Air pollution transport in the Himalayas of Nepal and Tibet during the 1995–1996 dry season

Hindman, Edward E.; Upadhyay, Bidur Prasad

doi:10.1016/s1352-2310(01)00495-2

Cited by 84 publications

(58 citation statements)

References 15 publications

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“…Role of Weather. In contrast to expectation, the majority of northward-flying geese began climbing during the night or early morning in what were, on the basis of conditions at the Pyramid station and the known prevalence of mountain-valley wind systems in the Himalaya (22,23), likely to be light headwind (katabatic) conditions, and two geese completed their entire climb before anabatic conditions should have begun. The majority of climbing flights took place before 10:00 h and the four highest climb rates were recorded before 07:00 h (range 1.5-2.2 km·h −1 ).…”

Section: Resultsmentioning

confidence: 62%

“…ac.uk/data/radiosonde/radhelp.html), the data were not temporally coincident and, therefore, did not improve our interpretation of wind patterns for the satellite tracks. Although topographic features such as valleys and slope angle will undoubtedly affect local wind conditions, anabatic/katabatic wind phenomena are common in every terrestrial mountain range on earth (19)(20)(21)(22)(23)(24)(25) and operate at the scale of mountain ranges, relevant to the migratory distance traveled by the geese. The Pyramid station data describe wind speed and direction at 30-min intervals for the year and cover the period over which we tracked birds migrating.…”

Section: Methodsmentioning

confidence: 99%

“…Large mountainous areas are characterized by daily slope winds that occur due to predictable changes in daily solar radiation and thermal conditions [e.g., the Alps (19,20), the Andes (21), the Himalaya (22,23), and mountainous areas in the United States (24,25)]. These winds reach an upslope "anabatic" maximum during the warmest part of the day, and a downslope, "katabatic" maximum in the evening and overnight (19,20).…”

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confidence: 99%

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The trans-Himalayan flights of bar-headed geese ( Anser indicus )

Hawkes

Balachandran

Batbayar

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

143

125

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Birds that fly over mountain barriers must be capable of meeting the increased energetic cost of climbing in low-density air, even though less oxygen may be available to support their metabolism. This challenge is magnified by the reduction in maximum sustained climbing rates in large birds. Bar-headed geese (Anser indicus) make one of the highest and most iconic transmountain migrations in the world. We show that those populations of geese that winter at sea level in India are capable of passing over the Himalayas in 1 d, typically climbing between 4,000 and 6,000 m in 7-8 h. Surprisingly, these birds do not rely on the assistance of upslope tailwinds that usually occur during the day and can support minimum climb rates of 0.8-2.2 km·h −1 , even in the relative stillness of the night. They appear to strategically avoid higher speed winds during the afternoon, thus maximizing safety and control during flight. It would seem, therefore, that bar-headed geese are capable of sustained climbing flight over the passes of the Himalaya under their own aerobic power.exercise physiology | high altitude | satellite tracking | vertebrate migration | climbing flight M ountains and high plateaus present formidable obstacles to the migratory flights of a number of bird species. Large birds, such as cranes and geese, may find such barriers particularly challenging as the sustained climbing rates of birds scale negatively with increasing body mass (1). For example, brent geese (Branta bernicla) are unable to sustain climbing flights over the Greenland icecap (summit elevation 3,207 m, mean elevation >2,000 m) and make regular stops to recover, possibly from partly anaerobic flights (2). Nevertheless, populations of bar-headed geese (Anser indicus) that spend the winter at sea level in India and the summer in central Asia must perform the world's steepest migratory flight north over the highest mountain range on earth, the Himalaya (3). There, most passes are at altitudes greater than 5,000 m, where the air density and partial pressure of oxygen are only about half of those at sea level. As a consequence, the partial pressure of oxygen (PO 2 ) in the arterial blood may begin to limit maximum performance (4, 5), although negative effects on the rate of oxygen diffusion may be partially ameliorated by an increase in the gas diffusion coefficient (6). The thinner air at these higher altitudes will also reduce lift generation during flapping flight for any given air speed, thus increasing the energy costs of flying by around 30% (7,8).However, bar-headed geese have adapted in a variety of ways for living and flying at high altitudes (4, 5). Their skeletal and cardiac muscles are better supplied with oxygen, having greater capillary density, more homogenous capillary spacing, a higher proportion of mitochondria in a subsarcolemmal location, and a greater proportion of oxidative fibers than other waterfowl (9, 10). Bar-headed goose hemoglobin is also highly effective at oxygen loading (11), compared with many other bird species, largel...

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Section: Resultsmentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

See 1 more Smart Citation

The trans-Himalayan flights of bar-headed geese ( Anser indicus )

Hawkes

Balachandran

Batbayar

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

143

125

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“…Wind roses based on all data illustrate the temporal evolution of up-and down-valley flows at JSM_2 for each season ( is similar to that at other high elevation sites during non-monsoonal periods (Hindman et al, 2002;Hegde et al, 2007;. In contrast, O3 mixing ratios exhibited a distinct minimum in the early morning, increased during the morning, peaked in the early afternoon well before that of BC, and decreased overnight (Fig.…”

Section: Evolution Of the Local Wind System In The Kgvsupporting

confidence: 62%

Transport and Distribution of Short-lived Climate Pollutants in the Himalaya

Dhungel¹

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Major combustion sources in the Indo-Gangetic Plain (IGP) of southern Asia form persistent haze layers, also known as atmospheric brown clouds (ABC), from December through early June. ABC is a mixture of high concentrations of reactive trace gases and lightabsorbing and light-scattering particles like black carbon (BC) and ozone (O3) precursors. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, there is a lack of observational evidence to elucidate Himalayan valleys as major pollutant pathways. To evaluate the pathway of pollutants from IGP to higher Himalaya, I measured BC, O3, and associated meteorological conditions within the Kali-Gandaki Valley (KGV), Nepal, from January 2013 to July 2015. High concentrations of BC and O3 were observed during pre-monsoon (March-June) and post-monsoon (September-February) seasons. Frequent episodes of BC concentrations two to three fold higher than average persisted from several days to a week during non-monsoon months. Observation of increases in BC concentration and fluxes in the valley were found during pre-and post-monsoon seasons and in conjunction with widespread agricultural burning and wildfires over the IGP.In addition to surface sources, tropospheric O3 can also be transported from the stratosphere that contributes significantly to background concentrations. Tropospheric O3 modulates the atmospheric lifetime of many atmospheric gases and like BC influences climate via direct and indirect radiative forcing. I collected ozonesonde data from Pokhara, Nepal in winter (December 2015 -January 2016) focusing on the distribution and sources of tropospheric O3 in the Himalayan region. Stratospheric influence was inferred when tropospheric air masses had potential vorticity (PV) above 1.5 PVU, relative humidity (RH) under 20% and potential temperature (theta) above 320 K. I found that the ozonesondes that stayed south of the Himalaya measured higher O3 concentrations between 3 and 10 km and ozonesondes launched during high PV period were 10-20 ppbv higher between 9 and 13 km. I also found that the topography and surface temperature induced a consistent thermal structure over the Tibetan plateau. When the jet was positioned south of the thermal gradient, high O3 concentrations were observed above 8 km. Higher O3 concentrations were detected when the jet stream had high wind speeds (above 60 ms -1 ) and during periods of high PV given the location of the SJS was south of the thermal gradient. Layers of diffused air masses were frequently detected with PV values showing both stratospheric and tropospheric origin. This dissertation supports the hypothesis that trans-Himalayan valleys are important conduits for transport of pollutants from the IGP to TP and provides insight, for the first time, on the vertical concentrations O3 adjacent to Himalaya using MERRA-2 as a tool to understand the role of SJS and the influence of stratosph...

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“…For studies aiming to investigate the influences on regional climate change, water resources and glacier retreat by polluted aerosols from south Asia, considerable attention has been focused on the south slope of the TP (Hindman and Upadhyay, 2002;Ramanathan et al, 2007;Bonasoni et al, 2008Bonasoni et al, , 2010Decesari et al, 2010). However, these studies have not given substantial attention to the southeast TP.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Variation, Sources and Transport of Aerosols at Lijiang, Southeast Tibetan Plateau

Cao

Huang

et al. 2016

Aerosol Air Qual. Res.

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Aerosol samples were collected during pre-monsoon, monsoon and post-monsoon periods in 2009 in Lijiang, a tourism city located on the southeast Tibetan Plateau, southwest China. To determine the seasonal variation and sources of aerosol species, main elements and water soluble ions were analyzed. The results showed that crustal elements (Si, K, Ca, Ti and Fe) were the main elements with an enrichment whose enrichment factor (EF) value were lower than 10, with the large value (except Ca) occurring during the pre-monsoon period. The EF values of S, Cl, Zn, As, Br, Sb, Pb, and Cu were higher than those of the crustal elements and the large concentration appeared during the monsoon period. Ca 2+ and SO 4 2-were the dominant cation and anion, respectively. The greatest value of total ionic concentration was found during the monsoon period, mainly because of the high concentration of SO 4 2-and NH 4 + . Using the positive matrix factorization model, it was found that the main sources of species were from crustal source, transport from south Asia and eastern China, local vehicle emissions and sea salt. Further results indicated that the pollutants mixed with dust, anthropogenic pollutants and biomass burning emissions can be transported to Lijiang from south Asia and Southeast Asia during the premonsoon period. In addition, pollutants rich in SO 4 2-and heavy metal from the Sichuan Basin and eastern Yunnan Province can also be occasionally transported to Lijiang during the monsoon period. The seasonal differences in chemical composition and transportation pathway may have important implications for regional climate change.

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Air pollution transport in the Himalayas of Nepal and Tibet during the 1995–1996 dry season

Cited by 84 publications

References 15 publications

The trans-Himalayan flights of bar-headed geese ( Anser indicus )

The trans-Himalayan flights of bar-headed geese ( Anser indicus )

Transport and Distribution of Short-lived Climate Pollutants in the Himalaya

Seasonal Variation, Sources and Transport of Aerosols at Lijiang, Southeast Tibetan Plateau

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