## 1 Introduction  
Mid-latitude glaciers in the Southern Hemisphere, particularly in South America, are less studied than their northern counterparts [1]. The Echaurren Norte Glacier has the longest and most continuous record of glacier mass balance in the Southern Hemisphere, from 1975 to present. This is particularly relevant as a climate indicator for the Southern Andes. However, glacier mass balance for some Andean regions remains largely unknown, such as in the Central Andes [2]. Therefore, there is a serious lack of information for understanding the impacts of global climate change on glacier behavior in this region [3]. Due to their sensitive response to climatic conditions, glaciers are important indicators of climate change [4; 5]. Several studies report that most mountain glaciers and ice caps worldwide are retreating and thinning in response to current global warming [6; 7]. The Central Andes of Chile (31\({}^{\circ}\)-35\({}^{\circ}\)S) are characterized by a Mediterranean climate with marked winter and summer seasons. Winter precipitation is caused by predominant westerly circulation and the orographic enhancement by the Andes. Precipitation displays a high interannual variability generally associated with El Nino-Southern Oscillation (ENSO) events [8]. Spring runoff is mainly generated by seasonal snow melt, while later in the summer glacier melt becomes more dominant [9; 10]. Precipitation in Central Chile has decreased since 2010 [11; 12] and between 1976 and 2006 a warming of about +0.25 \({}^{\circ}\)C per decade was detected [13]. In addition, an increase in elevation of the 0 \({}^{\circ}\)C-isotherm was observed between 1975 and 2001 [14]. This is associated with a rise of the Equilibrium Line Altitude (ELA) of glaciers in this region [14; 15]. Due to these changes, glaciers in the Central Andes have shrunken significantly in recent decades [16; 17]. In northern and central Chile, information on glacier mass balance and runoff plays a key role for management of water resources [18]. These have been under increasing pressure during recent decades due to economic and population growth, in addition to droughts [19]. Previous hydrological modelling has highlighted the importance of glaciers in the Maipo river basin at the end of the summer season [20]. The authors estimated that, during the severe drought of 1969 67% of the water discharge flowing into the central valley originated from glacier meltwater. This large contribution from glaciers at the end of the summer during extremely dry years was confirmed by more recent studies, which show glacier runoff contributions of 63% and 67%, respectively [21; 22]. However, at a catchment-wide and annual time scale, glacier contribution is less relevant with snowmelt being the main contributor to runoff [22]. The mass balance of Chilean glaciers has been calculated by different methods, ranging from the traditional glaciological method (e.g., [23; 24; 25]) to remote sensing techniques (e.g., [26]). Additionally, ice cores can be used as mass balance proxies. These have been extracted from glacier sites such as Cerro Tapado in North-Central Chile [27], Glacier Nef in the Northern Patagonia Icefield [28], Cerro Gorra Blanca, Glacier Pio XI and Glacier Tyndall in the Southern Patagonia Icefield [29]. Numerical simulations of Surface Mass Balance (SMB) driven by reanalysis data have also been used to compute mass balance at a larger spatial scale [30; 31]. A brief overview of mass balance data from southern South America (30\({}^{\circ}\)S-56\({}^{\circ}\)S) is given by [PERSON] et al. [32]. However, most of these studies have addressed Patagonia glaciers, with only a few presenting results from the Central Andes despite their hydrological importance. More recently, [PERSON] et al. [33] reconstructed the annual mass balance of Echaurren Norte Glacier for the period 1909-2013 using local and regional hydroclimatic data. In this study, we provide the first comprehensive long-term analysis of Echaurren Norte Glacier from 1955 to 2015.