For the period February 14 to 28th, 1975, the second phase of the Airmass Transformation Experiments (AMTEX) over Southwest Islands of Japan, heat and moisture budgets have been estimated. Three different case studies (average for the whole period, average for the undisturbed period, and average for the disturbed period) have been carried-out over a square area.
For the period as a whole, on the average there is an inversion layer around 800mb and the downward motion (ω-positive) is maximum near that level. The apparent moisture source is also maximum near that level. Through there is no apparent heat sink, heat source of the large-scale motion system is minimum near that level. In the disturbed case, when the area was under the influence of warm southerlies, there is a depression to the north of the area, and there is no inversion. There is no significant apparent moisture source, but there is a significant apparent moisture sink around 750mb. The apparent heat source is also near 750mb with a maximum upward motion (ω-negative). The undisturbed period is characterized by the cold northerly winds. Just like in general case, in this case also there is an apparent moisture source near 800mb, the lower inversion level.
For a similar study of AMTEX '74, Nitta (1976) used a low-pass filter to remove short period fluctuations less than a day. For determining the height (Pt), at which the transportation of heat flux due to convective clouds vanishes, he used the vertical thermal structure of individual observations and computed the cloud tops. From that he evaluated the area averaged Pt. In the present study, no filter has been used. Further, the total heat transports by eddies are assumed to be confined below the inversion base and so Pt has been taken as the base of the inversion layer. In the case of no-inversion, the layer of minimum lapse-rate is assumed to limit the vertical heat transport.
The average total heat supply from the sea surface (873ly day-1) is in general agreement with that estimated by the bulk aerodynamic method independently. While it is only 140ly per day in the case of disturbed situation, it is as high as 1200ly per day during the period of cold air out-break, similar to that estimated by Ninomiya (1968).
For the general as well as the other two cases, sensible heat and Bowen's ratio have also been computed.
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