scholarly journals Evaluation of the MERIS aerosol product over land with AERONET

2008 ◽  
Vol 8 (1) ◽  
pp. 3721-3759 ◽  
Author(s):  
J. Vidot ◽  
R. Santer ◽  
O. Aznay

Abstract. The Medium Resolution Imaging Spectrometer (MERIS) launched in February 2002 on-board the ENVISAT spacecraft is making global observations of top-of-atmosphere (TOA) radiances. Aerosol optical properties are retrieved over land using Look-Up Table (LUT) based algorithm and surface reflectances in the blue and the red spectral regions. We compared instantaneous aerosol optical thicknesses retrieved by MERIS in the blue and the red at locations containing sites within the Aerosol Robotic Network (AERONET). Between 2002 and 2005, a set of 500 MERIS images were used in this study. The result shows that, over land, MERIS aerosol optical thicknesses are well retrieved in the blue and poorly retrieved in the red, leading to an underestimation of the Angstrom coefficient. Correlations are improved by applying a simple criterion to avoid scenes probably contaminated by thin clouds. To investigate the weakness of the MERIS algorithm, ground-based radiometer measurements have been used in order to retrieve new aerosol models, based on their Inherent Optical Properties (IOP). These new aerosol models slightly improve the correlation, but the main problem of the MERIS aerosol product over land can be attributed to the surface reflectance model in the red.

2008 ◽  
Vol 8 (24) ◽  
pp. 7603-7617 ◽  
Author(s):  
J. Vidot ◽  
R. Santer ◽  
O. Aznay

Abstract. The Medium Resolution Imaging Spectrometer (MERIS) launched in February 2002 on-board the ENVISAT spacecraft is making global observations of top-of-atmosphere (TOA) radiances. Aerosol optical properties are retrieved over land using Look-Up Table (LUT) based algorithm and surface reflectances in the blue and the red spectral regions. We compared instantaneous aerosol optical thicknesses retrieved by MERIS in the blue and the red at locations containing sites within the Aerosol Robotic Network (AERONET). Between 2002 and 2005, a set of 500 MERIS images were used in this study. The result shows that, over land, MERIS aerosol optical thicknesses are well retrieved in the blue and poorly retrieved in the red, leading to an underestimation of the Angstrom coefficient. Correlations are improved by applying a simple criterion to avoid scenes probably contaminated by thin clouds. To investigate the weakness of the MERIS algorithm, ground-based radiometer measurements have been used in order to retrieve new aerosol models, based on their Inherent Optical Properties (IOP). These new aerosol models slightly improve the correlation, but the main problem of the MERIS aerosol product over land can be attributed to the surface reflectance model in the red.


2015 ◽  
Vol 15 (9) ◽  
pp. 5007-5026 ◽  
Author(s):  
E. Dieudonné ◽  
P. Chazette ◽  
F. Marnas ◽  
J. Totems ◽  
X. Shang

Abstract. In June 2013, a ground-based mobile lidar performed the ~10 000 km ride from Paris to Ulan-Ude, near Lake Baikal, profiling for the first time aerosol optical properties all the way from western Europe to central Siberia. The instrument was equipped with N2-Raman and depolarization channels that enabled an optical speciation of aerosols in the low and middle troposphere. The extinction-to-backscatter ratio (also called lidar ratio or LR) and particle depolarization ratio (PDR) at 355 nm have been retrieved. The LR in the lower boundary layer (300–700 m) was found to be 63 ± 17 sr on average during the campaign with a distribution slightly skewed toward higher values that peaks between 50 and 55 sr. Although the difference is small, PDR values observed in Russian cities (>2%, except after rain) are systematically higher than the ones measured in Europe (<1%), which is probably an effect of the lifting of terrigenous aerosols by traffic on roads. Biomass burning layers from grassland or/and forest fires in southern Russia exhibit LR values ranging from 65 to 107 sr and from 3 to 4% for the PDR. During the route, desert dust aerosols originating from the Caspian and Aral seas regions were characterized for the first time, with a LR (PDR) of 43 ± 14 sr (23 ± 2%) for pure dust. The lidar observations also showed that this dust event extended over 2300 km and lasted for ~6 days. Measurements from the Moderate Resolution Imaging Spectrometer (MODIS) show that our results are comparable in terms of aerosol optical thickness (between 0.05 and 0.40 at 355 nm) with the mean aerosol load encountered throughout our route.


1996 ◽  
Author(s):  
Gilles Baudin ◽  
Steven Matthews ◽  
Richard Bessudo ◽  
Jean-Loup Bezy

2013 ◽  
Vol 864-867 ◽  
pp. 2750-2755
Author(s):  
Ying Liu ◽  
An Ming Bao ◽  
Xi Chen

The Chlorophyll-a (Chla) concentration in Bosten Lake was estimated and mapped using the data of the Medium Resolution Imaging Spectrometer (MERIS) on board the ENVIronmental SATellite (ENVISAT) platform. The fixed aerosol option was chosen and local aerosol optical thickness was used in SeaDAS. The Chla concentration was retrieved by the OC3E algorithm and verified by Field data with high correlation coefficient of 0.79. It showed strong horizontal heterogeneities, which is high at the Huangshuigou region, mediate along the boundary area, and low at the middle of the lake, and decreases from the boundary to the center of the Lake. Its spatial distribution is controlled by the location of inlet and outlet and the type and quantity of discharging around the lake. On sep. 22, 2010, its value is up to 10.98 mg m-3. The minimum, maximum, average and median value of Chla concentration on Aug. 6, 2011 from MERIS data in Bosten Lake is 2.72, 8.93, 3.90 and 3.69 mg m-3.


2017 ◽  
Author(s):  
Linlu Mei ◽  
Vladimir Rozanov ◽  
Marco Vountas ◽  
John P. Burrows ◽  
Andreas Richter

Abstract. A prolonged pollution haze event occurred in the northeast part of China during December 16–21, 2016. To assess the impact of such events, the amounts and distribution of aerosol particles formed in such events need to be quantified. The newly launched Ocean Land Color Instrument (OLCI) onboard Sentinel-3 is the successor of the MEdium Resolution Imaging Spectrometer (MERIS). It provides measurements of the radiance and reflectance at the top of the atmosphere which can be used to retrieve the Aerosol Optical Thickness (AOT) on both synoptic to global scales. In this paper, the recently developed AOT retrieval algorithm – eXtensible Bremen AErosol Retrieval (XBAER) has been applied to data from the OLCI instrument for the first time to inlustrate the feasibility of transferring XBAER to new instrument. The first global retrieval results show similar patterns as MODIS and MISR aerosol products. The AOT retrieved from OLCI is validated by comparison with AERONET observations and a correlation coefficient of 0.819 and bias (root mean square) of 0.115 is obtained. The haze episode is well-captured by the OLCI-derived AOT product. XBAER is shown to retrieve AOT from the observations of MERIS and OLCI.


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