Coverage for wrainfo/precipitation.py: 100%

1"""Precipitation estimation module.""" 

2 

3# WRaINfo, Is a software to process FURUNO weather radar data. 

4# 

5# Copyright (c) 2022, FernLab (GFZ Potsdam, fernlab@gfz-potsdam.de) 

6# 

7# This software was developed within the context of the RaINfo ("Potential use of 

8# high resolution weather data in agriculture") project of FernLab funded by 

9# the Impulse and Networking Fund of the Helmholtz Association. 

10# 

11# Licensed under the Apache License, Version 2.0 (the "License"); 

12# you may not use this file except in compliance with the License. 

13# 

14# You may obtain a copy of the License at 

15# http://www.apache.org/licenses/LICENSE-2.0 

16# 

17# Unless required by applicable law or agreed to in writing, software 

18# distributed under the License is distributed on an "AS IS" BASIS, 

19# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 

20# See the License for the specific language governing permissions and 

21# limitations under the License. 

22 

23# imports 

24# ------- 

25 

26import wradlib as wrl 

27import xarray as xr 

28from wrainfo.reader import read_config_file 

29 

30 

31# quantitative precipitation estimation (QPE): R(Z) 

32# ------------------------------------------------- 

33 

34def qpe_zr(ds, 

35 moment, 

36 path, 

37 a=200, 

38 b=1.6): 

39 """Qualitative precipitation estimation with z-R conversion. 

40 

41 Parameters 

42 ---------- 

43 ds : xarray.Dataset 

44 moment : str 

45 name of the clutter and attenuation corrected data array in the dataset. 

46 path : str 

47 path to configuration file 

48 a : integer 

49 parameter for the z-R-conversion 

50 (Marschall Palmer default value: a = 200, German Weather Service = 256) 

51 b : float 

52 parameter for the z-R-conversion 

53 (Marschall Palmer default value: b = 1.6, German Weather Service = 1.42) 

54 

55 Returns 

56 ------- 

57 : xarray.Dataset 

58 xarray.Dataset with a data array of derived precipitation amounts. 

59 """ 

60 # read setting from configuration file 

61 dims = read_config_file(path=path, selection="dimensions") 

62 interval = read_config_file(path=path, selection="scan_interval") 

63 

64 # precipitation attributes 

65 prec_attrs = {"standard_name": "precipitation_amount_z_r_relationship", 

66 "long_name": "precipitation_amount_z_r_relationship", 

67 "unit": "mm", } 

68 

69 # QPE Z(R) 

70 rr = ds[moment].pipe(wrl.trafo.idecibel).pipe(wrl.zr.z_to_r, a=a, b=b) 

71 depth = wrl.trafo.r_to_depth(rr, interval) 

72 

73 # add to dataset 

74 ds["PREC_ZR"] = xr.DataArray(depth, dims=dims, attrs=prec_attrs) 

75 

76 # fix encoding 

77 chunk = read_config_file(path=path, selection="chunksize") 

78 

79 comp = dict(zlib=True, complevel=7, chunksizes=(chunk[0], chunk[1], chunk[2])) 

80 ds.PREC_ZR.encoding = comp 

81 

82 return ds