Simulation of aerosol optical properties over a tropical urban site in India using a global model and its comparison with ground measurements

Abstract

Abstract. Aerosols have great impacts on atmospheric environment, human health, and earth's climate. Therefore, information on their spatial and temporal distribution is of paramount importance. Despite numerous studies have examined the variation and trends of BC and AOD over India, only very few have focused on their spatial distribution or even correlating the observations with model simulations. In the present study, a three-dimensional aerosol transport-radiation model coupled with a general circulation model. SPRINTARS, simulated atmospheric aerosol distributions including BC and aerosol optical properties, i.e., aerosol optical thickness (AOT),Ångström Exponent (AE), and single scattering albedo (SSA). The simulated results are compared with both BC measurements by aethalometer and aerosol optical properties measured by ground-based skyradiometer and by satellite sensor, MODIS/Terra over Hyderabad, which is a tropical urban area of India, for the year 2008. The simulated AOT and AE in Hyderabad are found to be comparable to ground-based measured ones. The simulated SSA tends to be higher than the ground-based measurements. Both these comparisons of aerosol optical properties between the simulations with different emission inventories and the measurements indicate that, firstly the model uncertainties derived from aerosol emission inventory cannot explain the gaps between the simulations and the measurements and secondly the vertical transport of BC and the treatment of BC-containing particles can be the main issue in the global model to solve the gap.

Sensitivity of aerosol to assumed optical properties over Asia using a global aerosol model and AERONET

“…The AOT values in the Asian aerosol source regions are larger than those in similar sites in North America and Europe [e.g., Remer et al , 2005]. In Kanpur, the variability of simulated AOT is very large because simulated AOT due to dust from the Middle East region is large in India during summer as confirmed by Goto et al [2011a]. We also find a tendency of underestimates of the simulated AOT over aerosol source regions and its overestimates over outflow regions.…”

“…During the model simulations meteorological fields are nudged to NCAR/NCEP reanalysis (wind, water vapor, and temperature). Emission inventories for 2000 for aerosols and its precursors are those described by Takemura et al [2005], Goto et al [2011a] and Goto et al (submitted manuscript, 2011).…”

Influence of anomalous dry conditions on aerosols over India: Transport, distribution and properties

“…In SPRINTARS model, emission processes for dust with 10 bins ranging from 0.13 to 8.2 μ m are online‐calculated according to an empirical relation by Gillette [1978], depending on near‐surface wind speed above a threshold of 6.5 ms −1 , soil moisture and snow amount [ Takemura et al , 2000; Goto et al , 2011a]. For the other components (sulfates, nitrates, organics, sea salt, etc), emission processes and inventories are described by Goto et al [2011b, 2011c], which use the anthropogenic SO 2 and BC emission fluxes from Streets et al [2003] over Asia. Transitions of the emission strength for anthropogenic matters were based on emission inventories widely used in the AeroCom project.…”

Assessment of changes in atmospheric dynamics and dust activity over southwest Asia using the Caspian Sea–Hindu Kush Index

“…The dust emission fluxes are calculated using the empirical relation from Gillette (1978), as functions of the cubic wind speed at 10-m height, a wind-speed threshold of 6.5 ms −1 , vegetation, leaf area index, soil moisture and snow cover (Takemura et al, 2000(Takemura et al, , 2009. Several studies took advantage of the model performance for dust simulations over various regions of Asia, giving satisfactory results (Takemura et al, 2002;Goto et al, 2011;Huneeus et al, 2011;Kaskaoutis et al, , 2016.…”