Simulation of past variability in seasonal snow in the Southern Alps, New Zealand

Abstract

There are no systematic measurements of seasonal snow in the Southern Alps, New Zealand, so little information is available as to its past variability. To rectify this, a conceptual model is developed that calculates seasonal snow deposition, ablation and accumulation. The model is based on daily temperature and precipitation data from long-established climate stations about the Southern Alps. Output is given as daily specific net balance of snow at five elevation bands from 1000 to 2200 m and as total water stored as seasonal snow over several major river catchments. Model output is in general agreement when tested against the few historical observations of snow and is tuned to the long-term water balance. A chronology of seasonal snow is reconstructed from 1931 to 1993. Area-averaged annual maxima average 366 mm. They show no trend, but large inter-annual variability from less than 200 to over 650 mm w.e. Seasonal snow can peak at any time between September and January.