Model data from publicly-available MeteoFrance System8 (MF8) seasonal forecasts for the calculation of buildup index and comparison to observations for the 1994-2018 Alaska wildfire seasons

This dataset includes model output from the MeteoFrance System8 (MF8) seasonal forecasts. The time period spans the years 1994-2018 for the Alaska fire season (April 1 - September 30) from March-initialized and May-initialized seasonal forecasts.

MF8 model data were collected from the Copernicus Climate Data Store (https://cds.climate.copernicus.eu/cdsapp#!/dataset/seasonal-monthly-single-levels?tab=form) for the years 1994-2018. Variables downloaded include 2 meter temperature, 2 meter dew point temperature, precipitation, 10 meter wind speeds, and sea level pressure. These models consist of 25 ensembles.

Details about the model can be found in its reference publication:
Batté, L., Dorel, L., Ardilouze, C., & Guérémy, J.-F. (2021). Documentation of the METEO-FRANCE seasonal forecasting system 8. http://www.umr-cnrm.fr/IMG/pdf/system8-technical.pdf

Model data were extracted for 13 Predictive Service Areas (PSA) in Alaska at 0000 UTC (the time closest to 1400 AKDT) and saved as a weighted area-average in text files by year. Buildup index was calculated from the area-averaged variables and saved in annual text files. Calculations were done with NCAR Command Line (NCL) version 6.3.0.

Sub-directory Naming Convention
The MF8 directory is divided into 15 sub-directories: one sub-directory for each of the 13 PSAs in this study (named for each PSA), one sub-directory for March-initialized forecast data (step1_mf8data_march), and one sub-directory for May-initialized forecast data (step1_mf8data_may).

The step1_mf8data_march and step1_mf8data_may folders contain raw model data from MeteoFrance System8 March-initialized and May-initialized seasonal forecasts, respectively, saved by ensemble in one file for the calculation of buildup index. Data in each file include precipitation (precip), surface pressure (P), 2 meter dewpoint temperature (DP), 2 meter air temperature (T), and 10 meter wind speeds (UV). Data were subset for the state of Alaska and for the Alaska fire season (months of April, May, June, July, August, and September) and saved by year. There are 26 files at a size of 158MB (25 ensembles) for March-initialized forecasts and 26 files at a size of 132MB (25 ensembles) for May-initialized forecasts.

Each PSA sub-directory (PSA AKXX) contains 4 additional sub-directories:

step2_mf8data_march
step2_mf8data_may
step3_mf8data_march_BUI
step3_mf8data_may_BUI

where 'march' or 'may' denotes data from March-initialized forecasts of May-initialized forecasts, respectively. The step2 folders contain precipitation (precip), surface pressure (press), 2 meter dew point temperature (dp), relative humidity (rh), 2 meter air temperature (tmp2m), and 10 meter wind speeds (uv).. These data were extracted from the data files in the step1 sub-directories and saved as annual files. The step3 folders contain the resulting BUI values saved as annual files.

本数据集包含法国气象局System8（MF8）季节预报的模型输出结果。时间范围覆盖1994-2018年阿拉斯加火灾季（4月1日至9月30日），数据来源于3月初始化和5月初始化的季节预报。

MF8模型数据采集自1994-2018年哥白尼气候数据存储库（Copernicus Climate Data Store，网址：https://cds.climate.copernicus.eu/cdsapp#!/dataset/seasonal-monthly-single-levels?tab=form）。下载的变量包括2米气温、2米露点温度、降水量、10米风速及海平面气压。该模型包含25个集合成员。

模型详情可参见其参考出版物：Batté, L., Dorel, L., Ardilouze, C., & Guérémy, J.-F. (2021). 《法国气象局季节预报系统8技术文档》（Documentation of the METEO-FRANCE seasonal forecasting system 8），网址：http://www.umr-cnrm.fr/IMG/pdf/system8-technical.pdf。

模型数据针对阿拉斯加的13个预测服务区（Predictive Service Areas，PSA）提取，时间为协调世界时（UTC）00:00（最接近阿拉斯加夏令时14:00），并以年度文本文件形式保存为加权区域平均值。累积指数（Buildup index）由区域平均变量计算得出，同样保存为年度文本文件。计算过程使用NCAR命令行工具（NCAR Command Line，NCL）6.3.0版本。

### 子目录命名规则
MF8目录分为15个子目录：本研究涉及的13个PSA各一个子目录（以PSA命名）、一个3月初始化预报数据子目录（step1_mf8data_march）和一个5月初始化预报数据子目录（step1_mf8data_may）。

step1_mf8data_march和step1_mf8data_may文件夹分别包含法国气象局System8 3月初始化和5月初始化季节预报的原始模型数据，按集合成员保存于单个文件中，用于累积指数计算。每个文件包含降水量（precip）、地面气压（P）、2米露点温度（DP）、2米气温（T）和10米风速（UV）。数据已按阿拉斯加州范围及火灾季（4-9月）进行子集化，并按年度保存。3月初始化预报含26个文件（25个集合成员），总大小158MB；5月初始化预报含26个文件（25个集合成员），总大小132MB。

每个PSA子目录（PSA AKXX）包含4个额外子目录：step2_mf8data_march、step2_mf8data_may、step3_mf8data_march_BUI、step3_mf8data_may_BUI。其中“march”或“may”分别表示3月或5月初始化预报的数据。step2文件夹包含降水量（precip）、地面气压（press）、2米露点温度（dp）、相对湿度（rh）、2米气温（tmp2m）和10米风速（uv），数据从step1子目录提取并保存为年度文件。step3文件夹包含计算得到的累积指数（BUI）值，同样以年度文件形式保存。