沿西藏高原東部地方氣壓年變化調和分析首二項之比較

奥國故大氣象學家J.Hann所作關於氣壓年變化與日變化之研究最豐,且多偏愛於應用傅立葉級數Fourier Series。惟彼曾稱謂:‘吾避免應用Bessel氏式於氣壓年變化,顯然由於將氣壓年變化之以週期函數表示,實無功用可言。’(1)彼意謂氣壓年變化並非簡單,勢須甚多之過期項數始能合成一近似之年變化。然近年之研究,如F.Reuter(2)氏之應用數種進步底統計方法,證明確有半年氣壓週期之存在,且與大氣循環有關。V.Conrad氏(3)將Alps山三十一處所之氣壓年變化用傅立葉級數作調和分析,以研究其首二項與高度之關係,曾得如下之結論:(1)一年週期(卽第一項)之變幅(Amplitude)隨高度而增大,

ON THE HARMONIC CONSTANTS OF ANNUAL PRESSURE VARIATIONS AT 13 PLACES ALONG EAST TIBETAN PLATEAU

Harmonic Constants of the first two terms are calculated, as embodied in Table I. a, values (like the unperiodic annual amplitutes) decrease with height in the first 2.5 km.-opposite to the Alps condition (Courad, 1938). A_1 values increase with height, though the curve is quite different from the Alps condition (vide Fig. 1 & 2) The reason for this contrast in the lowest 2.5 km. is due to the fact that annual pressure change in China is solely controlled by monsoonal reverse, while in Alps region the condi...