Literature
To read
- Brown et al. (2008): review downscaling for Africa (dynamical & statistical, bias correction, advantages, best practices)
- Quintana Seguí et al. (2010): comparing statistical downscaling and bias correction: statistical, quantile mapping, anomaly for hydrology
- Tabor and Williams (2010): downscaling for conservation: CMIP3 with change-factor on CRU
- Zhang (2005): statistically downscaling GCM to station for crop, quantile mapping
- Solomon H. Gebrechorkos, Hülsmann, and Bernhofer (2019): statistical downscaling of GCM for East Africa
Similar approach
- Chakraborty et al. (2020)
- Euro-CORDEX
- ECLIPS (European CLimate Index ProjectionS)
- 80 annual, seasonal and monthly climate variables for two past (1961–1990 and 1991–2010) and five future (2011–2020, 2021–2140, 2041–2060, 2061–2080 and 2081–2100) periods
- five regional climate models (RCMs)
- RCP 4.5 and RCP 8.5
- ECLIPS 1.1 at 0.11° (RCM native)
- ECLIPS 2.0 30 arcsec downscaled with delta approach
- tested against independent station data from the European Climate Assessment (ECA) dataset
- ECLIPS 2.0 (CC 0.78-0.93) > ECLIPS 1.1 (CC 0.36-0.78)
- Cited: 13
- Shen et al. (2020) - EA-CORDEX - Bias Correction and Ensemble Projections of Temperature Changes over Ten Subregions in CORDEX East Asia - three common bias correction methods: variance scaling, additive scaling, and quantile mapping based on empirical distribution - two multi-model averaging methods:
- Bayesian model averaging (BMA)
- simple multi-model averaging (SMA) - calibrating historical (1980–2005) - Future (2006–49) temperature trends - RCP 4.5 and 8.5 - CRU validation
- McGinnis and Mearns (2021) - NA-CORDEX - Five of the major variables used by impacts researchers as well as decision makers have also been bias-corrected - Directly hosted with CORDEX outputs (included on ESGF) - Each RCM community as different experiments corresponding to their questions (ex USA, EU, CA) - Cannon’s MBCn algorithm to bias-correct the data, a multivariate quantile-mapping approach that has good all-around performance for multiple uses and corrects the relationships between variables as well as their individual distributions
- Falco et al. (2018) - SAM-CORDEX - 1990 to 2004 - 0.44° - monthly precipitation and 2-m-temperature - RCM - GCM - ERAi - CRU, UDEL, CPC-UNI evaluation
- A tremendous amount of country / region specific applications
Examples
- S. Gebrechorkos et al. (2023):
- What: statistically downscaled CMIP6
- Resolutions: 0.25° (28km) and daily
- How: BCCAQ
- Baseline: MSWX & MSWEP
- Projections: 18 CMIP6 GCMs
- Scenarios: SSP2-4.5, SSP5-3.4-OS & SSP5-8.5
- Variables: daily precipitation, air-temperature, maximum and minimum temperature, wind speed, air pressure, and relative humidity
- Tool: ClimDown R package
- Evaluation: Pearson, RMSE, bias, SE, Taylor diagram
- Access: CEDA
- Note: remove bias & reproduce extreme events
- Navarro-Racines et al. (2020):
- What: statistically downscaled CMIP6
- Resolutions: 30” (1km) and 30-year means
- How: delta method
- Baseline: WorldClim
- Projections: 35 CMIP5 GCM
- Scenarios: RCP 2.6, 4.5, 6.0 & 8.5
- Variables: mean monthly maximum and minimum temperatures and monthly rainfall
- Tool: ArcGIS & R
- Evaluation: perfect sibling
- Access: WDCC, CCAFS-Climate
- Note: thin-plate splines interpolation, Probability Density Function (PDF) comparisons
- Platts, Omeny, and Marchant (2014):
- What: statistically downscaled CORDEX CMIP5
- Resolutions: 30” (1km) and 20-year means
- How: change-factor (= delta method)
- Baseline: CRU, WorldClim, TAMSAT, CHIRPS
- Projections: 8 GCM CMIP5 x 2 RCM CORDEX
- Scenarios: RCP4.5 & RCP8.5
- Variables: monthly 2-m air temperature (mean, minimum and maximum) and monthly rainfall
- Tool: R & GRASS GIS
- Evaluation: No
- Access: York University
- Note: spline-interpolated
Downscaling
Bias correction
- delta or change-factor (Platts, Omeny, and Marchant 2014; Navarro-Racines et al. 2020)
Statistical
- SDSM: Statistical DownScaling Model (R. L. Wilby, Dawson, and Barrow 2002; R. L. Wilby and Dawson 2012)
Quantile
- BCCAQ: Bias Correction Constructed Analogues with Quantile mapping reordering (Cannon, Sobie, and Murdock 2015; Werner and Cannon 2016)
- CA: Constructed Analogues (Maurer et al. 2010)
- CI: Climate Imprint (Hunter and Meentemeyer 2005)
- DQM: Quantile Delta Mapping (Cannon, Sobie, and Murdock 2015)
- CDFt: cumulative distribution function transform (R CDFt) (Lanzante et al. 2019)
Other
- TLFN: time-lagged feed-forward neural network or temporal neural network (Coulibaly, Dibike, and Anctil 2005)
- kriging (KrigR) (Davy and Kusch 2021)
- Dynamical downscaling (RCM)
Climate data
https://climatedataguide.ucar.edu/type/satellite-data-products
Reanalysis
- ERA5-Land: reanalysis dataset from European Centre for Medium-Range Weather Forecasts (ECMWF) (Muñoz-Sabater et al. 2021)
- Resolutions: 0.1° (9km) & hourly (daily and monthly averages)
- Period: 1950-present
- Area: global
- Variables: 53 including temperature and precipitation
- Provider: CDS
- Projections: No (but CMIP & CORDEX on CDS)
- Tools: python cdsapi, R ewcmfr
- Note:
- CHELSA 2.1: Climatologies at High resolution for the Earth’s Land Surface Areas (Karger et al. 2017)
- Resolutions: 30” (1km) & 20-year means (daily & monthly available)
- Period: 1981-2100
- Area: global
- Variables: pr, rsds, tas, tasmax, tasmin, bioclim
- Provider: CHELSA
- Projections: downscaled CMIP5 & CMIP6
- Tools: R ntbox, chelsaDL
- Note:
- WorldClim 2: 1-km spatial resolution climate surfaces for global land areas (Fick and Hijmans 2017)
- Resolutions: 30” (1km) & 30-year means
- Period: 1970-2000
- Area: global
- Variables: tasmin, tasmax, tas, pr, rsds, ws, vapr, bioclim
- Provider: WorldClim
- Projections: CMIP6 23 GCM 4 SSP 20-year means
- Tools: R raster & geodata
- Note:
- CRU TS 4: monthly high-resolution gridded multivariate climate dataset (Climatic Research Unit Time Series) (Harris et al. 2020)
- Resolutions: 0.5° (45km) & monthly
- Period: 1901–2018
- Area: global
- Variables: cld, dtr, frs, pet, pre, tmn, tmp, tmx, vap, wet
- Provider: CRU
- Projections: No
- Tools: R cruts
- Note: angular-distance weighting (ADW)
- CHIRPS: Rainfall Estimates from Rain Gauge and Satellite Observations (Funk et al. 2015)
- Resolutions: 0.05°(900m) & daily, pentadal, and monthly
- Period: 1981-present
- Area: global
- Variables: rainfall
- Provider: CHIRPS
- Projections: No
- Tools: R chirps
- Note: infrared Cold Cloud Duration
- JRA-55: the Japanese 55-year Reanalysis (Kobayashi and Iwasaki 2016)
- Resolutions:
- Period: 1958-present
- Area: global
- Variables:
- Provider: JRA
- Projections: No
- Tools:
- Note:
- TerraClimate: a high-resolution global dataset of monthly climate and climatic water balance from 1958–2015 (Abatzoglou et al. 2018)
- Resolutions: 0.04° (4km) & monthly
- Period: 1958-2020
- Area: global
- Variables: Maximum temperature, minimum temperature, vapor pressure, precipitation accumulation, downward surface shortwave radiation, wind-speed
- Provider: TerraClimate
- Projections: No
- Tools: R TerraClimate
- Note: derived variables accessible, derived from WorldClim + CRU TS + JRA55
- GloH2O MSWX: Multi-Source Weather (Beck et al. 2022) & MSWEP: Multi-Source Weighted-Ensemble Precipitation (Beck et al. 2017; Beck et al. 2019)
- Resolutions: 0.1° (9km) & 3-hourly
- Period: 1979-present
- Area: global
- Variables: precipitation
- Provider: GloH2O
- Projections: No
- Tools:
- Note: gauge, ERA5, HydroGFD, PGF, WFDE5, …
Observations
- GHCNd: Historical Climatology Network Daily (Menne et al. 2012)
- GSOD: Global Summary of the Day (H Sparks, Hengl, and Nelson 2017)
- GPCC: Global Precipitation Climatology Centre (Becker et al. 2013)
Satellite
- TAMSAT: Tropical Applications of Meteorology using Satellite data and ground-based observations (Maidment et al. 2017)
- CMORPH: Climate Prediction Center morphing technique (Joyce et al. 2004)
- TRMM: Tropical Rainfall Measuring Mission (Kummerow et al. 1998)
- TMPA: Multi-satellite Precipitation Analysis (Huffman et al. 2009)
- GSMaP: Global Satellite Mapping (Okamoto et al., n.d.)
Climate projections
- CMIP5: the fifth phase of Coupled Model Intercomparison Project (Taylor, Stouffer, and Meehl 2012)
- CORDEX (CMIP5 based): Coordinated Regional Downscaling Experiment (Giorgi and Gutowski 2015)
- CMIP6: the sixth phase of Coupled Model Intercomparison Project (Tokarska et al. 2020)
- CMIP6 HighResMIP: High Resolution Model Intercomparison Project (Haarsma et al. 2016; Liang-Liang, Jian, and Ru-Cong 2022)
Providers
- CDS: Climate Data Store including CMIP (not HighRes), ERA5-Land, CORDEX (not all), …
- ESGF: Earth System Grid Federation for different providers (e.g. UK-CEDA, IPSL, LLNL, …) including HighResMIP, CMIP, and CORDEX
- WDCC: World Data Center for Climate
- CCAFS-Climate: global and regional future high-resolution climate datasets
Scenarios
- RCP: Representative Concentration Pathways
- Critics of RCP 8.5 used wrongly as buisness as usual in Hausfather and Peters (2020)
- SSP: Shared Socio-economic Pathways
Selection
Compromise for computation limitations.
- (1) initial selection of climate models based on the range of projected changes in climatic means, (2) refined selection based on the range of projected changes in climatic extremes and (3) final selection based on the climate model skill to simulate past climate (Lutz et al. 2016)
- envelope approach: representing the diversity of projections
- past-performance approach: capacity to reproduce past/present climate
Evaluation
- TSS: Taylor Skill Score (Liang-Liang, Jian, and Ru-Cong 2022)
- IA: index of agreement (Solomon Hailu Gebrechorkos, Hülsmann, and Bernhofer 2018)
- CC: Pearson correlation coefficient
- RMSE: Root mean square error
- MAE: Mean absolute error
- R: Relative bias
- SD: Standard deviation
- Taylor diagram (Taylor 2001)
- PS: perfect sibling (Hawkins et al. (2013)]
- Extreme indices from Expert Team on Climate Change Detection and Indices (ETCCDI) (Karl, Nicholls, and Ghazi 1999)
Tools
Standalone
- SAGA GIS
- CDO: Climate Data Operators
- singularity
Python
- xarray
- xesmf
- salem
- rioxarray
- snakemake
R
- terra
- netcdf4
- ClimDown: downscaling with Bias Correction/Constructed Analogues with Quantile mapping reordering (BCCAQ) (Hiebert et al. 2018)
- climdex.pcic: climate extremes indices
- KrigR (Davy and Kusch 2021)
- CDFt
- GSODR (H Sparks, Hengl, and Nelson 2017)