Atmospheric River Database for the Himalayas
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Atmospheric Rivers (ARs) are long and narrow regions of intense moisture transport in the lower troposphere. The dataset comprises of Atmospheric Rivers that have happened over the Himalayan Basins from 1982 to 2018. It includes the dates and times, duration, intensity/magnitude, tracks, and categories of the ARs. File Names and description: 1. ERA5_Persistant_Database2000km: This file includes the date, times, average Integrated Water Vapor Transport (IVT) magnitude (kg.m^-1s^-1), starting IVT, maximum IVT, and duration of ARs. These terms are explained below in greater details. Column “Date”: Gives the date and time (in Coordinated Universal Time UTC) of each AR timestep. The IVT data used to identify ARs is 6-hourly (00UTC, 06UTC, 12UTC and 18UTC). Column “AR_ID”: Each identified persistent AR, lasting for at least 18 hours, is given a unique ID, which remains same for all timesteps of the AR. This column gives the ID of ARs. The ID of an AR is based on the year in which the AR occurred, the letters “AR”, and the occurrence serial of the AR in the year. For example, the first AR in 1990 has ID 1980AR1. If the AR lasted for 10 timesteps, all 10 timesteps will have the same ID. Column “Ind”: This column gives the python index of IVT data in 6-hour yearly data, giving the date and time of each AR timestep. This column can be ignored since the same information is more directly available in “Date” column. Column “AvgIVT”: This column gives the average IVT magnitude (kg.m^-1s^-1) along the AR major axis, i.e., the gridcells that have maximum IVT along the AR track. For example, the first value corresponds to the average of all values from column “0” to column “88”, which give the IVT magnitude at each gridcell of the major axis of the first timestep. Column “StartIVT”: This column gives the IVT magnitude (kg.m^-1s^-1) at the initial gridcell on the first timestep when AR condition was identified. Column “ARDuration”: This column gives duration of the AR in hours; for example, an AR lasting for three timesteps will have the duration of 18 hours, an AR lasting for four timesteps will have duration of 24 hours. Column “MaxIVT”: This column gives the maximum of all IVT values (kg.m^-1s^-1) at the starting gridcells on each timestep of an AR. Column “ARCat”: This column gives category of the AR, based on IVT magnitude and duration of the ARs. Six categories have been defined, Cat0 denoting the weakest AR and Cat5 denoting the strongest AR. More details on this can be found in the accompanying paper. Column “0” to the end. These columns give the IVT magnitude (kg.m^-1s^-1) at each gridcell of the major axis of each AR timestep. Note that the cyclone dates were not available before 1982, so AR dates for 1979 to 1981 includes cyclonic IVT structures. 2. ERA5_Persistant_Database_lats_2000km: The file gives the latitudes of grid points of maximum IVT, i.e., the latitude of major axes of ARs throughout their duration. Columns “Date”, “AR_ID”, “Ind”, “AvgIVT”, “StartIVT”, “ARDuration”, “MaxIVT”, “ARCat” are the same as given above for “ERA5_Persistant_Database2000km.csv” file. Column “0” to end. These columns give the latitude ( in degrees North) at each gridcell of the major axis of each AR timestep. 3. ERA5_Persistant_Database_lons_2000km: The file gives the longitudes of grid points of maximum IVT, i.e., the longitudes of major axes of ARs throughout their duration Columns “Date”, “AR_ID”, “Ind”, “AvgIVT”, “StartIVT”, “ARDuration”, “MaxIVT”, “ARCat” are the same as given above for “ERA5_Persistant_Database2000km.csv” file. Column “0” to end. These columns give the longitude (in degrees East) at each gridcell of the major axis of each AR timestep
大气河流（Atmospheric Rivers, ARs）是对流层低层存在的狭长且高强度水汽输送区域。本数据集收录了1982年至2018年间发生于喜马拉雅盆地的大气河流事件，包含事件的日期与时间、持续时长、强度/量级、轨迹及分类等信息。 ### 文件名与说明 1. **ERA5_Persistant_Database2000km**：该文件包含大气河流事件的日期与时间、平均积分水汽输送（Integrated Water Vapor Transport, 以下简称IVT）量级（单位：kg·m⁻¹·s⁻¹）、初始IVT、最大IVT及持续时长。下文将对各术语进行详细阐释。 - 列“Date”：给出每个大气河流时间步的日期与时间，单位为协调世界时（Coordinated Universal Time, 以下简称UTC）。用于识别大气河流的IVT数据为6小时间隔（00UTC、06UTC、12UTC及18UTC）。 - 列“AR_ID”：每个被识别出的持续型大气河流（持续时长至少18小时）将被赋予唯一ID，该ID在事件的所有时间步中保持一致。本列即为大气河流的ID。ID由事件发生年份、字母“AR”及该年度内事件的发生序号组成。例如，1990年首个大气河流的ID为1980AR1。若某大气河流持续10个时间步，则全部10个时间步将共享同一ID。 - 列“Ind”：本列为每年6小时间隔IVT数据的Python索引，可对应每个大气河流时间步的日期与时间。该列可忽略，因为“Date”列已提供更直接的同类信息。 - 列“AvgIVT”：本列为沿大气河流主轴（即沿AR轨迹IVT最大的网格单元）的平均IVT量级（单位：kg·m⁻¹·s⁻¹）。例如，首个值对应第一个时间步主轴所有网格单元的“0”列至“88”列IVT量级的平均值。 - 列“StartIVT”：本列为识别到大气河流事件的首个时间步初始网格单元的IVT量级（单位：kg·m⁻¹·s⁻¹）。 - 列“ARDuration”：本列为大气河流的持续时长，单位为小时。例如，持续3个时间步的大气河流时长为18小时，持续4个时间步的时长为24小时。 - 列“MaxIVT”：本列为大气河流每个时间步初始网格单元的所有IVT值中的最大值（单位：kg·m⁻¹·s⁻¹）。 - 列“ARCat”：本列为基于IVT量级与持续时长划分的大气河流类别。共定义6个类别，Cat0表示最弱的大气河流，Cat5表示最强的大气河流。更多细节可参阅配套论文。 - 列“0”至末尾：这些列给出每个大气河流时间步主轴各网格单元的IVT量级（单位：kg·m⁻¹·s⁻¹）。 注：1982年之前尚无可用的气旋日期数据，因此1979年至1981年的大气河流日期包含气旋式IVT结构。 2. **ERA5_Persistant_Database_lats_2000km**：该文件给出IVT最大网格点的纬度，即整个持续期间大气河流主轴各点的纬度。 列“Date”、“AR_ID”、“Ind”、“AvgIVT”、“StartIVT”、“ARDuration”、“MaxIVT”、“ARCat”与上述“ERA5_Persistant_Database2000km.csv”文件中的列定义一致。 列“0”至末尾：这些列给出每个大气河流时间步主轴各网格单元的纬度（单位：北纬度数）。 3. **ERA5_Persistant_Database_lons_2000km**：该文件给出IVT最大网格点的经度，即整个持续期间大气河流主轴各点的经度。 列“Date”、“AR_ID”、“Ind”、“AvgIVT”、“StartIVT”、“ARDuration”、“MaxIVT”、“ARCat”与上述“ERA5_Persistant_Database2000km.csv”文件中的列定义一致。 列“0”至末尾：这些列给出每个大气河流时间步主轴各网格单元的经度（单位：东经度数）
