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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >SEASONAL TRENDS IN ENERGY, WATER, AND CARBON DIOXIDE FLUXES AT A NORTHERN BOREAL WETLAND
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SEASONAL TRENDS IN ENERGY, WATER, AND CARBON DIOXIDE FLUXES AT A NORTHERN BOREAL WETLAND

机译：北部北方湿地能源，水和二氧化碳排放的季节性趋势

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Micrometeorological measurements were made over a northern boreal fen near Thompson, Manitoba, Canada, as part of the Boreal Ecosystem-Atmosphere Study. The measurement period extended from the start of snowmelt until the early fall, at which time senescence was widespread throughout the fen. Data analysis concentrated on identifying seasonal trends in energy, water, and carbon dioxide fluxes and linking them to observed surface cover changes. Albedos (solar and photosynthetically active radiation (PAR)) showed large decreases over the melt period, reaching seasonal lows at the end of melt. Solar albedo increased in the summer in response to vegetation growth on the fen, while PAR albedo remained constant. Incoming and outgoing longwave flux seasonal trends were similar, so seasonal changes in net radiation were driven by the net solar flux. During the spring thaw, the melting of snow and ground ice was equal to about 28% of the daily total net radiation, while the soil heat flux accounted for about 5%. Bowen ratios at this time were above unity. Mean Bowen ratio decreased to 0.70 during the period between spring thaw and leaf-out. As the vascular vegetation cover developed, Bowen ratios decreased to seasonal lows of 0.10-0.20 near midsummer and then increased to above unity during senescence. The daily evaporative fraction (EF) was highest (greater than or equal to 0.80) during midsummer when the vascular vegetation was in full leaf and actively photosynthesizing, and EF decreased to a mean of 0.55 during senescence. Eddy correlation measurements of carbon dioxide flux showed the fen acting as a net sink for CO, only while the vascular vegetation was actively photosynthesizing with a daily mean flux of -0.81 g CO2-C m(-2) d(-1) (standard error = 0.16). Before leafing and during senescence the fen was a net source of CO2. Integrated over the study period of 124 days, the fen experienced a net loss of 30.4 g CO2 m(-2) to the atmosphere. [References: 31]
机译：北方生态系统-大气研究的一部分是在加拿大曼尼托巴省汤普森附近的北方寒进行了微气象测量。测量期从融雪开始一直延伸到初秋，那时衰老在整个小芬中普遍存在。数据分析的重点是确定能源，水和二氧化碳通量的季节性趋势，并将其与观测到的地表覆盖率变化联系起来。反照率（太阳和光合有效辐射（PAR））在整个融化期间显示出较大的下降，在融化结束时达到季节性低点。夏季，由于the的植被生长，太阳反照率增加，而PAR反照率保持恒定。传入和传出的长波通量的季节趋势相似，因此净辐射的季节性变化是由净太阳通量驱动的。在春季解冻期间，雪和冰的融化约占每日总净辐射的28％，而土壤热通量约占5％。此时的博恩比率高于1。在春季解冻到退耕期之间，平均鲍恩比降低到0.70。随着维管束植被的发展，鲍文比率在仲夏附近下降至季节性低点0.10-0.20，然后在衰老期间增至1以上。在盛夏时，当脉管植被在全叶中并活跃地进行光合作用时，每日蒸发分数（EF）最高（大于或等于0.80），并且在衰老期间，EF下降至平均值0.55。二氧化碳通量的涡流相关测量表明，只有当血管植被以光日平均通量为-0.81 g CO2-C m（-2）d（-1）的方式活跃地进行光合作用时，fen才是CO的净汇。误差= 0.16）。在生叶之前和衰老期间，the是二氧化碳的净来源。在研究期124天的综合时间内，该芬对大气的净损失为30.4 g CO2 m（-2）。 [参考：31]

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