CGRG Bibliography of Canadian Geomorphology
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Author : Boon, S.
Date : 2007.
Title : Air temperature lapse rates at Andrei Glacier, northwestern BC.
Publication : CMOS, CGU, AMS Congress 2007. "Air, Ocean, Earth and Ice on the Rock". May 28 - June 1, 2007. St. John's Congress Centre, Newfoundland and Labrador, Canada.
Issue :
Page(s) : H06-2DP .1.
Abstract
Air temperature lapse rates are often used in numerical models of alpine glacier melt and mass balance to extrapolate data from a single meteorological station to locations distant from that station. As field measurements of alpine lapse rates are limited, however, they are often assumed to be constant at -6ºC km-1 (moist adiabatic lapse rate; MALR). How do measured lapse rates compare with the MALR? Can 500 mb synoptic maps be used to derive surface air temperature lapse rates in areas for which measurements are unavailable? To explore these questions, three meteorological stations were installed along an elevational transect in the Andrei Glacier catchment (56° 55' N, 130° 55' W), recording hourly average air temperature (ºC), barometric pressure (kPa), and precipitation (mm) from July – September, 2006. Daily lapse rates between the lowest and highest stations are far from constant: the standard deviation is 1.5ºC, with a range of ±2 standard deviations. 52% of daily lapse rates fall between –6 to –8ºC km-1 and correlate with surface pressure measurements, indicating a potential link to large-scale synoptic configurations. The high elevation station is most representative of these larger-scale climatic conditions, as the low elevation station is often trapped within the glacier boundary layer despite its location 2 km downvalley from the glacier toe. While upper-level synoptic maps show a general relationship with surface conditions, the connection between upper-level and surface conditions must be determined prior to using these maps to derive surface air temperature lapse rates. Interactions between the glacier and local meteorology can alter the thickness and extent of the glacier surface boundary layer, effectively decoupling surface air temperature lapse rates from the regional synoptic configuration.
Bibliography of Canadian Geomorphology