Long-Term Satellite Record Reveals Likely Recent Aerosol Trend

Mishchenko, Michael I.; Geogdzhayev, Igor V.; Rossow, William B.; Cairns, Brian; Carlson, Barbara E.; Lacis, Andrew A.; Liu, Li; Travis, Larry D.

doi:10.1126/science.1136709

Cited by 217 publications

(147 citation statements)

References 10 publications

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“…Ice core data show that aerosols decrease as the climate warms, probably because increased water vapour and rainfall wash out aerosols. Aerosol amount in the Earth's atmosphere seems to have decreased in the past two decades (Mishchenko et al 2007), while human-made aerosol sources were believed to be increasing. We suggest that the aerosol decrease may be due to rapid global warming, approximately 0.28C per decade (Hansen et al 2006a), and resulting moistening of the atmosphere.…”

Section: Climate Sensitivitymentioning

confidence: 99%

Climate change and trace gases

Hansen

Sato

Kharecha

et al. 2007

Phil. Trans. R. Soc. A.

356

272

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Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the 'albedo flip' property of ice/water, provides a powerful trigger mechanism. A climate forcing that 'flips' the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO 2 ) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO 2 emissions and reduce non-CO 2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO 2 forcings is methane (CH 4 ), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O 3 ), which is the third largest GHG forcing. Nitrous oxide (N 2 O) should also be a focus of climate mitigation efforts. Black carbon ('black soot') has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment.

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Section: Climate Sensitivitymentioning

confidence: 99%

Climate change and trace gases

Hansen

Sato

Kharecha

et al. 2007

Phil. Trans. R. Soc. A.

356

272

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“…For example, quite good agreement is found in Ispra during the whole day; 90 % of the values show differences smaller than 0.05. Note that the absolute error of typical AOD retrieval approaches is larger than 0.05 (Mishchenko et al, 2007). Occasionally, however, there are spikes in the MSG observations where AODs are overestimated or underestimated.…”

Section: Time Series Analysis Of Aodmentioning

confidence: 95%

Retrieval of aerosol optical depth over land based on a time series technique using MSG/SEVIRI data

et al. 2012

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Abstract.A novel approach for the joint retrieval of aerosol optical depth (AOD) and aerosol type, using Meteosat Second Generation -Spinning Enhanced Visible and Infrared Imagers (MSG/SEVIRI) observations in two solar channels, is presented. The retrieval is based on a Time Series (TS) technique, which makes use of the two visible bands at 0.6 µm and 0.8 µm in three orderly scan times (15 min interval between two scans) to retrieve the AOD over land. Using the radiative transfer equation for plane-parallel atmosphere, two coupled differential equations for the upward and downward fluxes are derived. The boundary conditions for the upward and downward fluxes at the top and at the bottom of the atmosphere are used in these equations to provide an analytic solution for the AOD. To derive these fluxes, the aerosol single scattering albedo (SSA) and asymmetry factor are required to provide a solution. These are provided from a set of six pre-defined aerosol types with the SSA and asymmetry factor. We assume one aerosol type for a grid of 1 • ×1 • and the surface reflectance changes little between two subsequent observations. A k-ratio approach is used in the inversion to find the best solution of atmospheric properties and surface reflectance. The k-ratio approach assumes that the surface reflectance is little influenced by aerosol scattering at 1.6 µm and therefore the ratio of surface reflectances in the solar band for two subsequent observations can be wellapproximated by the ratio of the reflectances at 1.6 µm. A further assumption is that the surface reflectance varies only slightly over a period of 30 min. The algorithm makes use of numerical minimisation routines to obtain the optimal solution of atmospheric properties and surface reflectance by selection of the most suitable aerosol type from pre-defined sets.A detailed analysis of the retrieval results shows that it is suitable for AOD retrieval over land from SEVIRI data. Six AErosol RObotic NETwork (AERONET) sites with different surface types are used for detailed analysis and 42 other AERONET sites are used for validation. From 445 collocations representing stable and homogeneous aerosol type, we find that >75 % of the MSG-retrieved AOD at 0.6 and 0.8 µm values compare favourably with AERONET observed AOD values, within an error envelope of ± 0.05 ± 0.15τ and a high correlation coefficient (R>0.86). The AOD datasets derived Published by Copernicus Publications on behalf of the European Geosciences Union. L. Mei et al.: Retrieval of aerosol optical depth over landusing the TS method with SEVIRI data is also compared with collocated AOD products derived from NASA TERRA and AQUA MODIS (The Moderate-resolution Imaging Spectroradiometer) data using the Dark Dense Vegetation (DDV) method and the Deep Blue algorithms. Using the TS method, the AOD could be retrieved for more pixels than with the NASA Deep Blue algorithm. This method is potentially also useful for surface reflectance retrieval using SEVIRI observations. The current paper focuses on AOD retrieval ...

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“…그리 고 역사상 가장 큰 화산 폭발 중 하나인 Pinatubo 화산폭 발과 El Chichon 화산폭발은 전 지구적인 기후변화 효과 를 유발한 것으로 알려져 있다 (Mishchenko et al, 2007). (Lee et al, 2004;2006a;2006b), 위 성 탑재 센서의 특징에 따라 다양한 화산재 탐지 알고리 즘이 개발되었다 (Francis et al, 2012;Ellord et al, 2003;Prata et al, 1989).…”

Section: 서 론unclassified

Sensitivity Analysis of Volcanic Ash Inherent Optical Properties to the Remote Sensed Radiation

Lee¹,

Jang²

2014

Korean Journal of Remote Sensing

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: Volcanic ash (VA) can be estimated by remote sensing sensors through their spectral signatures determined by the inherent optical property (IOP) including complex refractive index and the scattering properties. Until now, a very limited range of VA refractive indices has been reported and the VA from each volcanic eruption has a different composition. To improve the robustness of VA remote sensing, there is a need to understanding of VA -radiation interactions. In this study, we calculated extinction coefficient, scattering phase function, asymmetry factor, and single scattering albedo which show different values between andesite and pumice. Then, IOPs were used to analyze the relationship between theoretical remote sensed radiation calculated by radiative transfer model under various aerosol optical thickness (τ) and sun-sensor geometries and characteristics of VA. It was found that the mean rate of change of radiance at top of atmosphere versus τ is six times larger than in radiance values at 0.55 μm. At the surface, positive correlation dominates when τ<1, but negative correlation dominates when τ>1. However, radiance differences between andesite and pumice at 11 μm are very small. These differences between two VA types are expressed as the polynomial regression functions and that increase as VA optical thickness increases. Finally, these results would allow VA to be better characterized by remote sensing sensors.

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Long-Term Satellite Record Reveals Likely Recent Aerosol Trend

Cited by 217 publications

References 10 publications

Climate change and trace gases

Climate change and trace gases

Retrieval of aerosol optical depth over land based on a time series technique using MSG/SEVIRI data

Sensitivity Analysis of Volcanic Ash Inherent Optical Properties to the Remote Sensed Radiation

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