散射辐射对青藏高原高寒草地总初级生产力模拟的影响

发布时间：2019-06-11 03:10

【摘要】：太阳辐射的散射组分能够增强植被冠层LUE(light use efficiency,光能利用率),因此需要在生产力模型中显式地加入散射辐射的影响,从而更准确地模拟植被冠层光合作用.以青藏高原高寒草地为研究对象,改进光能利用率模型,增加散射辐射模块,利用站点通量观测数据估计模型关键参数;结合区域尺度气象数据和遥感数据,模拟了2003—2008年青藏高原高寒草地区域尺度GPP(gross primary production,总初级生产力),并量化了GPP模拟的不确定性,进而通过分析模型改进前后GPP空间分布及其不确定性的差异量化了散射辐射的作用.结果表明:考虑散射辐射对LUE的影响后,模型参数优化效果明显提升,青藏高原高寒草地GPP的模拟效果得到提升;2003—2008年青藏高原高寒草地GPP模拟值呈现东南部较大,西北部较小的空间格局,与不考虑散射辐射的结果一致,但GPP平均值由312.3 g/(m~2·a)增至341.7 g/(m~2·a),增幅约9.4%,说明不考虑散射辐射会低估青藏高原高寒草地GPP;GPP模拟值不确定性的空间分布与不考虑散射辐射的结果一致,但是平均不确定性大小有所降低,从9.15%降至8.66%.研究显示,若在青藏高原高寒草地的GPP模拟中不考虑散射辐射,虽不会影响其空间格局,但会低估GPP模拟值的大小,同时增加其不确定性.
[Abstract]:The scattering components of solar radiation can enhance the utilization rate of LUE (light use efficiency, light energy in vegetation canopy, so it is necessary to explicitly add the influence of scattered radiation to the productivity model in order to simulate the photosynthesis of vegetation canopy more accurately. Taking the alpine grassland of Qinghai-Xizang Plateau as the research object, the light energy utilization model is improved, the scattering radiation module is added, and the key parameters of the model are estimated by using the site flux observation data. Combined with regional scale meteorological data and remote sensing data, the total primary productivity of GPP (gross primary production, on regional scale of alpine grassland in Qinghai-Xizang Plateau from 2003 to 2008 was simulated, and the uncertainty of GPP simulation was quantified. Furthermore, the effect of scattering radiation is quantified by analyzing the spatial distribution of GPP and the difference of its uncertainty before and after the improvement of the model. The results show that after considering the influence of scattering radiation on LUE, the optimization effect of model parameters is obviously improved, and the simulation effect of GPP in alpine grassland of Qinghai-Xizang Plateau is improved. From 2003 to 2008, the GPP simulation values of alpine grassland in Qinghai-Xizang Plateau showed a large spatial pattern in the southeast and a small spatial pattern in the northwest, which was consistent with the results without considering scattering radiation. However, the average value of GPP increased from 312.3 g / (m ~ 2 路a) to 341.7 g / (m ~ 2 路a), which indicated that the GPP; of alpine grassland in Qinghai-Xizang Plateau would be underestimated without considering scattered radiation. The spatial distribution of uncertainty in GPP simulation value is consistent with that without considering scattering radiation, but the average uncertainty decreases from 9.15% to 8.66%. The results show that if the scattering radiation is not considered in the GPP simulation of alpine grassland in Qinghai-Xizang Plateau, the spatial pattern will not be affected, but the GPP simulation value will be underestimated and its uncertainty will be increased at the same time.
【作者单位】：中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室;中国科学院大学资源与环境学院;中国科学院地球化学研究所环境地球化学国家重点实验室;
【基金】：国家重点研发计划项目(2016YFC0500204) 国家自然科学基金项目(41571424) 科技基础性工作专项(2015FY110700)
【分类号】：S812

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