What is the main mechanism for enhancing the impact of aerosols?

Suppression of precipitation in the updrafts of very deep clouds, especially in the tropics, can also transport more water and aerosols into the upper troposphere and the lower stratosphere.

What did the suppression of coalescence by smoke and air pollution cause?

The suppression of coalescence by smoke and air pollution also induced lower freezing temperature of the cloud supercooled water and suppression of the ice precipitation processes (39).

What is the effect of the aerosols on the precipitation efficiency?

If the condensed moisture inside the cloud is not altered by the increase in aerosols, the droplet radius will decrease because of the increase in its number concentration resulting in a decrease in the precipitation efficiency (2, 3, 8).

What is the role of biomass in the emission of organics?

Biomass burning plays a major role in the emission of organics (10), whereas fossil fuel combustion and biomass burning contribute about equally to BC emission (2).

What is the reliable information about aerosols?

On account of the large spatial and temporal variability of these aerosols, remote sensing from satellites delivers the most reliable information about global aerosol distributions (4).

What does the effect of BC have on the solar radiation at the surface?

The presence of trace amounts of BC can result in a large atmospheric solar absorption (13), which reduces substantially the solar radiation reaching the surface (14), as shown directly from observations (15, 16).

What is the global average indirect forcing for aerosols?

The global average indirect forcing (3, 8) varies from –0.3 W m22 to about –1 W m22 for just sulfate aerosols and about –0.5 to –2 W m22 for sulfate plus carbonaceous aerosols (3, 8).

What is the role of sulfate aerosols on radiative forcing?

The role of sunlight-absorbing, BC-containing particles on radiative forcing have come to the forefront (6, 8, 17) in climate-change studies, especially as a result of findings of some major field programs such as Tropospheric Aerosol Radiative Forcing Observational Experiment (18), Smoke, Clouds, and Radiation–Brazil Experiment (19), Aerosol-Characterization Experiment–II (20), and the Indian Ocean Experiment, INDOEX (16, 21– 23).

What is the effect of aerosols on cloud drop size?

In situ aircraft observations (28–32) of continental and marine clouds show that anthropogenic aerosols enhance CCN and cloud drop number density (Fig. 5) and reduce their sizes.

What is the effect of the first indirect effect on clouds?

The INDOEX cloud and aerosol data (Fig. 5), when integrated with realistic cloud-radiation models, yield –5 W m22 for the TOA forcing because of the first indirect effect (23) (Fig. 4).

How did the effect of sulfate aerosols affect the hydrologic cycle?

In more recent studies (47, 48), which include both the direct and the indirect radiative effect of sulfate aerosols, the strength of the hydrologic cycle also decreased, and this decrease was large enough to reverse the effect of GHGs in one of the models (48).

What is the average chemical composition of the aerosols by mass?

The average chemical composition of the aerosols by mass included (22) sulfates (32%), ammonium (8%), organics (26%), nitrates (10%), BC (14%), fly ash (5%), dust (10%), and potassium (2%).

Open AccessJournal Article10.1126/SCIENCE.1064034

Aerosols, climate, and the hydrological cycle

Veerabhadran Ramanathan, +4 more

- 07 Dec 2001

- Science

- Vol. 294, Iss: 5549, pp 2119-2124

3.9K

TL;DR: Human activities are releasing tiny particles (aerosols) into the atmosphere that enhance scattering and absorption of solar radiation, which can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.

Abstract: Human activities are releasing tiny particles (aerosols) into the atmosphere. These human-made aerosols enhance scattering and absorption of solar radiation. They also produce brighter clouds that are less efficient at releasing precipitation. These in turn lead to large reductions in the amount of solar irradiance reaching Earth's surface, a corresponding increase in solar heating of the atmosphere, changes in the atmospheric temperature structure, suppression of rainfall, and less efficient removal of pollutants. These aerosol effects can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.

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Most frequently asked questions

1. What are the contributions in "Aerosols, climate, and the hydrological cycle" ?

In the 21st century, human activities are releasing tiny particles ( aerosols ) into the atmosphere, which enhance scattering and absorption of solar radiation this paper.

2. What future works have the authors mentioned in the paper "Aerosols, climate, and the hydrological cycle" ?

Directions for Future Research First and foremost, the authors need a reliable global inventory of aerosol emission rates, lifetimes, and concentrations.. The authors urgently need the capability to observe the global distribution and transport of BC around the planet.

3. What is the effect of aerosols on the hydrologic cycle?

Inclusion of just the direct radiative forcing of sulfate aerosols (without GHG forcing) leads to a net reduction in the hydrologic cycle, with the reduction in solar insolation balanced partially by a reduction in the latent heat flux due to evaporation.

4. How does the effect of aerosols affect the hydrologic cycle?

Reduction in the evaporation will have to be balanced by a reduction in rainfall and effectively spin down the hydrological cycle.

Fig. 2. Global distribution of natural and anthropogenic aerosol optical depth (AOD). (A) AOD at 0.55 mm derived from moderateresolution imaging spectrometer, MODIS, on board the TERRA satellite (4). MODIS uses new techniques (4) to derive AOD over the land. Data are shown only for one month. A complete year is still not available. Many land regions are missing (black shaded areas), because these are mostly desert land areas with too bright background for retrieving the AOD. (B) Annual mean AOD (at 0.63 mm) estimated by a four-dimensional assimilation model (5) that uses satellitederived AOD for the oceans to constrain the model AODs. The AOD here represents the sum of natural and anthropogenic aerosol. (C) Anthropogenic contribution to the AOD estimated by a three-dimensional model (6, 7). Biomass burning is the major contributor to the high aerosol regions in Africa and South America. Both biomass burning and fossil fuel combustion contribute to the loading in South and Southeast Asia (the model does not capture the full impact of the anthropogenic aerosols in this region). Fossil fuel combustion is the major contributor to the mid- and high latitude aerosol loading.

Fig. 4. Comparison of anthropogenic aerosol forcing with greenhouse forcing. (A) The IndoAsian region. Results are similar to those shown in (23) but for a much longer period. The greenhouse forcing was estimated from the NCAR community climate model (9) with an uncertainty of 6 20%. (B) Same as above, but for global and annual average conditions. The global average values are a summary of published estimates (3, 6, 8, 17).

Fig. 3. Dependence of the aerosol direct forcing at the TOA (top panel) and at the surface (bottom panel) on low cloud fraction, SSA, and surface albedo (land or ocean albedo). The results are diurnally averaged and are based on a Monte Carlo aerosol-cloud-radiation model mentioned in (23). References that describe this model in detail can be seen in (23), and the model assumes an AOD of 0.3. The SSA for the upper dashed line and the upper boundary of the blue-shaded region is 0.85 for the top panel and 0.95 for the bottom panel. A similar convention applies to the lower dashed line and the lower boundary of the blue-shaded region.

Fig. 5. Aircraft data illustrating the increase in cloud drops with aerosol number concentration. References for the data are as follows: North Sea (28), Nova Scotia and North Atlantic (29), ACE-2 (30), Astex (31), the thick red line is obtained from a composite theoretical parameterization that fits the INDOEX aircraft data for the Arabian Sea (23). The gray-shaded region is the INDOEX aircraft data for the Arabian Sea (32).

Fig. 6. Satellite-retrieved median effective radius of particles near the top of deep convective clouds at various stages of their vertical development, as a function of the cloud top temperature, which serves as a surrogate for cloud top height. The effective radius is the ratio of the integral of the third moment (r3) of the radius, weighted with the number concentration at that radius, to its second moment (r2). This is shown for clouds forming in polluted (solid lines) and pristine air (broken lines). The red lines denoted by “INDOEX polluted” are for data along a track that runs from South West India into the Indian Ocean. The blue lines are for tracks over urban Southeastern Australia (38). Violet lines are for Thailand pre-monsoon clouds with suppressed coalescence. Green lines are for biomass smoke over the Amazon; and black lines are for desert dust over Israel (40). The vertical green line denotes the 14-mm precipitation threshold radius. The references that justify this threshold value are given in (38, 39).

Citations

•Journal Article•10.5194/ACP-6-1937-2006

Hygroscopic growth and critical supersaturations for mixed aerosol particles of inorganic and organic compounds of atmospheric relevance

Birgitta Svenningsson, +10 more

- 09 May 2005

- Atmospheric Chemistry and Physics

TL;DR: In this paper, the interaction between water vapor and aerosol particles was studied at different relative humidities: at subsaturation using a hygroscopic tandem differential mobility analyzer (H-TDMA) and at supersaturation using cloud condensation nuclei spectrometer (CCN spectrometers).

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•Journal Article•10.5194/ACP-9-7067-2009

Aerosol- and updraft-limited regimes of cloud droplet formation: influence of particle number, size and hygroscopicity on the activation of cloud condensation nuclei (CCN)

Philipp Reutter, +9 more

- 24 Sep 2009

- Atmospheric Chemistry and Physics

TL;DR: In this article, the formation of cloud droplets under pyro-convective conditions using a cloud parcel model with detailed spectral microphysics and with the κ-Kohler model approach for efficient and realistic description of the cloud condensation nucleus (CCN) activity of aerosol particles.

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Urban Aerosol Impacts on Downwind Convective Storms

Susan C. van den Heever, +1 more

- 01 Jun 2007

- Journal of Applied Meteorology and Clima...

TL;DR: In this article, the impacts of urban-enhanced aerosol concentrations on convective storm development and precipitation over and downwind of St. Louis, Missouri, were investigated through the use of a cloud-resolving mesoscale model, in which sophisticated land use processes and aerosol microphysics were both incorporated.

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Impact of global dimming and brightening on global warming

Martin Wild, +2 more

- 01 Feb 2007

- Geophysical Research Letters

TL;DR: In this article, the authors analyzed trends in diurnal temperature range to disentangle surface solar and greenhouse influences on global warming, and found that solar brightening cannot supersede the greenhouse effect as main cause of global warming.

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Journal Article•10.1002/JOC.2044

Urbanization signature in the observed heavy rainfall climatology over India.

C. M. Kishtawal, +4 more

- 15 Nov 2010

- International Journal of Climatology

TL;DR: In this article, the authors investigated the relationship between urbanization and Indian monsoon rainfall changes by analyzing in situ and satellite-based precipitation and population datasets using a long-term daily rainfall dataset and high-resolution gridded analysis of human population.

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348

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References

Journal Article•10.2307/20033020

Climate change 2001: the scientific basis

John Theodore Houghton, +7 more

- 01 Jan 2002

- Foreign Affairs

TL;DR: In this article, the authors present an overview of the climate system and its dynamics, including observed climate variability and change, the carbon cycle, atmospheric chemistry and greenhouse gases, and their direct and indirect effects.

...read moreread less

16K

Journal Article•10.1126/SCIENCE.250.4988.1669

Biomass Burning in the Tropics: Impact on Atmospheric Chemistry and Biogeochemical Cycles

Paul J. Crutzen, +1 more

- 21 Dec 1990

- Science

TL;DR: Widespread burning of biomass serves to clear land for shifting cultivation, to convert forests to agricultural and pastoral lands, and to remove dry vegetation in order to promote agricultural productivity and the growth of higher yield grasses, but it may also disturb biogeochemical cycles, especially that of nitrogen.

...read moreread less

2.7K

•Journal Article•10.1029/96JD03436

Radiative forcing and climate response

James Hansen, +2 more

- 27 Mar 1997

- Journal of Geophysical Research

TL;DR: This paper examined the sensitivity of a climate model to a wide range of radiative forcings, including changes of solar irradiance, atmospheric CO2, O3, CFCs, clouds, aerosols, surface albedo, and a "ghost" forcing introduced at arbitrary heights, latitudes, longitudes, seasons, and times of day.

...read moreread less

2.3K

Journal Article•10.1029/1999RG000078

Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review

Jim Haywood, +1 more

- 01 Nov 2000

- Reviews of Geophysics

TL;DR: A review of the many developments in estimates of the direct and indirect global annual mean radiative forcing due to present-day concentra- tions of anthropogenic tropospheric aerosols since the Inter- governmental Panel on Climate Change (1996) is presented in this paper.

...read moreread less

2.2K

Journal Article•10.1016/0004-6981(74)90004-3

Pollution and the Planetary Albedo

S. Twomey

- 01 Dec 1974

- Atmospheric Environment

TL;DR: In this paper, the albedo of a cloud is proportional to optical thickness for thin clouds, but changes more slowly with increasing thickness as the number of cloud nuclei is increased.

...read moreread less

2.2K

...

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Aerosols, climate, and the hydrological cycle

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AI Agents for this Paper

Most frequently asked questions

1. What are the contributions in "Aerosols, climate, and the hydrological cycle" ?

2. What future works have the authors mentioned in the paper "Aerosols, climate, and the hydrological cycle" ?

3. What is the effect of aerosols on the hydrologic cycle?

4. How does the effect of aerosols affect the hydrologic cycle?

5. What is the main mechanism for enhancing the impact of aerosols?

6. What did the suppression of coalescence by smoke and air pollution cause?

7. What is the effect of the aerosols on the precipitation efficiency?

8. What is the role of biomass in the emission of organics?

9. What is the reliable information about aerosols?

10. What does the effect of BC have on the solar radiation at the surface?

11. What is the global average indirect forcing for aerosols?

12. What is the role of sulfate aerosols on radiative forcing?

13. What is the effect of aerosols on cloud drop size?

14. What is the effect of the first indirect effect on clouds?

15. How did the effect of sulfate aerosols affect the hydrologic cycle?

16. What is the average chemical composition of the aerosols by mass?

Figures

Citations

Hygroscopic growth and critical supersaturations for mixed aerosol particles of inorganic and organic compounds of atmospheric relevance

Aerosol- and updraft-limited regimes of cloud droplet formation: influence of particle number, size and hygroscopicity on the activation of cloud condensation nuclei (CCN)

Urban Aerosol Impacts on Downwind Convective Storms

Impact of global dimming and brightening on global warming

Urbanization signature in the observed heavy rainfall climatology over India.

References

Climate change 2001: the scientific basis

Biomass Burning in the Tropics: Impact on Atmospheric Chemistry and Biogeochemical Cycles

Radiative forcing and climate response

Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review

Pollution and the Planetary Albedo

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