DOI: 10.5061/dryad.bzkh189qd
title: Data and code from: Rising flood risks in semi-arid South Asia driven by changing intraseasonal oscillations under global warming

description: Northwestern South Asia, encompassing the historically semi-arid regions
 of Pakistan and northwest India, has seen increased persistent heavy
 rainfall and catastrophic flooding in recent decades. While most studies
 emphasize seasonal mean changes, the role of subseasonal dynamics remains
 unclear. Here, we present observational evidence that the
 northward-propagating monsoon intraseasonal oscillation (ISO) has
 strengthened and penetrated farther inland, with its convective anomalies
 amplifying rainfall extremes. Simultaneously, the
 southeastward-propagating midlatitude ISO along the westerly jet has
 slowed, prolonging anomalous circulations that sustain rainfall episodes.
 Together, these ISOs account for ~44% of the observed increase in flood
 frequency, a contribution comparable to that from mean-state changes
 (~40%). CMIP6 projections suggest that these ISO–driven processes will
 further intensify flood risks, posing escalating threats to this
 climate-sensitive region under continued global warming. Our findings
 reveal a fundamental yet overlooked mechanism linking subseasonal
 variability to emerging hydroclimatic extremes in a warmer world.
description: # Data and code from: Rising flood risks in semi-arid South Asia driven by
 changing intraseasonal oscillations under global warming Dataset DOI:
 [10.5061/dryad.bzkh189qd](https://doi.org/10.5061/dryad.bzkh189qd) ##
 Description of the data and file structure Code Repository for
 "Rising flood risks in semi-arid south Asia driven by changing
 intraseasonal oscillations under global warming". This repository
 contains the key code for reproducing all analyses and figures presented
 in the manuscript "Rising Flood Risks in Semi-Arid South Asia Driven
 by Changing Intraseasonal Oscillations under Global Warming" and its
 Supplementary Information. ## Data availability All source data used in
 this study are publicly available from the respective official websites.
 Therefore, this repository provides: * Plotting codes for all figures *
 Key data processing scripts * Major computational algorithms For detailed
 methodological descriptions, including common analytical approaches,
 please refer to the Methods section of the manuscript. ## Code/software
 ### Programming Languages * Python 3.8+ * NCL 6.6.2+ * MATLAB R2023a+ (for
 selected analyses) ## Access information Data was derived from the
 following sources: * The CPC precipitation data are available from NOAAs
 Physical Sciences Laboratory at
 [https://downloads.psl.noaa.gov/Datasets/cpc_global_precip/](https://downloads.psl.noaa.gov/Datasets/cpc_global_precip/). File used in this study: /CPC/CPC.precip.1979-2025.nc (daily precipitation) * The ERA5 data are available from the Copernicus Climate Change Service (C3S) Climate Data Store (CDS) at [https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=dataset](https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=dataset). Files used in this study: /ERA5/era5_land_mask.grib (land and sea); /ERA5/ERA5.precip.1979-2023.nc (precipitation); /ERA5/Z_1979-2023.nc (geopotential; Z); /ERA5/U_1979-2023.nc (zonal wind; U); /ERA5/V_1979-2023.nc (meridional wind; V); /ERA5/Q_1979-2023.nc (specific humidity; Q); /ERA5/W_1979-2023.nc (vertical velocity; W); /ERA5/T_1979-2023.nc (temperature; T); /ERA5/T2m_1979-2023.nc (2m temperature; T2m); /ERA5/ERA5_Ps_1979-2022_daily.nc (surface pressure); /ERA5/SST_1979-2023.nc (sea surface temperature); /ERA5/SKT_1979-2023.nc (skin temperature); /ERA5/divergence_1979-2023.nc (divergence); /ERA5/MSL_1979-2023.nc (mean sea level pressure; MSL); /ERA5/MSE_1979-2023.nc (moist static energy; MSE; Indirect calculation); /ERA5/MFC_1979-2023.nc (moisture flux convergence; MFC; Indirect calculation); /ERA5/theta_se_1979-2022.nc (equivalent potential temperature; Indirect calculation) * The MSWEP data are available at [https://www.gloh2o.org/mswep/](https://www.gloh2o.org/mswep/). File used in this study: /MSWEP/precip.1979-2022.nc (daily precipitation) * The MERRA2 data are available at [https://disc.gsfc.nasa.gov/information/glossary?title=MERRA-2](https://disc.gsfc.nasa.gov/information/glossary?title=MERRA-2). File used in this study: /MERRA2/MERRA2.precip.1980-2022.nc (daily precipitation) * The OLR data are available from NOAA at [https://psl.noaa.gov/data/gridded/data.olrcdr.interp.html](https://psl.noaa.gov/data/gridded/data.olrcdr.interp.html). File used in this study: /OLR/olr.day.mean.nc (daily OLR) * CMIP6 data are available at [https://aims2.llnl.gov/search/cmip6/](https://aims2.llnl.gov/search/cmip6/). Files used in this study: /CMIP6/pr_day_model_1979-2100.nc (daily precipitation; historical + SSP585); /CMIP6/hus_JJAS_model_1970-2100.nc (monthly specific humidity; historical + SSP585); /CMIP6/ua_JJAS_model_1970-2100.nc (monthly zonal wind; historical + SSP585); /CMIP6-PI/q850_JJAS_model.nc (monthly specific humidity at 850 hPa; PI-control); /CMIP6-PI/pr_day_model.nc (daily precipitation; PI-control) * NEX-GDDP-CMIP6 data are available at [https://www.nccs.nasa.gov/services/data-collections/land-based-products/nex-gddp-cmip6](https://www.nccs.nasa.gov/services/data-collections/land-based-products/nex-gddp-cmip6). File used in this study: /CMIP6_correct/pr_day_model_1970-2100.nc (daily precipitation; pr) The aforementioned files are not provided here. Users can download and organize them by clicking the provided link(s). ## Code structure ### Files and variables #### File: codes_2026.zip ##### Flood_define **Definition of Flood Events** Flood events are defined according to Equation (1) in the main text. The corresponding code and required data are described below. * **a.** The raw data of ERA5, CPC, MERRA-2, and MSWEP can be directly downloaded from public websites. Process the raw data into multi-year daily data in the format of day × lat × lon. * **b.** Run /codes_2026/Flood_define/00.precip.ave.ncl. This script reads eight precipitation datasets (to be downloaded by users), calculates the regional mean over the NWSA region, and stores the results in the format of N × day, where N represents the number of datasets and day represents time. The output file is /codes_2026/Flood_define/00.precip.ave.nc. * **c.** According to the WAP definition, run /codes_2026/Flood_define/01.cpc-ave.sh, /codes_2026/Flood_define/01.era5-ave.sh, /codes_2026/Flood_define/01.merra2-ave.sh, and /codes_2026/Flood_define/01.MSWEP-ave.sh. These scripts read /codes_2026/Flood_define/00.precip.ave.nc and identify flood events under different parameter settings. The output files are located in /codes_2026/Flood_define/output_data/. * **d.** Download the raw CMIP6 data from public websites and process them into multi-year daily data in the format of day × lat × lon. Use /codes_2026/Flood_define/02.pr_avg.ncl to calculate the regional mean precipitation time series from the raw data and obtain the original precipitation, synoptic-scale component, Intraseasonal component, low-frequency component, and climatological component. The final format is 5 × day. The output results are located in /codes_2026/Flood_define/output_data/CMIP6/. * **e.** Run /codes_2026/Flood_define/02.cmip6_flood.ncl to identify flood events in CMIP6. The output results are located in /codes_2026/Flood_define/output_data/CMIP6/. * **f.** Read the CMIP6_corrected data and use /codes_2026/Flood_define/03.pr_avg.ncl to calculate the regional mean precipitation time series. The output results are located in /codes_2026/Flood_define/output_data/CMIP6_correct/. Then read the output files and run /codes_2026/Flood_define/03.flood1.ncl and /codes_2026/Flood_define/03.flood2.ncl to identify flood events in CMIP6_corrected. The output results are located in /codes_2026/Flood_define/output_data/CMIP6_correct/. * /codes_2026/Flood_define/extreme.ncl is a subroutine used to identify consecutive dates. ##### Shapley **Shapley Calculation in CMIP6** Run /codes_2026/Shapley/01.shapley.sh to calculate the Shapley contributions in CMIP6. The output results are located in /codes_2026/Shapley/output_data/. ##### CMIP6-ISO **Identification of ISO Events in CMIP6** **Midlatitude ISO Events** * **a.** Run /codes_2026/CMIP6-ISO/mid/01.ERA5-eof.ncl to obtain the observed midlatitude ISO modes. * **b.** Run /codes_2026/CMIP6-ISO/mid/01.project.ncl to obtain the projection coefficients in CMIP6. * **c.** Run /codes_2026/CMIP6-ISO/mid/01.v200-base.ncl to obtain the dates of midlatitude ISO events in CMIP6. * **d.** Run /codes_2026/CMIP6-ISO/mid/01.ISO-event.ncl to obtain the midlatitude ISO events in CMIP6. The output results are all located in /codes_2026/CMIP6-ISO/mid/output_data/. **Tropical ISO Events** * **a.** Run /codes_2026/CMIP6-ISO/tropical/CMIP6/pr_reg.sh to obtain tropical ISO events in the CMIP6 simulations. The output results are located in /codes_2026/CMIP6-ISO/tropical/CMIP6/output_data/. * **b.** Run /codes_2026/CMIP6-ISO/tropical/PIcontrol/pr_reg.sh to obtain tropical ISO events in the CMIP6 PI-control simulations. The output results are located in /codes_2026/CMIP6-ISO/tropical/PIcontrol/output_data/. **Filtering** All original datasets in the manuscript — including precipitation, OLR, and circulation variables — are filtered using the same parameters to obtain: Synoptic-scale component; ISO component (suffix: 10-90_bp, e.g., 01.U850.10-90_bp.nc); Low-frequency component and Climatological component. An example of the filtering procedure can be found in /codes_2026/Flood_define/02.pr_avg.ncl. *Note:* The filtered results are not provided in this repository. *Naming Convention* Variable names follow this format: [variable][level].[filter_type].nc Numbers immediately following variables indicate pressure levels, e.g., U200 = zonal wind at 200 hPa *Suffix definitions*: bp = band-pass filter; lp = low-pass filter; clim = daily climatology; 10-90_bp = 10–90-day band-pass filtered component; 90.lp = low-pass filtered component (&gt; 90 days) **Filtered files generated in this study** ***ERA5 (derived products):*** /ERA5/filter/01.MSE.10-90_bp.nc; /ERA5/filter/01.Z200.10-90_bp.nc; /ERA5/filter/01.V200.10-90_bp.nc; /ERA5/filter/01.T2m.10-90_bp.nc; /ERA5/filter/01.W500.10-90_bp.nc; /ERA5/filter/01.divergence.10-90_bp.nc; /ERA5/filter/01.U850.10-90_bp.nc; /ERA5/filter/01.V850.10-90_bp.nc; /ERA5/filter/01.Z850.10-90_bp.nc; /ERA5/filter/01.MSL.10-90_bp.nc; /ERA5/filter/01.Q.90.lp.nc; /ERA5/filter/01.Q.clim.nc; /ERA5/filter/01.W.clim.nc; /ERA5/filter/01.MFC.10-90_bp.nc; /ERA5/filter/01.T.10-90_bp.nc; /ERA5/filter/01.precip.10-90_bp.nc ***CPC (derived):*** /CPC/filter/01.CPC.precip.clim.nc ***OLR (derived):*** /OLR/filter/olr.20-90_bp.nc ***CMIP6 (derived):*** /CMIP6/filter/v250_10-90_bp_model_1979-2099.nc; /CMIP6/filter/pr_model_10-90_bp.nc ***CMIP6 PI-control (derived):*** /CMIP6-PI/filter/pr_10-90_bp_model.nc ##### K-means **K-means Clustering** * **a.** Identification of tropical ISO events. Run /codes_2026/K-means/20.20-90-olr.ncl. This script reads filtered OLR data (not provided) and identifies tropical ISO events. Output: /codes_2026/K-means/20.event_20-90.nc * **b.** Composite latitude–time structure. Run /codes_2026/K-means/20.20-90-chose.ncl. This script generates latitude–time composites of tropical ISO events. Output: /codes_2026/K-means/20.ISO_cluster_20-90.nc * **c.** Clustering analysis. Run /codes_2026/K-means/tropical_20_90.m. This MATLAB script performs clustering analysis based on the latitude–time structure. Outputs: /codes_2026/K-means/20.idx_20-90.txt, /codes_2026/K-means/20.silhou_20-90.txt. These files record cluster categories and silhouette values. ##### Main **Figure 1** * **a.** Run /codes_2026/Main/Fig1/00.filter.ncl to obtain the band-pass filtered results. The output results are located in /codes_2026/Main/Fig1/output_data/. * **b.** Run /codes_2026/Main/Fig1/01.Fig1.ncl. This script reads the files in /codes_2026/Main/Fig1/output_data/ and generates Fig. 1. **Figure 2** * **a.** Run /codes_2026/Main/Fig2/00.fig21.ncl. This script composites the convection data before and after flood events defined by CPC, and outputs /codes_2026/Main/Fig2/output_data/00.fig21.nc. * **b.** Run /codes_2026/Main/Fig2/00.fig22.ncl. This script composites the circulation data before and after flood events defined by CPC, and outputs /codes_2026/Main/Fig2/output_data/00.fig22.nc. * **c.** Run /codes_2026/Main/Fig2/00.test.ncl to perform a Monte Carlo test for tropical northward-propagating ISO precipitation before and after 2000. The output is /codes_2026/Main/Fig2/output_data/test.nc. * **d.** Run /codes_2026/Main/Fig2/00.pre-iso.ncl to composite the circulation and convection of tropical northward-propagating ISO events before and after 2000. The output is /codes_2026/Main/Fig2/output_data/012.pre-iso.nc. * **e.** Run /codes_2026/Main/Fig2/01.Fig2.ncl. This script reads the files in /codes_2026/Main/Fig2/output_data/ and generates Fig. 2. **Figure 3** * **a.** Run /codes_2026/Main/Fig3/00.flood-WAF.ncl to composite the midlatitude wave activity flux before and after Flood events. The output is /codes_2026/Main/Fig3/output_data/01.flood-WAF.nc. * **b.** Run /codes_2026/Main/Fig3/00.data.ncl to calculate the composite fields of V200 and T2m before and after Flood events. The output is /codes_2026/Main/Fig3/output_data/03.data.nc. * **c.** Run /codes_2026/Main/Fig3/00.flood-VW.ncl to composite the midlatitude circulation field before and after Flood events. The output is /codes_2026/Main/Fig3/output_data/031.flood-vw.nc. * **d.** Run /codes_2026/Main/Fig3/032.data.ncl to composite the midlatitude wave activity flux before and after Flood events. The output is /codes_2026/Main/Fig3/output_data/032.data.nc. * **e.** Run /codes_2026/Main/Fig3/052.data.ncl to composite the midlatitude wave activity flux before and after Flood events that are only regulated by midlatitude ISO. The output is /codes_2026/Main/Fig3/output_data/052.data.nc. * **f.** Run /codes_2026/Main/Fig3/v_test.ncl to test the propagation speed of midlatitude ISO before and after 2000. The output is /codes_2026/Main/Fig3/output_data/v_test.nc. * **g.** Run /codes_2026/Main/Fig3/01.Fig31.ncl and /codes_2026/Main/Fig3/01.Fig32.ncl. These scripts read the files in /codes_2026/Main/Fig3/output_data/ and generate Fig. 3. **Figure 4** * **a.** Run /codes_2026/Main/Fig4/01.budget-his.ncl to calculate the equation diagnostic results for the historical period based on observational data. The output is /codes_2026/Main/Fig4/output_data/01.budget-his.nc. * **b.** Run /codes_2026/Main/Fig4/01.shapley-his.ncl to calculate the Shapley results for the historical period based on observational data. The output is /codes_2026/Main/Fig4/output_data/01.shapley-his.nc. * **c.** Run /codes_2026/Main/Fig4/01.Sensitivity-his.ncl to calculate the contributions of different seasonal oscillations during the historical period based on observational data. The output is /codes_2026/Main/Fig4/output_data/01.Sensitivity-his.nc. * **d.** Run /codes_2026/Main/Fig4/01.budget-future.ncl to calculate the equation diagnostic results based on CMIP6 data. The output is /codes_2026/Main/Fig4/output_data/01.budget-future.nc. * **e.** Run /codes_2026/Main/Fig4/01.shapley-future.ncl to calculate the Shapley results for the historical period based on CMIP6 data. The output is /codes_2026/Main/Fig4/01.shapley-future.nc. * **f.** Run /codes_2026/Main/Fig4/01.sha2.ncl to calculate the Shapley results for the future period based on CMIP6 data. The output is /codes_2026/Main/Fig4/output_data/sha2.nc. * **g.** Run /codes_2026/Main/Fig4/02.Fig4.ncl. This script reads the files in /codes_2026/Main/Fig4/output_data/ and generates Fig. 4. **Figure 5** * **a.** Run /codes_2026/Main/Fig5/01.deta_mean.ncl to calculate the results according to Equation (3) in the main text. The output is /codes_2026/Main/Fig5/01.deta_mean_CPC.nc. * **b.** Run /codes_2026/Main/Fig5/01.P_var.ncl to calculate the results according to Equation (4) in the main text. The output is /codes_2026/Main/Fig5/output_data/01.P_var.nc. * **c.** Run /codes_2026/Main/Fig5/01.split.ncl to calculate the results according to Equation (5) in the main text. The output is /codes_2026/Main/Fig5/output_data/01.split.nc. * **d.** Run /codes_2026/Main/Fig5/02.Fig5.ncl. This script reads the files in /codes_2026/Main/Fig5/output_data/ and generates Fig. 5. **Figure 6** * **a.** Run /codes_2026/Main/Fig6/01.model.ncl to composite the changes in flood characteristics in CMIP6 data. The output is /codes_2026/Main/Fig6/output_data/20.model.nc. * **b.** Run /codes_2026/Main/Fig6/01.model-cor.ncl to composite the changes in flood characteristics in CMIP6-corrected data. The output is /codes_2026/Main/Fig6/output_data/20.model-cor.nc. * **c.** Run /codes_2026/Main/Fig6/02.Fig6.ncl. This script reads the files in /codes_2026/Main/Fig6/output_data/ and generates Fig. 6. **Figure 7** * **a.** Run /codes_2026/Main/Fig7/01.Q850.ncl to calculate the Q (specific humidity) time series in CMIP6 data. The output is /codes_2026/Main/Fig7/output_data/01.Q850.nc. * **b.** Run /codes_2026/Main/Fig7/01.U250.ncl to calculate the U (zonal wind) time series in CMIP6 data. The output is /codes_2026/Main/Fig7/output_data/01.U250.nc. * **c.** Run /codes_2026/Main/Fig7/01.SR.ncl to composite the changes in midlatitude wave trains in different periods of CMIP6. The output is /codes_2026/Main/Fig7/output_data/01.SR.nc. * **d.** Run /codes_2026/Main/Fig7/01.v_test1.ncl to test the changes in propagation speed of midlatitude ISO in CMIP6. The output is /codes_2026/Main/Fig7/output_data/01.v_test1.nc. * **e.** Run /codes_2026/Main/Fig7/02.Fig7.ncl. This script reads the files in /codes_2026/Main/Fig7/output_data/ and generates Fig. 7. ##### Sup **Figure S1** Read the data in /codes_2026/Flood_define/, run /codes_2026/Sup/00.FigS1_data.sh to generate Flood events identified by different methods. The output directory is /codes_2026/Sup/output_data/1/. Run /codes_2026/Sup/01.FigS1.ncl to generate Fig. S1. **Figure S2** Read the data in /codes_2026/Flood_define/, run /codes_2026/Sup/00.FigS2_data.sh to generate Flood events identified by different methods. The output directory is /codes_2026/Sup/output_data/2/. Run /codes_2026/Sup/01.FigS2.ncl to generate Fig. S2. **Figure S3** Read /codes_2026/Main/Fig2/output_data/01.olr.10-90_bp.nc, /codes_2026/Flood_define/output_data/ERA5/ERA5-event_ave7.nc, and the filtered precipitation data of ERA5. Run /codes_2026/Sup/01.FigS3.ncl to generate Fig. S3. **Figure S4** * **a.** Run /codes_2026/Sup/00.FigS4-data.ncl, read the files under /codes_2026/K-means/, and generate convection data of tropical intraseasonal oscillations for different categories. The output is /codes_2026/Sup/output_data/4/00.FigS4-data.nc. * **b.** Run /codes_2026/Sup/01.FigS4.ncl, read /codes_2026/Sup/output_data/4/00.FigS4-data.nc, and generate Fig. S4. **Figure S5** * **a.** Run /codes_2026/Sup/00.FigS5-data.ncl, read the files under /codes_2026/K-means/ and the filtered ERA5 data, and generate convection data of tropical intraseasonal oscillations for different categories. The output is /codes_2026/Sup/output_data/5/00.FigS5-data.nc. * **b.** Run /codes_2026/Sup/01.FigS5.ncl and generate Fig. S5. **Figure S6** * **a.** Run /codes_2026/Sup/00.FigS6-data1.ncl, read CMIP6 historical simulation data, and generate data describing the relationship between background moisture and ISO propagation. The outputs are /codes_2026/Sup/output_data/6/1.nc and /codes_2026/Sup/output_data/6/skill-final.nc. * **b.** Run /codes_2026/Sup/00.FigS6-data2.ncl, read CMIP6 PI-Control data, and generate data describing the relationship between background moisture and ISO propagation. The output is /codes_2026/Sup/output_data/6/PI.nc. * **c.** Run /codes_2026/Sup/00.FigS6-data3.ncl, read ERA5 data, and generate the mean background fields before and after 2000. The output is /codes_2026/Sup/output_data/6/01.FigS6.nc. * **d.** Run /codes_2026/Sup/01.FigS6.ncl, read the files under /codes_2026/Sup/output_data/6/, and generate Fig. S6. **Figure S7** * **a.** Run /codes_2026/Sup/00.FigS7-data.ncl, read the filtered ERA5 data, and generate the annual mean circulation fields. The output is /codes_2026/Sup/output_data/7/03.data.nc. * **b.** Run /codes_2026/Sup/01.FigS7.ncl, read /codes_2026/Sup/output_data/7/03.data.nc, and generate Fig. S7. **Figure S8** * **a.** Run /codes_2026/Sup/00.FigS8-data1.sh, read ERA5 data, and composite the circulation data before and after Flood events (The results are not provided in this repository). * **b.** Run /codes_2026/Sup/00.FigS8-data2.ncl, read ERA5 data, calculate the temperature budget equation, and output /codes_2026/Sup/output_data/8/ERA5.T_budget.nc and /codes_2026/Sup/output_data/8/ERA5.T_budget1.nc. * **c.** Run /codes_2026/Sup/00.FigS8-data3.ncl, read ERA5 data and the temperature budget data, composite the results, and output /codes_2026/Sup/output_data/8/03.var-data.nc and /codes_2026/Sup/output_data/8/03.var-data1.nc. * **d.** Run /codes_2026/Sup/01.FigS8.ncl, read the files under /codes_2026/Sup/output_data/8/ and ERA5 data, and generate Fig. S8. **Figure S9** Read /ERA5/U_1979-2023.nc (ERA5 summer zonal wind), /codes_2026/Sup/output_data/9/00.precip-MJJASO.nc (EOF results of ERA5 precipitation representing tropical ISO), /codes_2026/Sup/output_data/9/00.precip-eof.nc (lead–lag correlations of the first two PCs of precipitation EOF), /codes_2026/Sup/output_data/9/00.SR-MJJASO.nc (EOF results of ERA5 V200 representing midlatitude ISO), and /codes_2026/Sup/output_data/9/00.eof-V200.nc (lead–lag correlations of the first two PCs of V200 EOF). Run /codes_2026/Sup/01.FigS9.ncl to generate Fig. S9. **Figure S10** Read /codes_2026/Sup/output_data/10/00.precip-MJJASO.nc (EOF data of ERA5 precipitation), /codes_2026/Sup/output_data/10/00.precip.nc (composite precipitation of all tropical ISO events in ERA5), /codes_2026/Sup/output_data/10/02.tropical-data.nc (composite results of different types of tropical ISO events in ERA5), /codes_2026/Sup/output_data/10/02.tropical-type.nc (file recording the types of tropical ISO events), and /codes_2026/Flood_define/output_data/CPC/CPC-event_ave7.nc. Run /codes_2026/Sup/01.FigS10.ncl to generate Fig. S10. **Figure S11** Read /codes_2026/Sup/output_data/11/00.SR-MJJASO.nc (EOF data of ERA5 V200), /codes_2026/Sup/output_data/11/00.V200.nc (composite V200 of all midlatitude ISO events in ERA5), /codes_2026/Sup/output_data/11/02.mid-data.nc (composite results of different types of midlatitude ISO events in ERA5), /codes_2026/Sup/output_data/11/02.mid-type.nc (file recording the types of midlatitude ISO events), and /codes_2026/Flood_define/output_data/CPC/CPC-event_ave7.nc. Run /codes_2026/Sup/01.FigS11.ncl to generate Fig. S11. **Figure S12** Read the LP90 and CTRL experiment data under /codes_2026/Sup/output_data/12/. These two files describe the circulation results before and after Flood events in the GFDL model. Run /codes_2026/Sup/01.FigS12.ncl to generate Fig. S12. **Figure S13** Read /codes_2026/Sup/output_data/13/01.data.nc. This file describes the circulation results before and after Flood events before and after 2000 in ERA5. Run /codes_2026/Sup/01.FigS13.ncl to generate Fig. S13. **Figure S14** Read /codes_2026/Sup/output_data/14/01.SR-JJAS.nc (EOF results of summer Z200), /codes_2026/Sup/output_data/14/01.z200.std.nc (standard deviation of summer Z200), /codes_2026/Sup/output_data/14/01.spe1-1.nc (power spectrum of PC1 before 2000), and /codes_2026/Sup/output_data/14/01.spe1-2.nc (power spectrum of PC1 after 2000). Run /codes_2026/Sup/01.FigS14.ncl to generate Fig. S14. **Figure S15** Read /codes_2026/Sup/output_data/15/01.Jet-index.nc (annual index of jet position and intensity in ERA5), /codes_2026/Sup/output_data/15/02.event-AMP1.nc (intensity of each midlatitude ISO event in ERA5), /codes_2026/Sup/output_data/15/02.event-precip1.nc (associated precipitation of each midlatitude ISO event in ERA5), /codes_2026/Sup/output_data/15/02.event-V2001.nc (associated V200 of each midlatitude ISO event in ERA5), /codes_2026/Sup/output_data/15/10.mid.nc (annual data of midlatitude wave train period in CMIP6), and /codes_2026/Sup/output_data/15/10.U250.nc (propagation speed of midlatitude ISO events in CMIP6). Run /codes_2026/Sup/01.FigS15.ncl to generate Fig. S15. **Figure S16** Run /codes_2026/Sup/01.FigS16.ncl to generate Fig. S16. **Figure S17** Read /CPC/CPC.precip.1979-2025.nc, the Flood events identified by different datasets under /codes_2026/Flood_define/output_data/, the precipitation time series of different datasets under /codes_2026/Sup/output_data/17/, and /codes_2026/Sup/output_data/17/01.model.nc (precipitation associated with Flood events in different datasets). Run /codes_2026/Sup/01.FigS17.ncl to generate Fig. S17.