pyart.retrieve.conv_strat_yuter#

pyart.retrieve.conv_strat_yuter(grid, dx=None, dy=None, level_m=None, always_core_thres=42, bkg_rad_km=11, use_cosine=True, max_diff=5, zero_diff_cos_val=55, scalar_diff=1.5, use_addition=True, calc_thres=0.75, weak_echo_thres=5.0, min_dBZ_used=5.0, dB_averaging=True, remove_small_objects=True, min_km2_size=10, val_for_max_conv_rad=30, max_conv_rad_km=5.0, cs_core=3, nosfcecho=0, weakecho=3, sf=1, conv=2, refl_field=None, estimate_flag=True, estimate_offset=5)[source]#

Partition reflectivity into convective-stratiform using the Yuter et al. (2005) and Yuter and Houze (1997) algorithm.

Parameters:

  • grid (Grid) – Grid containing reflectivity field to partition.

  • dx, dy (float, optional) – The x- and y-dimension resolutions in meters, respectively. If None the resolution is determined from the first two axes values parsed from grid object.

  • level_m (float, optional) – Desired height in meters to classify with convective stratiform algorithm.

  • always_core_thres (float, optional) – Threshold for points that are always convective. All values above the threshold are classifed as convective See Yuter et al. (2005) for more detail.

  • bkg_rad_km (float, optional) – Radius to compute background reflectivity in kilometers. Default is 11 km. Recommended to be at least 3 x grid spacing

  • use_cosine (bool, optional) – Boolean used to determine if a cosine scheme (see Yuter and Houze (1997)) should be used for identifying convective cores (True) or if a simpler scalar scheme (False) should be used.

  • max_diff (float, optional) – Maximum difference between background average and reflectivity in order to be classified as convective. “a” value in Eqn. B1 in Yuter and Houze (1997)

  • zero_diff_cos_val (float, optional) – Value where difference between background average and reflectivity is zero in the cosine function “b” value in Eqn. B1 in Yuter and Houze (1997)

  • scalar_diff (float, optional) – If using a scalar difference scheme, this value is the multiplier or addition to the background average

  • use_addition (bool, optional) – Determines if a multiplier (False) or addition (True) in the scalar difference scheme should be used

  • calc_thres (float, optional) – Minimum percentage of points needed to be considered in background average calculation

  • weak_echo_thres (float, optional) – Threshold for determining weak echo. All values below this threshold will be considered weak echo

  • min_dBZ_used (float, optional) – Minimum dBZ value used for classification. All values below this threshold will be considered no surface echo See Yuter and Houze (1997) and Yuter et al. (2005) for more detail.

  • dB_averaging (bool, optional) – True if using dBZ reflectivity values that need to be converted to linear Z before averaging. False for other non-dBZ values (i.e. snow rate)

  • remove_small_objects (bool, optional) – Determines if small objects should be removed from convective core array. Default is True.

  • min_km2_size (float, optional) – Minimum size of convective cores to be considered. Cores less than this size will be removed. Default is 10 km^2.

  • val_for_max_conv_rad (float, optional) – dBZ for maximum convective radius. Convective cores with values above this will have the maximum convective radius

  • max_conv_rad_km (float, optional) – Maximum radius around convective cores to classify as convective. Default is 5 km

  • cs_core (int, optional) – Value for points classified as convective cores

  • nosfcecho (int, optional) – Value for points classified as no surface echo, based on min_dBZ_used

  • weakecho (int, optional) – Value for points classified as weak echo, based on weak_echo_thres

  • sf (int, optional) – Value for points classified as stratiform

  • conv (int, optional) – Value for points classified as convective

  • refl_field (str, optional) – Field in grid to use as the reflectivity during partitioning. None will use the default reflectivity field name from the Py-ART configuration file.

  • estimate_flag (bool, optional) – Determines if over/underestimation should be applied. If true, the algorithm will also be run on the same field wih the estimate_offset added and the same field with the estimate_offset subtracted. Default is True (recommended)

  • estimate_offset (float, optional) – Value used to offset the reflectivity values by for the over/underestimation application. Default value is 5 dBZ.

Returns:

convsf_dict (dict) – Convective-stratiform classification dictionary.

References

Yuter, S. E., and R. A. Houze, Jr., 1997: Measurements of raindrop size distributions over the Pacific warm pool and implications for Z-R relations. J. Appl. Meteor., 36, 847-867. https://doi.org/10.1175/1520-0450(1997)036%3C0847:MORSDO%3E2.0.CO;2

Yuter, S. E., R. A. Houze, Jr., E. A. Smith, T. T. Wilheit, and E. Zipser, 2005: Physical characterization of tropical oceanic convection observed in KWAJEX. J. Appl. Meteor., 44, 385-415. https://doi.org/10.1175/JAM2206.1