# Copyright (c) 2013-2015 Siphon Contributors.
# Distributed under the terms of the BSD 3-Clause License.
# SPDX-License-Identifier: BSD-3-Clause
"""Read upper air data from the Wyoming archives."""
from datetime import datetime
from io import StringIO
import warnings
from bs4 import BeautifulSoup
import numpy as np
import pandas as pd
from .._tools import get_wind_components
from ..http_util import HTTPEndPoint
def _safe_float(s):
"""Convert to float, handling ****** as a string for missing."""
return pd.NA if all(c == '*' for c in s) or s == '-9999.0' else float(s)
[docs]
class WyomingUpperAir(HTTPEndPoint):
"""Download and parse data from the University of Wyoming's upper air archive."""
[docs]
def __init__(self):
"""Set up endpoint."""
super().__init__('http://weather.uwyo.edu/cgi-bin/sounding')
[docs]
@classmethod
def request_data(cls, time, site_id, recalc=False, **kwargs):
r"""Retrieve upper air observations from the Wyoming archive.
Parameters
----------
time : datetime.datetime
The date and time of the desired observation.
site_id : str
The three letter ICAO identifier of the station for which data should be
downloaded.
recalc : bool
Whether to request the server recalculate the data (i.e. ignore its cache) before
returning it. Defaults to False. NOTE: This should be used sparingly because it
will increase the load on the service.
kwargs
Arbitrary keyword arguments to use to initialize source
Returns
-------
`pandas.DataFrame`
Parsed data
"""
endpoint = cls()
df = endpoint._get_data(time, site_id, recalc=recalc)
return df
def _get_data(self, time, site_id, recalc=False):
r"""Download and parse upper air observations from an online archive.
Parameters
----------
time : datetime.datetime
The date and time of the desired observation.
site_id : str
The three letter ICAO identifier of the station for which data should be
downloaded.
recalc : bool
Returns recalculated data if True. Defaults to False.
Returns
-------
`pandas.DataFrame`
"""
raw_data = self._get_data_raw(time, site_id, recalc=recalc)
soup = BeautifulSoup(raw_data, 'html.parser')
tabular_data = StringIO(soup.find_all('pre')[0].contents[0])
col_names = ['pressure', 'height', 'temperature', 'dewpoint', 'direction', 'speed']
df = pd.read_fwf(tabular_data, widths=[7] * 8, skiprows=5,
usecols=[0, 1, 2, 3, 6, 7], names=col_names)
df['u_wind'], df['v_wind'] = get_wind_components(df['speed'],
np.deg2rad(df['direction']))
# Drop any rows with all NaN values for T, Td, winds
df = df.dropna(subset=('temperature', 'dewpoint', 'direction', 'speed',
'u_wind', 'v_wind'), how='all').reset_index(drop=True)
# Parse metadata
meta_data = soup.find_all('pre')[1].contents[0]
lines = meta_data.splitlines()
# Convert values after table into key, value pairs using the name to the left of the :
post_values = dict(tuple(map(str.strip, line.split(': '))) for line in lines[1:])
station = post_values.get('Station identifier', '')
station_number = int(post_values['Station number'])
sounding_time = datetime.strptime(post_values['Observation time'], '%y%m%d/%H%M')
latitude = _safe_float(post_values.get('Station latitude', '******'))
longitude = _safe_float(post_values.get('Station longitude', '******'))
elevation = _safe_float(post_values.get('Station elevation', '******'))
pw = float(post_values['Precipitable water [mm] for entire sounding'])
df['station'] = station
df['station_number'] = station_number
df['time'] = sounding_time
df['latitude'] = latitude
df['longitude'] = longitude
df['elevation'] = elevation
df['pw'] = pw
# Add unit dictionary
with warnings.catch_warnings():
warnings.filterwarnings('ignore', "Pandas doesn't allow columns to be created",
UserWarning)
df.units = {'pressure': 'hPa',
'height': 'meter',
'temperature': 'degC',
'dewpoint': 'degC',
'direction': 'degrees',
'speed': 'knot',
'u_wind': 'knot',
'v_wind': 'knot',
'station': None,
'station_number': None,
'time': None,
'latitude': 'degrees',
'longitude': 'degrees',
'elevation': 'meter',
'pw': 'millimeter'}
return df
def _get_data_raw(self, time, site_id, recalc=False):
"""Download data from the University of Wyoming's upper air archive.
Parameters
----------
time : datetime.datetime
Date and time for which data should be downloaded
site_id : str
Site id for which data should be downloaded
recalc : bool
Returns recalculated data if True. Defaults to False.
Returns
-------
str
text of the server response
"""
path = ('?region=naconf&TYPE=TEXT%3ALIST'
f'&YEAR={time:%Y}&MONTH={time:%m}&FROM={time:%d%H}&TO={time:%d%H}'
f'&STNM={site_id}')
if recalc:
path += '&REPLOT=1'
resp = self.get_path(path)
# See if the return is valid, but has no data
if resp.text.find("Can't") != -1:
raise ValueError(
f'No data available for {time:%Y-%m-%d %HZ} '
f'for station {site_id}.')
return resp.text