scholarly journals Aerosol Optical Depth retrievals in Central Amazonia from a Multi-Filter Rotating Shadow-band Radiometer on-site calibrated

2018 ◽  
Author(s):  
Nilton E. Rosário ◽  
Thamara Sauini ◽  
Theotonio Pauliquevis ◽  
Henrique M. J. Barbosa ◽  
Marcia A. Yamasoe ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Spectral Response ◽  
Monitoring Site ◽  
Direct Normal Irradiance ◽  
Central Amazonia ◽  
Mean Square Errors ◽  
Term Monitoring ◽  
Band Radiometer

Abstract. Extraterrestrial spectral response calibration of a Multi-Filter Rotating Shadow band Radiometer (MFRSR) under Amazonian Forest atmosphere pristine conditions using the Langley plot method was performed and evaluated. The MFRSR is installed in central Amazonia as part of a long-term monitoring site, which was used in the context of the GoAmazon2014/5 Experiment. It has been operating continuously since 2011 without regular extraterrestrial calibration, preventing its application to accurate monitoring of aerosol particles. Once calibrated, the MFRSR measurements were applied to retrieve aerosols particles columnar optical properties, specifically Aerosol Optical Depth (AODλ) and Ångström Exponent (AE), which were evaluated against retrievals from a collocated CIMEL sunphotometer belonging to the AErosol RObotic NETwork (AERONET). Results obtained revealed that Amazonian pristine conditions are able to provide MFRSR extraterrestrial spectral response with relative uncertainty lower than 1.0 % at visible channels. The worst estimate (air mass = 1) for absolute uncertainty in AODλ retrieval varied from ~ 0.02 to ~ 0.03, depending on the assumption regarding uncertainty for MFRSR direct-normal irradiance measured at the surface. Obtained Root Mean Square Errors (RMSE ~ 0.025) from the evaluation of MFRSR retrievals against AERONET AODλ were, in general, lower than estimate MFRSR AODλ uncertainties, and close to AERONET field sunphotometers (~ 0.02).

scholarly journals Aerosol optical depth retrievals in central Amazonia from a multi-filter rotating shadow-band radiometer calibrated on-site

2019 ◽  
Vol 12 (2) ◽  
pp. 921-934
Author(s):  
Nilton E. Rosário ◽  
Thamara Sauini ◽  
Theotonio Pauliquevis ◽  
Henrique M. J. Barbosa ◽  
Marcia A. Yamasoe ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Spectral Response ◽  
Monitoring Site ◽  
Direct Normal Irradiance ◽  
Central Amazonia ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Band Radiometer

Abstract. Extraterrestrial spectral response calibration of a multi-filter rotating shadow band radiometer (MFRSR) under pristine Amazonian Forest atmosphere conditions was performed using the Langley plot method. The MFRSR is installed in central Amazonia as part of a long-term monitoring site, which was used in the context of the GoAmazon2014/5 experiment. It has been operating continuously since 2011 without regular extraterrestrial calibration, preventing its application to accurate monitoring of aerosol particles. Once calibrated, the MFRSR measurements were applied to retrieve aerosol particle columnar optical properties, specifically aerosol optical depth (AODλ) and Ångström exponent (AE), which were evaluated against retrievals from a collocated Cimel Sun photometer belonging to the AErosol RObotic NETwork (AERONET). Results obtained revealed that pristine Amazonian conditions are able to provide MFRSR extraterrestrial spectral response with relative uncertainty lower than 1.0 % in visible channels. The worst estimate (air mass =1) for absolute uncertainty in AODλ retrieval varied from ≈0.02 to ≈0.03, depending on the assumption regarding uncertainty for MFRSR direct normal irradiance measured at the surface. The obtained root mean square error (RMSE ≈0.025) from the evaluation of MFRSR retrievals against AERONET AODλ was, in general, lower than estimated MFRSR AODλ uncertainty, and close to the uncertainty of AERONET field Sun photometers (≈0.02).

scholarly journals A new zenith-looking narrow-band radiometer-based system (ZEN) for dust aerosol optical depth monitoring

2017 ◽  
Vol 10 (2) ◽  
pp. 565-579 ◽  
Author(s):  
A. Fernando Almansa ◽  
Emilio Cuevas ◽  
Benjamín Torres ◽  
África Barreto ◽  
Rosa D. García ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Narrow Band ◽  
Low Cost ◽  
Sensitivity Study ◽  
Standard Uncertainty ◽  
Dust Aerosol ◽  
Coefficient Of Determination ◽  
Mean Square Errors ◽  
Band Radiometer

Abstract. A new zenith-looking narrow-band radiometer based system (ZEN), conceived for dust aerosol optical depth (AOD) monitoring, is presented in this paper. The ZEN system comprises a new radiometer (ZEN-R41) and a methodology for AOD retrieval (ZEN-LUT). ZEN-R41 has been designed to be stand alone and without moving parts, making it a low-cost and robust instrument with low maintenance, appropriate for deployment in remote and unpopulated desert areas. The ZEN-LUT method is based on the comparison of the measured zenith sky radiance (ZSR) with a look-up table (LUT) of computed ZSRs. The LUT is generated with the LibRadtran radiative transfer code. The sensitivity study proved that the ZEN-LUT method is appropriate for inferring AOD from ZSR measurements with an AOD standard uncertainty up to 0.06 for AOD500 nm  ∼  0.5 and up to 0.15 for AOD500 nm  ∼  1.0, considering instrumental errors of 5 %. The validation of the ZEN-LUT technique was performed using data from AErosol RObotic NETwork (AERONET) Cimel Electronique 318 photometers (CE318). A comparison between AOD obtained by applying the ZEN-LUT method on ZSRs (inferred from CE318 diffuse-sky measurements) and AOD provided by AERONET (derived from CE318 direct-sun measurements) was carried out at three sites characterized by a regular presence of desert mineral dust aerosols: Izaña and Santa Cruz in the Canary Islands and Tamanrasset in Algeria. The results show a coefficient of determination (R2) ranging from 0.99 to 0.97, and root mean square errors (RMSE) ranging from 0.010 at Izaña to 0.032 at Tamanrasset. The comparison of ZSR values from ZEN-R41 and the CE318 showed absolute relative mean bias (RMB)  <  10 %. ZEN-R41 AOD values inferred from ZEN-LUT methodology were compared with AOD provided by AERONET, showing a fairly good agreement in all wavelengths, with mean absolute AOD differences  <  0.030 and R2 higher than 0.97.

scholarly journals Supplementary material to "Aerosol Optical Depth retrievals in Central Amazonia from a Multi-Filter Rotating Shadow-band Radiometer on-site calibrated"

2018 ◽  
Author(s):  
Nilton E. Rosário ◽  
Thamara Sauini ◽  
Theotonio Pauliquevis ◽  
Henrique M. J. Barbosa ◽  
Marcia A. Yamasoe ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Central Amazonia ◽  
Supplementary Material ◽  
Band Radiometer

scholarly journals Aerosol optical depth retrievals at the Izaña Atmospheric Observatory from 1941 to 2013 by using artificial neural networks

2016 ◽  
Vol 9 (1) ◽  
pp. 53-62 ◽  
Author(s):  
R. D. García ◽  
O. E. García ◽  
E. Cuevas ◽  
V. E. Cachorro ◽  
A. Barreto ◽  
...  
Keyword(s):  
Neural Networks ◽  
Time Series ◽  
Artificial Neural Networks ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Mineral Dust ◽  
Dust Particles ◽  
Filter Radiometer ◽  
Artificial Neural

Abstract. This paper presents the reconstruction of a 73-year time series of the aerosol optical depth (AOD) at 500 nm at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (Canary Islands, Spain). For this purpose, we have combined AOD estimates from artificial neural networks (ANNs) from 1941 to 2001 and AOD measurements directly obtained with a Precision Filter Radiometer (PFR) between 2003 and 2013. The analysis is limited to summer months (July–August–September), when the largest aerosol load is observed at IZO (Saharan mineral dust particles). The ANN AOD time series has been comprehensively validated against coincident AOD measurements performed with a solar spectrometer Mark-I (1984–2009) and AERONET (AErosol RObotic NETwork) CIMEL photometers (2004–2009) at IZO, obtaining a rather good agreement on a daily basis: Pearson coefficient, R, of 0.97 between AERONET and ANN AOD, and 0.93 between Mark-I and ANN AOD estimates. In addition, we have analysed the long-term consistency between ANN AOD time series and long-term meteorological records identifying Saharan mineral dust events at IZO (synoptical observations and local wind records). Both analyses provide consistent results, with correlations  >  85 %. Therefore, we can conclude that the reconstructed AOD time series captures well the AOD variations and dust-laden Saharan air mass outbreaks on short-term and long-term timescales and, thus, it is suitable to be used in climate analysis.

scholarly journals Nine years of UV aerosol optical depth measurements at Thessaloniki, Greece

2007 ◽  
Vol 7 (8) ◽  
pp. 2091-2101 ◽  
Author(s):  
S. Kazadzis ◽  
A. Bais ◽  
V. Amiridis ◽  
D. Balis ◽  
C. Meleti ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Back Trajectories ◽  
Air Masses ◽  
North Eastern ◽  
Range Transport ◽  
Air Quality Monitoring Stations ◽  
Pm 10 ◽  
The City

Abstract. Spectral measurements of the aerosol optical depth (AOD) and the Ångström coefficient were conducted at Thessaloniki, Greece (40.5° N, 22.9° E) between January 1997 and December 2005 with a Brewer MKIII double-monochromator spectroradiometer. The dataset was compared with collocated measurements of a second spectroradiometer (Brewer MKII) and a CIMEL sun-photometer, showing correlations of 0.93 and 0.98, respectively. A seasonal variation of the AOD was observed at Thessaloniki, with AOD values at 340 nm of 0.52 and 0.28 for August and December respectively. Back trajectories of air masses for up to 4 days were used to assess the influence of long-range transport from various regions to the aerosol load over Thessaloniki. It is shown that part of the observed seasonality can be attributed to air masses with high AOD originating from North-Eastern and Eastern directions during summertime. The analysis of the long-term record (9 years) of AOD showed a downward tendency. A similar decreasing tendency was found in the record of the PM$_{10}$ aerosol measurements, which are conducted near the surface at 4 air-quality monitoring stations in the area of the city of Thessaloniki.

Long-term (1995–2018) aerosol optical depth derived using ground based AERONET and SKYNET measurements from aerosol aged-background sites

2019 ◽  
Vol 10 (2) ◽  
pp. 608-620 ◽  
Author(s):  
Shantikumar S. Ningombam ◽  
E.J.L. Larson ◽  
U.C. Dumka ◽  
Victor Estellés ◽  
M. Campanelli ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth
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