Sensitivity of a general circulation model to global changes in leaf area index
Sensitivity of a general circulation model to global changes in leaf area index
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DOI：
10.1029/95jd02417
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发表时间：
1996-03
影响因子：
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通讯作者：
T. Chase;R. Pielke;T. Kittel;R. Nemani;S. Running
中科院分区：
文献类型：
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作者：
T. Chase;R. Pielke;T. Kittel;R. Nemani;S. Running
最近已经有了利用卫星数据估计地球表面叶面积的方法。此外，还提供了全球叶面积模式的模拟估计，如果植被与当前当地气候和土壤条件保持平衡，全球叶面积模式将是什么样子。实际植被分布与潜在植被分布之间的差异可能反映了人类活动对地球表面的影响。为了检验模式对叶面积指数（LAI）变化的敏感性，将最大LAI的全球分布用作国家大气研究中心社区气候模式（NCAR CCM 2）中的地面边界条件，并结合生物圈大气传输方案（BATS）。从10年的合奏平均的1月和7月的结果表明，在实际的LAI模拟减少叶面积指数的最大影响发生在北方半球冬季高纬度地区，尽管事实上，直接叶面积指数强迫是可以忽略不计的，在这些地区在每年的这个时候。这可能是由于热带地区的叶面积指数强迫在两半球的冬季都有长期的影响。对亚洲季风区7月份的评估表明，从地面潜热通量减少，表面温度升高，降水量减少与实际LAI分布。虽然在这些模拟结果的统计意义还没有明确建立，我们怀疑，模拟的大气环流动力学的影响已经发生，由于最大叶面积指数的变化，这表明需要进一步注意的植被参数的准确指定。合并的伴随变化，植被覆盖度，粗糙度长度，建议进一步研究。
Methods have recently become available for estimating the amount of leaf area at the surface of the Earth using satellite data. Also available are modeled estimates of what global leaf area patterns would look like should the vegetation be in equilibrium with current local climatic and soil conditions. The differences between the actual vegetation distribution and the potential vegetation distribution may reflect the impact of human activity on the Earth's surface. To examine model sensitivity to changes in leaf area index (LAI), global distributions of maximum LAI were used as surface boundary conditions in the National Center for Atmospheric Research community climate model (NCAR CCM2) coupled with the biosphere atmosphere transfer scheme (BATS). Results from 10-year ensemble averages for the months of January and July indicate that the largest effects of the decreased LAI in the actual LAI simulation occur in the northern hemisphere winter at high latitudes despite the fact that direct LAI forcing is negligible in these regions at this time of year. This is possibly a result of LAI forcing in the tropics which has long-ranging effects in the winter of both hemispheres. An assessment of the Asian monsoon region for the month of July shows decreased latent heat flux from the surface, increased surface temperature, and decreased precipitation with the actual LAI distribution. While the statistical significance of the results has not been unambiguously established in these simulations, we suspect that an effect on modeled general circulation dynamics has occurred due to changes of maximum LAI suggesting that further attention needs to be paid to the accurate designation of vegetation parameters. The incorporation of concomitant changes in albedo, vegetation fractional coverage, and roughness length is suggested for further research.