| """Small plotting helpers for the CAMulator timescales tutorial.""" |
|
|
| import cartopy.crs as ccrs |
| import numpy as np |
|
|
|
|
| def map_axis(fig, nrows, ncols, index, region=None, extent=None, central_longitude=180): |
| """Add a map axis with coastlines. region = {'lat': (min, max), 'lon': (min, max)}, longitudes in degrees east |
| (negative = west; lon min > max crosses the date line). (The older extent = (lon_min, lon_max, lat_min, lat_max) in |
| 0-360 also works.)""" |
| if region is not None: |
| lo0, lo1 = region["lon"] |
| if lo1 < lo0: |
| lo1 += 360 |
| extent = (lo0, lo1, *region["lat"]) |
| central_longitude = (lo0 + lo1) / 2 |
| ax = fig.add_subplot(nrows, ncols, index, projection=ccrs.PlateCarree(central_longitude=central_longitude)) |
| if extent is not None: |
| ax.set_extent(extent, crs=ccrs.PlateCarree()) |
| ax.coastlines(linewidth=0.6) |
| return ax |
|
|
|
|
| DATA_CRS = ccrs.PlateCarree() |
|
|
|
|
| def sinlat_axis(ax, ticks=(-60, -30, -10, 0, 10, 30, 60)): |
| """Label an x axis that holds sin(latitude) with latitudes, so each band takes the room its area does.""" |
| ax.set_xticks(np.sin(np.deg2rad(ticks))) |
| ax.set_xticklabels([f'{abs(t)}°{"S" if t < 0 else "N" if t > 0 else ""}' for t in ticks]) |
| ax.set_xlabel("Latitude (spaced by area)") |
|
|
|
|
| def sinlat(lat): |
| return np.sin(np.deg2rad(lat)) |
|
|
|
|
| def polar_axis(fig, nrows, ncols, index, lat_min=50): |
| """Add a north-polar stereographic map axis with coastlines, showing latitudes north of lat_min.""" |
| ax = fig.add_subplot(nrows, ncols, index, projection=ccrs.NorthPolarStereo()) |
| ax.set_extent([-180, 180, lat_min, 90], crs=ccrs.PlateCarree()) |
| ax.coastlines(linewidth=0.6) |
| return ax |
|
|
|
|
| |
| |
| VARIABLES = { |
| "FLUT": ("OLR", "W/m²", "outgoing longwave radiation; lower = more deep cloud"), |
| "PRECT": ("Rain", "mm/day", None), |
| "TREFHT": ("2-m temperature", "K", None), |
| "TS": ("Surface temperature", "K", None), |
| "PS": ("Surface pressure", "hPa", None), |
| "U10": ("10-m wind speed", "m/s", None), |
| "westerly_stress": ("Surface wind stress", "mN/m²", "positive = westerly"), |
| "rain": ("Rain", "mm/day", None), |
| "T": ("2-m temperature", "K", None), |
| "vapour": ("Column water vapour", "mm", None), |
| } |
|
|
|
|
| def name(variable): |
| """Short display name, e.g. 'OLR', 'Rain'.""" |
| return VARIABLES[variable][0] if variable in VARIABLES else variable |
|
|
|
|
| def units(variable): |
| return VARIABLES[variable][1] if variable in VARIABLES else "" |
|
|
|
|
| def label(variable): |
| """Axis / colour-bar label: name, units and a reading note, e.g. 'OLR (W/m²; ... lower = more deep cloud)'.""" |
| if variable not in VARIABLES: |
| return variable |
| short, unit, note = VARIABLES[variable] |
| return f"{short} ({unit}; {note})" if note else f"{short} ({unit})" |
|
|
|
|
| def symmetric_limit(field, quantile=0.98): |
| """A colour limit that covers almost all of a field's values, the same on both sides of zero.""" |
| return float(np.nanquantile(np.abs(np.asarray(field)), quantile)) or 1.0 |
|
|
|
|
| def km_axis(ax, circumference_km): |
| """Add a top x axis showing the wavelength in km for an axis of zonal wavenumbers.""" |
| top = ax.secondary_xaxis("top", functions=(lambda k: circumference_km / np.maximum(k, 1e-9), |
| lambda km: circumference_km / np.maximum(km, 1e-9))) |
| top.set_xlabel("Wavelength (km)") |
| return top |
|
|
|
|
| def region_text(region): |
| """{'lat': (-5, 5), 'lon': (35, 45)} -> '5°S-5°N, 35-45°E' (for titles).""" |
| def lat(v): |
| return f"{abs(v):g}°{'S' if v < 0 else 'N'}" if v else "0°" |
| def lon(v): |
| return f"{abs(v):g}°{'W' if v < 0 else 'E'}" if v else "0°" |
| la0, la1 = region["lat"] |
| text = f"{lat(la0)}-{lat(la1)}" |
| if "lon" in region: |
| text += f", {lon(region['lon'][0])}-{lon(region['lon'][1])}" |
| return text |
|
|
