET photometers for calibration, quality control and data processing purposes. This paper exploits the potential of this tool in order to obtain products like the aerosol optical depth (AOD) and Ångström exponent (AE), which are of high interest for atmospheric and climate studies, as well as to enhance the quality control of the instruments and data managed by CÆLIS. The AOD and cloud screening algorithms implemented in CÆLIS, both based on AERONET version 3, are described in detail. The obtained products are compared with the AERONET database. In general, the differences in daytime AOD between CÆLIS and AERONET are far below the expected uncertainty of the instrument, ranging in mean differences between -1.3×10-4 at 870 nm and 6.2×10-4 at 380 nm. The standard deviations of the differences range from 2.8×10-4 at 675 nm to 8.1×10-4 at 340 nm. The AOD and AE at nighttime calculated by CÆLIS from Moon observations are also presented, showing good continuity between day and nighttime for different locations, aerosol loads and Moon phase angles. Regarding cloud screening, around 99.9 % of the observations classified as cloud-free by CÆLIS are also assumed cloud-free by AERONET; this percentage is similar for the cases considered cloud-contaminated by both databases. The obtained results point out the capability of CÆLIS as a processing system. The AOD algorithm provides the opportunity to use this tool with other instrument types and to retrieve other aerosol products in the future.

scholarly journals Day- and night-time aerosol optical depth implementation in CÆLIS

2020 ◽  
Author(s):  
Ramiro González ◽  
Carlos Toledano ◽  
Roberto Román ◽  
David Fuertes ◽  
Alberto Berjón ◽  
...  
Keyword(s):  
Quality Control ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Processing System ◽  
Software Tool ◽  
Night Time ◽  
Mean Differences ◽  
The University ◽  
Phase Angles ◽  
Cloud Screening

Abstract. The University of Valladolid (UVa, Spain) manages since 2006 a calibration center of the AErosol RObotic NETwork (AERONET). The CÆLIS software tool, developed by UVa, was created to manage the data generated by the AERONET photometers, for calibration, quality control and data processing purposes. This paper exploits the potential of this tool in order to obtain products like the aerosol optical depth (AOD) and Angstrom exponent (AE), which are of high interest for atmospheric and climate studies, as well as to enhance the quality control of the instruments and data managed by CÆLIS. The AOD and cloud screening algorithms implemented in CÆLIS, both based on AERONET version 3, are described in detail. The obtained products are compared with the AERONET database. In general, the differences in daytime AOD between CÆLIS and AERONET are far below the expected uncertainty of the instrument, ranging the mean differences between −1.3×10−4 at 870 nm and 6.2×10−4 at 380 nm. The standard deviations of the differences range from 2.8×10−4 at 675 nm to 8.1×10−4 at 340 nm. The AOD and AE at night-time calculated by CÆLIS from Moon observations are also presented, showing good continuity between day and night-time for different locations, aerosol loads and moon phase angles. Regarding cloud screening, around 99.9 % of the observations classified as cloud-free by CÆLIS are also assumed cloud-free by AERONET; this percentage is similar for the cases considered as cloud-contaminated by both databases. The obtained results point out the capability of CÆLIS as processing system. The AOD algorithm provides the opportunity to use this tool with other instrument types and to retrieve other aerosol products in the future.

scholarly journals The World Optical Depth Research and Calibration Center (WORCC) quality assurance and quality control of GAW-PFR AOD measurements

2018 ◽  
Vol 7 (1) ◽  
pp. 39-53 ◽  
Author(s):  
Stelios Kazadzis ◽  
Natalia Kouremeti ◽  
Stephan Nyeki ◽  
Julian Gröbner ◽  
Christoph Wehrli
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
World Meteorological Organization ◽  
Instrument Calibration ◽  
Radiation Center ◽  
New Methods ◽  
The World ◽  
Processing Techniques

Abstract. The World Optical Depth Research Calibration Center (WORCC) is a section within the World Radiation Center at Physikalisches-Meteorologisches Observatorium (PMOD/WRC), Davos, Switzerland, established after the recommendations of the World Meteorological Organization for calibration of aerosol optical depth (AOD)-related Sun photometers. WORCC is mandated to develop new methods for instrument calibration, to initiate homogenization activities among different AOD networks and to run a network (GAW-PFR) of Sun photometers. In this work we describe the calibration hierarchy and methods used under WORCC and the basic procedures, tests and processing techniques in order to ensure the quality assurance and quality control of the AOD-retrieved data.

scholarly journals The World aerosol Optical depth Research and Calibration Center (WORCC), Quality assurance and quality control of GAW-PFR AOD measurements

2017 ◽  
Author(s):  
Stelios Kazadzis ◽  
Natalia Kouremeti ◽  
Stephan Nyeki ◽  
Julian Gröbner ◽  
Christoph Wehrli
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Instrument Calibration ◽  
Radiation Center ◽  
New Methods ◽  
The World ◽  
Processing Techniques

Abstract. The World Optical Depth Research Calibration Center (WORCC) is a section within the World Radiation Center at Physikalisches-Meteorologisches Observatorium (PMOD/WRC), Davos, Switzerland, established after the recommendations of WMO for calibration of AOD related sun-photometers. WORCC is mandated to develop new methods for instrument calibration, to initiate homogenization activities among different AOD networks and to run a network (GAW-PFR) of sun-photometers. In this work we describe: the calibration hierarchy and methods used under WORCC and the basic procedures, test and processing techniques in order to ensure the quality assurance and quality control of the AOD retrieved data.

scholarly journals Advancements in the Aerosol Robotic Network (AERONET) Version 3 Database – Automated Near Real-Time Quality Control Algorithm with Improved Cloud Screening for Sun Photometer Aerosol Optical Depth (AOD) Measurements

2018 ◽  
Author(s):  
David M. Giles ◽  
Alexander Sinyuk ◽  
Mikhail S. Sorokin ◽  
Joel S. Schafer ◽  
Alexander Smirnov ◽  
...  
Keyword(s):  
Quality Control ◽  
Standard Deviation ◽  
Real Time ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Near Infrared ◽  
Data Set ◽  
Automatic Data ◽  
Field Calibration ◽  
Cloud Screening

Abstract. The Aerosol Robotic Network (AERONET) provides highly accurate, ground-truth measurements of the aerosol optical depth (AOD) using Cimel Electronique Sun/Sky radiometers for more than 25 years. In Version 2 (V2) of the AERONET database, the near real-time AOD was semi-automatically quality controlled utilizing mainly cloud screening methodology, while additional AOD data contaminated by clouds or affected by instrument anomalies were removed manually before attaining quality assured status (Level 2.0). The large growth in the number of AERONET sites over the past 25 years resulted in significant burden to manually quality control millions of measurements in a consistent manner. The AERONET Version 3 (V3) algorithm provides fully automatic cloud screening and instrument anomaly quality controls. All of these new algorithm updates apply to near real-time data as well as post-field deployment processed data, and AERONET reprocessed the database in 2018. A full algorithm redevelopment provided the opportunity to improve data inputs and corrections such as unique filter specific temperature characterizations for all visible and near-infrared wavelengths, updated gaseous and water vapor absorption coefficients, and ancillary data sets. The Level 2.0 AOD quality assured data set is now available within a month after post-field calibration, reducing the lag time from up to several months. Near real-time estimated uncertainty is determined using data qualified as V3 Level 2.0 AOD and considering the difference between the AOD computed with the pre-field calibration and AOD computed with pre-field and post-field calibration. This assessment provides a near real-time uncertainty estimate where average differences of AOD suggest a +0.02 bias and one sigma uncertainty of 0.02, spectrally, but the bias and uncertainty can be significantly larger for specific instrument deployments. Long-term monthly averages analyzed for the entire V3 and V2 databases produced average differences (V3–V2) of +0.002 with a ±0.02 standard deviation, yet monthly averages calculated using time-matched observations in both databases were analyzed to compute an average difference of −0.002 with a ±0.004 standard deviation. The high statistical agreement in multi-year monthly averaged AOD validates the advanced automatic data quality control algorithms and suggests that migrating research to the V3 database will corroborate most V2 research conclusions and likely lead to more accurate results in some cases.

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