pvtend.classify.classify_z_field

pvtend.classify.classify_z_field(z2d: ndarray, x_rel: ndarray, y_rel: ndarray, cfg: RWBConfig | None = None) → tuple[bool, bool][source]

Classify AWB / CWB Rossby-wave-breaking bays on one 2-D Z field.

Public, side-effect-free wrapper around the internal bay-overturning detector _classify_bays_z2d(). Intended for callers that already hold a single 2-D geopotential-height patch — e.g. the weighted-average Z(300/250/200) “single-field, threshold=1” classification used outside the per-event NPZ tree (other grids/datasets, precomputed patch arrays).

Parameters:

z2d – 2-D geopotential-height field (NY, NX) [m] on a block- or event-relative grid. NaNs (e.g. polar padding) are tolerated; an all-NaN field returns (False, False).
x_rel – Relative longitudes — 1-D (NX,) or 2-D (NY, NX).
y_rel – Relative latitudes — 1-D (NY,) or 2-D (NY, NX), ascending (north at top).
cfg – RWBConfig; None uses the RWBConfig() dataclass defaults (area_min_deg2=30, try_levels=300). Note the pvtend-pipeline classify CLI tunes these to area_min_deg2=20, try_levels=400 for ERA5; pass an explicit cfg to reproduce that.

Returns:

(is_awb, is_cwb) — both True when the field exhibits both an anticyclonic and a cyclonic overturning bay (an Omega block); see label_from_flags() to collapse to a single class string.