Purdie H.,Victoria University of Wellington |
Purdie H.,University of Canterbury |
Mackintosh A.,Victoria University of Wellington |
Lawson W.,University of Canterbury |
And 4 more authors.
Global and Planetary Change | Year: 2011
Mid-latitude maritime glaciers are responding quickly and directly to climate change. This response is expected to continue, and will result in maritime glaciers making a large contribution to sea level rise over the coming decades. Maritime glaciers in the New Zealand Southern Alps provide an opportunity to learn more about climate-glacier mass balance relationships in a high precipitation setting, and how these relationships might change in the future. Ice core and direct glaciological measurements are used to construct a 24-year record of net accumulation, the longest of its type in New Zealand. We demonstrate that variations in net accumulation on Tasman Glacier are more strongly influenced by temperature than by precipitation. Further, it is temperature during the ablation season that exerts most control. Atmospheric circulation patterns, in particular the state of the El Niño Southern Oscillation (ENSO) and Southern Annular Mode (SAM), were found to influence net accumulation. When the SAM is positive and the ENSO in a La Niña phase, easterly and northerly wind anomalies are enhanced, temperatures increase in the Southern Alps region and more negative glacier mass balances result. Conversely when SAM is negative and ENSO in an El Niño phase, westerly and southerly wind anomalies occur, and temperatures decrease in the Southern Alps region. In this case, glacier mass balance is more likely to be positive. However, relationships between glacier mass balance and these atmospheric circulation modes are not simply linear, with some of the lowest net accumulation years associated with inverse polarity between the SAM and the ENSO. © 2011 Elsevier B.V.
Chinn T.,Alpine and Polar Processes |
Fitzharris B.B.,University of Otago |
Willsman A.,NIWA - National Institute of Water and Atmospheric Research |
Salinger M.J.,University of Auckland
Global and Planetary Change | Year: 2012
New Zealand has a long, continuous record of annual end-of-summer-snowline measurements for a set of Southern Alps 'index glaciers' from 1977 to present. These index glaciers are used to estimate annual mass balance and volume water equivalent changes for the over 3000 glaciers on the Southern Alps. Two methods are employed to monitor ice volume changes. Method I deals with the rapid to normal response time glaciers, which tend to be small to medium in size. It uses mass balance gradients and glacier areas to convert changes in snowlines to changes in ice volume water equivalent. Ice volume changes for the period 1976-2008 are calculated for each index glacier, and then extrapolated to most other glaciers of the Southern Alps, using the New Zealand glacier inventory. Method II deals with 12 protracted response glaciers, which tend to be large in size. These have been slow in reacting to a long-term regional warming trend. Instead they still largely retain the ablation areas of a century ago and are in a state of disequilibrium with the present climate. These valley glaciers have recently sustained substantial ice losses that are not able to be detected using Method I. Mass balance deficits and ablation from the 12 large protracted response glaciers are estimated using a geodetic approach based on topographic and lake changes determined from repeated surveys. Results show that estimated ice volume (in water equivalents) for the Southern Alps has decreased from 54.5km3 in 1976 to 46.1km3 by 2008. This equates to a rate of -0.3km3a-1 over the last three decades, but this is considerably less than the rate of ice volume loss estimated for the previous 100years. More than 3000 small and medium-size glaciers account for just 29% of the overall ice volume loss from the Southern Alps, while 71% of the loss occurs from the 12 large protracted response glaciers. Terminus calving contributes 0.8km3 and down-wasting of ice tongues in the ablation zone contributes 5.2km3. Some preliminary results show that ice volume changes are related to changes in circulation over the New Zealand region. © 2012 Elsevier B.V.
Chinn T.,Alpine and Polar Processes |
Mason P.,NIWA - National Institute of Water and Atmospheric Research
Polar Record | Year: 2015
This paper summarises the first 25 years of data on hydrological work carried out each summer on the Onyx River, Wright Valley, by summer teams of field hydrologists of the New Zealand Antarctic Research Programme. The assignment expanded from the single water-level recording weir site near Lake Vanda to a second site near the Wright Lower Glacier together with a number of tributary stream measurements that were installed as the programme progressed. This work was carried out together with Dry Valleys lake level and glacial measurements and is as of much historical as of scientific interest as it contains much inaugural Antarctic hydrology work. Copyright © Cambridge University Press 2015