def plot(self, ax): # Get global u/v wind data ug, vg = self.chart.get_data(self.gfs_vars, apply_domain=False) # Get level coordinates for U/V wind components ug_lv_coord = gfs_utils.get_level_coord(ug, self.level_units) vg_lv_coord = gfs_utils.get_level_coord(vg, self.level_units) # Constrain to specified level(s) ugc = gfs_utils.get_coord_constraint(ug_lv_coord.name(), self.level) ug = ug.extract(ugc) vgc = gfs_utils.get_coord_constraint(vg_lv_coord.name(), self.level) vg = vg.extract(vgc) # Apply smoothing ug_data = wrf_smooth2d(ug.data, 6) ug.data = ug_data.data vg_data = wrf_smooth2d(vg.data, 6) vg.data = vg_data.data # Set up windspharm wind vector object w = VectorWind(ug, vg) # Get nondivergent component of wind upsi, vpsi = w.nondivergentcomponent() Vpsi = VectorWind(upsi, vpsi) # Partition streamfunction vorticity into curvature and shear # components # Bell and Keyser 1993 Appendix equation A.3b # Relative curvature vorticity: # V dalpha/ds = 1/V^2[u^2 dv/dx - v^2 du/dy - uv(du/dx - dv/dy)] dupsi_dx, dupsi_dy = Vpsi.gradient(upsi) dvpsi_dx, dvpsi_dy = Vpsi.gradient(vpsi) ws = Vpsi.magnitude() vrt = (upsi**2 * dvpsi_dx - vpsi**2 * dupsi_dy - upsi * vpsi * (dupsi_dx - dvpsi_dy)) / ws**2 # Calculate advection of non-divergent curvature vorticity dvrt_dx, dvrt_dy = Vpsi.gradient(vrt) advec = -1 * (upsi * dvrt_dx + vpsi * dvrt_dy) # Second order advection term needed for masking dadv_dx, dadv_dy = Vpsi.gradient(advec) advec2 = upsi * dadv_dx + vpsi * dadv_dy # Apply domain constraint domain_constraint = gfs_utils.get_domain_constraint(self.chart.domain) upsi = upsi.extract(domain_constraint) vrt = vrt.extract(domain_constraint) advec = advec.extract(domain_constraint) advec2 = advec2.extract(domain_constraint) # Masking rules from Berry & Thorncroft 2007, Table 1 # A1. Mask streamfunction curvature vorticity to exclude AEW # ridges axes or weak systems (BT2007: K1T = 0.5 * 10^-5 s^-1) K1T = 1.5 * 10**-5 # s^-1 m1t = vrt.data <= K1T # mask for troughs m1r = vrt.data >= -K1T # mask for ridges # A2. Remove "pseudoridge" axes in nondivergent flow that is # highly cyclonically curved K2T = 0 # m s^-3 m2 = advec2.data <= K2T # A3. Removes trough axes in westerly flow K3T = 0 # m s^-1 m3 = upsi.data >= K3T trough_mask = m1t | m2 | m3 ridge_mask = m1r | ~m2 | m3 troughs = self.apply_size_mask(trough_mask, advec.data) ridges = self.apply_size_mask(ridge_mask, advec.data) # Plot troughs and ridges ax.contour(self.lon, self.lat, troughs, levels=0, **self.options) ax.contour(self.lon, self.lat, ridges, levels=0, **self.options, linestyles="dotted")