A long-term database of the Integrated Drought Index for Brazil from 2003 to 2023

The Integrated Drought Index (IDI) was developed at the National Center for Monitoring and Early Warning of Natural Disasters (Cemaden, www.cemaden.gov.br), in Brazil, to support the monitoring of agricultural drought. The index is a combination of three components: the 3-month Standardized Precipitation Index (SPI3), the Root Zone Soil Moisture (RZSM), and the Vegetation Health Index (VHI). The SPI3 is calculated from a long-term dataset of precipitation records in Brazil with a spatial resolution of 10 km (https://ftp.cptec.inpe.br/modelos/tempo/MERGE/). The RZSM is obtained from NASA's Gravity Recovery and Climate Experiment (GRACE; 2002-2017) and GRACE Follow On (GRACE-FO; 2018-present) satellites (https://nasagrace.unl.edu). The product is released weekly since 2003 with a spatial resolution of 25 km. The VHI is obtained from NOAA's polar-orbiting satellites, available weekly with a spatial resolution of approximately 4 km (https://www.star.nesdis.noaa.gov/smcd/emb/vci/VH/vh_ftp.php).
The IDI is used in Cemaden's continuous monitoring activities of drought over Brazil, including monthly meetings with stakeholders, preparing of reports on drought conditions, and updates of an online platform (https://mapasecas.cemaden.gov.br). A previous version of IDI without RZSM was already used in reports of droughts over Brazil, such as in Cunha et al. (2019, https://doi.org/10.3390/atmos10110642). The current version of IDI is routinely assessed against reports of yield losses and other drought indicators. A publication is currently being prepared to assess its spatial and temporal accuracy when compared with other indices. Preliminary results indicate good agreement with the Standardized Precipitation Evapotranspiration Index (SPEI).
This dataset contains a netCDF file (IDI3.nc) with the index in the variable IIS3. The variable has values ranging from 1 to 6, corresponding to the following drought classes: Exceptional, Extreme, Severe, Moderate, Weak, and Normal conditions.

综合干旱指数（Integrated Drought Index，IDI）由巴西国家自然灾害监测与预警中心（National Center for Monitoring and Early Warning of Natural Disasters，Cemaden，www.cemaden.gov.br）研发，旨在支撑农业干旱监测工作。该指数由三个组分融合构建而成：3个月标准化降水指数（3-month Standardized Precipitation Index，SPI3）、根区土壤湿度（Root Zone Soil Moisture，RZSM）以及植被健康指数（Vegetation Health Index，VHI）。其中SPI3基于巴西长期降水记录数据集计算得到，空间分辨率为10 km，数据来源为https://ftp.cptec.inpe.br/modelos/tempo/MERGE/。RZSM的数据来源于美国国家航空航天局（National Aeronautics and Space Administration，NASA）的重力恢复与气候实验卫星（Gravity Recovery and Climate Experiment，GRACE；2002-2017年）及其后续任务GRACE-FO（2018年至今），数据获取地址为https://nasagrace.unl.edu。该产品自2003年起每周发布，空间分辨率为25 km。VHI的数据来自美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration，NOAA）极轨卫星，每周更新，空间分辨率约为4 km，数据获取地址为https://www.star.nesdis.noaa.gov/smcd/emb/vci/VH/vh_ftp.php。
IDI目前应用于Cemaden开展的巴西全国干旱持续监测工作，包括与利益相关方举行月度会商、编制干旱状况报告以及更新在线平台（https://mapasecas.cemaden.gov.br）。此前未集成RZSM组分的IDI版本已被用于巴西干旱相关报告，例如Cunha等人2019年的研究（https://doi.org/10.3390/atmos10110642）。当前版本的IDI会定期与作物减产报告及其他干旱指标开展比对评估。目前有一篇旨在对比该指数与其他干旱指数以评估其时空精度的学术论文正在筹备中，初步结果显示其与标准化降水蒸散指数（Standardized Precipitation Evapotranspiration Index，SPEI）的吻合度良好。
本数据集包含一个netCDF格式文件（IDI3.nc），其中变量IIS3存储了综合干旱指数数据。该变量的取值范围为1至6，依次对应以下干旱等级：异常极端（Exceptional）、极端（Extreme）、严重（Severe）、中等（Moderate）、轻度（Weak）与正常（Normal）状况。