DETECTION AND ATTRIBUTION ANALYIS OF TROPICAL PRECIPITATION

Figure number: Figure 3.14 From the IPCC Working Group I Contribution to the Sixth Assessment Report: Chapter 3

Description:

Wet (a) and dry (b) region tropical mean (30°S-30°N) annual precipitation anomalies. Observed data are shown with black lines (GPCP), ERA5 reanalysis in grey, single model simulations results are shown with light blue/red lines (CMIP6), and multi-model-mean results are shown with dark blue/red lines (CMIP6). Wet and dry region annual anomalies are calculated as the running mean over 12 months relative to a 1988-2020 based period. The regions are defined as the wettest third and driest third of the surface area, calculated for the observations and for each model separately for each season (following Polson and Hegerl, 2017). Scaling factors (panels c,d) are calculated for the combination of the wet and dry region mean, where the observations, reanalysis and all the model simulations are first standardised using the mean standard deviation of the pre-industrial control simulations. Two total least squares regression methods are used: noise in variables (following Polson and Hegerl, 2017) which estimates a best estimate and a 5-95% confidence interval using the pre-industrial controls (circle and thick green line) and the pre-industrial controls with double the variance (thin green line); and a bootstrap method (DelSole et al., 2019) (5-95% confidence interval shown with a purple line and best estimate with a purple circle). Panel (c) shows results for GPCP and panel (d) for ERA5. Figure is adapted from Schurer et al. (2020).

Author list:

• Schurer, A.: University of Edinburgh, UK; A.Schurer@ed.ac.uk
• Kazeroni, R.: DLR, Germany

Publication sources:

Schurer, A. P., Hegerl, G. C., Ballinger, A., and Friedman, A. R. (2020). Human influence strengthens the contrast between tropical wet and dry regions. Environ. Res. Lett. 15. doi:https://doi.org10.1088/1748-9326/ab83ab.

ESMValTool Branch:

• ESMValTool-AR6-OriginalCode-FinalFigures: ar6_chapter_3

ESMValCore Branch:

• ESMValCore-AR6-OriginalCode-FinalFigures: fix_cmip6_models_newcore

Recipe & diagnostics:

Recipe used: recipes/ipccwg1ar6ch3/recipe_ipccwg1ar6ch3_wetdry_schurer2020.yml

Diagnostic used: diag_scripts/aschurer/WetDry_timeseries_smooth_scaling1.py

Expected image path:

This is the path of the image relative to the automatically generated ESMValTool output location:

• recipe_wetdry_newextendedv2_YYYYMMDD_HHMMSS/plots/schurer20_figs/script1/WetDry_timeseries_scalefactors.png

Software description:

• ESMValTool environment file: IPCC_environments/ar6_newcore_remi_conda_environment.yml
• pip file: IPCC_environments/ar6_newcore_remi_pip_environment.txt

Hardware description:

Machine used: Mistral