Aerosols are the tiny suspended particles in the atmosphere playing a major role in influencing the net radiation budget of the earth. The aerosols also affect cloud microphysics and those with land origin, possibly r...Aerosols are the tiny suspended particles in the atmosphere playing a major role in influencing the net radiation budget of the earth. The aerosols also affect cloud microphysics and those with land origin, possibly reduce the monsoon rainfall. Dynamic and diverse nature of the aerosols varies according to different locations. The aerosols originating due to desert dust, rural atmospheric situations, urban pollutants and marine areas have wide variations and display specific characteristics. Routine monitoring of aerosol events and their subsequent dispersal pattern are important in order to understand their role in climatic process. Hence, it is very important to study the aerosols and their retrieval strategy from the ocean colour remote sensing sensors. The satellite sensors provide platform for making observations covering large area as also their short-term and frequent repetivity. Ocean-colour sensors e.g. CZCS, SeaWiFS, MODIS, POLDAR, Oceansat-1?& 2 OCM have been used to study aerosols, apart from being used to study ocean-colour. Most of the ocean-colour sensors are equipped with a few additional near infrared (NIR) bands (λ?> 700 nm), which are helpful in providing vital information on atmospheric aerosols due to strong absorption by water in NIR wavelengths. The present work is an attempt to study the temporal and spatial variations of Aerosol Optical Depth (AOD) over the Bay of Bengal using Oceansat-2 Ocean Colour Monitor (OCM).展开更多
Atmospheric aerosols being an important component of the atmosphere play an important role in global and regional climate change. Aerosols can affect air quality, climate change and human health and have a significant...Atmospheric aerosols being an important component of the atmosphere play an important role in global and regional climate change. Aerosols can affect air quality, climate change and human health and have a significant effect on the solar energy budget. To study their quantitative effect is a challenging task due to their high spatial and temporal variability. This parameter represents one of the extinction coefficients of solar radiation and rate of suspended particles in the atmosphere. Ocean Colour Remote Sensing provides information about the four major geophysical parameters like chlorophyll and total suspended sediment concentration, vertical diffuse attenuation co-efficient and the aerosol optical thickness measured at 865 nm. Aerosol optical depth can be expressed as function of wavelength through Angstrom’s equation ?, where “α” and “β” are known as Angstrom parameters. The Angstrom exponent, “α” is related to the size distribution of the aerosol particles and “β” represents the amount of aerosols present in the atmosphere. In this present study, an attempt is made to study the impact of these two parameters by changing values from 0 to 0.05 for “α” and from 0.0 to 0.6 for “β” in SeaDAS processing for estimating the aerosol optical depth. From this study, it is clear that for most of the applications either in the coastal or open ocean waters, alpha value varies from 0.0 to 0.3 over the north Indian Ocean. However, this has been further evaluated by various combinations for retrieving the AOD using OCM-2 data.展开更多
Ocean colour remote sensing is one of the conventional methods in satellite oceanography used to study the biological response of the upper ocean to the tropical cyclones. This paper aims to study the impact of the Ve...Ocean colour remote sensing is one of the conventional methods in satellite oceanography used to study the biological response of the upper ocean to the tropical cyclones. This paper aims to study the impact of the Very Severe Cyclonic storm PHAILIN, and its consequence on the surface chlorophyll-aconcentration distribution in the Bay of Bengal using Oceansat-2 Ocean Colour Monitor (OCM). The impact of this cyclone on ocean primary productivity has been studied using MODIS-A data. Sea surface temperature (SST) plays an important role in the generation of primary productivity along with the other oceanographic parameters;SST patterns in the Bay of Bengal during the cyclone period were studied. From the analysis, it is observed that the chlorophyll-aconcentration has increased from 1.08 (before) to 7.06 mg/m3 after the cyclone with an SST drop of ~3°C (29.19°C to 26°C). The primary productivity has increased from 410.0506 to 779.9814 mg/C/m2/day after the cyclone. In addition to the above analysis, an attempt has also been made to study the impact of cyclone intensity on the chlorophyll concentration. The study shows that the comparison between cyclone intensity (CI) and chlorophyll concentration shows a positive relationship.展开更多
文摘Aerosols are the tiny suspended particles in the atmosphere playing a major role in influencing the net radiation budget of the earth. The aerosols also affect cloud microphysics and those with land origin, possibly reduce the monsoon rainfall. Dynamic and diverse nature of the aerosols varies according to different locations. The aerosols originating due to desert dust, rural atmospheric situations, urban pollutants and marine areas have wide variations and display specific characteristics. Routine monitoring of aerosol events and their subsequent dispersal pattern are important in order to understand their role in climatic process. Hence, it is very important to study the aerosols and their retrieval strategy from the ocean colour remote sensing sensors. The satellite sensors provide platform for making observations covering large area as also their short-term and frequent repetivity. Ocean-colour sensors e.g. CZCS, SeaWiFS, MODIS, POLDAR, Oceansat-1?& 2 OCM have been used to study aerosols, apart from being used to study ocean-colour. Most of the ocean-colour sensors are equipped with a few additional near infrared (NIR) bands (λ?> 700 nm), which are helpful in providing vital information on atmospheric aerosols due to strong absorption by water in NIR wavelengths. The present work is an attempt to study the temporal and spatial variations of Aerosol Optical Depth (AOD) over the Bay of Bengal using Oceansat-2 Ocean Colour Monitor (OCM).
文摘Atmospheric aerosols being an important component of the atmosphere play an important role in global and regional climate change. Aerosols can affect air quality, climate change and human health and have a significant effect on the solar energy budget. To study their quantitative effect is a challenging task due to their high spatial and temporal variability. This parameter represents one of the extinction coefficients of solar radiation and rate of suspended particles in the atmosphere. Ocean Colour Remote Sensing provides information about the four major geophysical parameters like chlorophyll and total suspended sediment concentration, vertical diffuse attenuation co-efficient and the aerosol optical thickness measured at 865 nm. Aerosol optical depth can be expressed as function of wavelength through Angstrom’s equation ?, where “α” and “β” are known as Angstrom parameters. The Angstrom exponent, “α” is related to the size distribution of the aerosol particles and “β” represents the amount of aerosols present in the atmosphere. In this present study, an attempt is made to study the impact of these two parameters by changing values from 0 to 0.05 for “α” and from 0.0 to 0.6 for “β” in SeaDAS processing for estimating the aerosol optical depth. From this study, it is clear that for most of the applications either in the coastal or open ocean waters, alpha value varies from 0.0 to 0.3 over the north Indian Ocean. However, this has been further evaluated by various combinations for retrieving the AOD using OCM-2 data.
文摘Ocean colour remote sensing is one of the conventional methods in satellite oceanography used to study the biological response of the upper ocean to the tropical cyclones. This paper aims to study the impact of the Very Severe Cyclonic storm PHAILIN, and its consequence on the surface chlorophyll-aconcentration distribution in the Bay of Bengal using Oceansat-2 Ocean Colour Monitor (OCM). The impact of this cyclone on ocean primary productivity has been studied using MODIS-A data. Sea surface temperature (SST) plays an important role in the generation of primary productivity along with the other oceanographic parameters;SST patterns in the Bay of Bengal during the cyclone period were studied. From the analysis, it is observed that the chlorophyll-aconcentration has increased from 1.08 (before) to 7.06 mg/m3 after the cyclone with an SST drop of ~3°C (29.19°C to 26°C). The primary productivity has increased from 410.0506 to 779.9814 mg/C/m2/day after the cyclone. In addition to the above analysis, an attempt has also been made to study the impact of cyclone intensity on the chlorophyll concentration. The study shows that the comparison between cyclone intensity (CI) and chlorophyll concentration shows a positive relationship.
