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Engineering Vertical Velocity Estimator

This repository hosts models for updraft estimation for animal movement studies.

Orographic Updraft

An improved orographic updraft model based on that of Brandes and Ombalski (2004). The improved model is described in Thedin et al. (2023).

The inputs are: digital elevation model (DEM) of the region of interest, the wind direction, the desired height, and the wind speed at a reference height of 80 m. The orographic updraft using the EVVE model can be obtained using

from evve.orographic import orographic
import xarray as xr

# Open xarray Dataset containing the DEM information
ds = xr.open_dataset('examples/')  # see file for example format

# Initialize the object
evve_orog = orographic(ds)

# Estimate the orographic updraft using the EVVE model
evve_orog.calcOrographicUpdraft(wdir = 270,      # desired wind dir in typical wind convention
                                h = 120,         # height where the updrafts will be estimated
                                wspdAtRef = 8,   # wind speed at a reference height of 80 m AGL
                                model = 'evve'   # model of interest. Options are 'evve' or 'bo04'

# Plot the resulting orographic field
evve_orog.plotOrographicUpdraft(cmap='RdBu_r', vmin=-1, vmax=1)

Note that a more complete example is provided in the examples directory.

Thermal Updraft

The thermal updraft model is a work in progress. It requires coupling to HRRR. The version available here is not in working condition yet. A working version, with the appropriate coupling to HRRR is available in the companion repository SSRS.


  • Thedin, R, Brandes, D, Quon, E, Sandhu, R, Tripp, C. "A three-dimensional model of terrain-induced updrafts for movement ecology studies". Under review, Journal of Movement Ecology, 2023.

  • Brandes, D., & Ombalski, D. W. "Modeling raptor migration pathways using a fluid-flow analogy". Journal of Raptor Research, v. 38, 2004