4.1. Outdoor Thermal Comfort: ExtremeFinder

Contributor

Name

Institution

Bei Huang

Reading

Andy Gabey

Reading

Fredrik Lindberg

Gothenburg
Current Options
Identifies extreme high events (e.g. Heat waves) and low events (e.g. Cold Waves). Designed primarily for temperature data (heat waves identified from daily maximum and mean T; cold waves from daily minimum), but can also be used to indicate potential high and low extremes in other meteorological variables.
Data must be provided by the user, and can be
- Previously-downloaded ERA5 data in a NetCDF (*-scf.nc) file (this can be obtained from the ERA5 downloader)
- Other NetCDF (.nc) file containing sub-daily measurements, or daily maximum/mean/minimum values. Must contain a ‘time’ dimension, and variable(s) with name(s) matching those being analysed using the ExtremeFinder.
- Text (.txt) file, daily T_max, T_avg or T_min (file sample: 1979-01-01 to 2009-12-31). Only temperature analysis can be performed using a text file.
Method
Basis for thresholds - set into Input.nml (namelist)
Meehl and Tebaldi (2004): 81st, 97.5th

Fischer and Schär (2010): 90th

Vautard et al. (2013): 90th

Schoetter et al. (2014): 98th

Sirje Keevallik (2015): 10th

A. K. Srivastava (2009): 3 °C

Busuioc et al. (2010): 5 °C
Dialog box

Fig. 4.1 The interface for the ExtremeFinder plugin
Steps to use
1. Select climate data: The ExtremeFinder will use all the data available in its analysis. You will be prompted for a text (.txt) or NetCDF (.nc) file:
  - NetCDF file: The latitude, longitude, start and end date boxes will be populated automatically, if the data is available in the NetCDF file.
  - Text file: The latitude, longitude, start and end date boxes must be filled in by the user, as the information is needed in calculations:
    
    Latitude (degrees N) and Longitude (degrees E) are WGS84 co-ordinates
    
    Start and end date are inclusive and must match the data extent
2. Select the extreme event type and the calculation method:
  - Event types are either Extreme high (e.g. Heat wave) or low (e.g. Cold wave)
  - There are several different ways to identify extremes, depending on the event type
  - Choose the meteorological variable to analyse for extremes
    
    Note: The methods in the Extreme Finder are based on Tair and may not be appropriate for other variables
3. Select Output File: A list of extreme events will be written to the file
  - Note: this will be overwritten if not a new name
4. Run: Performs the analysis
Output: Extreme events (heat waves used as example below)
1. Daily T_max (or T_avg / T_min) with time (Y=Year, X=Month)
  - Colour gives Temperature (see key)
  - Yellow Box Highlights Heatwave (Coldwave) periods This loads the model interface dialog box:
    
    Fig. 4.2 Heat/Cold wave periods
2. Box plot of distribution of heat (cold) wave by year.
  - whiskers =1.5* IQR
  - outliers - any data beyond the whiskers
    
    Fig. 4.3 Box-and-whisker plot of Heat/Cold wave days each year
3. Number of heat (cold) waves days per year
  
  Fig. 4.4 Histogram showing number of Heat/Cold wave days each year

Name	Institution
Bei Huang	Reading
Andy Gabey	Reading
Fredrik Lindberg	Gothenburg