The Role of Meteorological Variables on Arctic Wetland Evaporation

Anna Liljedahl
International Arctic Research Center, University of Alaska, Fairbanks

Larry Hinzman
International Arctic Research Center, University of Alaska, Fairbanks

Yoshinobu Harazono
Osaka Prefecture University, Sakai, Osaka, Japan


As the climate warms, it is generally expected that the air will be able to hold more moisture and evaporation from water bodies will increase. However, literature shows decreased historical trends in pan-evaporation with increased air temperatures, opening a discussion about the components and dependence of evapotranspiration (ET) on meteorological variables. The latter and its temporal dependency were examined at a coastal arctic wetland in Barrow, northern Alaska.

Today, the area is an energy-limited system, with incoming radiation as the main driver of evapotranspiration. Analysis of directly measured latent heat fluxes by the eddy covariance method during June-August 1999-2003, incoming (R^2 = 0.83±0.06, p-value <0.001) and net (0.84±0.06) short-wave radiation and all net radiation (0.81±0.06) continuously showed the top three R^2 in the 30 minute time scale. Long-wave net radiation showed high correlation to ET in the daily time step not seen in 30 minute scale. Wind speed, air temperature and vapor pressure deficit had no or minor correlation to ET in both the daily and half hourly scale. In June, surface temperatures showed as high correlation to ET as incoming and net short-wave radiation, but it was not found in the daily time step. The relative importance of the different variables remained nearly unchanged throughout the measured years.

The correlation of ET to the different meteorological variables shows temporal scaling dependency. Knowledge of the site specific drivers of ET and their role in different time scales allows for a suitable model selection in estimating historical or in projecting future scenarios of near-surface hydrological conditions. A similar analysis is planned on a nearby eddy covariance tower to examine any spatial differences.


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