DataSet for Research Article: FHD: An Extended Disturbance Storm-Time Index Based on Fitted Functions of Horizontal Geomagnetic Field Variation

Data Description This dataset contains three comprehensive components for the FHD (Fitted Horizontal Disturbance) geomagnetic index calculation and validation: 01_DataSet_FHD_index.zip FHD Index Dataset Structure The FHD index dataset is organized by year and month, with each folder following the naming convention FHD-YYYYMM (e.g., FHD-200812 for December 2008). File Contents and Descriptions: 01 FHD_global.csv Content: FHD_global index values for the corresponding month Description: This file contains the global FHD index calculated using the Fourier series fitting method. The index represents the fitted horizontal disturbance in the Earth's magnetic field, derived from low-latitude geomagnetic stations (magnetic latitude ≤ 50°). The data provides minute-by-minute resolution of geomagnetic activity. Format: CSV file with columns: DATE: Timestamp in YYYY-MM-DD HH:MM:SS format FHD_global: Global FHD index values in nT (nanotesla) 02 FHD_mean.csv Content: FHD_mean index values for the corresponding month Description: This file contains the mean FHD index calculated using direct averaging of corrected Dst values from all available low-latitude stations. This provides a straightforward estimate of the horizontal disturbance without Fourier series fitting. Format: CSV file with columns: DATE: Timestamp in YYYY-MM-DD HH:MM:SS format FHD_mean: Mean FHD index values in nT (nanotesla) 03 mat_fit_paras_for_FHD_mlt.csv Content: Fourier series fitting parameters Description: This file contains the Fourier series fitting parameters that can be used to reconstruct all FHD_mlt index family members. These parameters enable the generation of magnetic local time (MLT) dependent FHD indices, providing a complete characterization of the fitted horizontal disturbance pattern as a function of local time. Format: CSV file with columns: DATE: Timestamp in YYYY-MM-DD HH:MM:SS format Parameter_columns: Various Fourier series coefficients (a0, a1, b1, a2, b2, a3, b3) for each time point 07 station_avaliable_df_v2.csv Content: Final station information used in index calculation Description: This file contains comprehensive information about all stations that were ultimately included in the FHD index calculation. It includes station metadata such as geographic coordinates, geomagnetic coordinates, data quality metrics, and availability flags. Format: CSV file with columns: Station codes as index glon, glat: Geographic longitude and latitude mlon, mlat: Geomagnetic longitude and latitude NaNprop: Proportion of missing data Additional quality control parameters Data Coverage The dataset spans from December 2008 to April 2024, providing continuous coverage of geomagnetic activity over approximately 15.5 years. Each monthly folder contains the complete set of files necessary for both the global FHD index and the reconstruction of MLT-dependent index variations. Quality Control The dataset incorporates multiple levels of quality control: Station selection based on magnetic latitude criteria (≤ 50°) Data completeness verification Over-fitting detection and station removal Fourier series fitting quality assessment 02_Cubic Spline Interpolation Verification Figures.zip Cubic Spline Interpolation Effect Verification Figure Collection This collection contains comprehensive verification figures demonstrating the effectiveness of cubic spline interpolation in processing geomagnetic station data. The figures include: Data quality assessment plots for individual stations Interpolation effect comparisons before and after processing Station-specific verification images showing data integrity Quality control visualization for the FHD index calculation process These figures provide essential validation for the data processing methodology and ensure the reliability of the FHD index calculations. 03_Code_Data_Download&Process.zip FHD Index Calculation Code Package This comprehensive code package provides the complete software solution for downloading, processing, and calculating the FHD geomagnetic index. The package includes: Main Scripts: dataDL&process_partA.py: Data download and initial processing module dataDL&process_partB.py: Advanced processing and FHD calculation module Function Modules: DstCalculation/func_DstCalculation.py: Dst index calculation functions add_mlt_time_columns/func_mlt_time_calculator.py: Magnetic Local Time calculation functions process_station_data/func_process_station_data.py: Station data processing and validation functions fit_dst_data_paras/func_fit_curve_paras.py: Fourier series fitting parameter calculation functions API Interface: supermag-api-2025.py: SuperMAG API interface module Features: Automated data download from SuperMAG API Comprehensive data quality control and station filtering Dual FHD index calculation methods (direct averaging and Fourier series fitting) Debug mode for testing and development Complete documentation and usage instructions