Albedo reduction by absorbing aerosols over China

Krüger, Olaf; Graßl, Hartmut

doi:10.1029/2003gl019111

Cited by 28 publications

(23 citation statements)

References 9 publications

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“…Absorbing aerosols, such as black carbon and mineral dust, could contribute to large diabatic heating in the atmosphere that often enhances cloud evaporation (semi-indirect effect) (Ackerman et al, 2000;Koren et al, 2004;Kruger and Graßl, 2004;Huang et al, 2006). The magnitude of the global mean radiative effect of dust aerosols is comparable to that of anthropogenic aerosols from sulphates and biomass combustion (Sokolik and Toon, 1999).…”

Section: Introductionmentioning

confidence: 94%

Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

et al. 2009

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Abstract. The dust aerosol radiative forcing and heating rate over the Taklimakan Desert in Northwestern China in July 2006 are estimated using the Fu-Liou radiative transfer model along with satellite observations. The vertical distributions of the dust aerosol extinction coefficient are derived from the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) lidar measurements. The CERES (Cloud and the Earth's Energy Budget Scanner) measurements of reflected solar radiation are used to constrain the dust aerosol type in the radiative transfer model, which determines the dust aerosol single-scattering albedo and asymmetry factor as well as the aerosol optical properties' spectral dependencies. We find that the dust aerosols have a significant impact on the radiative energy budget over the Taklimakan desert. In the atmospheres containing light, moderate and heavy dust layers, the dust aerosols heat the atmosphere (daily mean) by up to 1, 2, and 3 K day −1 , respectively. The maximum daily mean radiative heating rate reaches 5.5 K day −1 at 5 km on 29 July. The averaged daily mean net radiative effect of the dust are 44.4, −41.9, and 86.3 W m −2 , respectively, at the top of the atmosphere (TOA), surface, and in the atmosphere. Among these effects about two thirds of the warming effect at the TOA is related to the longwave radiation, while about 90% of the atmospheric warming is contributed by the solar radiation. At the surface, about one third of the dust solar radiativeCorrespondence to: J. Huang (hjp@lzu.edu.cn) cooling effect is compensated by its longwave warming effect. The large modifications of radiative energy budget by the dust aerosols over Taklimakan Desert should have important implications for the atmospheric circulation and regional climate, topics for future investigations.

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Section: Introductionmentioning

confidence: 94%

Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

et al. 2009

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“…As one possibility, Krüger and Grassl (2004) presented evidence from a near-infrared satellite channel that absorbing aerosols have caused reductions in low-level and middle-level cloud cover over southeast China (presumably by heating and evaporating cloud droplets). However, in the case of high clouds we caution that some of the trends could be artificial.…”

Section: Regional Trendsmentioning

confidence: 99%

A Survey of Changes in Cloud Cover and Cloud Types over Land from Surface Observations, 1971–96

2007

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From a dataset of weather observations from land stations worldwide, about 5400 stations were selected as having long periods of record with cloud-type information; they cover all continents and many islands. About 185 million synoptic reports were analyzed for total cloud cover and the amounts of nine different cloud types, for the 26-yr period 1971-96. Monthly and seasonal averages were formed for day and night separately.Time series of total-cloud-cover anomalies for individual continents show a large decrease for South America, small decreases for Eurasia and Africa, and no trend for North America. The largest interannual variations (2.7%) are found for Australia, which is strongly influenced by ENSO. The zonal average trends of total cloud cover are positive in the Arctic winter and spring, 60°-80°N, but negative in all seasons at most other latitudes. The global average trend of total cloud cover over land is small, Ϫ0.7% decade Ϫ1, offsetting the small positive trend that had been found for the ocean, and resulting in no significant trend for the land-ocean average.Significant regional trends are found for many cloud types. The night trends agree with day trends for total cloud cover and for all cloud types except cumulus. Cirrus trends are generally negative over all continents. A previously reported decline in total cloud cover over China and its neighbors appears to be largely attributable to high and middle clouds. Global trends of the cloud types exhibit trade-offs, with convective cloud types increasing at the expense of stratiform clouds, in both the low and middle levels.Interannual variations over Europe, particularly of nimbostratus, are well correlated with the North Atlantic Oscillation; significant correlations are also found across northern Asia. Interannual variations in many parts of the Tropics are well correlated with an ENSO index. Little correlation was found with an index of smoke aerosol, in seven regions of seasonal biomass burning.In the middle latitudes of both hemispheres, seasonal anomalies of cloud cover are positively correlated with surface temperature in winter and negatively correlated in summer, as expected if the direction of causality is from clouds to temperature.

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“…Satellite observations show an albedo reduction because of absorbing aerosols and their impact on cloud absorbance over urbanized regions in China. 111 Surface temperature records in urbanized regions of China 108,112,113 and India 113 show a measurable cooling since the 1950s. Analyses of meteorological data in heavily urbanized regions of China demonstrate significant downward trends in both sunshine duration (1% to 3% per decade) and max daily temperatures (0.2-0.6°C per decade).…”

Section: Regional Ecosystem Impactsmentioning

confidence: 99%

Megacities and Atmospheric Pollution

Molina

2004

Journal of the Air & Waste Management Association

692

372

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About half of the world's population now lives in urban areas because of the opportunity for a better quality of life. Many of these urban centers are expanding rapidly, leading to the growth of megacities, which are defined as metropolitan areas with populations exceeding 10 million inhabitants. These concentrations of people and activity are exerting increasing stress on the natural environment, with impacts at urban, regional and global levels. In recent decades, air pollution has become one of the most important problems of megacities. Initially, the main air pollutants of concern were sulfur compounds, which were generated mostly by burning coal. Today, photochemical smog-induced primarily from traffic, but also from industrial activities, power generation, and solvents-has become the main source of concern for air quality, while sulfur is still a major problem in many cities of the developing world. Air pollution has serious impacts on public health, causes urban and regional haze, and has the potential to contribute significantly to climate change. Yet, with appropriate planning, megacities can efficiently address their air quality problems through measures such as application of new emission control technologies and development of mass transit systems.This review is focused on nine urban centers, chosen as case studies to assess air quality from distinct perspectives: from cities in the industrialized nations to cities in the developing world. While each city-its problems, resources, and outlook-is unique, the need for a holistic approach to the complex environmental problems is the same. There is no single strategy in reducing air pollution in megacities; a mix of policy measures will be needed to improve air quality. Experience shows that strong political will coupled with public dialog is essential to effectively implement the regulations required to address air quality problems.

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Albedo reduction by absorbing aerosols over China

Cited by 28 publications

References 9 publications

Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

A Survey of Changes in Cloud Cover and Cloud Types over Land from Surface Observations, 1971–96

Megacities and Atmospheric Pollution

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