feat: generate hazard descriptions programmatically

[ciaransweet]

What this PR is

• Undoes some model description changes as we haven't touched those indicators
• Refactors days_tas_above.py and degree_days.py to have a generate_description function
• Adds the relevant source datasets description to the indicator description
• Adds the periods for which an indicator is generated, based on its scenarios and other parameters

How you can test it

You should be able to run the workflow:

$ cwltool hazard_workflow.cwl#produce-hazard-indicator input.yml

Where input.yml contains:

source_dataset: UKCP18
source_dataset_kwargs: "{'resolution':'60km','domain':'uk'}"
scenario_list: "[rcp85]"
gcm_list: "[ukcp18]"
threshold_list: "[20,25,28,30,32,35,40,45,50,55]"
central_year_list: "[2030,2040,2050,2060,2070,2080,2090]"
central_year_historical: 2005
window_years: 20
inventory_format: "all"
write_xarray_compatible_zarr: true
store: "./indicator"
indicator: "days_tas_above_indicator"
ceda_ftp_username: username
ceda_ftp_url: "ftp.ceda.ac.uk"
ceda_ftp_password: "password"

And you should see a description like:

"Days per year for which the average near-surface temperature 'tas' is above a threshold specified in \u00b0C.\n\n$$\nI =  \\frac{365}{n_y} \\sum_{i = 1}^{n_y} \\boldsymbol{\\mathbb{1}}_{\\; \\, T^{avg}_i > T^\\text{ref}} \\nonumber\n$$\n\n$I$ is the indicator, $T^\\text{avg}_i$ is the daily average near-surface temperature for day index $i$ in \u00b0C, $n_y$ is the number of days in the year\nand $T^\\text{ref}$ is the reference temperature.\n\nUK Climate Projections (UKCP) by the [Met Office Hadley Centre](https://www.metoffice.gov.uk/research/approach/collaboration/ukcp), sourced from the [Centre for Environmental Data Analysis (CEDA)](http://catalogue.ceda.ac.uk/?q=ukcp18&record_types=Observation&sort_by=relevance). Projections until 2080 on global (60km), regional (12km) and local (5km and 2.2km) scales, for a high emissions scenario, RCP8.5.\n\nIndicators are generated for periods: 2030 (2020-2040), 2040 (2030-2050), 2050 (2040-2060), 2060 (2050-2070), 2070 (2060-2080), 2080 (2070-2090), and 2090 (2080-2100)."

This was from chronic_heat_osc_v2_days_tas_above_20c_ukcp18_rcp85_2030.json for example

Diff here: https://www.diffchecker.com/l3fUzyxc/ - The degree symbol changes are just because the 'before' was copy and pasted from elsewhere, the degree symbol still renders fine in the 'after'.

[ciaransweet]

Diff will be slightly out as I had to fix the UKCP18 years, but it's close enough.

[ciaransweet]

Before

After

Example of the changes on the frontend

[j08lue]

Dynamically generating the hazard indicator descriptions based on source and parameters is a great improvement that may make the descriptions even more valuable to downstream applications.

Clean implementation and the generate descriptions read well. 👌