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are of deep concern. Ecosystem conservation in mountain is also important for the tourism industry in alpine countries. The knowledge of local EWC modification is important for understanding and predicting quantitatively the surface of hydro-meteorological elements in high altitude areas (Viviroli et al., 2007; Viviroli and Weingartner, 2004). 2.4.3 Transportation processes of water-vapour/energy Most water vapour remains in the warm low-level troposphere. Mountain-valley circulation has been identified as an important function in accumulating WV over mountains (Kimura and Kuwagata, 1995), but sub-continental scale transport WV, air pollution and aerosols from lowlands to high elevations is still unclear. Recently, possible mechanisms of aerosol effects on the activity of Indian monsoon have been proposed (Meehl et al., 2008), stressing the importance of plateau-plain circulation processes and latitudinal temperature gradient changes. Chemical reactions between the dry gases/aerosols and wet convections are another complicated mechanism. Given the complexity of such mechanisms, multiple steps must be considered. First, it is necessary to understand the 3D structure of mixing layer development over the lowlands with horizontal upslope circulation in the daytime and gravity currents with stable inversion layer at nighttime. Secondly, attention must be addressed to the development of vertical deep moist convections, which give rise to precipitation systems and their propagation. The convection breaks the dry mixing layers and washout the atmospheric materials. Thirdly, such diurnal modes are strongly modified by intraseasonal variability or the seasonal progress of upper general flows with the changing land-surface conditions. Numerical simulations with multiple nesting and back-trajectory analysis are useful tools for diagnosing the key factors in the multiple steps. In simulations data analyses are used to define the boundary conditions on large environment scale, even if the accuracy of data close to massive topography is always difficult. Since isotopic concentration in water vapour and consequent precipitation are sensitive to condensation and evaporation processes during circulation, isotopes can be used to verify the numerical simulations and back-trajectory analyses (e.g., Yoshimura et al., 2003), leading to an accurate estimation of the evaporative source of water vapour (Yoshimura et al., 2004). The longterm range of annual and seasonal variability in atmospheric aerosols (natural and anthropic) can be recovered from high elevation ice cores (Kand, et al, 2001; Kreutz, et al., 2002; Aizen, et al., 2008). Cross-cutting study works with monsoon and aerosol CEOP’s groups are strongly recommended to attain further understanding from different points of view, as well as collaboration with the Stable Water Isotope Intercomparison Group (SWING) Project for isotope Global Climate Models (GCM). 2.4.4 Influences of mountains on extreme weather, water resources and sub-continental scale climate changes It is well known that regional climates are strongly influenced by topography. Continental scale mountain ranges especially produce drastic changes in climate distribution with an unbalance of surface water availability over the continent. For instance around the TP, abundant precipitation in the south causes frequent landslides and flooding that fertilize the lands, while the extreme dry climate of the north induces desertification, so that human life is reliant on underground water supplied by the plateau. Interactions between the terrain and induced mesoscale circulations or between the terrain and general flows, such as low-level monsoon flows, cause stagnant precipitation in the lands around mountains (Barros and Lang, 2003). Extreme weathers, such as heavy rains and cold waves in southern China, are also influenced by thermo-dynamic effects in the lee of the plateau (e.g. Tao and Ding, 1981, Murakami, 1981). Numerical models suggest that rising temperatures over TP may lead to increasing summer frontal rainfall in East Asia (Wang et al., 2008). It is of concern that, while sub-continental scale climate variability is expected to determine benefits and damage to the human life, their physical mechanisms and ranges have not been fully diagnosed in terms of mountain impact studies. Multiple data and studies carried out by numerical simulations are suitable to assure the up-scaling effects (Beniston et al., 2007b). Analysis of water and the lower troposphere by the CEOP-HE 10
infrastructure on the mountain and data transfer and assimilation techniques will improve forecasting of extreme weather down stream. Over longer-timescales, the cryosphere changes at high elevations, such as retreating glaciers and outburst flooding, are already known. Changes of precipitation type from solid to liquid influences the downstream runoff in the semi-arid lowlands by altering glacier mass-balance (Aizen et al., 1997). Impacts of changing water resources on irrigation for agriculture needs to be predicted with availability of waters at high elevations (López-Moreno et al., 2008). As one of the application component of CEOP-HE, assessment of the impact should be studied by comparing the different climate zones under continental scale EWC flows. 2.4.5 High elevations as cold regions Snow cover Seasonal snow contributes up to 60% of snowmelt runoff in non-glacial catchments (Aizen et al., 1996). Seasonal snow that covers mountain areas at different elevations for a period of one week to 12 months is the most important source of melt water in high elevated mountain areas. Over the mountains, energy used for snowmelt amounted to 30x1012 MJ yr -1 with a maximum from the end of spring to the middle of summer. The annual air volume cooled 5 o C by snowmelt amounted, on average, to 0.9x107 km 3 yr -1 . The heat loss from snowmelt in mountains amounted to about one third of heat loss in the plains, and air volume cooled by snowmelt in mountains amounted to about one half of air volume over plains. The difference in the proportions occurred as a result of lesser air thickness in mountains than over plains, which allowed the cooling of a larger air volume in mountains under the same amounts of heat losses. The process of snow ablation and atmospheric cooling in mountains due to snowmelt occurs more slowly and without the abrupt changes observed on the plains, and energy losses in mountains smooth the general process of atmospheric cooling prolonging it until the beginning of autumn (Aizen et al., 2000). The feedback of the spring and summer snow ablation can explain the long-term rise in air temperatures being more pronounced from early summer to August (Aizen et al., 1997), when maximum energy loss from snowmelt occurs over the mountainous areas. The study of seasonal snow cover extension and the energy spent during the snowmelt are important in the development of regional and global climatic models in the frame of the HE Program. Glaciers Glacier ice at high elevated mountain areas covers approximately 3% of the Earth’s total land surface, or 500,000 km 2 , and they store about 180,000 km 3 of world’s fresh water (Benn and Evans, 1998). Glacier melt water is particularly important when the lower courses flow through semi-arid and arid regions with high evaporation rates and high demands for irrigation water during the vegetation period in many mid-latitude areas adjacent to mountain systems, such as the Alps and the mountains of central Asia and western China (Viviroli, 2007). A decrease in glacial and seasonal snow covered areas reduces these portions of water in total river runoff, increasing the proportion of precipitation runoff. Glaciers integrate climate variations over a wide range of timescales, making them natural sensors of climate variability and providing a visible expression of climate changes, preserving climatic signatures that can be used to reconstruct past climatic and environmental records though the chemical analyses of glacier deep ice-cores. Ice-coring research and paleo-climatic and environmental reconstruction would be a great asset to the HE Program. Changes in air temperature and moisture income may influence mountain regions differently at the macro- and meso-scale and even at the scale of small catchments For example, glaciers in the European Alps, South and North America are more vulnerable, and retreat faster than Tien Shan, Pamir or Tibetan glaciers due to their lower absolute elevations (Paul et al., 2004; Naftz et al., 2002; Francou et al., 2003). Glaciers of the high TP, Himalayas and central Asia may be more stable and may even advance (Bahadur and Naithani, 1999; Ageta et al., 2001; Fujita et al., 2001; Aizen et al., 2006a; Liu et al., 2006; Narama et al., 2006). There is much evidence that glaciers have been retreating globally since the mid-19th century, after the “Little Ice Age” (Adamenko and Subaev, 1977; Mayewski and Jeschke, 1979; Naftz et al., 1996; Thompson et al., 2003), and that glacier recession began to accelerate from the middle of 1970s in CEOP-HE 11
Page 1 and 2: January 2010
Page 3 and 4: Table of contents Executive summary
Page 5 and 6: Executive summary High Elevations (
Page 7 and 8: Foreword The main purpose of the HE
Page 9 and 10: central Asia and South America, bot
Page 11 and 12: account for approximately 20% of th
Page 13: dealing with the effects of mountai
Page 17 and 18: ut to a decrease in rainfall during
Page 19 and 20: monsoon season is very attractive f
Page 21 and 22: mountain environments occur when wi
Page 23 and 24: Changes with altitude are particula
Page 25 and 26: 3.2 HE network of observatories The
Page 27 and 28: Among the 52 sites, only four are l
Page 29 and 30: precipitation and windy weather nee
Page 31 and 32: egions. Monsoon HE would need infor
Page 33 and 34: investigate funding sources to main
Page 35 and 36: Research and Development, 10, 161-1
Page 37 and 38: Gorbunov A.P., S.S. Marchenko, E.V.
Page 39 and 40: Nesbitt, S.W., D.J. Gochis and T. L
Page 41 and 42: Yanai M. and G. Wu. 2006. Effects o
Page 43 and 44: IGBP Geosphere-Biosphere Programme
Page 45: HE Steering Committee Members Insti

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