Application of Wavelet Analysis for Examining Climate and Meltwater Runoff in the Paakitsoq Region, West Greenland

• Main Author: Fuhrmann, Jonathan
• Format: Master Thesis
• Language: English
• Published: Scott Polar Research Institute, University of Cambridge 2012
• Subjects: Greenland; Ice Sheet
• Online Access: https://doi.org/10.17863/CAM.22263; https://www.repository.cam.ac.uk/handle/1810/275087

Land-terminating areas of the Greenland ice sheet have experienced significant mass loss over the last two decades, and a feedback between surficial meltwater production, resultant basal lubrication and ice-sheet flow velocity during the summer ablation season has been suggested as an explanation. Meteorological conditions have long been known to be an important driver of surface melt, and the seasonal acceleration pattern observed in Greenland is overlaid by shorter trends as well as diurnal fluctuations and even shorter one-off discharge and acceleration peaks. This project aims to investigate the relationship between net shortwave radiation, air temperature and proglacial discharge using wavelet analysis in order to establish the variability of discharge on short (<1-3 days) timescales and how this is driven by meteorological factors on similar (<1-4 days) timescales. Wavelets produce a high-resolution breakdown of the time series in the frequency domain, allowing for a study which is continuous in three dimensions: time, frequency and power of variability. Both univariate and multivariate analyses are performed, providing an improvement over conventional time-series analysis which requires data to be split into arbitrary sections if these are to be analysed separately. Diurnal fluctuations are found in each of the time series analysed, although their magnitude and the duration and consistency of their presence varies both between series and years. The relationships between air temperature and discharge and net shortwave radiation and discharge are found to differ. Air temperature covaries with discharge on shorter timescales (up to 1 day) while net radiation exhibits stronger coherence with discharge on longer timesclaes (3-4 days).