scholarly journals Quantifying aerosol direct radiative effect with Multiangle Imaging Spectroradiometer observations: Top-of-atmosphere albedo change by aerosols based on land surface types

2009 ◽  
Vol 114 (D2) ◽  
Author(s):  
Yang Chen ◽  
Qinbin Li ◽  
Ralph A. Kahn ◽  
James T. Randerson ◽  
David J. Diner
Keyword(s):  
Land Surface ◽  
Radiative Effect ◽  
Albedo Change ◽  
Multiangle Imaging ◽  
Multiangle Imaging Spectroradiometer

Multiangle Imaging Spectroradiometer: optical characterization of the calibration panels

1997 ◽  
Vol 36 (27) ◽  
pp. 7016 ◽  
Author(s):  
Brendan T. McGuckin ◽  
David A. Haner ◽  
Robert T. Menzies
Keyword(s):  
Optical Characterization ◽  
Multiangle Imaging ◽  
Multiangle Imaging Spectroradiometer

scholarly journals Direct Radiative Effect by Multicomponent Aerosol over China*

2015 ◽  
Vol 28 (9) ◽  
pp. 3472-3495 ◽  
Author(s):  
Xin Huang ◽  
Yu Song ◽  
Chun Zhao ◽  
Xuhui Cai ◽  
Hongsheng Zhang ◽  
...  
Keyword(s):  
Land Surface ◽  
Radiation Flux ◽  
Seasonal Pattern ◽  
Model Performance ◽  
Wrf Model ◽  
Incident Radiation ◽  
Heterogeneous Reactions ◽  
Radiative Heating ◽  
Radiative Effect ◽  
Hygroscopic Growth

Abstract The direct radiative effect (DRE) of multiple aerosol species [sulfate, nitrate, ammonium, black carbon (BC), organic carbon (OC), and mineral aerosol] and their spatiotemporal variations over China were investigated using a fully coupled meteorology–chemistry model [Weather Research and Forecasting (WRF) Model coupled with Chemistry (WRF-Chem)] for the entire year of 2006. This study made modifications to improve the model performance, including updating land surface parameters, improving the calculation of transition-metal-catalyzed oxidation of SO2, and adding heterogeneous reactions between mineral dust aerosol and acid gases. The modified model generally reproduced the magnitude, seasonal pattern, and spatial distribution of the measured meteorological conditions, concentrations of PM10 and its components, and aerosol optical depth (AOD), although some low biases existed in modeled aerosol concentrations. A diagnostic iteration method was used to estimate the overall DRE of aerosols and contributions from different components. At the land surface, the incident net radiation flux was reduced by 10.2 W m−2 over China. Aerosols significantly warmed the atmosphere with the national mean DRE of +10.8 W m−2. BC was the leading radiative heating component (+8.7 W m−2), followed by mineral aerosol (+1.1 W m−2). At the top of the atmosphere (TOA), BC introduced the largest radiative perturbation (+4.5 W m−2), followed by sulfate (−1.4 W m−2). The overall perturbation of aerosols on radiation transfer is quite small over China, demonstrating the counterbalancing effect between scattering and adsorbing aerosols. Aerosol DRE at the TOA had distinct seasonality, generally with a summer maximum and winter minimum, mainly determined by mass loadings, hygroscopic growth, and incident radiation flux.

scholarly journals The effect of a dynamic background albedo scheme on Sahel/Sahara precipitation during the mid-Holocene

2011 ◽  
Vol 7 (1) ◽  
pp. 117-131 ◽  
Author(s):  
F. S. E. Vamborg ◽  
V. Brovkin ◽  
M. Claussen
Keyword(s):  
Land Surface ◽  
Dynamic Behaviour ◽  
External Forcing ◽  
Satellite Measurements ◽  
Dynamic Background ◽  
Area Index ◽  
Desert Region ◽  
Albedo Change ◽  
Standing Dead ◽  
Surface Scheme

Abstract. We have implemented a new albedo scheme that takes the dynamic behaviour of the surface below the canopy into account, into the land-surface scheme of the MPI-ESM. The standard (static) scheme calculates the seasonal canopy albedo as a function of leaf area index, whereas the background albedo is a gridbox constant derived from satellite measurements. The new (dynamic) scheme additionally models the background albedo as a slowly changing function of organic matter in the ground and of litter and standing dead biomass covering the ground. We use the two schemes to investigate the interactions between vegetation, albedo and precipitation in the Sahel/Sahara for two time-slices: pre-industrial and mid-Holocene. The dynamic scheme represents the seasonal cycle of albedo and the correspondence between annual mean albedo and vegetation cover in a more consistent way than the static scheme. It thus gives a better estimate of albedo change between the two time periods. With the introduction of the dynamic scheme, precipitation is increased by 30 mm yr−1 for the pre-industrial simulation and by about 80 mm yr−1 for the mid-Holocene simulation. The present-day dry bias in the Sahel of standard ECHAM5 is thus reduced and the sensitivity of precipitation to mid-Holocene external forcing is increased by around one third. The locations of mid-Holocene lakes, as estimated from reconstructions, lie south of the modelled desert border in both mid-Holocene simulations. The magnitude of simulated rainfall in this area is too low to fully sustain lakes, however it is captured better with the dynamic scheme. The dynamic scheme leads to increased vegetation variability in the remaining desert region, indicating a higher frequency of green spells, thus reaching a better agreement with the vegetation distribution as derived from pollen records.

scholarly journals Detecting thin cirrus in Multiangle Imaging Spectroradiometer aerosol retrievals

2010 ◽  
Vol 115 (D8) ◽  
Author(s):  
Jeffrey R. Pierce ◽  
Ralph A. Kahn ◽  
Matt R. Davis ◽  
Jennifer M. Comstock
Keyword(s):  
Multiangle Imaging ◽  
Multiangle Imaging Spectroradiometer

scholarly journals The impact of deforestation in the Amazonian atmospheric radiative balance: a remote sensing assessment

2012 ◽  
Vol 12 (6) ◽  
pp. 14837-14874 ◽  
Author(s):  
E. T. Sena ◽  
P. Artaxo ◽  
A. L. Correia
Keyword(s):  
Water Vapour ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Radiative Effect ◽  
Water Vapour Content ◽  
Albedo Change ◽  
Direct Radiative Forcing ◽  
The Mean ◽  
The Impact

Abstract. This paper addresses the Amazonian radiative budget after considering three aspects of deforestation: (i) the emission of aerosols from biomass burning due to forest fires; (ii) changes in surface albedo after deforestation and (iii) modifications in the column water vapour amount over deforested areas. Simultaneous Clouds and the Earth's Radiant Energy System (CERES) shortwave fluxes and aerosol optical depth (AOD) retrievals from the Moderate Resolution Imaging SpectroRadiometer (MODIS) were analysed during the peak of the biomass burning seasons (August and September) from 2000 to 2009. A discrete-ordinate radiative transfer (DISORT) code was used to extend instantaneous remote sensing radiative forcing assessments into 24-h averages. The mean direct radiative forcing of aerosols at the top of the atmosphere (TOA) during the biomass burning season for the 10-yr studied period was −5.6 ± 1.7 W m−2. Furthermore, the spatial distribution of the direct radiative forcing of aerosols over Amazon was obtained for the biomass burning season of each year. It was observed that for high AOD (larger than 1 at 550 nm) the imbalance in the radiative forcing at the TOA may be as high as −20 W m−2 locally. The surface reflectance plays a major role in the aerosol direct radiative effect. The study of the effects of biomass burning aerosols over different surface types shows that the direct radiative forcing is systematically more negative over forest than over savannah-like covered areas. Values of −15.7 ± 2.4 W m−2/τ550 nm and −9.3 ± 1.7 W m−2/τ550 nm were calculated for the mean daily aerosol forcing efficiencies over forest and savannah-like vegetation respectively. The overall mean annual albedo-change radiative forcing due to deforestation over the state of Rondônia, Brazil, was determined as −7.3 ± 0.9 W m−2. Biomass burning aerosols impact the radiative budget for approximately two months per year, whereas the surface albedo impact is observed throughout the year. Because of this difference, the estimated impact in the Amazonian annual radiative budget due to surface albedo-change is approximately 6 times higher than the impact due to aerosol emissions. The influence of atmospheric water vapour content in the radiative budget was also studied using AERONET column water vapour. It was observed that column water vapour is in average smaller by about 0.35 cm over deforested areas compared to forested areas. Our results indicate that this drying impact contributes to an increase in the shortwave radiative effect that varies from 0.4 W m−2 to 1.2 W m−2, depending on the column water vapour content before deforestation. The large radiative forcing values presented in this study point out that deforestation has strong implications in convection, cloud development and photosynthesis rate over the Amazon region.

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