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Modelling variable glacier lapse rates using ERA-Interim reanalysis climatology: an evaluation at Vestari- Hagafellsjökull, Langjökull, Iceland

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journal contribution
posted on 19.08.2013, 13:20 by Richard Hodgkins, S. Carr, F. Palsson, S. Gumundsson, H. Bjornsson
The near-surface air temperature lapse rate is an important tool for spatially distributing temperatures in snow- and ice-melt models, but is difficult to parameterize, as it is not simply correlated with boundary-layer meteorological variables, such as temperature itself. This contribution quantifies spring-autumn lapse rate variability over 5 years at Vestari-Hagafellsjökull, a southerly outlet of Langjökull in Iceland. It is observed that summer lapse rates (0.57 °C 100 m) are significantly lower than non-summer rates, and are also lower than the Saturated Adiabatic Lapse Rate (SALR), which is often adopted in melt models. This is consistent with reduced near-surface temperature sensitivity to free-atmosphere temperature change during the occurrence of melting. A Variable Lapse Rate (VLR) regression model is calibrated with standardized, 750 hPa temperature anomalies derived from ERA-Interim climatology, which is shown to be highly significantly correlated with near-surface temperatures. The modelled VLR overestimates cumulative June-September Positive Degree Days (PDDs) by 3% when used to extrapolate temperatures from 1100 to 500 m a.s.l. on the glacier, whereas the SALR overestimates cumulative PDDs by 14%. ERA-Interim data therefore appear to offer a good representation of free-atmosphere temperature variability over Vestari-Hagafellsjökull, and the modelling approach offers a simple means of improving lapse rate parameterizations in melt models. © 2012 Royal Meteorological Society.

History

School

  • Social Sciences

Department

  • Geography and Environment

Citation

HODGKINS, R. ... et al, 2013. Modelling variable glacier lapse rates using ERA-Interim reanalysis climatology: an evaluation at Vestari- Hagafellsjökull, Langjökull, Iceland. International Journal of Climatology, 33 (2), pp. 410 - 421

Publisher

Wiley © Royal Meteorological Society

Version

AM (Accepted Manuscript)

Publication date

2013

Notes

This article was published in the serial International Journal of Climatology [Wiley © Royal Meteorological Society]. The definitive version is available at: http://dx.doi.org/10.1002/joc.3440

ISSN

0899-8418

eISSN

1097-0088

Language

en

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