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AK K64G OLMT Meteorology Scaling Demo
DRAFT
ELM requires a set of forcing timeseries in order to run. In most E3SM simulations, ELM will be given forcing timeseries of variables such as temperature, humidity, precipitation rate, and nutrient deposition from the atmospheric model, EAM. When running ELM alone, however, these time series must be provided by the user. OLMT has several options that take care of specifying and altering the input data to ELM. Here, we will go through a single-pixel OLMT ELM simulation example for the Kougarok Mile 64 study site that uses OLMT options to alter temperature and precipitation (summer precipitation/winter precipitation as snow) separately and together (temperature+summer/winter precipitation changes). We analyze output against a base case to look at how these changes in scaling meteorological data will change the model output.
First, we will run the model scenarios for different iterations of temperature and rain/snow changes.
Mean annual temperature is projected to shift by up to +8.5°C at the NGEE sites by CMIP6 models, downscaled using a 13 member ensemble from CMIP6, calculated based on ClimateNA data (https://climatena.ca/). Precipitation in summer and winter precipitation as snow changes are based on percent differences from a climate normal (1971-2000). Temperature changes are the °C differences from this normal.
| Site | Temperature change (°C) | Summer precipitation change (%) | Winter precipitation Change |
|---|---|---|---|
| Council | 5.0/8.4 | 17/28 | 11/-29 |
| Kougarok | 5.4/5.6 | 21/20 | 11/12 |
| Teller | 5.2/8.5 | 21/32 | -1/-36 |
| Utqiagvik | X.X/X.X | YY/YY | ZZ/ZZ |
We can use options in OLMT as to see how ELM simulations would change under using these different temperature and precipitation conditions.
First, we run a case with no changes to the forcing data to use as a comparison with the other cases. If you have already run a case for Kougarok using these instructions. If you're not sure if you've run this case, you could always run the following to ensure you have the control case:
docker run -t -i --hostname=docker --user modeluser -v elmdata:/inputdata -v elmoutput:/output fasstsimulation/elm-builds:elm_v2-for-ngee_multiarch /scripts/OLMT_docker_example.sh --site_name=kougarok --ad_spinup_years=20 --final_spinup_years=30 --transient_years=10
This first case adds 5.6°C to the forcing temperature input files, starting on 1855-01-01. The --case_prefix flag here is important - if we did not supply it, running this case would overwrite the values from case 0! As we have specified 10 transient years in the simulation, our transient simulation will run from 1/1/1850 to 1/1/1860:
docker run -t -i --hostname=docker --user modeluser -v elmdata:/inputdata -v elmoutput:/output fasstsimulation/elm-builds:elm_v2-for-ngee_multiarch /scripts/OLMT_docker_example.sh --site_name=kougarok --ad_spinup_years=20 --final_spinup_years=30 --transient_years=10 --add_temperature=5.6 --startdate_add_temperature=18550101 --case_prefix=future_T
In the second case, we scale only precipitation and leave temperature unchanged. Rain and snowfall amounts are projected to change differently; in this case, we increase snowfall by 12% and rainfall by 20% in 1855. These are applied by multiplying the forcing data by a scaling factor (1.12 for snow, 1.20 for rain), instead of adding a constant as we did for temperature:
docker run -t -i --hostname=docker --user modeluser -v elmdata:/inputdata -v elmoutput:/output fasstsimulation/elm-builds:elm_v2-for-ngee_multiarch /scripts/OLMT_docker_example.sh --site_name=kougarok --ad_spinup_years=20 --final_spinup_years=30 --transient_years=10 --scale_snow=1.12 --startdate_scale_snow=18550101 --scale_rain=1.20 --startdate_scale_rain=18550101 --case_prefix=future_P
In the third case, we make changes to both temperature and precipitation, using the same values as above. This case will show us the combined impact of future precipitation and temperature changes. As above, the perturbations start in 1855 and continue 5 years until the end of the run:
docker run -t -i --hostname=docker --user modeluser -v elmdata:/inputdata -v elmoutput:/output fasstsimulation/elm-builds:elm_v2-for-ngee_multiarch /scripts/OLMT_docker_example.sh --site_name=kougarok --ad_spinup_years=20 --final_spinup_years=30 --transient_years=10 --scale_snow=1.12 --startdate_scale_snow=18550101 --scale_rain=1.20 --startdate_scale_rain=18550101 --add_temperature=5.6 --startdate_add_temperature=18550101 --case_prefix=future_TP
Go through analysis script.
Look at output and discuss.