Field campaigns in the Rongbuk valley on the northern slope of Mt. Qomolangma found that surface flows in the valley exhibit strong diurnal variations, but differ much from other valley wind systems: Valley winds are less than 2 m times s super(-1) from early morning to noon, while strong southerly winds from the direction of Mt. Qomolangma prevail from noon to mid-night. The distinctive feature of valley winds in the Rongbuk valley might be attributable to joint impacts of wind systems such as mountain-valley winds, katabatic winds and slope winds associated with complex topography and landuse on the northern slope of Mt. Qomolangma. In this paper a comprehensive mesoscale meteorological model is applied to simulate typical valley wind systems in the Rongbuk valley to investigate primary factors controlling the diurnal variations in surface valley winds, and model results are compared against in-situ observations.
The land surface over Mt. Qomolangma area is very heterogeneous. There are glacier, snow mountains, grassland, exposed mountains and Gobi desert etc. over this area. It is a very difficult issue to determine the regional land surface heat fluxes for the researchers for many years. In this study, a parameterization methodology based on satellite remote sensing data and field observations has been proposed for the determination of the regional distribution of surface parameters (surface reflectance and surface temperature), vegetation index (Normalized Difference Vegetation IndexNDVI, Modified Soil Adjusted Vegetation IndexMSAVI, vegetation fractional cover P sub(v) and Leaf Area IndexLAI) and land surface heat fluxes (net radiation fluxes, soil heat fluxes, sensible heat flux and latent heat flux). The advantage and the shortcoming of the methodology were also discussed.
Using the Planet Boundary Layer (PBL) observation data from September 2005 to August 2006, the characteristics of micrometeorological and soil were primarily analyzed on Mt. Qomolangma area. The results show that there was different monthly variation of micrometeorological and soil ones from other place on the Tibetan Plateau. The air temperature was lowest on December, while was highest on July. The soil freeze time was shorter on Mt. Qomolangma area than that on northern Tibetan Plateau.
The energy/matter exchange between the surface air and the troposphere is the important connection of the Tibetan Plateau and the global atmospheric systems. The great imhomogeneity in the topography and surface cover of the Tibetan mountain systems induces complicated local atmospheric circulations, and the circulations influence the exchange processes between the surface air and the troposphere over these regions. To better understand the local circulations in the Tibetan mountains, authors conducted the observational campaign HEST2006, in the Rongbuk Valley on the northern slope of Mt. Qomolangma, during May 29 and June 30, 2006. In this study, the diurnal atmospheric circulation is analyzed, using the observed data, including the distribution and variation of surface wind, the vertical structure, the vertical motion, and the possible driving forces. It results in that the local circulation in this region is driven by the solar radiative heating and cooling with strong impacts of the topography and surface
The feature of East Asian summer precipitation pattern is an important character of Asian summer monsoon. Using the NCEP/NCAR reanalysis data and CRU precipitation data, this study reveals the effect of the Tibetan Plateau (TP) heating on the East Asian summer rainfall. Result shows the close correspondence between TP diabatic heating and East Asian simmer rainfall pattern. The TP heating fluctuation is associated with a Rossby wavelike circulation pattern on the coast area of East Asia. The Rossby wavelike pattern in turn affects and modifies the Northwest Pacific anticyclone, the result causes the variation of East Asian rainfall pattern. Because of the persistent TP diabatic heating from spring to summer and its effect on the surrounding areas, the TP heating index defined in this study can be used as a good predictor for the summer East Asian precipitation distribution. In this work, evidences shown the SST is not an only dominate external condition but also to consider other factor for understanding Asia
Date of the LAP3000 Wind Profiler set in the Rongbuk Valley on the northern slope of Mt. Qomolangma in June 2006 are analyzed to estimate the volume (or mass) flux in the valley cross section. Volume fluxes of the strong wind periods (9 similar to 21 June), weak wind periods (22 similar to 30 June) and the averaged periods of June (l similar to 30 June) are calculated respectively. The results show that the diurnal averaged volume flux of the 3 periods are different, i. e., the averaged total volume flux in the valley are positive all the time both in June and strong wind period, while in the weak wind period, it has a small negative value in the morning. Generally speaking, the volume flux of the predominating complex katabatic flow in the valley is very large. For example, the averaged daily total volume flux in June is 6.3x10 super(11) m super(3), what more, the averaged daily total volume flux is much less in the weak wind period than in the strong wind period, and the former is about 53% of the latter.
Based on the open-path eddy covariance observation over an alpine meadow ecosystem during growing season (from May to July, October & November in 2005) and non-growing season (February & March in 2006) at Quzong station (30 degree 46'N, 90 degree 59'E, 4730 m a. s. l) which is located on the northern side of the Qomolangma, the diurnal and seasonal variations of the carbon dioxide flux are analyzed in this paper. CO sub(2) flux dynamics was distinct between the two seasons. During the growing season the negative CO sub(2) (CO sub(2) uptake) flux was observed from 08:00 to 19:00, but positive CO sub(2) flux (net CO sub(2) emission) from 20:00 to 09:00. In June, the maximum CO sub(2) uptake velocity was 0.61 g times m super(-2) times h super(-1) which appeared at 11:00. In July, this value reached 0.86 g times m super(-2) times h super(-1) which appeared at 14:00. The total monthly influx in June and July was 70 g times CO sub(2) times m super(-2), 104 g times CO sub(2) times m super(-2), respectively. The net
On the basis of the existing ripe remote sensing parameterization scheme of land surface energy fluxes, this study tries mapping the spatial distribution of autumn land surface fluxes over the vast southern Tibetan Plateau encompassing the Qomolangma region by combining MODIS data with the gradient data of surface layer atmosphere observed in the Qomolangma region from September to October of 2006. The result reveals that the land surface net radiation has a maximum value of 420.0 W lambda m super(-2) or so, mainly in the range from 200.0 to 620.0 W times m super(-2); the soil heat flux has a peak value of 110.0 W times m super(-2) or so, mainly in the range from 50.0 to 180.0 W times m super(-2); the sensible heat flux has a maximum value of 270.0 W times m super(-2) or so, mainly in the range from 120.0 to 280.0 W times m super(-2); and the latent heat flux has a peak value of 90.0 W times m super(-2) or so, mainly in the range from 0.0 to 250.0 W times m super(-2). Thus it is concluded that Autumn of in po
To study the atmospheric circulations in the Himalayas, Institute of Atmospheric Physics and Institute of Tibetan Plateau Research, Chinese Academy of Sciences, held HEST2007 experiment in 2007. after the HEST2006 in 2006. This study is to analyze the diurnal and day-to-day variations of the local circulations in the. Himalayas, observed by LAP3000 wind-profiler system in the Rongbuk Valley on the northern slope of Mt. Qomolangma. The study shows the close relation between the axial winds in the valley and the west wind circulation. This relation can be attributed to the impacts of surface radiation situation changes caused by the synoptic system changes on the local circulation.
Chemical composition of atmospheric aerosols at Lijiang, Yunnan Province, China was monitored and analyzed. The results show that crustal elements such as Mg, Al, Ca, Si, K, Fe are the main composition of atmospheric aerosols at Lijiang and account for 82% of the total 20 elements' concentration. Concentrations of Pb, Se, Br in atmospheric aerosol at Lijiang are much higher than that over Mount Qomolangma Region. Enrichment factors of S, As, Se, Br, Pb in atmospheric aerosol at Lijiang which have close relation to human activity are very high. These results indicate that the impact of human activity at Lijiang are obvious and could not be neglected.
Mount Qomolangma is a typical area with special land-surface atmosphere interaction over Tibetan Plateau, due to its high elevation and complicated terrain. The process can be better understood by observing the interaction itself and analyzing the variation of atmospheric elements and turbulent fluxes. Based on the turbulent data obtained in Rongbuk valley on northern slop of Mount Qomolangma during June 2006 and June 2007, the diurnal variation of micrometeorological elements and turbulent fluxes are investigated by using eddy covariance method. Results show that the diurnal cycles of micrometeorological elements and turbulent fluxes, such as wind, temperature, humility, sensible heat flux, latent heat flux etc., are evident. Glacier wind blowing from noon to midnight are observed in this area. They play an important role in the mass and energy exchanges in the land-surface process of Rongbuk valley.
The mountains of Himalayas are the important channels for the mass exchange between surface layer of Northern Hemisphere and troposphere atmosphere. The mountains relate surface layer atmosphere over the Tibetan Plateau and the above free atmosphere through many atmospheric circulation - systems including mountain-valley wind and glacier wind etc. Mt. Qomolangma is the highest peak in the world, and its nearby region is a representative case of mountains of Himalayas. Firstly the back ground of the establishment of the Atmospheric and Environmental Comprehensive Observation and Research Station on Mt. Qomolangma, Chinese Academy of Sciences (AECORSQ, CAS) and the role of the station in the study of the atmosphere-land interaction over Himalayas area was introduced in this paper. Then the preliminary observational analysis results, such as the characteristics of air temperature, pressure, air humidity, wind speed and wind direction, the structure of the Atmospheric Boundary Layer (ABL), the atmospheric turbule
The Regional Atmospheric Modeling System (RAMS) was used to simulate the atmospheric boundary layer structure over Rongbuk valley of Mt. Qomolangma from 6 to 12 June 2006, and the simulated results agree well with the observations obtained by LAP3000 of the same period. The result shows that the local circulation has obvious diurnal variations on Rongbuk valley, the mountain wind dominates from noon to midnight, lasting almost 12 hours a day with strong wind velocity, and the mountain wind s vertical thickness is up to 400 similar to 700 m during the period of mountain wind dominating. The along-valley temperature gradient induced by heterogeneous land surface produces the local circulation. RAMS can reveal the temporal and spatial distributions of the local circulation over the Rongbuk valley.
Using the observed data on an Atmospheric Boundary Layer (ABL) Tower located in the Atmospheric and Environmental Comprehensive Observation and Research Station on Mt. Qomolangma, Chinese Academy of Sciences (AECORSQ, CAS), in a Himalayan valley near Mt. Qomolangma; during dry season, the characteristics of the diurnal variations in wind, air temperature, and humidity on 28 May 2006 are analyzed. The influence of slope wind and glacier wind on local circulation is found. The strong glacier wind occurs at afternoon, which brings temperature decrease. It can help understand that the air temperature reaches maximum when glacier wind occurs. The glacier wind also has influence on variation of air humidity.
The Qinghai-Xizang Plateau and its unique dynamic thermal effect influences the East Asian region as well as global weather, climate and environmental change process. Steep terrain and diverse state of the surface cause the complex circulation system and the boundary layer characteristics. During May 28 to June 30, 2007, the Institute of Atmospheric Physics and the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences organized and implied the tropospheric atmosphere exchange research (HEST2007) on North Slope region in the Himalayas surface observation experiments to Study the local atmosphere circulation system of the mountains on the Qinghai-Xizang Plateau. In this Study, the virtual temperature obtained from LAP3000 is converted to temperature, by using other observed data, and the vertical distribution of temperature and its changes are preliminary analyzed. The analysis shows the obvious differences is existed between the virtual temperature and the real temperature, the differences
There is a cross place between the Himalayas with a west-east direction and Hengduan Mountains with a north-south directions in which the Yarlung Zangbo River, Nu River and Lang Chang River are moving through it on the southeast part of the Tibet Plateau. As there is a special topography conditions, both of the mountain blocking and moisture passage effects on the distribution of precipitation, climatic and natural zones are obvious. The mountain blocking effects resist the warm and humid stream to make the great difference of the precipitation, climatic and natural zones between the two sides of the mountains. Meanwhile, both of the mountain blocking and moisture passage effects form the special distribution of precipitation, climatic and natural zones in this region, which make a great natural contribution for mankind of forming an ideal heaven.
Using the data of Atmospheric Boundary Layer (ABL) tower, radio sonde and wind profiler set up on the Comprehensive Observation and Research Station of Qomolangma, Chinese Academy of Sciences, lower layer atmosphere characteristics (wind speed, wind direction, air temperature, potential temperature and air humidity etc.) during the rain season were analyzed in this paper. Wind speed, wind direction and temperature near surface have obvious diurnal variations. For the wind direction, it is divided into two phase, one blow nearly north wind derived by Valley wind, the other blow nearly south wind derived by Glacier wind. The change time is 14:30. The diurnal Glacier wind is stronger than the nightly valley wind. Maybe vertical shear of horizontal wind is one important reason for precipitation in this region. The low leveLjet is familiar during summer. Averaged temperature digression of troposphere is 0. 685K/100m. The.vapor content in the air of lower atmosphere has two peak, the maximal vapor content height is
The Himalayas is near the South Asian monsoon region, with a special local circulation system induced by its steep topography and complex terrains. For better understanding the circulation system and its possible relationship with the weather pattern over the South Asian regions, we analyzed the variation of surface wind in the Rongbuk valley on the northern slope of Mt. Qomolangma and its responses to the South Asian summer monsoon (SASM), using the observation data obtained during HEST2006 campaign in June 2006 and real-time atmospheric circulation data. During the weak SASM period, the Himalayan regions are mainly dominated by clear days, and the northward surface wind prevails in the Rongbuk valley with a strong solar radiation; while during the strong SASM period, the surface wind and the solar radiation in the Rongbuk valley becomes weak, and the Himalayan regions are mainly controlled by the cloudy and rainy weather conditions. The analyszd result showed that the local circulation in the Rongbuk valley
The strong southerly valley winds prevail in the Rongbuk Valley on the northern slope of Mt. Qomolangma from noon to mid-night, which is different from diurnal mountain-valley wind in other mountains. In this paper, we use RAMS model to simulate the local wind in Rongbuk Valley, and the control experiment shows that RAMS can reproduce the strong predominating southerly wind in the Rongbuk Valley. To study the effects of glacier/snow cover on the local wind, we run a removing glacier/snow cover numerical simulation. The sensitivity experiment shows even though the glacier/snow vegetation has been substituted with bare ground, southerly wind can still develop in the valley from late afternoon (17:00 BJT). So glacier/snow cover play a very important role in the local wind in Rongbuk Valley, and ' thermally driven valley wind in the south slope of Mt. Qomolangma is the main factor to maintain the southerly wind in Rongbuk Valley from late afternoon to night.
It is very important to study the regional heat fluxes in Mt. Qomolangma area. Using the data of Mt. Qomolangma site, the land surface heat fluxes are analyzed. Those are the net radiation flux (R sub(n)), sensible heat fluxes (H), latent heat fluxes ( lambda E) and soil heat fluxes (G sub(0)). Some new results are gotten about surface energy fluxes in Mt. Qomolangma Area. The annual variations of downward short wave radiation, downward long wave radiation, upward short wave radiation, and net radiation were very obvious. The daily variations of net radiation flux, sensible heat flux, latent heat flux and soil heat flux were also obvious. Finally few ways of calculating surface heat fluxes are talked.