scholarly journals Multi-Satellite Retrieval of SSA using OMI-MODIS algorithm

2018 ◽  
Author(s):  
Kruthika Eswaran ◽  
Sreedharan Krishnakumari Satheesh ◽  
Jayaraman Srinivasan
Keyword(s):  
Radiative Forcing ◽  
Single Scattering ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Aerosol Composition ◽  
Aerosol Radiative Forcing ◽  
Aerosol Absorption ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Absorbing Aerosols ◽  
Aerosol Type

Abstract. Single scattering albedo (SSA) represents a unique identification of aerosol type and aerosol radiative forcing. However, SSA retrievals are highly uncertain due cloud contamination and aerosol composition. Recent improvement in the SSA retrieval algorithm has combined the superior cloud masking technique of Moderate Resolution Imaging Spectroradiometer (MODIS) and the better sensitivity of Ozone Monitoring Instrument (OMI) to aerosol absorption. The combined OMI-MODIS algorithm has been validated over a small spatial and temporal scale only. The present study validates the algorithm over global oceans for the period 2008–2012. The geographical heterogeneity in the aerosol type and concentration over the Atlantic Ocean, the Arabian Sea and the Bay of Bengal was useful to delineate the effect of aerosol type on the retrieval algorithm. We also noted that OMI overestimates SSA when absorbing aerosols were present closer to the surface. We attribute this overestimation to data discontinuity in the aerosol height climatology derived from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. OMI uses pre-defined aerosol heights over regions where CALIPSO climatology is not present leading to overestimation of SSA. The importance of aerosol height was also studied using the Santa Barbara DISORT radiative transfer (SBDART) model. The results from the joint retrieval were validated with ground-based measurements and it was seen that OMI-MODIS SSA retrievals were better constrained than OMI only retrieval.

scholarly journals Multi-satellite retrieval of single scattering albedo using the OMI–MODIS algorithm

2019 ◽  
Vol 19 (5) ◽  
pp. 3307-3324 ◽  
Author(s):  
Kruthika Eswaran ◽  
Sreedharan Krishnakumari Satheesh ◽  
Jayaraman Srinivasan
Keyword(s):  
Bay Of Bengal ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Aerosol Composition ◽  
Aerosol Radiative Forcing ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Aerosol Type

Abstract. Single scattering albedo (SSA) represents a unique identification of aerosol type and can be a determinant factor in the estimation of aerosol radiative forcing. However, SSA retrievals are highly uncertain due to cloud contamination and aerosol composition. The recent improvement in the SSA retrieval algorithm has combined the superior cloud-masking technique of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the higher sensitivity of the Ozone Monitoring Instrument (OMI) to aerosol absorption. The combined OMI–MODIS algorithm has only been validated over a small spatial and temporal scale. The present study validates the algorithm over global oceans for the period from 2008 to 2012. The geographical heterogeneity in the aerosol type and concentration over the Atlantic Ocean, the Arabian Sea and the Bay of Bengal was useful to delineate the effect of aerosol type on the retrieval algorithm. We also noted that OMI overestimated SSA when absorbing aerosols were present closer to the surface. We attribute this overestimation to data discontinuity in the aerosol height climatology derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. OMI uses predefined aerosol heights over regions where CALIPSO climatology is not present, leading to the overestimation of SSA. The importance of aerosol height was also studied using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. The results from the joint retrievals were validated using cruise-based measurements. It was seen that OMI–MODIS SSA retrievals performed better than the OMI only retrieval over the Bay of Bengal during winter, when the aerosols are present closer to the surface. Discrepancy between satellite retrievals and cruise measurements was seen when elevated aerosols were present which might not have been detected by the cruise instruments.

scholarly journals Contrasting variation in aerosol optical properties during dust episodes in the Middle East and Southwest Asia: Model results and ground measurement

2019 ◽  
Vol 99 ◽  
pp. 04006
Author(s):  
Khan Alam ◽  
Maqbool Ahmad
Keyword(s):  
Middle East ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Dust Storms ◽  
Radiative Properties ◽  
Southwest Asia ◽  
Gulf Region ◽  
Aerosol Radiative Forcing ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Using Data

Dust storms deteriorated air quality over the Gulf Region, Iraq, Iran, and Pakistan during the last decade. The purpose of this study is to investigate the changes in aerosol optical and radiative properties during a dust episode over the various locations in the Middle East and Southwest Asia using data from the MODerate resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET) during March, 2012. Maximum aerosol optical depth (AOD) values were found to be 2.18, 1.30, 4.33 and 1.80 over Lahore, Kanpur, Kaust, and Mezaira, respectively. The Volume Size Distributions, Single Scattering Albedo, Refractive Index, and Asymmetry parameter indicated that coarse mode aerosols were predominant relative to fine mode aerosols during the dust event. The average shortwave aerosol radiative forcing (ARF) values at the earth’s surface were found to be -96±45 W m-2, -86±22 W m-2, -77±51 W m-2, and -75±40 W m-2, over Lahore, Kanpur, Kaust and Mezaira, respectively. Likewise, the averaged ARF values over Lahore, Kanpur, Kaust and Mezaira at the top of the atmosphere (TOA) were found to be -45±25 W m-2, -27±9 W m-2, -41±29 W m-2, and -75±40 W m-2, respectively. The large differences between surface and TOA forcing produced significant heating within the atmosphere.

scholarly journals Estimates of aerosol absorption over India using multi-satellite retrieval

2013 ◽  
Vol 31 (10) ◽  
pp. 1773-1778 ◽  
Author(s):  
D. Narasimhan ◽  
S. K. Satheesh
Keyword(s):  
Regional Distribution ◽  
Single Scattering ◽  
Ozone Monitoring Instrument ◽  
Satellite Retrieval ◽  
Aerosol Absorption ◽  
Moderate Resolution ◽  
Indian Landmass ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
First Time

Abstract. Aerosol absorption is poorly quantified because of the lack of adequate measurements. It has been shown that the Ozone Monitoring Instrument (OMI) aboard EOS-Aura and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard EOS-Aqua, which fly in formation as part of the A-train, provide an excellent opportunity to improve the accuracy of aerosol retrievals. Here, we follow a multi-satellite approach to estimate the regional distribution of aerosol absorption over continental India for the first time. Annually and regionally averaged aerosol single-scattering albedo over the Indian landmass is estimated as 0.94 ± 0.03. Our study demonstrates the potential of multi-satellite data analysis to improve the accuracy of retrieval of aerosol absorption over land.

scholarly journals Measurements of aerosol intensive properties over Visakhapatnam, India for 2007

2011 ◽  
Vol 29 (6) ◽  
pp. 973-985 ◽  
Author(s):  
K. Niranjan ◽  
B. Spandana ◽  
T. Anjana Devi ◽  
V. Sreekanth ◽  
B. L. Madhavan
Keyword(s):  
Asymmetry Parameter ◽  
Radiative Forcing ◽  
Single Scattering ◽  
Peninsular India ◽  
Aerosol Radiative Forcing ◽  
Scattering Coefficients ◽  
Aerosol Absorption ◽  
Angular Scattering ◽  
The Asymmetry ◽  
First Time

Abstract. Information on the aerosol intensive properties like Single Scattering Albedo (SSA) and asymmetry parameter are very limited, particularly over the peninsular India, though extensive reports are available on the aerosol bulk properties. In view of the importance of these parameters in evaluating the aerosol radiative forcing, we present for the first time the temporal variation in SSA with measurements on aerosol absorption and scattering coefficients over Visakhapatnam (17.72° N, 83.32° E; located on the east coast of India) for the year 2007. The inferred SSA was in the range of 0.65 and 0.9 with an annual mean of 0.76 ± 0.013 and with a probable value of 0.80, indicating a marginal atmospheric warming over the region. The mixed layer contribution to column Aerosol Optical depth is found to be 35 % in summer while it is well above 35 % in winter, indicating the confinement of aerosol within the boundary layer during winter. The asymmetry parameter which represents the angular scattering in radiative forcing estimation is found to be around 0.65 ± 0.1 for the location. The day to day variability in SSA is found to be well correlated with the variations in surface BC mass concentrations and/or the relative dominance of the fine/coarse mode aerosol. The results are discussed in light of the aerosol physical and optical properties and the asymmetry parameter.

scholarly journals Rethinking the correction for absorbing aerosols in the OMI- and TROPOMI-like surface UV algorithms

2021 ◽  
Vol 14 (7) ◽  
pp. 4947-4957
Author(s):  
Antti Arola ◽  
William Wandji Nyamsi ◽  
Antti Lipponen ◽  
Stelios Kazadzis ◽  
Nickolay A. Krotkov ◽  
...  
Keyword(s):  
Optical Depth ◽  
Uv Radiation ◽  
Correction Factor ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Aerosol Absorption ◽  
Uv Irradiance ◽  
Absorbing Aerosols

Abstract. Satellite estimates of surface UV irradiance have been available since 1978 from the TOMS UV spectrometer and have continued with significantly improved ground resolution using the Ozone Monitoring Instrument (OMI 2004–current) and Sentinel 5 Precursor (S5P 2017–current). The surface UV retrieval algorithm remains essentially the same: it first estimates the clear-sky UV irradiance based on measured ozone and then accounts for the attenuation by clouds and aerosols, applying two consecutive correction factors. When estimating the total aerosol effect in surface UV irradiance, there are two major classes of aerosols to be considered: (1) aerosols that only scatter UV radiation and (2) aerosols that both scatter and absorb UV radiation. The former effect is implicitly included in the measured effective Lambertian-equivalent scene reflectivity (LER), so the scattering aerosol influence is estimated through cloud correction factor. Aerosols that absorb UV radiation attenuate the surface UV radiation more strongly than non-absorbing aerosols of the same extinction optical depth. Moreover, since these aerosols also attenuate the outgoing satellite-measured radiance, the cloud correction factor that treats these aerosols as purely scattering underestimates their aerosol optical depth (AOD), causing underestimation of LER and overestimation of surface UV irradiance. Therefore, for correction of aerosol absorption, additional information is needed, such as a model-based monthly climatology of aerosol absorption optical depth (AAOD). A correction for absorbing aerosols was proposed almost a decade ago and later implemented in the operational OMI and TROPOMI UV algorithms. In this study, however, we show that there is still room for improvement to better account for the solar zenith angle (SZA) dependence and nonlinearity in the absorbing aerosol attenuation, and as a result we propose an improved correction scheme. There are two main differences between the new proposed correction and the one that is currently operational in OMI and TROPOMI UV algorithms. First, the currently operational correction for absorbing aerosols is a function of AAOD only, while the new correction additionally takes the solar zenith angle dependence into account. Second, the second-order polynomial of the new correction takes the nonlinearity in the correction as a function of AAOD better into account, if compared to the currently operational one, and thus better describes the effect by absorbing aerosols over a larger range of AAOD. To illustrate the potential impact of the new correction in the global UV estimates, we applied the current and new proposed correction for global fields of AAOD from the aerosol climatology currently used in OMI UV algorithm, showing a typical differences of ±5 %. This new correction is easy to implement operationally using information of solar zenith angle and existing AAOD climatology.

Aerosol Characterization and Direct Radiative Forcing Assessment over the Ocean. Part II: Application to Test Cases and Validation

2004 ◽  
Vol 43 (12) ◽  
pp. 1818-1833 ◽  
Author(s):  
Maria João Costa ◽  
Vincenzo Levizzani ◽  
Ana Maria Silva
Keyword(s):  
Radiative Forcing ◽  
Radiant Energy ◽  
Energy System ◽  
Single Scattering ◽  
Space Time ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Aerosol Radiative Forcing ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract A method based on the synergistic use of low earth orbit and geostationary earth orbit satellite data for aerosol-type characterization and aerosol optical thickness (AOT: τa) retrieval and monitoring over the ocean is presented in Part I of this paper. The method is now applied to a strong dust outbreak over the Atlantic Ocean in June 1997 and to two other relevant transport events of biomass burning and desert dust aerosol that occurred in 2000 over the Atlantic and Indian Oceans, respectively. The retrievals of the aerosol optical properties are checked against retrievals from sun and sky radiance measurements from the ground-based Aerosol Robotic Network (AERONET). The single-scattering albedo values obtained from AERONET are always within the error bars presented for Global Ozone Monitoring Experiment (GOME) retrievals, resulting in differences lower than 0.041. The retrieved AOT values are compared with the independent space–time-collocated measurements from the AERONET, as well as to the satellite aerosol official products of the Polarization and Directionality of the Earth Reflectances (POLDER) and the Moderate Resolution Imaging Spectroradiometer (MODIS). A first estimate of the AOT accuracy derived from comparisons with AERONET data leads to ±0.02 ± 0.22τa when all AOT values are retained or to ±0.02 ± 0.16τa for aerosol transport events (AOT > 0.4). The upwelling flux at the top of the atmosphere (TOA) was computed with radiative transfer calculations and used to estimate the TOA direct shortwave aerosol radiative forcing; a comparison with space–time-collocated measurements from the Clouds and the Earth's Radiant Energy System (CERES) TOA flux product was also done. It was found that more than 90% of the values differ from CERES fluxes by less than ±15%.

scholarly journals Aerosol Characteristics and Their Impact on the Himalayan Energy Budget

2021 ◽  
Vol 14 (1) ◽  
pp. 179
Author(s):  
Kesar Chand ◽  
Jagdish Chandra Kuniyal ◽  
Shruti Kanga ◽  
Raj Paul Guleria ◽  
Gowhar Meraj ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Satellite Observation ◽  
Transfer Model ◽  
Hysplit Model ◽  
Aerosol Radiative Forcing ◽  
Alpine Regions ◽  
Himalayan Glaciers ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer

The extensive work on the increasing burden of aerosols and resultant climate implications shows a matter of great concern. In this study, we investigate the aerosol optical depth (AOD) variations in the Indian Himalayan Region (IHR) between its plains and alpine regions and the corresponding consequences on the energy balance on the Himalayan glaciers. For this purpose, AOD data from Moderate Resolution Imaging Spectroradiometer (MODIS, MOD-L3), Aerosol Robotic Network (AERONET), India, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) were analyzed. Aerosol radiative forcing (ARF) was assessed using the atmospheric radiation transfer model (RTM) integrated into AERONET inversion code based on the Discrete Ordinate Radiative Transfer (DISORT) module. Further, air mass trajectory over the entire IHR was analyzed using a hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. We estimated that between 2001 and 2015, the monthly average ARF at the surface (ARFSFC), top of the atmosphere (ARFTOA), and atmosphere (ARFATM) were −89.6 ± 18.6 Wm−2, −25.2 ± 6.8 Wm−2, and +64.4 ± 16.5 Wm−2, respectively. We observed that during dust aerosol transport days, the ARFSFC and TOA changed by −112.2 and −40.7 Wm−2, respectively, compared with low aerosol loading days, thereby accounting for the decrease in the solar radiation by 207% reaching the surface. This substantial decrease in the solar radiation reaching the Earth’s surface increases the heating rate in the atmosphere by 3.1-fold, thereby acting as an additional forcing factor for accelerated melting of the snow and glacier resources of the IHR.

scholarly journals Global maps of aerosol single scattering albedo using combined CERES-MODIS retrieval

2021 ◽  
Author(s):  
Archana Devi ◽  
Sreedharan Krishnakumari Satheesh
Keyword(s):  
Climate Models ◽  
Radiant Energy ◽  
Energy System ◽  
Single Scattering ◽  
Global Scale ◽  
Single Scattering Albedo ◽  
Accurate Information ◽  
Climatic Impact ◽  
Aerosol Absorption ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. Single Scattering Albedo (SSA) is a leading contributor to the uncertainty in aerosol radiative impact assessments. Therefore accurate information on aerosol absorption is required on a global scale. In this study, we have applied a multi-satellite algorithm to retrieve SSA using the concept of ‘critical optical depth.’ Global maps of SSA were generated following this approach using spatially and temporally collocated data from Clouds and the Earth’s Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board Terra and Aqua satellites. The method has been validated using the data from aircraft-based measurements of various field campaigns. The retrieval uncertainty is ±0.03 and depends on both the surface albedo and aerosol absorption. Global mean SSA estimated over land and ocean is 0.93 and 0.97, respectively. Seasonal and spatial distribution of SSA over various regions are also presented. The global maps of SSA, thus derived with improved accuracy, provide important input to climate models for assessing the climatic impact of aerosols on regional and global scales.

scholarly journals Direct Aerosol Radiative Forcing Uncertainty Based on a Radiative Perturbation Analysis

2010 ◽  
Vol 23 (19) ◽  
pp. 5288-5293 ◽  
Author(s):  
Norman G. Loeb ◽  
Wenying Su
Keyword(s):  
Radiative Forcing ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Radiative Perturbation ◽  
Sky Conditions ◽  
Global Mean ◽  
Aerosol Properties ◽  
Aerosol Radiative

Abstract To provide a lower bound for the uncertainty in measurement-based clear- and all-sky direct aerosol radiative forcing (DARF), a radiative perturbation analysis is performed for the ideal case in which the perturbations in global mean aerosol properties are given by published values of systematic uncertainty in Aerosol Robotic Network (AERONET) aerosol measurements. DARF calculations for base-state climatological cloud and aerosol properties over ocean and land are performed, and then repeated after perturbing individual aerosol optical properties (aerosol optical depth, single-scattering albedo, asymmetry parameter, scale height, and anthropogenic fraction) from their base values, keeping all other parameters fixed. The total DARF uncertainty from all aerosol parameters combined is 0.5–1.0 W m−2, a factor of 2–4 greater than the value cited in the Intergovernmental Panel on Climate Change’s (IPCC’s) Fourth Assessment Report. Most of the total DARF uncertainty in this analysis is associated with single-scattering albedo uncertainty. Owing to the greater sensitivity to single-scattering albedo in cloudy columns, DARF uncertainty in all-sky conditions is greater than in clear-sky conditions, even though the global mean clear-sky DARF is more than twice as large as the all-sky DARF.

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