Assessment of current methods of positive degree-day calculation using in situ observations from glaciated regions

Wake, Leanne and Marshall, Shawn (2015) Assessment of current methods of positive degree-day calculation using in situ observations from glaciated regions. Journal of Glaciology, 61 (226). pp. 329-344. ISSN 0022-1430

PDF (Article)
Wake_L_glaciated_regions.pdf - Published Version

Download (5MB) | Preview
Official URL:


The continued use of the Positive Degree-Day (PDD) method to predict ice sheet melt is generally favoured over surface energy balance methods partly due to the computational efficiency of the algorithm and the requirement of only one input variable (temperature). In this paper we revisit some of the assumptions governing the application of the PDD method. Using hourly temperature data from the GC-Net network we test the assumption that monthly PDD total (PDDm) can be represented by a Gaussian distribution with fixed standard deviation of monthly temperature (σM). The results presented here show that the common assumption of fixed σM does not hold, and that σM may be represented more accurately as a quadratic function of average monthly temperature. For Greenland, the mean absolute error in predicting PDDm using our methodology is 3.9°C*day, representing a significant improvement on current methods (7.8°C*day, when σM = 4.5°C). Over a range of glaciated settings, our method reproduces PDDm, on average, to within 1.5 - 8.5°C*day, compared to 4.4 - 15.7°C*day when σM = 4.5°. The improvement arises because we capture the systematic reduction in temperature variance that is observed over melting snow and ice, when surface temperatures cannot warm above O°C.

Item Type: Article
Uncontrolled Keywords: glacier mass balance, glacier meteorology, glacier modelling, ice-sheet mass balance, ice-sheet modelling
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Paul Burns
Date Deposited: 18 Mar 2015 13:48
Last Modified: 17 May 2017 12:51

Actions (login required)

View Item View Item


Downloads per month over past year

View more statistics

Policies: NRL Policies | NRL University Deposit Policy | NRL Deposit Licence