| Title | Near-surface temperature lapse rates over Arctic glaciers and their implications for temperature downscaling |
| Author | Gardner, A S; Sharp, M J; Koerner, R M; Labine, C; Boon, S; Marshall, S J; Burgess, D O; Lewis, D |
| Source | Journal of Climatology 2009 p. 4281-4298, https://doi.org/10.1175/2009JCLI2845.1 (Open Access) |
| Year | 2009 |
| Alt Series | Earth Sciences Sector, Contribution Series 20080384 |
| Publisher | American Meteorological Society |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Nunavut |
| NTS | 39; 48H; 49; 120A |
| Area | Ellesmere Island; Devon Island; Arctic Archipelago |
| Lat/Long WENS | -84.0000 -70.0000 82.0000 75.0000 |
| Subjects | environmental geology; temperature; glaciers; climatic fluctuations; modelling; lapse rates; Quaternary |
| Illustrations | location maps; analyses |
| Abstract | Distributed glacier surface melt models are often forced using air temperature fields that are either
downscaled from climate models or reanalysis, or extrapolated from station measurements.
Typically, the
downscaling and/or extrapolation are performed using a constant temperature lapse rate, which is often taken
to be the free-air moist adiabatic lapse rate (MALR: 68--8C km-1). To explore the validity of this approach,
the
authors examined altitudinal gradients in daily mean air temperature along six transects across four
glaciers in the Canadian high Arctic. The dataset includes over 58 000 daily averaged temperature measurements
from 69 sensors covering the
period 1988--2007. Temperature lapse rates near glacier surfaces vary on
both daily and seasonal time scales, are consistently lower than theMALR(ablation seasonmean: 4.98 Ckm-1),
and exhibit strong regional covariance. A significant fraction
of the daily variability in lapse rates is associated
with changes in free-atmospheric temperatures (higher temperatures 5 lower lapse rates). The temperature
fields generated by downscaling point location summit elevation temperatures to the
glacier surface using
temporally variable lapse rates are a substantial improvement over those generated using the static MALR.
These findings suggest that lower near-surface temperature lapse rates can be expected under awarming climate
and
that the air temperature near the glacier surface is less sensitive to changes in the temperature of the free
atmosphere than is generally assumed. |
| GEOSCAN ID | 225820 |
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