Insolation library

This library file contains one function:

load_insolation:

We are using surface clear-sky downwelling UVb as an easily-available proxy for top-of-atmosphere shortwave. We don’t care bout how it varies with the weather, only the diurnal and seasonal cycles, so only one year of data is needed (1969 is downloaded). This function loads the equuivalent 1969 data for the specified time-point.

# Functions for handling insolation data

# The weather data can mostly be handled by IRData. 
# But the insolation data needs special handling.

import iris
import os

# load the insolation data
def load_insolation(year,month,day,hour):
    if month==2 and day==29: day=28
    time_constraint=iris.Constraint(time=iris.time.PartialDateTime(
                                    year=1969,
                                    month=month,
                                    day=day,
                                    hour=hour))
    ic=iris.load_cube("%s/20CR/version_2c/ensmean/cduvb.1969.nc" % os.getenv('SCRATCH'),
                      iris.Constraint(name='3-hourly Clear Sky UV-B Downward Solar Flux') &
                      time_constraint)
    coord_s=iris.coord_systems.GeogCS(iris.fileformats.pp.EARTH_RADIUS)
    ic.coord('latitude').coord_system=coord_s
    ic.coord('longitude').coord_system=coord_s
    return ic