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Horinouchi, T., 2014: Influence of upper tropospheric disturbances on the synoptic variability of precipitation and moisture transport over summertime East Asia and the northwestern Pacific. J. Meteor. Soc. Japan, 92, 519-541.
https://doi.org/10.2151/jmsj.2014-602

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Highlights:

• By using satellite precipitation and reanalysis data, a clear relationship is found between upper tropospheric isentropic potential vorticity (PV) disturbances, surface precipitation, and lower tropospheric humidity through July and August from the eastern coastal region of China to the northwestern Pacific (Fig. 1); a precipitation band of several hundred kilometers wide and a thousand to several thousand kilometers long is formed frequently on the equatorward and low-PV side of the northernmost 1.5 PVU contours at 350 K (∼ 200 hPa).
• A thorough analysis reveals that this vertical association is due the downward forcing from the upper tropospheric Rossby waves; they exert positive forcing to low-level potential enstrophy, induce secondary circulation to initiate precipitation, and affect low-level moisture transport (Fig. 2).
• This study proposes a novel way to diagnose vertical interaction based on the quasi-geostrophic (QG) potential enstrophy defined using the QG PV in which boundary contributions are incorporated.