Investigation into the wavelength dependence of the aerosol optical depth in the Athens area

2006 ◽  
Vol 132 (620) ◽  
pp. 2217-2234 ◽  
Author(s):  
D. G. Kaskaoutis ◽  
H. D. Kambezidis
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Wavelength Dependence ◽  
Athens Area

scholarly journals Daytime aerosol optical depth above low-level clouds is similar to that in adjacent clear skies at the same heights: airborne observation above the southeast Atlantic

2020 ◽  
Author(s):  
Yohei Shinozuka ◽  
Meloë S. Kacenelenbogen ◽  
Sharon P. Burton ◽  
Steven G. Howell ◽  
Paquita Zuidema ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Wavelength Dependence ◽  
Single Scattering ◽  
Airborne Lidar ◽  
Aerosol Layer ◽  
Low Level ◽  
Satellite Retrieval ◽  
Biomass Burning Aerosol ◽  
The Difference

Abstract. To help satellite retrieval of aerosols and studies of their radiative effects, we demonstrate that daytime 532 nm aerosol optical depth over low-level clouds is similar to that in neighboring clear skies at the same heights in recent airborne lidar and sunphotometer observations above the southeast Atlantic. The mean AOD difference is between 0 and −0.01, when comparing the two sides, each up to 20 km wide, of cloud edges. The difference is not statistically significant according to a paired t-test. Systematic differences in the wavelength dependence of AOD and in situ single scattering albedo are also minute. These results hold regardless of the vertical distance between cloud top and aerosol layer bottom. AOD aggregated over ~ 2° grid boxes for each of September 2016, August 2017 and October 2018 also shows little correlation with the presence of low-level clouds. We posit that a satellite retrieval artifact is entirely responsible for a previous finding of generally smaller AOD over clouds (Chung et al., 2016), at least for the region and season of our study. Our results also suggest that the same values can be assumed for the intensive properties of free-tropospheric biomass-burning aerosol regardless of whether clouds exist below.

Diurnal variation of the aerosol optical depth for two distinct cases in the Athens area, Greece

2005 ◽  
Vol 78 (1-2) ◽  
pp. 79-92 ◽  
Author(s):  
G.M. Giavis ◽  
H.D. Kambezidis ◽  
N. Sifakis ◽  
Z. Toth ◽  
A.D. Adamopoulos ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Athens Area

scholarly journals Daytime aerosol optical depth above low-level clouds is similar to that in adjacent clear skies at the same heights: airborne observation above the southeast Atlantic

2020 ◽  
Vol 20 (19) ◽  
pp. 11275-11285 ◽  
Author(s):  
Yohei Shinozuka ◽  
Meloë S. Kacenelenbogen ◽  
Sharon P. Burton ◽  
Steven G. Howell ◽  
Paquita Zuidema ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Wavelength Dependence ◽  
Single Scattering ◽  
Airborne Lidar ◽  
Aerosol Layer ◽  
Low Level ◽  
Satellite Retrieval ◽  
Biomass Burning Aerosol ◽  
The Difference

Abstract. To help satellite retrieval of aerosols and studies of their radiative effects, we demonstrate that daytime aerosol optical depth over low-level clouds is similar to that in neighboring clear skies at the same heights. Based on recent airborne lidar and sun photometer observations above the southeast Atlantic, the mean aerosol optical depth (AOD) difference at 532 nm is between 0 and −0.01, when comparing the cloudy and clear sides, each up to 20 km wide, of cloud edges. The difference is not statistically significant according to a paired t test. Systematic differences in the wavelength dependence of AOD and in situ single scattering albedo are also minuscule. These results hold regardless of the vertical distance between cloud top and aerosol layer bottom. AOD aggregated over ∼2∘ grid boxes for each of September 2016, August 2017 and October 2018 also shows little correlation with the presence of low-level clouds. We posit that a satellite retrieval artifact is entirely responsible for a previous finding of generally smaller AOD over clouds (Chung et al., 2016), at least for the region and time of our study. Our results also suggest that the same values can be assumed for the intensive properties of free-tropospheric biomass-burning aerosol regardless of whether clouds are present below.

scholarly journals Horizontal variability of aerosol optical depth observed during the ARCTAS airborne experiment

2011 ◽  
Vol 11 (5) ◽  
pp. 16245-16264 ◽  
Author(s):  
Y. Shinozuka ◽  
J. Redemann
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Remote Sensing ◽  
Wavelength Dependence ◽  
Long Range Transport ◽  
Straight Line ◽  
Relative Standard ◽  
Range Transport ◽  
Local Emissions ◽  
Airborne Experiment

Abstract. We present statistics on the horizontal variability of aerosol optical depth (AOD) directly measured from the NASA P-3 aircraft. Our measurements during two contrasting phases (in Alaska and Canada) of the ARCTAS mission arguably constrain the variability in most aerosol environments common over the globe. In the Canada phase, which features local emissions, 499 nm AOD has a median relative standard deviation (stdrel,med) of 19 % and 9 % and an autocorrelation (r) of 0.37 and 0.71 over 20 km and 6 km horizontal segments, respectively. In the Alaska phase, which features long-range transport, the variability is considerably lower (stdrel,med = 3 %, r = 0.92 even over 35.2 km). Compared to the magnitude of AOD, its wavelength dependence varies less in the Canada phase, more in the Alaska phase. We translate these findings from straight-line flight tracks into grid boxes and points, to help interpretation and design of satellite remote sensing, suborbital observations and transport modeling.

Cases of aerosol optical depth estimation in the Athens area, Greece

2005 ◽  
Vol 67 (16) ◽  
pp. 1524-1532 ◽  
Author(s):  
George M. Giavis ◽  
Harry D. Kambezidis ◽  
Athanasios K. Basdekis ◽  
Nikolaos Sifakis ◽  
Zoltan Toth ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Depth Estimation ◽  
Athens Area

scholarly journals Horizontal variability of aerosol optical depth observed during the ARCTAS airborne experiment

2011 ◽  
Vol 11 (16) ◽  
pp. 8489-8495 ◽  
Author(s):  
Y. Shinozuka ◽  
J. Redemann
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Remote Sensing ◽  
Wavelength Dependence ◽  
Long Range Transport ◽  
Straight Line ◽  
Relative Standard ◽  
Range Transport ◽  
Local Emissions ◽  
Airborne Experiment

Abstract. We present statistics on the horizontal variability of aerosol optical depth (AOD) directly measured from the NASA P-3 aircraft. Our measurements during two contrasting phases (in Alaska and Canada) of the ARCTAS mission arguably constrain the variability in most aerosol environments common over the globe. In the Canada phase, which features local emissions, 499 nm AOD has a median relative standard deviation (stdrel, med) of 19 % and 9 % and an autocorrelation (r) of 0.37 and 0.71 over 20 km and 6 km horizontal segments, respectively. In the Alaska phase, which features long-range transport, the variability is considerably lower (stdrel, med = 3 %, r = 0.92 even over 35.2 km). Compared to the magnitude of AOD, its wavelength dependence varies less in the Canada phase, more in the Alaska phase. We translate these findings from straight-line flight tracks into grid boxes and points, to help interpretation and design of satellite remote sensing, suborbital observations and transport modeling.

scholarly journals Harmonized and high-quality datasets of aerosol optical depth at a US continental site, 1997–2018

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Evgueni Kassianov ◽  
Erol Cromwell ◽  
Justin Monroe ◽  
Laura D. Riihimaki ◽  
Connor Flynn ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Temporal Resolution ◽  
Wavelength Dependence ◽  
High Temporal Resolution ◽  
High Quality ◽  
Wide Range ◽  
Climate Change Assessment ◽  
The Individual

AbstractAerosol optical depth (AOD) characterizes the aerosol burden in the atmosphere, while its wavelength dependence is a sign of particle size. Long-term records of wavelength-resolved AOD with high quality and suitable continuity are required for climate change assessment. Typically, climate-related studies use AOD products provided by several, and perhaps different, ground-based instruments. The measurements from these instruments often have different accuracy and temporal resolution. To preserve the advantages of these products (high quality) and to reduce their disadvantages (patchy records), we generate a merged dataset obtained from four instruments deployed at a US continental site in which a nearly-continuous AOD record is found at two wavelengths (500 and 870 nm) with high quality and high temporal resolution (1-min) for a 21-yr period (1997–2018). The combined dataset addresses: (1) varying data quality and resolution mismatch of the individual AOD records, and (2) the uncertainty of the merged AOD and its relevance for user-specified needs. The generated dataset will be beneficial for a wide range of applications including aerosol-radiation interactions.

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