Tundra water budget and implications of precipitation underestimation.
Tundra water budget and implications of precipitation underestimation.
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DOI：
10.1002/2016wr020001
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发表时间：
2017-08
影响因子：
5.4
通讯作者：
Zona D
中科院分区：
文献类型：
--
作者：
Liljedahl AK;Hinzman LD;Kane DL;Oechel WC;Tweedie CE;Zona D
由于传统的降雪和雨量计在大风环境中的性能挑战，在获得准确的降水测量的困难限制了有意义的水文评估超过世纪。在这里，我们比较了降雪观测和偏差调整降雪量，以结束冬季积雪的地面测量16年（1999-2014年），并评估降水低估对水平衡的影响Utqiagvik（原巴罗），阿拉斯加（2007-2009年）附近的低梯度苔原湿地。与其他研究一致，不考虑升华，传统的降雪仪捕获了23-56%的冬末积雪。一旦降雪量和降雨量进行偏差调整，长期年降水量估计值将增加一倍以上（从123毫米到274毫米），这突出了使用常规或未经调整的降水量进行研究的风险，这些降水量严重低估了水平衡分量。应用常规降水信息的水平衡分析产生一致的存储赤字（79至152毫米），都大于最大的实际赤字（75毫米），这是在异常低的降雨量的2007年夏季观察到的。调整后的降雨量（±33 mm）的年际变化大于蒸散量（±13 mm）。在冬末积雪（分别为180和164 mm）相似的年份中，测得的积雪转化为径流的年际变化（2008年为29%，2009年为68%）突出了前一个夏天的降雨量（分别为25和60 mm）对春季径流生产的重要性。因此，不正确的降水表示可能对北极水预算的描述产生重大影响，进而可能改变对碳和能量通量的估计。当降水量没有被调整为低估时，水储存赤字一直被高估。与暖季总降雨量相比，7月融雪结束时的降雨量是衡量干旱状况的更有效指标。由于高估了前期水储存赤字和低估了降雪量，降水偏差导致低估了融雪径流量。
Difficulties in obtaining accurate precipitation measurements have limited meaningful hydrologic assessment for over a century due to performance challenges of conventional snowfall and rainfall gauges in windy environments. Here, we compare snowfall observations and bias adjusted snowfall to end‐of‐winter snow accumulation measurements on the ground for 16 years (1999–2014) and assess the implication of precipitation underestimation on the water balance for a low‐gradient tundra wetland near Utqiagvik (formerly Barrow), Alaska (2007–2009). In agreement with other studies, and not accounting for sublimation, conventional snowfall gauges captured 23–56% of end‐of‐winter snow accumulation. Once snowfall and rainfall are bias adjusted, long‐term annual precipitation estimates more than double (from 123 to 274 mm), highlighting the risk of studies using conventional or unadjusted precipitation that dramatically under‐represent water balance components. Applying conventional precipitation information to the water balance analysis produced consistent storage deficits (79 to 152 mm) that were all larger than the largest actual deficit (75 mm), which was observed in the unusually low rainfall summer of 2007. Year‐to‐year variability in adjusted rainfall (±33 mm) was larger than evapotranspiration (±13 mm). Measured interannual variability in partitioning of snow into runoff (29% in 2008 to 68% in 2009) in years with similar end‐of‐winter snow accumulation (180 and 164 mm, respectively) highlights the importance of the previous summer's rainfall (25 and 60 mm, respectively) on spring runoff production. Incorrect representation of precipitation can therefore have major implications for Arctic water budget descriptions that in turn can alter estimates of carbon and energy fluxes. Water storage deficits are consistently overestimated when precipitation is not adjusted for underestimation End‐of‐snowmelt through July rainfall is a more effective measure of drought conditions than total warm season rainfall Precipitation bias lead to underestimated snowmelt runoff, due to overestimated antecedent water storage deficits and underestimated snowfall