Historical irradiance measurements from Taastrup from the World Radiation Data Center (WRDC)

[AdamRJensen]

Related to #5.

The World Radiation Data Center allegedely has data from Taastrup from 1981: http://wrdc.mgo.rssi.ru/

[AdamRJensen]

import pvlib
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np


def get_taastrup_data(year):
    """
    Retrieve irradiance data from Taastrup, Denmark.

    Data is from the World Radiation Data Center.

    Parameters
    ----------
    year: int
        Year should be between 1965 and 2001. The year 2002 is incomplete
        and thus cannot be parsed currently.
    """
    # specifier should be one of ['', '.1', '.2']
    url = "http://wrdc.mgo.rssi.ru/wrdccgi/protect.exe?data_list_full_protected/t6/"\
        f"denmark/copenhagen_taastrup/copenhagen_taastrup_{year}_t6.csv.html"
    months = pd.date_range('2020-01-01', freq='1MS', periods=12).strftime('%b').to_list()
    header = [x+mod for x in months for mod in ['', '_F']]
    df = pd.read_csv(url, names=header, usecols=range(24))
    index = [i+1 for i in range(31)] + ['Sum', 'Mean']
    df.index = index
    # Value "-32768" - no data available or bad data
    df = df.replace(-32768, np.nan)
    # Drop sum/mean and only keep daily data
    df_daily = df.loc[:31, months]
    df_daily = df_daily.stack(level=0).reset_index()
    # Drop days that are nan (most of these days don't exist, e.g. February 31st)
    df_daily = df_daily[df_daily[0].notna()]
    dates_str = df_daily['level_0'].astype(str).str.zfill(2) \
        + ' ' + df_daily['level_1'] + ' ' + str(year)
    df_daily.index = pd.to_datetime(dates_str, format='%d %b %Y')
    df_daily = df_daily[0].asfreq('1d')
    return df_daily


years = range(1965, 2001+1)

dfs = [get_taastrup_data(year) for year in years]

df = pd.concat(dfs, axis='rows')

# %% Missing data

df.isna().resample('1MS').sum().plot(ylabel='Missing days per month')
df.isna().resample('1Y').sum().plot(ylabel='Missing days per year')

# %%

df.resample('Y').mean().plot(ylabel='Daily average irradiance per year [J/cm$^2$]')

[AdamRJensen]

• Implement the procedure below from the WRDC to calculate monthly and annual irradiance: