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  • Author or Editor: ELMAR R. REITER x
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Elmar R. Reiter

Mountain ranges and high plateaus influence atmospheric circulation patterns on all scales, ranging from ultralong planetary waves to small turbulent eddies. Some of these effects are brought about simply by orographic obstacles acting as barriers to the flow. Of equal importance, however, are the thermal effects of elevated land masses, which can generate considerable baroclinicity. Various time scales have to be considered in the thermal forcing of the atmosphere by large elevated land masses. Diurnal variations of the heating and cooling cycle have been shown to be prominent factors over Tibet. On time scales from days to weeks, the Northern Hemisphere plateaus seem to influence the monsoon circulations. There are strong indications that interseasonal “memory” exists in the heat balance of plateaus that might affect seasonally abnormal monsoon behavior. Such “memory” could be caused by feedback between thermal effects of land masses and “near-resonant” planetary waves.

In order to assess the thermal impact of mountains and plateaus, we need considerably more detailed knowledge of the energy transfer processes between the valley atmosphere, the yet poorly delineated planetary boundary layer over mountains, and the “free atmosphere.” To achieve such knowledge, experimental and theoretical studies involving micro-, meso-, and macroscales will have to intermesh more closely than in the past.

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R. Elmar and Gabriella J. Reiter

From 2 to 14 June 1980 the authors participated in an excursion by jeep across Tibet, following the road from Lhasa via Gyangze, Xigaze, Tingri, and Nyalam to Zham on the Nepal border. The excursion was organized by the Academia Sinica, with direct support by Vice-Chairman and Vice-Premier Deng Xiaoping and Vice-Premier Feng Yi, and relied on the excellent logistic support of the Chinese People's Liberation Army. This report gives an account of impressions, including those of local and regional meteorological and climatological problems.

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Elmar R. Reiter, H. Gote Ostlund, and William F. Marlow
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Elmar R. Reiter, J. D. Sheaffer, J. E. Bossert, Eric A. Smith, Greg Stone, Robert McBeth, and Qinglin Zheng

A long-planned field-measurement program to determine surface-energy budgets at two sites in Tibet was carried out during June 1986 in collaboration with scientists from the State Meteorological Administration, Academy of Meteorological Sciences, People's Republic of China. The data set obtained in Tibet is unique for this remote region of the world. The present report describes some of the experiences of the United States scientific team and its medical officer, M. Otteman of Ft. Collins, Colorado. The data are presently being archived on computer tapes. Preliminary analysis results are presented as typical examples of the conditions encountered at the two experimental sites near Lhasa (3635 m) and Nagqu (4500 m).

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Elmar R. Reiter, John D. Sheaffer, James E. Bossert, Richard C. Fleming, William E. Clements, J. T. Lee, Sumner Barr, John A. Archuleta, and Donald E. Hoard

During the late summer of 1985 a field experiment was conducted to investigate mountaintop winds over a broad area of the Rocky Mountains extending from south central Wyoming through northern New Mexico. The principal motivation for this experiment was to further investigate an unexpectedly strong and potentially important wind cycle observed at mountaintop in north central Colorado during August 1984. These winds frequently exhibited nocturnal maxima of 20 to 30 m · s−1 from southeasterly directions and often persisted for eight to ten hours. It appears that these winds originate as outflow from intense mesoscale convective systems that form daily over highland areas along the Continental Divide. However, details of the spatial extent and variability of these winds could not be determined from “routine” regional weather data that are mostly collected in valleys. Although synoptic conditions during much of the 1985 experiment period did not favor diurnally recurring convection over the study area, sufficient data were obtained to verify the regional-scale organization of strong convective outflow at mountaintop elevations. In addition, the usefulness and feasibility of a mountain-peak weather-data network for routine synoptic analysis is demonstrated.

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