热源强迫对大气长波调整的可能影响

为了研究热源强迫对大气长波调整的作用,利用考虑热源强迫和涡动耗散的β通道准地转正压位涡方程,通过数值计算的方法,揭示了热源强迫及热源强迫下基流和初始场对长波调整的可能影响。结果表明:除了非线性作用和基流的纬向非均匀性外,热源强迫也是长波调整的机制之一。在有热源强迫时,初始波动和热源强迫在纬向结构上的差异是长波出现调整的关键因子。强迫的纬向非均匀性有利于调整的出现,但调整对强迫的经向非均匀性不敏感。基流较大或较小时,都不利于调整现象的发生;而较大的基流切变能够加速调整的出现。热源强迫相同时,初始波动的振幅越小,流场演变越快,波动出现调整的时间就越早;当振幅取较大值时,则情况相反。

Possible impacts of thermal forcing on adjustment of atmospheric long-wave

To study the effect of thermal forcing on the adjustment of atmospheric long-wave, this paper adopted numerical calculation based β lane quasi-geostrophic potential vorticity equation with consideration of the external heat sources and eddy dissipation to reveal some possible impacts of thermal forcing and heated atmospheric components (including basic flow and initial wave condition) on the adjustment of long-wave. The result indicates that thermal forcing is another mechanism for the adjustment in addition to non-linear effects and zonal non-uniformity in basic flow. When thermal forcing exists, difference in zonal structures of the initial wave and heating is the key factor leading to the occurrence of the adjustment. The adjustment could be induced by the zonal non-uniform heating, but it is not sensitive to the meridional non-uniform heating. Long-wave has fewer tendencies to present adjustment when basic flow is strong or weak; however, adjustment occurs earlier as the shear in basic flow strengthens. The initial wave amplitude is also correlated with the adjustment. When influenced by the same thermal forcing, the smaller the initial wave amplitude is, the faster the flow field evolves, and the earlier the adjustment occurs. The situation is the opposite with larger amplitude.