Python code to calculate Excess Heat Factor and derived heatwave metrics
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HWvariables_info.py
README.md
compute_EHFheatwaves.py
constants.py

README.md

EHF

Python code to calculate Excess Heat Factor and derived heatwave metrics 12/06/2015 Daniel Argüeso @ University of New South Wales email: d.argueso@unsw.edu.au

This is a Python 3 code to calculate Excess Heat Factor and heatwave metrics on a temperature array (time,lat,lon).

The main function is located in compute_EHFheatwaves.py and is called compute_EHF You will need to provide:

Input Description
tave Daily Mean temperature computed from daily tmax and tmin.
dates An list of datetime objects
thres_file [OPTIONAL] A netCDF file with the thresholds used to calculate extreme temperature (95th or 90th percentiles)
bsyear [OPTIONAL] If no thres_file is provided, this is the first year of the reference period to calculate thresholds
beyear [OPTIONAL] If no thres_file is provided, this is the last year of the reference period to calculate thresholds
month_starty [OPTIONAL] Month that we consider the first of the year. For Southern Hemisphere, you may set this to 7 - no summers split
mask [OPTIONAL] Array with mask where EHF wont be calculated. For example, Land-Sea mask
method Choose between Nairn and Fawcett (2013) [NF13] or Perkins and Alexander (2013) [PA13]. Differences in the calculations of percentiles
nwindow For PA13 method, length of the window to calculate the calendar day thresholds. Default 15 days
EHFaccl True/False. Whether to use Acclimatization over the previous 30 days. Default False
season Calculate EHF and metrics over particular seasons only. Only NH and SH summer supported. Yearly (no seasons) also supported

Outputs are

Output Description Units
HWA Peak of the hottest heatwave per year - yearly maximum of each heatwave peak degC or degC2 (depending on EHFaccl)
HWM Average magnitude of the yearly heatwave - yearly average of heatwave magnitude degC or degC2 (depending on EHFaccl)
HWF Number of heatwave days - expressed as the percentage relative to the total number of days days
HWN Number of heatwaves per year hw/year
HWD Duration of the longest heatwave per year days
HWT Time of the first heat wave day of the year from 1st month of the year day
pct Percentile 90th or 95th over the entire base_period degC
EHF Excess Heat Factor index degC or degC2 (depending on EHFaccl)
HWMt Average temperature for all yearly heatwave - yearly average of temperature heatwave days degC
HWAt Temperature at the peak of the hottest heatwave per year - yearly maximum of each heatwave peak degC
spell_all Length of the heatwave in days after the date days
HWL Mean duration of heat waves days

constants.py contains a bunch of constanst that may be used in the calculation. HWvariables_info.py contains a dictionary with information on the output variables for reference in the netCDF writing out.

(25/07/2018) NOTE: Now, only the functions are provided. I will update soon a sample script to call them