Contribution to a comparative meteorology of n10untain areas

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60 HERMANN FLOHNheat ofconstant pressure, p is density, T is temperature, V is horizontal wind vector, andz is the vertical coordinate.The heat of condensation liberated by precipitation (L' P) is, even with moderateamounts of precipitation (10 mm:::: 600 Ly), larger than the flux of sensible heat U L •However, this energy is first used with heat storage LlW to maintain the moist-adiabaticlapse rate. Only what is then left over is available for heat advection (divergence termc p pTV). We now know that this heat source in the humid, tropical mountains, along withthe orographically triggered rains, plays a very important role in the tropical circulation.In addition to the classical Hadley circulation in a meridional plane, we have the conceptofa zonal (Walker) circulation (Bjerknes, 1969) whose interaction is only partly explained(Flohn, 1971).The radiation and heat balance terms which occur in these fundamental equations oftheoretical climatology (or 'climatonomy': Lettau, 1967) can be formulated as nondimensionalbasic parameters."IiIRadiation: surface albedo a. -~ (short-wave)-S+HAngstrom ratio A = Et ĒfGt (long-wave)Rotplanetary albedo a p (short-wave)= SotU LHeat budget: Bowen ratio Bo (U = turbulent heat fluxes)= U vBudyko ratio Bu =~ (aridity index)L·PNWater budget: runoff ratio RR = - (N = runoff)P..,VDynamics: surface Rossby no. RO$ (zo = roughness parameter)= Zoethermal Rossby no. ROTV.T=rtJ(V.T = thermal zonal wind)Thus on the basis of measurements of the radiation and heat balances at surface in thePamirs (Aisenshtat, 1966) and the radiation flux at the upper boundary of the atmosphere,as measured by satellites (Raschke and Bandeen, 1970), we can estimate the heatbudget ofthe atmosphere (Qum) forsummerin an air column over the Tibetan highlands.In contrast to the estimates made by Gutman and Schwerdtfeger (1965) in the Altiplano(Peru-Bolivia) in which the advection was calculated from data from only one aerologicalstation, the total advection is here evaluated under stationary conditions (LlW = 0)since it is estimated as the residual of the area-averaged heat balance.
A COMPARATIVE METEOROLOGY OF MOUNTAIN AREAS 61Radiation budgetsurface (July):Heat budget (July):extraterrestrialatmosphere= 320 ly day-I (Aisenshtat)= ggo ly day-l a p 0.32 (Raschke)675 ly day-I = 545 ly day-I (Raschke) = 675 - 545 = 130 ly day-l Qo-Q, 130 -320 =-lgolyday-l= 150 ly day-l (arid 250 ly day-I, humid50 ly day-I) (Aisenshtat)obs. precipitationheat storageexport of heatPL·PAW= 120 mm month- I = 4 mm day-I= 240 ly day-l= 0When we combine the important terms for the troposphere in Tibet (considering alayer between 580 and 100 mb 480 mb or g cm- 2 ) and calculate an equivalent temperaturechange, we find a cooling due to a negative net radiation of 190 ly day-Iequivalent to -1.6S o C day-J and a heating due to the flux ofsensible heat from the groundand the latent heat released by precipitation of 390 ly day-lor +3.4"C day-I. Thus theadvective heat export results in a net cooling of 200 ly day-lor -1.74°C day-I, For thiscalculation a minimum value was used for precipitation, namely the average for the006007008009003o· 120'E..,eo' '2d'wAttontic: N A'(ico S W Atlo Tlbtt Japan P ocifi:c USAFig. 2B.2. Zonal cross-section of temperature COG; deviations from latitudinal average) along32°N in July.
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