Determination of the Broadband Aerosol Optical Depth Baseline and comparison with sunphotometer data

Parrado, Frank García; Estevan, René; Marrero, Juan Carlos Antuña; Rosas, Jorge Luis Mejía; Morejón, Iralmy Platero; Antuña, Juan Carlos; Spencer, Nelson Díaz

doi:10.7149/opa.48.4.249

Cited by 2 publications

(4 citation statements)

References 7 publications

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“…In particular, the distinctive rainy season signatures in the Caribbean are largely explained by the activation of African dust emissions, along with the predominance of trade winds and associated easterly waves in summer induced by seasonal changes in the configuration and position of the subtropical anticyclone. We note here that Camagüey shows a secondary peak of AOD440 during the dry season, in agreement with previous studies (García et al, 2015).…”

Section: Conclusion and Discussionsupporting

confidence: 93%

Climatology of Aerosols over the Caribbean Islands: Aerosol Types, Synoptic Patterns, and Transport

Rodríguez-Vega¹,

Marrero

Barriopedro

et al. 2022

Journal of Applied Meteorology and Climatology

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We present a climatological study of aerosols in four representative Caribbean islands based on daily mean values of aerosol optical properties for the period 2008- 2016, using the Aerosol Optical Depth (AOD) and Ångström Exponent (AE) to classify the dominant aerosol type. A climatological assessment of the spatio-temporal distribution of the main aerosol types, their links with synoptic patterns and the transport from different sources is provided. Maximum values of AOD occur in the rainy season, coinciding with the minimum in AE and an increased occurrence of dust, while the minimum of AOD occurs in the dry season, due to the predominance of marine aerosols. Marine and dust aerosol are more frequent in the easternmost islands and decrease westwards due to an increasing of continental and mixture dust aerosols. Therefore, the westernmost station displays the most heterogeneous composition of aerosols. Using a weather type classification, we identify a quantifiable influence of the atmospheric circulation in the distribution of Caribbean aerosols. However, they can occur under relatively weak and/or diverse synoptic patterns, typically involving transient systems and specific configurations of the Azores High that depend on the considered station. Backward trajectories indicate that dry-season marine aerosols and rainy-season dust are transported by air parcels travelling within the tropical easterly winds. The main source region for both types of aerosols is the subtropical eastern Atlantic, except for Cuba, where the largest contributor to dry-season marine aerosols is the subtropical western Atlantic. Different aerosol types follow similar pathways, suggesting a key role of emission sources in determining the spatio-temporal distribution of Caribbean aerosols.

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Section: Conclusion and Discussionsupporting

confidence: 93%

Climatology of Aerosols over the Caribbean Islands: Aerosol Types, Synoptic Patterns, and Transport

Rodríguez-Vega¹,

Marrero

Barriopedro

et al. 2022

Journal of Applied Meteorology and Climatology

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“…For a detailed description of the derivation of Eq. (2) and the parameterisation of the variables, see Gueymard (1998), Fonte and Antuña (2011) and García et al (2015) for the method's application to our data. In order to avoid cloud contamination in BAOD retrieval, we used only DNI observations with the cloud-free condition in the line of sight to the sun.…”

Section: Solar Direct Irradiance Measurements and Derived Baodmentioning

confidence: 99%

“…For Camagüey, we calculated the monthly mean PW values from the sun photometer PW observations from 2008 to 2014 (García et al, 2015). For each of the three other stations, we calculated the monthly mean PW values using the vertical integrated water vapour (kg m −2 ) from spatially coincident ERA-Interim reanalysis between 1979 and 2013 (Barja et al, 2015).…”

Section: Solar Direct Irradiance Measurements and Derived Baodmentioning

confidence: 99%

“…The first BAOD calculations used for DNI measurement were conducted at Camagüey under clear-sky conditions for the period 1985-2007 using Gueymard's (1998) improved parameterisations . García et al (2015) used this kind of DNI observation for a longer period and compared this BAOD to sun photometer AOD data. They used observations under the clear line of sight between the broadband pyrheliometer and a region of 5 • around the sun as well as improved climatological values of the integrated water vapour.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of aerosol optical depth from satellite (MODIS), sun photometer and broadband pyrheliometer ground-based observations in Cuba

Marrero¹,

Revilla

Parrado³

et al. 2018

Atmos. Meas. Tech.

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Abstract. In the present study, we report the first comparison between the aerosol optical depth (AOD) and Ångström exponent (AE) of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra (AOD t ) and Aqua (AOD a ) satellites and those measured using a sun photometer (AOD SP ) at Camagüey, Cuba, for the period 2008 to 2014. The comparison of Terra and Aqua data includes AOD derived with both deep blue (DB) and dark target (DT) algorithms from MODIS Collection 6. Combined Terra and Aqua (AOD ta ) data were also considered. Assuming an interval of ±30 min around the overpass time and an area of 25 km around the sun photometer site, two coincidence criteria were considered: individual pairs of observations and both spatial and temporal mean values, which we call collocated daily means. The usual statistics (root mean square error, RMSE; mean absolute error, MAE; median bias, BIAS), together with linear regression analysis, are used for this comparison. Results show very similar values for both coincidence criteria: the DT algorithm generally displays better statistics and higher homogeneity than the DB algorithm in the behaviour of AOD t , AOD a , AOD ta compared to AOD SP . For collocated daily means, (a) RMSEs of 0.060 and 0.062 were obtained for Terra and Aqua with the DT algorithm and 0.084 and 0.065 for the DB algorithm, (b) MAE follows the same patterns, (c) BIAS for both Terra and Aqua presents positive and negative values but its absolute values are lower for the DT algorithm; (d) combined AOD ta data also give lower values of these three statistical indicators for the DT algorithm; (e) both algorithms present good correlations for comparing AOD t , AOD a , AOD ta vs. AOD SP , with a slight overestimation of satellite data compared to AOD SP , (f ). The DT algorithm yields better figures with slopes of 0.96 (Terra), 0.96 (Aqua) and 0.96 (Terra + Aqua) compared to the DB algorithm (1.07, 0.90, 0.99), which displays greater variability. Multi-annual monthly means of AOD ta establish a first climatology that is more comparable to that given by the sun photometer and their statistical evaluation reveals better agreement with AOD SP for the DT algorithm. Results of the AE comparison showed similar results to those reported in the literature concerning the two algorithms' capacity for retrieval. A comparison between broadband aerosol optical depth (BAOD), derived from broadband pyrheliometer observations at the Camagüey site and three other meteorological stations in Cuba, and AOD observations from MODIS on board Terra and Aqua show a poor correlation with slopes below 0.4 for both algorithms. Aqua (Terra) showed RMSE values of 0.073 (0.080) and 0.088 (0.087) for the DB and DT algorithms. As expected, RMSE values are higher than those from the MODIS-sun photometer comparison, but within the same order of magnitude. Results from the BAOD derived from solar radiation measurements demonstrate its reliability in describing climatological AOD series estimates.

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Determination of the Broadband Aerosol Optical Depth Baseline and comparison with sunphotometer data

Cited by 2 publications

References 7 publications

Climatology of Aerosols over the Caribbean Islands: Aerosol Types, Synoptic Patterns, and Transport

Climatology of Aerosols over the Caribbean Islands: Aerosol Types, Synoptic Patterns, and Transport

Comparison of aerosol optical depth from satellite (MODIS), sun photometer and broadband pyrheliometer ground-based observations in Cuba

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