Verification of satellite-derived aerosol optical thickness over land with AERONET data

2009 ◽  
Vol 60 ◽  
pp. 7-16 ◽  
Author(s):  
Yuzo Mano ◽  
Toru Hashimoto ◽  
Arata Okuyama
Keyword(s):  
Optical Thickness ◽  
Aerosol Optical Thickness

Satellite-based PM2.5 estimation using fine-mode aerosol optical thickness over China

2017 ◽  
Vol 170 ◽  
pp. 290-302 ◽  
Author(s):  
Xing Yan ◽  
Wenzhong Shi ◽  
Zhanqing Li ◽  
Zhengqiang Li ◽  
Nana Luo ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
Fine Mode ◽  
Fine Mode Aerosol

scholarly journals Global model simulations of the impact of ocean-going ships on aerosols, clouds, and the radiation budget

2007 ◽  
Vol 7 (19) ◽  
pp. 5061-5079 ◽  
Author(s):  
A. Lauer ◽  
V. Eyring ◽  
J. Hendricks ◽  
P. Jöckel ◽  
U. Lohmann
Keyword(s):  
Particulate Matter ◽  
Chemical Composition ◽  
Optical Thickness ◽  
Emission Inventory ◽  
Cloud Microphysics ◽  
Number Concentration ◽  
Climate Impacts ◽  
Aerosol Optical Thickness ◽  
Radiation Budget ◽  
International Shipping

Abstract. International shipping contributes significantly to the fuel consumption of all transport related activities. Specific emissions of pollutants such as sulfur dioxide (SO2) per kg of fuel emitted are higher than for road transport or aviation. Besides gaseous pollutants, ships also emit various types of particulate matter. The aerosol impacts the Earth's radiation budget directly by scattering and absorbing the solar and thermal radiation and indirectly by changing cloud properties. Here we use ECHAM5/MESSy1-MADE, a global climate model with detailed aerosol and cloud microphysics to study the climate impacts of international shipping. The simulations show that emissions from ships significantly increase the cloud droplet number concentration of low marine water clouds by up to 5% to 30% depending on the ship emission inventory and the geographic region. Whereas the cloud liquid water content remains nearly unchanged in these simulations, effective radii of cloud droplets decrease, leading to cloud optical thickness increase of up to 5–10%. The sensitivity of the results is estimated by using three different emission inventories for present-day conditions. The sensitivity analysis reveals that shipping contributes to 2.3% to 3.6% of the total sulfate burden and 0.4% to 1.4% to the total black carbon burden in the year 2000 on the global mean. In addition to changes in aerosol chemical composition, shipping increases the aerosol number concentration, e.g. up to 25% in the size range of the accumulation mode (typically >0.1 μm) over the Atlantic. The total aerosol optical thickness over the Indian Ocean, the Gulf of Mexico and the Northeastern Pacific increases by up to 8–10% depending on the emission inventory. Changes in aerosol optical thickness caused by shipping induced modification of aerosol particle number concentration and chemical composition lead to a change in the shortwave radiation budget at the top of the atmosphere (ToA) under clear-sky condition of about −0.014 W/m² to −0.038 W/m² for a global annual average. The corresponding all-sky direct aerosol forcing ranges between −0.011 W/m² and −0.013 W/m². The indirect aerosol effect of ships on climate is found to be far larger than previously estimated. An indirect radiative effect of −0.19 W/m² to −0.60 W/m² (a change in the atmospheric shortwave radiative flux at ToA) is calculated here, contributing 17% to 39% of the total indirect effect of anthropogenic aerosols. This contribution is high because ship emissions are released in regions with frequent low marine clouds in an otherwise clean environment. In addition, the potential impact of particulate matter on the radiation budget is larger over the dark ocean surface than over polluted regions over land.

scholarly journals Aerosol's optical and physical characteristics and direct radiative forcing during a shamal dust storm, a case study

2014 ◽  
Vol 14 (7) ◽  
pp. 3751-3769 ◽  
Author(s):  
T. M. Saeed ◽  
H. Al-Dashti ◽  
C. Spyrou
Keyword(s):  
Optical Thickness ◽  
Dust Storm ◽  
Radiative Forcing ◽  
Longwave Radiation ◽  
Aerosol Optical Thickness ◽  
Radiative Heating ◽  
Dust Layer ◽  
Surface Level ◽  
Maximum Value ◽  
Direct Radiative Forcing

Abstract. Dust aerosols are analyzed for their optical and physical properties during an episode of a dust storm that blew over Kuwait on 26 March 2003 when the military Operation Iraqi Freedom was in full swing. The intensity of the dust storm was such that it left a thick suspension of dust throughout the following day, 27 March. The synoptic sequence leading to the dust storm and the associated wind fields are discussed. Ground-based measurements of aerosol optical thickness reached 3.617 and 4.17 on 26 and 27 March respectively while the Ångstrom coefficient, α870/440, dropped to −0.0234 and −0.0318. Particulate matter concentration of 10 μm diameter or less, PM10, peaked at 4800 μg m−3 during dust storm hours of 26 March. Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved aerosol optical depth (AOD) by Deep Blue algorithm and Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI) exhibited high values. Latitude–longitude maps of AOD and AI were used to deduce source regions of dust transport over Kuwait. The vertical profile of the dust layer was simulated using the SKIRON atmospheric model. Instantaneous net direct radiative forcing is calculated at top of atmosphere (TOA) and surface level. The thick dust layer of 26 March resulted in cooling the TOA by −60 Wm−2 and surface level by −175 Wm−2 for a surface albedo of 0.35. Slightly higher values were obtained for 27 March due to the increase in aerosol optical thickness. Radiative heating/cooling rates in the shortwave and longwave bands were also examined. Shortwave heating rate reached a maximum value of 2 K day−1 between 3 and 5 km, dropped to 1.5 K day−1 at 6 km and diminished at 8 km. Longwave radiation initially heated the lower atmosphere by a maximum value of 0.2 K day−1 at surface level, declined sharply at increasing altitude and diminished at 4 km. Above 4 km longwave radiation started to cool the atmosphere slightly reaching a maximum rate of −0.1 K day−1 at 6 km.

Using aerosol optical thickness to predict ground-level PM2.5 concentrations in the St. Louis area: A comparison between MISR and MODIS

2007 ◽  
Vol 107 (1-2) ◽  
pp. 33-44 ◽  
Author(s):  
Yang Liu ◽  
Meredith Franklin ◽  
Ralph Kahn ◽  
Petros Koutrakis
Keyword(s):  
Optical Thickness ◽  
Ground Level ◽  
Aerosol Optical Thickness
Sign in / Sign up

Export Citation Format

Share Document