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The Little Ice Age climate of New Zealand reconstructed from Southern Alps cirque glaciers: a synoptic type approach

Citation

Lorrey, A and Fauchereau, N and Stanton, C and Chappell, P and Phipps, SJ and Mackintosh, A and Renwick, J and Goodwin, I and Fowler, A, The Little Ice Age climate of New Zealand reconstructed from Southern Alps cirque glaciers: a synoptic type approach, Climate Dynamics, 42, (11-12) pp. 3039-3060. ISSN 0930-7575 (2014) [Refereed Article]

Copyright Statement

Copyright 2013 Springer-Verlag Berlin Heidelberg

DOI: doi:10.1007/s00382-013-1876-8

Abstract

Little Ice Age (LIA) austral summer temperature anomalies were derived from palaeoequilibrium line altitudes at 22 cirque glacier sites across the Southern Alps of New Zealand. Modern analog seasons with temperature anomalies akin to the LIA reconstructions were selected, and then applied in a sampling of high-resolution gridded New Zealand climate data and global reanalysis data to generate LIA climate composites at local, regional and hemispheric scales. The composite anomaly patterns assist in improving our understanding of atmospheric circulation contributions to the LIA climate state, allow an interrogation of synoptic type frequency changes for the LIA relative to present, and provide a hemispheric context of the past conditions in New Zealand. An LIA summer temperature anomaly of -0.56 °C (±0.29 °C) for the Southern Alps based on palaeo-equilibrium lines compares well with local tree-ring reconstructions of austral summer temperature. Reconstructed geopotential height at 1,000 hPa (z1000) suggests enhanced southwesterly flow across New Zealand occurred during the LIA to generate the terrestrial temperature anomalies. The mean atmospheric circulation pattern for summer resulted from a crucial reduction of the `HSE'-blocking synoptic type (highs over and to the west of NZ; largely settled conditions) and increases in both the `T'- and `SW'-trough synoptic types (lows passing over NZ; enhanced southerly and southwesterly flow) relative to normal. Associated land-based temperature and precipitation anomalies suggest both colder- and wetter-than-normal conditions were a pervasive component of the base climate state across New Zealand during the LIA, as were colder-than-normal Tasman Sea surface temperatures. Proxy temperature and circulation evidence were used to corroborate the spatially heterogeneous Southern Hemisphere composite z1000 and sea surface temperature patterns generated in this study. A comparison of the composites to climate mode archetypes suggests LIA summer climate and atmospheric circulation over New Zealand was driven by increased frequency of weak El Niño-Modoki in the tropical Pacific and negative Southern Annular Mode activity.

Item Details

Item Type:Refereed Article
Keywords:Little Ice Age, New Zealand, glaciers, equilibrium line altitude, synoptic types, Southern Hemisphere, palaeoclimate
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Palaeoclimatology
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Effects of Climate Change and Variability on New Zealand (excl. Social Impacts)
Author:Phipps, SJ (Dr Steven Phipps)
ID Code:104733
Year Published:2014
Web of Science® Times Cited:22
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-18
Last Modified:2017-10-30
Downloads:0

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