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- Title
Simulations of seasonal snowpack duration and water storage across New Zealand.
- Authors
Conway, J.; Carey-Smith, T.; Cattoën-Gilbert, C.; Moore, S.; Sirguey, P.; Zammit, C.
- Abstract
Seasonal snow dramatically alters surface-atmosphere exchanges of heat and moisture, particularly in the South Island of New Zealand. Despite this, detailed simulations of seasonal snow and comparisons to remotely sensed snow observations are lacking in New Zealand, partly due to uncertainties in nearsurface meteorology in mountainous areas with sparse in-situ observations. Here we simulate seasonal snow cover and water storage across New Zealand on a 250 m x 250 m grid over a 3-year period (April 2017 to March 2020) with a simple snow model and near-surface meteorology extracted from the New Zealand Convective Scale Model (NZCSM). Simulations are validated against snow cover derived from MODerate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing observations. While NZCSM nearsurface meteorology is generally colder and wetter than observations, we find that the spatial patterns and elevation distribution of simulated snow cover duration (SCD) agrees well with MODIS observations. Biases in SCD are found in areas, particularly the ranges east of the main divide, where simulated snow cover persists longer than observed. In contrast, alternate simulations using daily gridded observations of near-surface meteorology show a poor fit to MODIS SCD, with large areas having little or no simulated snow cover. The simulated seasonal cycle of New Zealand-wide total snow water storage shows a peak around 1 September equating to around half the long-term average monthly total rainfall for the South Island. The correspondence between simulated and MODIS snow covered area is found to be sensitive to the threshold used to define simulated snow cover, particular in early winter when widespread thin snow cover is common. To improve estimates of snow cover and water storage, future work should exploit new remote sensing products for validation and assimilation as well as disentangle uncertainties in snow model parameters and meteorological input using detailed meteorological and snow observations.
- Subjects
NEW Zealand; SOUTH Island (N.Z.); SNOW cover; MODIS (Spectroradiometer); WATER storage; SEASONS; ATMOSPHERIC models; RAINFALL; METEOROLOGICAL observations
- Publication
Weather & Climate (01115499), 2021, Vol 41, Issue 1, p72
- ISSN
0111-5499
- Publication type
Article
- DOI
10.2307/27127990