Forzamiento radiativo directo debido a los aerosoles atmosféricos en Perú utilizando técnicas de sensoramiento remoto

Describimos los resultados del estudio del espesor óptico de aerosol (EOA) y el Forzamiento Radiativo Directo (FRD) en la cima de la atmósfera (TOA), obtenidos en el periodo 2004 utilizando el sensor MODIS del satélite TERRA para Perú. Donde se observa que el valor del EOA puede tomar valores máximos alrededor de 0.5, obteniéndose como resultado el FRD de aerosol en la parte superior de la atmósfera. Los resultados indican que, la FRD está entre [-5 0] W / m2.Describimos los resultados del estudio del espesor óptico de aerosol (EOA) y el Forzamiento Radiativo Directo (FRD) en la cima de la atmósfera (TOA), obtenidos en el periodo 2004 utilizando el sensor MODIS del satélite TERRA para Perú. Donde se observa que el valor del EOA puede tomar valores máximos alrededor de 0.5, obteniéndose como resultado el FRD de aerosol en la parte superior de la atmósfera. Los resultados indican que, la FRD está entre [-5 0] W / m2

Forçante radiativo direto devido a aerossóis atmosféricos no Peru usando técnicas de sensoriamento remoto

We describe the results of the study of aerosol optical depth (AOD) and Direct Radiative Forcing (DRF) at the top of the atmosphere (TOA), obtained in the period 2004 using the MODIS sensor of the TERRA satellite for Peru. Where it is observed that the AOD value can take maximum values around 0.5, resulting in aerosol DRF in the upper part of the atmosphere. The results indicate that the FRD is between [-5 0] W / m2.Describimos los resultados del estudio del espesor óptico de aerosol (EOA) y el Forzamiento Radiativo Directo (FRD) en la cima de la atmósfera (TOA), obtenidos en el periodo 2004 utilizando el sensor MODIS del satélite TERRA para Perú. Donde se observa que el valor del EOA puede tomar valores máximos alrededor de 0.5, obteniéndose como resultado el FRD de aerosol en la parte superior de la atmósfera. Los resultados indican que, la FRD está entre [-5 0] W / m2.Descrevemos os resultados do estudo da espessura óptica do aerossol (EOA) e do Direct Radiative Forcing (DRF) no topo da atmosfera (TOA), obtidos no período de 2004 usando o sensor MODIS do satélite TERRA para o Peru. Onde se observa que o valor do EOA pode assumir valores máximos em torno de 0,5, obtendo como resultado o FRD do aerossol na parte superior da atmosfera. Os resultados indicam que o FRD está entre [-5 0] W/m2

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

Since the reform and opening up of China, the increasing aerosol emissions have posted great challenges to the country’s climate change and human health. The aerosol optical depth (AOD) is one of the main physical indicators quantifying the atmospheric turbidity and air pollution. In this study, 38-years (1980–2017) of spatial and temporal variations of AOD in China were analyzed using AOD records derived from MODIS atmosphere products and the MERRA-2 dataset. The results showed that the annual mean AOD values throughout China have gone through an increasing, but fluctuating, trend, especially in 1982 and in 1992 due to two volcano eruptions; the AOD values experienced a dramatically increasing period during 2000–2007 with the rapid economic development and “population explosions” in China/after 2008, the AOD values gradually decreased from 0.297 (2008) to 0.257 (2017). The AOD values in China were generally higher in spring than that in other seasons. The Sichuan Basin has always been an area with high AOD values owing to the strong human activity and the basin topography (hindering aerosol diffusions in the air). In contrast, the Qinghai Tibet Plateau has always been an area with low AOD values due to low aerosol emissions and clear sky conditions there. The trend analysis of AOD values during 1980–2017 in China indicated that the significant increasing trend was mainly observed in Southeastern China. By contrast, the AOD values in the northernmost of China showed a significant decreasing trend. Then, the contributions (AODP) of the AOD for black carbon aerosol (BCAOD), dust aerosol (DUAOD), organic carbon aerosol (OCAOD), sea salt aerosol (SSAOD), and SO4 aerosol (SO4AOD) to the total AOD values were calculated. The results showed that DUAOD (25.43%) and SO4AOD (49.51%) were found to be the main driving factors for the spatial and temporal variations of AOD values. Finally, the effects of anthropogenic aerosol emissions, socioeconomic factors, and land-use and land coverage changes on AOD were analyzed. The GDP, population density, and passenger traffic volume were found to be the main socioeconomic drivers for AOD distributions. Relatively larger AOD values were mainly found in urban land and land covered by water, while lower AOD values were found in grassland and permanent glacier areas

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

Since the reform and opening up of China, the increasing aerosol emissions have posted great challenges to the country’s climate change and human health. The aerosol optical depth (AOD) is one of the main physical indicators quantifying the atmospheric turbidity and air pollution. In this study, 38-years (1980–2017) of spatial and temporal variations of AOD in China were analyzed using AOD records derived from MODIS atmosphere products and the MERRA-2 dataset. The results showed that the annual mean AOD values throughout China have gone through an increasing, but fluctuating, trend, especially in 1982 and in 1992 due to two volcano eruptions; the AOD values experienced a dramatically increasing period during 2000–2007 with the rapid economic development and “population explosions” in China/after 2008, the AOD values gradually decreased from 0.297 (2008) to 0.257 (2017). The AOD values in China were generally higher in spring than that in other seasons. The Sichuan Basin has always been an area with high AOD values owing to the strong human activity and the basin topography (hindering aerosol diffusions in the air). In contrast, the Qinghai Tibet Plateau has always been an area with low AOD values due to low aerosol emissions and clear sky conditions there. The trend analysis of AOD values during 1980–2017 in China indicated that the significant increasing trend was mainly observed in Southeastern China. By contrast, the AOD values in the northernmost of China showed a significant decreasing trend. Then, the contributions (AODP) of the AOD for black carbon aerosol (BCAOD), dust aerosol (DUAOD), organic carbon aerosol (OCAOD), sea salt aerosol (SSAOD), and SO4 aerosol (SO4AOD) to the total AOD values were calculated. The results showed that DUAOD (25.43%) and SO4AOD (49.51%) were found to be the main driving factors for the spatial and temporal variations of AOD values. Finally, the effects of anthropogenic aerosol emissions, socioeconomic factors, and land-use and land coverage changes on AOD were analyzed. The GDP, population density, and passenger traffic volume were found to be the main socioeconomic drivers for AOD distributions. Relatively larger AOD values were mainly found in urban land and land covered by water, while lower AOD values were found in grassland and permanent glacier areas

Large contribution of meteorological factors to inter-decadal changes in regional aerosol optical depth

Aerosol optical depth (AOD) has become a crucial metric for assessing global climate change. Although global and regional AOD trends have been studied extensively, it remains unclear what factors are driving the inter-decadal variations in regional AOD and how to quantify the relative contribution of each dominant factor. This study used a long-term (1980–2016) aerosol dataset from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis, along with two satellite-based AOD datasets (MODIS/Terra and MISR) from 2001 to 2016, to investigate the long-term trends in global and regional aerosol loading. Statistical models based on emission factors and meteorological parameters were developed to identify the main factors driving the inter-decadal changes of regional AOD and to quantify their contribution. Evaluation of the MERRA-2 AOD with the ground-based measurements of AERONET indicated significant spatial agreement on the global scale (r= 0.85, root-mean-square error = 0.12, mean fractional error = 38.7 %, fractional gross error = 9.86 % and index of agreement = 0.94). However, when AOD observations from the China Aerosol Remote Sensing Network (CARSNET) were employed for independent verification, the results showed that MERRA-2 AODs generally underestimated CARSNET AODs in China (relative mean bias = 0.72 and fractional gross error =−34.3 %). In general, MERRA-2 was able to quantitatively reproduce the annual and seasonal AOD trends on both regional and global scales, as observed by MODIS/Terra, although some differences were found when compared to MISR. Over the 37-year period in this study, significant decreasing trends were observed over Europe and the eastern United States. In contrast, eastern China and southern Asia showed AOD increases, but the increasing trend of the former reversed sharply in the most recent decade. The statistical analyses suggested that the meteorological parameters explained a larger proportion of the AOD variability (20.4 %–72.8 %) over almost all regions of interest (ROIs) during 1980–2014 when compared with emission factors (0 %–56 %). Further analysis also showed that SO2 was the dominant emission factor, explaining 12.7 %–32.6 % of the variation in AOD over anthropogenic-aerosol-dominant regions, while black carbon or organic carbon was the leading factor over the biomass-burning-dominant (BBD) regions, contributing 24.0 %–27.7 % of the variation. Additionally, wind speed was found to be the leading meteorological parameter, explaining 11.8 %–30.3 % of the variance over the mineral-dust-dominant regions, while ambient humidity (including soil moisture and relative humidity) was the top meteorological parameter over the BBD regions, accounting for 11.7 %–35.5 % of the variation. The results of this study indicate that the variation in meteorological parameters is a key factor in determining the inter-decadal change in regional AOD.This research has been supported by the National Science Fund for Distinguished Young Scholars (grant no. 41825011), the National Key R & D Program Pilot Projects of China (grant nos. 2016YFA0601901 and 2016YFC0203304), the National Natural Science Foundation of China (grant no. 41590874), the CAMS Basis Research Project (grant no. 2017Z011), the European Union Seventh Framework Programme(FP7/2007-2013) (grant no. 262254), and the AERONET-Europe ACTRIS-2 program, European Union's Horizon 2020 research and innovation programme (grant no. 654109)