Snowpack inputs versus outputs

Snowpack needs several kind of information to be provided for a simulation and then writes out several kind of information. Some formats can be used for both the inputs and the outputs while some others are restricted to either one or the other (simply because Snowpack does not read or write out the parameters contained in the said format).

Snowpack required inputs

Several kind of information need to be given to Snowpack for a simulation:

the description of the place where the snow pack has to be simulated: latitutde, longitude, elevation, slope, ...
the time series of the various meteorological parameters
the intial state of the various soil and snow layers

Very often, 1) and 2) are provided together. But this depends ultimately on the file format that is used ot provide such data (SMET, INP, etc). These two points are handled by MeteoIO, so please check its documentation (for the last official release, it is available online), in the "Available plugins and usage" section for the relevant formats. It is recommended to prepare the data in the SMET file format for its ease of use. In this case, you should also consider providing 1) as SMET for a simulation starting without snow on the ground (have a look at the files provided in the examples) or as CAAML for a simulation starting with snow on the ground (have a look at niViz to create a CAAML snow profile).

Please also check the Data requirements page.

Snowpack outputs

Snowpack creates various output files:

the current state of its soil and snow layers in ".sno" files;
the current state of its hazard relevant data in ".haz" files;
a time serie of snow profiles;
a time serie of the meteorological data and fluxes as used in the model.

Depending on the chosen output format, 1) and 2) might be provided as one file or two files. Moreover, since Snowpack pre-processes all the meteorological input data with MeteoIO, the forcing data that is seen in the core of the model might be different than the provided input data. In order to better fine tune the parameters of this pre-processing, it is possible to request a copy of the pre-processed meteorological data by setting the key WRITE_PROCESSED_METEO to TRUE in the [Output] section.

Single snow profiles

The Snowpack specific data are supported directly in Snowpack and the formats listed in the table below are available, both for input and output of snow profiles with the "SNOW" keyword. Please read the documentation for each plugin in order to know the plugin-specific keywords!

Key	Description	Extra requirements
SMET	SMET based profile (including the hazard data), recommended
CAAML	CAAML profile
SNOOLD	legacy Snowpack profile (including the hazard data)

Snow profiles time series

The Snowpack specific data are supported directly in Snowpack and the formats listed in the table below are available for output of snow profiles time series with the "PROF_FORMAT" keyword. Note that the keys AGGREGATE_PRO and AGGREGATE_PRF will allow to aggregate model layers to a smaller number. Please read the documentation for each plugin in order to know the plugin-specific keywords!

Key	Description	Extra requirements
PRO	legacy Snowpack profile time series for visualization with SnopViz and sngui
PRF	tabular profile time series
IMIS	write profile time series to the IMIS database	Oracle's OCCI library

When the snow grain shapes are provided as Swiss Code, it means the following: the code is made of three decimal numbers, noted as F1F2F3. Here F1 represents the primary grain shape and F2 the secondary grain shape. The grain shapes can be any of the following:

Code	Grain shape	Code	Grain shape
1	Precipitation particules (PP)	6	Surface hoar (SH)
2	Decomposing fragmented PP (DF)	7	Melt forms (MF)
3	Rounded grains (RG)	8	Ice formations (IF)
4	Faceted crystals (FC)	9	Rounding faceted particules (FCxr)
5	Depth hoar (DH)

In case of Melt-freeze crust (MFcr), it is marked by using the 772 code.

Fluxes time series

Snowpack computes various meteorological parameters as well as fluxes and can write them out as time series.

Key	Description	Extra requirements
MET	legacy Snowpack time series for visualization with sngui
SMET	smet formatted time series for visualization with SnopViz