A climatological perspective of deep convection penetrating the TTL during the Indian summer monsoon from the AVHRR and MODIS instruments

Devasthale, Abhay; Fueglistaler, S.

doi:10.5194/acp-10-4573-2010

Cited by 66 publications

(78 citation statements)

References 32 publications

(24 reference statements)

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“…Enhancements in trace gases have been observed between ∼10 and 20 km, with maximum values for longer lived compounds observed around 15 km, and for shorter lived compounds around 13 km (Park et al, 2008). Satellite observations also suggest that deep convection is most frequent in July and August, but reaches higher in May and June (Devasthale and Fueglistaler, 2010).…”

Section: Introductionmentioning

confidence: 76%

Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft

et al. 2011

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Abstract. Between April and December 2008 the CARIBIC commercial aircraft conducted monthly measurement flights between Frankfurt, Germany and Chennai, India. These flights covered the period of the Asian summer monsoon (June-September), during which enhancements in a number of atmospheric species were observed in the upper troposphere over southwestern Asia. In addition to in situ measurements of trace gases and aerosols, whole air samples were collected during the flights, and these were subsequently analyzed for a suite of trace gases that included a number of C 2 -C 8 non-methane hydrocarbons. Non-methane hydrocarbons are relatively short-lived compounds and the large enhancements in their mixing ratios in the upper troposphere over southwestern Asia during the monsoon, sometimes more than double their spring and fall means, provides qualitative evidence for the influence of convectively uplifted boundary layer air. The particularly large enhancements of the combustion tracers benzene and ethyne, along with the similarity of their ratios with carbon monoxide and emission ratios from the burning of household biofuels, indicate a strong influence of biofuel burning to NMHC emissions in this region. Conversely, the ratios of ethane and propane to carbon monoxide, along with the ratio between i-butane and n-butane, indicate a significant source of these compounds from the use of fossil fuels, and comparison to previous campaigns suggests that this source could be increasing. Photochemical aging patterns of NMHCs showed that the CARIBIC samples were collected in two distinctly different regions of the monsoon circulation: a southern region where air masses had been recently influenced by low level contact and a northern region, where air parcels had Correspondence to: A. K. Baker (angela.baker@mpic.de) spent substantial time in transit in the upper troposphere before being probed. Estimates of age using ratios of individual NMHCs have ranges of 3-6 days in the south and 9-12 days in the north.

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Section: Introductionmentioning

confidence: 76%

Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft

et al. 2011

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“…), and that only small amounts reach the Tibetan Plateau, arguing against the hypothesized elevated heat pump effect of aerosol pollution. Second, Devasthale and Fueglistaler (2010) have reassessed satellite data from the AVHRR and MODIS instruments and have determined that the strongest convection in the Asian summer monsoon is south of the Himalayas, particularly over the Bay of Bengal, and that there is relatively little intense, very deep convection over the Tibetan Plateau. And third, it has been found in GCM simulations that the thin band of very high peaks in the Himalayas appears to play a larger role in determining the exceptional strength of the Asian summer monsoon than the broad Tibetan Plateau (Boos and Kuang, 2010).…”

Section: Meteorological Elementsmentioning

confidence: 99%

Atmospheric pollutant outflow from southern Asia: a review

2010

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Abstract. Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern AsianCorrespondence to: M. G. Lawrence (mark.lawrence@mpic.de) atmospheric pollutant outflow and its large scale effects. An outlook is provided as a guideline for future research, pointing out particularly critical issues such as: resolving discrepancies between top down and bottom up emissions estimates; assessing the processing and aging of the pollutant outflow; developing a better understanding of the observed elevated pollutant layers and their relationship to local sea breeze and large scale monsoon circulations; and determining the impacts of the pollutant outflow on the Asian monsoon meteorology and the regional hydrological cycle, in particular the mountain cryospheric reservoirs and the fresh water supply, which in turn directly impact the lives of over a billion inhabitants of southern Asia.

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“…The level of convective detrainment is approximately ∼200 hPa (e.g. Kazuaki et al, 2004;Devasthale and Fueglistaler, 2010), and the amount of ice water at this level is proportional to convective intensity. MLS IWC has been found to be indicative of convective strength.…”

Section: Introductionmentioning

confidence: 99%

Influence of convection and aerosol pollution on ice cloud particle effective radius

Jiang

Zhai

et al. 2011

Atmos. Chem. Phys.

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Abstract. Satellite observations show that ice cloud effective radius (r e ) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using leastsquares fitting to the observed data, we obtain an analytical formula to describe the variations of r e with IWC and AOT for several regions with distinct characteristics of r e -IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling r e in different geographical regions, and to establish a framework for parameterization of aerosol effects on r e in climate models.

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A climatological perspective of deep convection penetrating the TTL during the Indian summer monsoon from the AVHRR and MODIS instruments

Cited by 66 publications

References 32 publications

Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft

Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft

Atmospheric pollutant outflow from southern Asia: a review

Influence of convection and aerosol pollution on ice cloud particle effective radius

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