Climatogenic north–south asymmetry of local glaciers in Spitsbergen and other parts of the Arctic Ian S. EVANS, Nicholas J. COX Department of Geography, Durham University, Durham DH1 3LE, UK E-mail: i.s.evans@durham.ac.uk ABSTRACT. Although World Glacier Inventory (WGI) data for 241 local glaciers (>1km 2 in area) in Svalbard show a mean aspect of 0148  248, their mid-altitudes are lowest for an aspect of 1098  468, which is inconsistent. Further data are generated here for the altitude, length and source aspect of 205 local glaciers (0.3–6.0 km long) in the main area of local glaciation in Svalbard, Nordenskio ¨ld Land. All four mountain blocks have mean glacier source aspects of 3568 to 0188; the overall mean is 0118  88. Mid-altitudes are lowest at 0428  218, predicted to be 53 m lower than on opposite aspects. Lowest altitudes are predicted at 0098 to 0308, averaging 157m lower than on opposite aspects. These results show that local, land-terminating glaciers around 788 N are affected more by north–south radiation receipt contrasts than by wind effects, consistent with the trend found across most other Arctic regions. It is concluded that, although weaker than in mid-latitudes, contrasts due to slope climates are substantial even in Arctic glaciers. This is apparent only when small, steep glaciers are inventoried: WGI data are incomplete and users need to check the thresholds of coverage. INTRODUCTION The distribution of glaciers, both locally and regionally, provides valuable information on climate in mountain regions. Indeed, the paucity of climatic observations at altitude means that glaciers often constitute the most important sources of evidence for spatial variations in climate in mountain regions with numerous glaciers (Humlum, 2002). An economical method for investigating regional variations in climate, supplementing more resource-intensive studies of localized mass balance, lies in the interrogation of glacier inventory data, such as those contained in the World Glacier Inventory (WGI). While most studies emphasize glacier altitudes, espe- cially equilibrium-line altitudes (ELAs), as climate indicators, variations with aspect provide useful further evidence of cloudiness and wind regimes (Evans, 1977). Aspect tenden- cies, more specifically local asymmetry in mountain glaci- ation, relate essentially to glacier energy and mass balance on different slopes, modulated by topographic lineation. North–south contrasts in glacier balance and thus glacier distribution due to solar radiation incidence effects exist worldwide, but diminish toward the Poles and Equator (Evans and Cox, 2005). Topography permitting, it is expected that slope aspects with the most positive mass balance will generate more glaciers, and that these glaciers will have lower ELAs and mid-altitudes. However, based on the WGI, a global survey by Evans and Cox (2005; Evans, 2006) identified anomalies in a number of Arctic datasets, where the favoured aspect (direction, azimuth) in terms of numbers of glaciers differed from that with the lowest glaciers. These anomalies are investigated here, with special reference to the glaciers of Spitsbergen, Svalbard. Consistency between the favoured aspect for numbers and that for altitudes is expected if local asymmetry is related to glacier balance. Such consistency was found by Evans (2006) for non-Arctic regions. Recently Schiefer and others (2008, table 4) found consistency in eight out of ten regions in British Columbia (B.C.), Canada, with more glaciers facing between north and northeast; these glaciers reached lower altitudes and had lower mid-altitudes. The exceptions were the St Elias Range, where only one side is in B.C., and Vancouver Island, where there are too few south- facing glaciers to give a statistically significant altitude relation. Arctic anomalies therefore raise several questions: 1. Is the observed asymmetry of non-climatic origin, for example, because of topographic lineation? 2. In Svalbard, does the importance of tidewater glaciers bias the results? 3. Is there some problem with the data? Or 4. Is there some problem with the assumptions of the methodology? In this paper, we investigate the possible causes of the previously reported anomalies in glacier aspect, length and gradient data for Svalbard using new inventory data, and compare our findings with results from other Arctic regions. METHODS Following on from recent work (e.g. Evans and Cox, 2005; Evans 2006), this paper deals with the variation of glacier numbers and glacier altitudes with accumulation-area aspect (direction, azimuth). As conventional linear statistics are inappropriate for circular data such as aspect, where 08  3608, the techniques used are vector analysis (for glacier numbers) and Fourier (circular, periodic, trigono- metric) regression for altitudes. The vector mean is the net tendency, given by the aspect of the resultant vector: this can be derived graphically from a cumulative vector plot, or computationally via separate summation of sine and cosine components of aspect. 95% confidence limits on mean direction are indicated by  throughout, using a non- parametric procedure from Fisher (1993). The strength of any tendency to a single favoured aspect is given by the vector strength, the ratio of the length of the Annals of Glaciology 51(55) 2010 16