Prof Hanna delivers talk at the Royal Meteorological Society

Professor Edward Hanna recently delivered a lecture to the Royal Meteorological Society’s Southeast Centre about his trip to the Chilean High Andes glacier.

rmets

An excerpt from Professor Hanna’s lecture:

Surface air temperature variations and lapse rates on Olivares Gamma Glacier, Rio Olivares Basin, Central Chile, from a novel meteorological sensor network

Empirical-based studies of glacier meteorology, especially for the Southern Hemisphere, are relatively sparse in the literature. Here we use an innovative network of highly-portable, low-cost thermometers to report on high-frequency (1-min time resolution) surface air temperature variations and lapse rates in an 800-m elevational range across Olivares Gamma Glacier in the little-studied Rio Olivares Basin in central Chile. Temperatures were measured during the course of about a week in late Southern summer, 19–27 March 2015, under varying weather conditions. We found a complex dependence of lapse rate on time of day, topography and wider meteorological conditions, with hourly temperature variations mainly associated with short- and long-wave radiation changes and not with wind speed/direction changes. Through the use of various pairs of sites within our station network we also analyse spatial variations in lapse rate. Uniquely in this study we compare temperatures measured at heights of 1 and 2 metres above the glacier surface for the network of five sites, and found that temperatures at these two heights occasionally differed by over 4degC during the early afternoons, although the mean temperature difference is much smaller (2-1 metres is about 0.3degC). A further key result is that daily or even hourly-averaged lapse rate may be insufficient for feeding into accurate melt models of glacier change, with the adoption of sub-hourly (ideally 1–10-minute) resolution lapse rate likely to prove fruitful in new innovative high-time-resolution melt modelling. Our results are useful for feeding into glacier melt models and for improving understanding of glacier response to climate change.”