NH-SWE dataset file formats:  
The NH-SWE dataset is provided in two different formats.

1) NH_SWE_dataset_vector_files.zip
This zip file contains 11003 csv files, one for each NH-SWE station. The file names are NH_SWE_ID_XXXXX.csv, where XXXXX is the NH-SWE station ID.  
Each file contains 5 columns separated by commas, containing:
- The date in yyyy/MM/dd format. Each file starts/ends at the first/last date with a non-missing SWE value. 
- The modelled Snow Water Equivalent (SWE) in millimeters (mm). (empty = missing data)
- The modelled Snow Density value in kg m-3. (empty = missing data)
- The quality control flag, (0 = not flagged, 1 = flagged, 2 = missing data).
- The gap filling flag (empty = not gap filled, "N" = neural network gap filled, "L" = linear interpolation gap filled)
See data descriptor manuscript by Fontrodona-Bach et al., (2023) for more details. 

2) NH_SWE_dataset_matrix_files.zip
This zip file contains the NH-SWE dataset in a matrix format.
Each matrix file contains 26663 rows, representing dates from 1949/09/01 to 2022/08/31. 
A date vector corresponding to matrix rows is provided in "NH_SWE_matrix_Date_vector.csv"
Each matrix contains 11003 colums, separated by commas, representing each of the NH-SWE dataset stations.
A NH-SWE ID vector corresponding to matrix columns is provided in "NH_SWE_matrix_NHSWEID_vector.csv"
There is one matrix file for each of the NH-SWE data fields: 
"NH_SWE_matrix_SWE_mm.csv" contains the modelled Snow Water Equivalent (SWE) in millimeters (mm). (empty = missing data)
"NH_SWE_matrix_snowdensity_kgm3.csv" contains the modelled Snow Density value in kg m-3. (empty = missing data)
"NH_SWE_matrix_QC_flag.csv" contains the quality control flag, (0 = not flagged, 1 = flagged, 2 = missing data).
"NH_SWE_matrix_gapfill_flag.csv" contains the gap filling flag (empty = not gap filled, "N" = neural network gap filled, "L" = linear interpolation gap filled)
See data descriptor manuscript by Fontrodona-Bach et al., (2023) for more details.  

Note that in format 1, each time series starts (ends) at the first (last) non-missing value of the dataset for that specific NH-SWE station, 
while in format 2 the matrix covers the entire period from 1949/09/01 to 2022/08/31. This means format 2 contains more missing data. 

NH-SWE METADATA: 
The "NH_SWE_METADATA.csv" file contains the metadata of the NH-SWE dataset stations. The fields of the metadata file are the following: 

1) NHSWEID: This is the NH-SWE dataset station ID: XYYYY, where X is the original snow depth data source (1 = ECA&D, 2 = FMI, 3 = Matiu 2020, 4 = RIHMI-WDC, 5 = GHCNd, 6 = MeteoSwiss), and YYYY a station count for that source.
2) SOURCE: The source of the original snow depth data used to derive the NH-SWE dataset.
3) ORIGID: The station ID as taken from the original data source. These have different formarts for each data source. 
4) CN: Two letter country code. 
5) STANAME: Station name, as per the original data source. 
6) LAT: Latitude in decimal degrees. 
7) LON: Longitude in decimal degrees. 
8) ELEV: Elevation above sea level in meters. 
9) START: Date of first non-missing SWE value of station. Format yyyyMMdd.
10) END: Date of last non-missing SWE value of station. Format yyyyMMdd. 
11) VALIDYEARS: Number of years between START and END with valid SWE data (sometimes there are long gaps). 
12) rhonull: The "new snow density" parameter (in kg m-3) used to run the ΔSNOW model from Winkler et al. 2021.    
13) rhomax: The "maximum snow density" parameter (in kg m-3) used to run the ΔSNOW model from Winkler et al. 2021.
14) Tbarstar: Dimensionless Temperature climate index from Woods (2009). Used for the estimation of rhomax (see model parameter regionalisation). 
15) VP_DJF: Mean December-January-February Vapour Pressure (VP) in the atmosphere (in kPa), from WorldClim2 dataset. Used for the estimation of rhonull (see model parameter regionalisation).
16) meanmaxHS: Average maximum snow depth in the time series (in meters of snow depth). 
17) meanpeakSWE: Average peak SWE in the time series (in millimeters of water equivalent).
18) meanmaxSCD: Average duration of the longest snow cover period per year (in days). 
See data descriptor manuscript by Fontrodona-Bach et al., (2023) for more details.