TCOM-HF : Daily global gap-free stratospheric hydrogen fluoride (HF) profile data set based on TOMCAT CTM and Occultation Measurements

Methodology: TOMCAT simulation is performed at T64L32 resolution for the 2000-2024 time period. Collocated hydrogen fluoride (HF) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, model-measurement differences are calculated for each zonal bins (51 height levels, 10km to 60km). Note that if enough ACE measurements are not avaliable for a particular level then data is purely based on TOMCAT simulated output field. Separate XGBoost regression models are trained for the differences between TOMCAT and measurements at each level for a given latitude bin. XGBoost model is then used to estimate error corrections for all the TOMCAT grids. TOMCAT output sampled at 1.30 pm local time at the equator. Estimated corrections for a given model grid that are added to the original TOMCAT simulated day and night time hydrogen fluoride profiles. Height resolved data are then interpolated on 28-pressure levels (300 - 0.1hPa). For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Previous version use both HALOE and ACE data. Here only ACE data is used. Dataset also includes two files containing daily mean zonal mean hydrogen fluoride profiles on height (10-50 km) and pressure (300-0.1 hPa) levels: zmhf_TCOM_hlev_T2Dz_2000_2024.nc – height level data (10 to 50 km) zmhf_TCOM_plev_T2Dz_2000_2024.nc – pressure level data (300 to 0.1 hPa) Daily 3D profiles on height and pressure levels would be made available on request.研究方法：针对2000-2024年时段，采用T64L32分辨率开展TOMCAT模拟。将同步匹配的氟化氢（hydrogen fluoride, HF）廓线划分为5个纬度带：南极高纬区（90°S-50°S）、南半球中纬区（70°S-20°S）、热带区（40°S-40°N）、北半球中纬区（20°N-70°N）以及北极高纬区（50°N-90°N）。 首先针对每个纬向分区（共51个高度层，高度范围为10km至60km）计算模式模拟值与观测值的差值。需注意：若某一高度层缺乏足够的ACE观测数据，则仅采用TOMCAT模拟输出场。 针对给定纬度带内各高度层的TOMCAT模拟值与观测值之间的差值，分别训练极限梯度提升（XGBoost）回归模型。随后利用训练好的XGBoost模型对所有TOMCAT网格开展误差校正量估算。 TOMCAT模拟输出在赤道处采用本地时间13:30进行采样。将估算得到的校正量叠加至原始TOMCAT模拟的昼夜氟化氢廓线中。随后将高度分辨数据插值至28个气压层（300~0.1 hPa）。对于存在重叠的纬度带，先取其平均值，再计算逐日纬向均值。 更多细节详见所附演示文稿。本数据集的前期版本同时使用了HALOE与ACE观测数据，本次仅采用ACE观测数据。 本数据集还包含两个文件，存储了高度（10~50 km）与气压（300~0.1 hPa）层上的逐日平均纬向平均氟化氢廓线： 1. zmhf_TCOM_hlev_T2Dz_2000_2024.nc — 高度层数据（10~50 km） 2. zmhf_TCOM_plev_T2Dz_2000_2024.nc — 气压层数据（300~0.1 hPa） 高度层与气压层上的逐日三维廓线可按需申请获取。