DOI: 10.5061/dryad.nvx0k6f0z
title: Data from: Tropical Indian Ocean drives Hadley circulation change in a warming climate

description: This study examines how future warming in different ocean basins may
 affect the Hadley circulation—a crucial component of the global climate
 system. We find that warming in the tropical Indian Ocean is the primary
 driver of future changes in this circulation, while variations in tropical
 Pacific warming contribute to uncertainties in climate projections. Our
 findings enhance our understanding of the potential impacts of global
 warming on atmospheric circulation.
description: All the CMIP5 experiments listed in the Table S1 are available:
 [https://www.ipcc-data.org/sim/gcm_monthly/AR5/Reference-Archive.html](https://www.ipcc-data.org/sim/gcm_monthly/AR5/Reference-Archive.html). Access to the data used for the plots in this study is available online (released by dryad). Additional results of the SST perturbation simulations are available from the corresponding author: Dr. Yong Sun, [yongsun@itpcas.ac.cn](mailto:yongsun@itpcas.ac.cn). **Data Description for Dryad Repository** This dataset supports the analyses presented in Figures 1–4 of the associated publication, detailing the impacts of CO₂ radiative forcing and sea surface temperature (SST) changes on the Hadley circulation and the ITCZ. It comprises model simulation outputs and processed results used to investigate the role of global and regional ocean warming patterns. **Figure 1: Impacts of CO₂ Radiative Forcing and Ocean Warming** * **Contents**: Changes in Southern and Northern Hadley cell extents (LatSHC, LatNHC), ITCZ position (LatITCZ), and Northern Hemisphere Hadley cell intensity (IntensityNHC; units: 10¹⁰ kg s⁻¹) during boreal winter (DJF). * **Simulations**: * Full anthropogenic greenhouse gas effects (RCP8.5-historical). * Direct CO₂ radiative effects (amip4xCO₂ minus amip). * Uniform SST warming (amip4K minus amip). * Non-uniform SST warming patterns (amipFuture minus amip). **Variables in NetCDF Files:** There are four NetCDF files included: \- `Fig.1A_data.nc` \- `Fig.1B_data.nc` \- `Fig.1C_data.nc` \- `Fig.1D_data.nc` Since the data structure in the four NetCDF files is similar, with only the variable names differing (`latSHC`, `latNHC`, `latITCZ`, `IntensityNHC`), we will use the variable `latSHC` in `Fig.1A_data.nc` as an example for description. The other three variables can be described analogously. Variable Descriptions for `latSHC` in `Fig.1A_data.nc`: 1\. **`plotbox_rcp85_latSHC_response`**: \- Represents the **LatSHC response** (RCP8.5 minus historical) based on **32 models**. \- Shown as a **blue boxplot**. 2\. **`plotbox_rcp85_as_amip_latSHC_response`**: \- Represents the same as above but based on **11 models**. \- Shown as a **red boxplot**. 3\. **`plotbox_amip4xCO2_latSHC_response`**: \- Represents the **LatSHC response** to **direct CO₂ radiative effects** (amip4xCO2 minus amip) based on **11 models**. \- Shown as a **red boxplot**. 4\. **`plotbox_amip4K_latSHC_response`**: \- Represents the **LatSHC response** to **uniform SST warming** (amip4K minus amip) based on **11 models**. \- Shown as a **red boxplot**. 5\. **`plotbox_amipFuture_latSHC_response`**: \- Represents the **LatSHC response** to **non-uniform SST warming patterns** (amipFuture minus amip) based on **11 models**. \- Shown as a **red boxplot**. This structure is repeated for the other variables (`latNHC`, `latITCZ`, `IntensityNHC`) in their respective NetCDF files. **Figure 2: Idealized Ocean Basin Warming Experiments** * **Contents**: Responses of LatITCZ, LatNHC, LatSHC, and IntensityNHC to amplified historical SST warming in individual ocean basins. * **Details**: Experiments use scaling factors to amplify historical warming patterns in the Tropical Indian Ocean, South Atlantic, and North Atlantic, to find the candidate basin that potentially impact the future Hadley circulation. * **Data Source**: idealized experiments. * **NetCDF File Description for `Fig.2.nc`:** The file `Fig.2.nc` contains four variables used to generate Figure 2. These variables are: 1. **`plot_show_latSHC`**: * Represents the data for the **Southern Hadley Cell extent (LatSHC)** used in Figure 2. 2. **`plot_show_latNHC`**: * Represents the data for the **Northern Hadley Cell extent (LatNHC)** used in Figure 2. 3. **`plot_show_latITCZ`**: * Represents the data for the **ITCZ position (LatITCZ)** used in Figure 2. 4. **`plot_show_IntensityNHC`**: * Represents the data for the **Northern Hemisphere Hadley Cell intensity (IntensityNHC)** used in Figure 2. **Figure 3: Responses to Global and Basin-Specific Warming** * **Contents**: Changes in LatSHC, LatNHC, LatITCZ, and IntensityNHC under 1.5°C, 2°C, and 3°C warming thresholds above pre-industrial levels. * **Analyses**: Global and individual ocean basin forcings are evaluated for their impacts on atmospheric circulation. * **Data Source**: large ensemble of SST perturbation experiments under 1.5°C, 2°C, and 3°C warming thresholds. * **Figure 3 Data Description:** Figure 3 consists of four NetCDF files, each corresponding to a specific subplot: 1. **`whiskerboxplot_latSHC_data_Fig.3A.nc`**: * Contains the variable **`yval_five_SHCE`**, which represents the data for the **Southern Hadley Cell extent (LatSHC)** used in Figure 3A. 2. **`whiskerboxplot_latNHC_data_Fig.3B.nc`**: * Contains the variable **`yval_five_NHCE`**, which represents the data for the **Northern Hadley Cell extent (LatNHC)** used in Figure 3B. 3. **`whiskerboxplot_latITCZ_data_Fig.3C.nc`**: * Contains the variable **`yval_five_ITCZP`**, which represents the data for the **ITCZ position (LatITCZ)** used in Figure 3C. 4. **`whiskerboxplot_IntensityNHC_data_Fig.3D.nc`**: * Contains the variable **`yval_five_NHCI`**, which represents the data for the **Northern Hemisphere Hadley Cell intensity (IntensityNHC)** used in Figure 3D. Each file contains a single variable, and the data is used to generate whisker-box plots for the respective metrics in Figure 3. **Figure 4: Mechanisms Driving Hadley Cell and ITCZ Responses** * **Contents**: Examination of LatITCZ, LatSHC, LatNHC, and IntensityNHC responses to regional SST warming patterns under the same temperature thresholds as in Figure 3. * **Key Variables**: * ITCZ migration versus interhemispheric thermal contrast. * Hadley cell shifts versus SST gradients. * Contrasting effects of South Atlantic and Tropical Indian Ocean on tropical diabatic heating. - **Data Source**: large ensemble of SST perturbation experiments under 1.5°C, 2°C, and 3°C warming thresholds. **Figure 4 Data Description:** Figure 4 consists of six individual NetCDF files, each corresponding to a specific subplot: 1. **`Fig.4A.nc`**: * Used to plot the response of **latITCZ** to the **maximum heat source in the Tropical Indian Ocean (TIO)** under three warming thresholds. * Contains the following variable pairs: * `maxSSTAValue_rcp45_1p5_TIN_show` and `latITCZ_rcp45_1p5_TIN_show` * `maxSSTAValue_rcp45_2_TIN_show` and `latITCZ_rcp45_2_TIN_show` * `maxSSTAValue_rcp85_3_TIN_show` and `latITCZ_rcp85_3_TIN_show` 2. **`Fig.4B.nc`**, **`Fig.4C.nc`**, **`Fig.4D.nc`**, and **`Fig.4E.nc`**: * These files have a similar data structure to `Fig.4A.nc` and are used for analogous analyses. 3. **`Fig.4F.nc`**: * Describes the **tropical atmospheric diabatic heating (Q) response** to **TIO and SA (South Atlantic) forcing**. * Contains the variable: * `yval_two_TDH` All the uploaded files can be reviewed by NCL  ([https://www.ncl.ucar.edu/](https://www.ncl.ucar.edu/)) or panoply ([https://www.giss.nasa.gov/tools/panoply/](https://www.giss.nasa.gov/tools/panoply/))