MHW_Drivers

Code to support publication: Holbrook et al., Nature Communications, A global assessment of marine heatwaves and their drivers.

Figure 1

Scripts to generate Figure 1 are in the 'Figure_1' folder.

• mhw_census.py generates the mean MHW intensity, duration and frequency data globally, following Oliver et al. (Nat. Comms., 2018) and identical code supporting that paper here.
• mhw_census_plots_MHWDrivers.py uses the data generated by the previous script, and the coordinates of the region boxes in the 'data/' subfolder, to generate the figure in the manuscript.

Figure 3

Scripts to generate Figure 3 are in the 'Figure_3_4_Table_2' folder.

• summary_fig_detrended_corrected.m Collates information for significant increases/decreases in MHW day occurrence associated with different climate indices and generates fig. 4

• summaryFig_modesVSmhw_detrended_corrected_aug2018.m Generates data for the above script. Calculates increase/decrease in marine heatwave days at each grid point and tests if the change is significant (based on Monte Carlo test)

• load_modes.m Used in the above. Loads climate indices (based on the following data files): NAO.txt AMO.txt nino34.txt PDO.txt TPI_IPO.txt ANino.txt SAM.txt MODOKI.txt DMI.txt NPGO.txt

• parallel_process_MHW_regional_blocks_2degree.sh Calculate regional MHW statistics from raw NOA OI SSST data for use in summary_fig_detrended_corrected.m Uses: regional_MHW_pc90_reducedFileSize_2degree.py

Figure 4

Scripts to generate Figure 4 are in the 'Figure_3_4_Table_2' folder.

• plot_regional_anomaly_drivers_corrected.m Processes data for Figure 4: MHW days associated with each mode/region

• regional_anomaly_drivers_cummulatice_stats_detrended_corrected.m Generates data for above script. Calculates increase/decrease in marine heatwave days for each region and tests if the change is significant (based on Monte Carlo test)

Table 2

Scripts to generate Table 2 are in the 'Figure_3_4_Table_2' folder.

• MHWControlGUI_updated.m
• MHWControlGUI_updated.fig

Above code uses the processed region MHW data and opens it in a GUI that calculates the size, maximum intensity etc of manually selected MHW. Data derived from the output of this function are used to populate table 2

Process raw NOAA OI data to regional subsets that contain SSTA and MHW categories (for use in the above codes):

• parallel_process_data_to_regional_blocks.sh Concatenates files into continuous time series in blocks of 30 deg. x 20 deg. (lon x lat). Automatically spans multiple parallel jobs, 1 for each block

• parallel_process_MHW_regional_blocks.sh Parallel processing of regional blocks to calculate MHW statistics using marineHeatWaves90.py

• parallel_process_MHW_regional_blocks_98pc.sh As above but uses the 98% criteria used for Table 2. Uses: marineHeatWaves98.py

Figure 4

Additional scripts to generate Figure 4 are in the 'Figure_4' folder.