- <code>CreateInputsCrit()</code> now returns a <code>idLayer</code> element to indicate which layer to use for SCA or SWE aggregation.

- <code>CreateRunOptions()</code>, <code>CreateIniStates()</code> and <code>CreateCalibOptions()</code> now present a <code>IsHyst</code> argument to give the possibility to use the hysteresis with CemaNeige.

- <code>CreateRunOptions()</code>, <code>CreateIniStates()</code> and <code>CreateCalibOptions()</code> now present a <code>IsHyst</code> argument to give the possibility to use the Linear Hysteresis with CemaNeige.

- <code>CreateRunOptions()</code> now presents a <code>warnings</code> argument to replace the verbose action (the <code>verbose</code> argument is kept to print messages).

- <code>CreateCalibOptions()</code> now presents a <code>IsHyst</code> argument to give the possibility to use the hysteresis with CemaNeige.

- <code>CreateCalibOptions()</code> now presents a <code>IsHyst</code> argument to give the possibility to use the Linear Hysteresis with CemaNeige.

- Added <code>TransfoParam_CemaNeigeHyst()</code> function in order to take into account transformation of the parameters of the CemaNeige module when the hysteresis is used.

- Added <code>TransfoParam_CemaNeigeHyst()</code> function in order to take into account transformation of the parameters of the CemaNeige module when the Linear Hysteresis is used.

- Added the <code>X0310010</code> dataset to run the examples using the hysteresis with CemaNeige.

- Added the <code>X0310010</code> dataset to run the examples using the Linear Hysteresis with CemaNeige.

- Added the cemaneige_hysteresis vignette to explain how to manage the use of the hysteresis with CemaNeige.

- Added the cemaneige_hysteresis vignette to explain how to manage the use of the Linear Hysteresis with CemaNeige.

Rainfall-runoff models that include a snow accumulation and melt module are still often calibrated using only discharge observations.

After the work of Riboust et al. (2019), we propose now in **airGR** an improved version of the degree-day CemaNeige snow and accumulation module. This new version is based on a more accurate representation of the relationship that exists at the basin scale between the Snow Water Equivalent (SWE) and the Snow Cover Area (SCA). To do so, a linear SWE-SCA hysteresis, which represents the fact that snow accumulation is rather homogeneous and snow melt is more heterogeneous, was implemented.

After the work of @riboust_revisiting_2019, we propose now in **airGR** an improved version of the degree-day CemaNeige snow and accumulation module. This new version is based on a more accurate representation of the relationship that exists at the basin scale between the Snow Water Equivalent (SWE) and the Snow Cover Area (SCA). To do so, a linear SWE-SCA hysteresis, which represents the fact that snow accumulation is rather homogeneous and snow melt is more heterogeneous, was implemented.

This new CemaNeige version presents two more parameters to calibrate. It also presents the advantage of allowing using satellite snow data to constrain the calibration in addition to discharge.

Riboust et al. (2019) show that while the simulated discharge is not significantly improved, the snow simulation is much improved. In addition, they show that the model is more robust (i.e. transferable) in terms of discharge, which has many implications for climate change impact studies.

@riboust_revisiting_2019 show that while the simulated discharge is not significantly improved, the snow simulation is much improved. In addition, they show that the model is more robust (i.e. transferable) in terms of discharge, which has many implications for climate change impact studies.

The configuration that was identified as optimal by Riboust et al. (2019) includes a CemaNeige module run on 5 elevation bands and an objective function determine by a composite function of KGE' calculated on discharge (75 % weight) and KGE' calculated on each elevation band (5 % for each).

The configuration that was identified as optimal by @riboust_revisiting_2019 includes a CemaNeige module run on 5 elevation bands and an objective function determine by a composite function of KGE' calculated on discharge (75 % weight) and KGE' calculated on each elevation band (5 % for each).

In this page, we show how to use and calibrate this new CameNeige version.

In order to calibrate and assess the model performance, we will follow the recommendations of Riboust et al. (2019). This is now possible in **airGR** with the added functionality that permits calculated composite criteria by combining different metrics.

In order to calibrate and assess the model performance, we will follow the recommendations of @riboust_revisiting_2019. This is now possible in **airGR** with the added functionality that permits calculated composite criteria by combining different metrics.

```{r, warning=FALSE}

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@@ -242,6 +242,5 @@ We can see below that the performance of the initial model is similar to the new

However, over the validation period, we see that the discharge simulated by the new version brings better performance (in addition to improved SCA also). This shows the interests of the combined use of an hysteresis and of SCA data for calibration in CemaNeige.

Reference

Riboust, P., Thirel, G., Le Moine, N., and Ribstein, P.: Revisiting a simple degree-day model for integrating satellite data: implementation of SWE-SCA hystereses. Journal of Hydrology and Hydromechanics, DOI: 10.2478/johh-2018-0004, 67, 1, 70–81, 2019.