Michael Barlage

1 INTRODUCTION Land data assimilation (DA) has been used in operational numerical weather prediction (NWP) since 1985, when Météo-France introduced a simple scheme to constrain their model soil moisture and soil temperature using observations of screen-level relative humidity ( R H SL $$ R{H}_{\mathrm{SL}} $$ ) and screen-level temperature ( T SL $$ {T}_{\mathrm{SL}} $$ : Coiffier et al., 1987; Mahfouf, 2009).

1 Introduction Snow cover area plays an important role in hydrometeorological systems due to the high albedo of snow and the corresponding land-atmosphere feedback (Cohen & Entekhabi, 2001; Déry & Brown, 2007). For example, the snow-albedo feedback is known to amplify warming in snow-covered environments on seasonal to multi-decadal scales (Déry & Brown, 2007) and may be responsible for enhanced warming at higher elevations (Ghatak et al., 2014; Rangwala & Miller, 2012).

1 Introduction Snow is an important component of global, regional and local climate and weather systems due to its high albedo which modulates the amount of radiation absorbed by the land surface (Barlage et al., 2010; Cohen & Entekhabi, 2001; Gao et al., 2017).