Experimental GFS based Low Pressure System tracking

A methodology is developed based on the lower-tropospheric streamfunction of the horizontal wind. This captures the full rotational flow, like vorticity, but has the smoothness of pressure or geopotential height (while, unlike those variables, not making any assumption about the geostrophic nature of the flow). We track streamfunction extrema using a methodology developed at the University of California Berkeley that leverages the TempestExtremes algorithm, a computationally efficient Lagrangian feature tracker developed at the University of California Davis that can operate on the native grid of high-resolution forecast models. We optimized the criteria used in tracking to best match a hand-analyzed track dataset of monsoon lows and depressions.