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Controls on evapotranspiration at a subarctic sedge fen
Author(s) -
Eaton Andrea K.,
Rouse Wayne R.
Publication year - 2001
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.1029
Subject(s) - subarctic climate , environmental science , precipitation , evapotranspiration , latent heat , sensible heat , climatology , atmospheric sciences , water balance , latitude , geography , meteorology , geology , ecology , geotechnical engineering , geodesy , biology , archaeology
Abstract In this study, 10 years (1990–99) of summertime data collected at a representative sedge fen in the Hudson Bay Lowland (HBL) are used to investigate the energy and water balance dynamics of subarctic wetlands. The summertime climatic characteristics at the study site during the 10 year study period are also examined. It is shown that mean cumulative summertime precipitation P avg for the study decade closely approximates the 30 year mean P avg . However, the mean summertime air temperature T avg for the study decade is 1 °C higher than the 30 year mean T avg . To examine the energy and water balance dynamics at the study site, the variation in each of their respective components throughout the study decade is considered. Little variation is observed in cumulative summertime net radiation $Q^{*}_{\rm cum}$ and cumulative summertime ground heat flux Q Gcum ; however, substantial year‐to‐year variation is evident in cumulative summertime water deficit WD cum , cumulative summertime precipitation P cum , cumulative summertime sensible heat flux Q Hcum , and cumulative summertime latent heat flux Q Ecum . It is noted that the variability in Q Ecum is particularly significant because it consumes the largest proportion of the available summertime energy, and is the largest component of the summertime water balance at this subarctic wetland. Past research has suggested that Q *, P , and T have the most influence on summertime Q E at high‐latitude wetlands. To test this hypothesis at our study site, Q Ecum , P cum , T avg and $Q^{*}_{\rm cum}$ from each year in the study decade were examined. It is observed that high Q Ecum is associated with high P cum , T avg and $Q^{*}_{\rm cum}$ , and that low Q Ecum is associated with low P cum and T avg . To identify the hydroclimatological variables that are most responsible for controlling Q Ecum dynamics at the sedge fen, a stepwise linear regression was performed. This analysis indicates that P cum and $Q^{*}_{\rm cum}$ are the most important hydroclimatological controls over Q Ecum . However, it is demonstrated that the variability in P cum is more responsible than the variability in $Q^{*}_{\rm cum}$ for the variability in Q Ecum during the study decade because of its higher coefficient of variation. The results of this study have broader applicability to wetlands in other parts of the subarctic ecoregion, including the Mackenzie River Basin (MRB). For example, past studies have shown similarities in the energy balance regimes at wetland sites from the HBL and MRB. Copyright © 2001 John Wiley & Sons, Ltd.