Applying single and two layer canopy models to derive conductances of a Scots pine plantation from micrometeorological measurements
Applying single and two layer canopy models to derive conductances of a Scots pine plantation from micrometeorological measurements
复制标题
应用单层和双层树冠模型从微气象测量中推导出欧洲赤松人工林的电导
DOI：
10.1007/bf00866414
复制
发表时间：
1996
影响因子：
3.4
通讯作者：
M. Wedler
中科院分区：
文献类型：
--
作者：
C. Bernhofer;J. Blanford;R. Siegwolf;M. Wedler
总结单层（Penman-Monteith）和两层（修改的Shuttlewallace）蒸散（ET）模型交替使用，从一个半封闭的苏格兰松种植园的水蒸汽的主导通量相关的电导。推导是基于微气象测量上述冠层能量通量密度和一个简单的电阻网络。在一段连续的好天气期间，冠层下净辐射和冠层下ET约为冠层上相应值的20%。由此产生的潜热通量的传导同意与孔隙测量的松树和林下植被冠层水平缩放。从单到两层建模的转变减少了林冠电导率的松树电导率的林下ET的分数。然而，孔隙度计的结果和micrometeorologically派生电导的特点是完全不同的：孔隙度计的电导率估计是高度可变的，由于气孔响应当地的环境条件或“自然”的变化，树冠和植被斑块的特点是森林林下。微气象学导出的电导在空间上整合，导致相对平滑和重复的日常模式，缺乏小尺度变化的信息。只要小尺度生物多样性不相关，这被看作是微气象导出的电导用于气候研究的大气模式参数化时的有利特征。
SummaryA single layer (Penman-Monteith) and a two layer (modified Shuttleworth-Wallace) evapotranspiration (ET) model are used alternatively to derive conductances related to the dominant fluxes of water vapor from a semi-closed Scots pine plantation. The derivations are based on micrometeorological measurements of above canopy energy flux densities and a simple resistance network. For a period of consecutive fine weather days, below canopy net radiation and below canopy ET were about 20 percent of the corresponding above canopy values. Resulting conductances for latent heat flux agreed well with porometric measurements of pines and understory scaled to canopy level. The shift from single to two layer modelling reduced the canopy conductance to pine conductance by the fraction of understory ET.However, characteristics of porometer results and micrometeorologically derived conductances were quite different: The porometer estimates of conductance were highly variable due to stomatal response to local environmental conditions or “natural” variability within the tree canopy and vegetation patches which characterized the forest understory. Micrometeorologically derived conductances integrate spatially resulting in relatively smooth and repetitive daily patterns that lack the information of small scale variability. This is seen as a favorable feature of micrometeorological derived conductances when used for the parameterization of atmospheric models for climate research as long as small scale bio-diversity is irrelevant.