School of Marine and Atmospheric Sciences

Persistent Maxima of 500-hPa Geopotential Height (PMZ)

This page updates the persistent maxima of 500-hPa geopotential height (PMZ) over (15oN-75oN, 170oE-310oE) every day for research purpose. The predictions of the PMZ by GEFS ensemble mean are experimental and made available in collaboration with the Climate Prediction Center (CPC) and the Environmental Modeling Center (EMC) of NCEP/NOAA.

About PMZ

A PMZ event is identified and tracked using eddy field of daily (avearge of 06, 12, 18, and 24Z UTC) 500-hPa geopotential height. The event can be open ridges, blocking episodes, or both persistent longer than one day. A paper to be provided will describe the tracking algorithm in detail.

PMZ Distribution

The 500-hPa geopotential height is retrieved from NOAA GDAS analysis and GEFS predictions (Figs. 1 and 2; up to 00Z for the analysis and 16-day predictions from then), and the NCEP-NCAR Reanalysis Project (Fig. 3; 2-day lag without predictions for comparison purpose). Shown below are the PMZ centers (red square for the most recent day and black for its predecessors) and their current impact areas (shading in blue) during recent 11 days to 00Z . Open diamonds are for the predicted PMZ centers starting from today by the GEFS forecasts (ensemble mean of 20 members).

PMZ plot coming soon.

Fig. 1 500-hPa geopotential height (contours; gpm; GDAS/GEFS), PMZ centers (red squares for current day; black dots for previous 10 days and the smaller the earlier), and current PMZ impact areas (shading in blue). Open diamonds are predicted centers in the coming days.

PMZ animation coming soon.

Fig. 2 Day-by-day animation for the PMZ episode in Fig. 1.


Fig. 3 Same as Fig. 1 but for the PMZ up to 2 days ago in the NCEP-NCAR Reanalysis.


(To be provided)