摘要
The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations.Therefore,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing datasets.The performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(i.e.ITPCAS,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference datasets.Compared with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior performance.At the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET.GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET.The simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP.These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP.This study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.
陆面模式中碳水过程模拟的准确性很大程度依赖于大气驱动数据。因此,选取适当的大气强迫数据可以有效减少陆面模式在高海拔地区水碳过程模拟的不确定性。本研究利用4套常用大气强迫数据(CRUNCEP、ITPCAS、GSWP3和WFDEI)分别驱动陆面模式CLM4.5,开展青藏高原净初级生产力(NPP)和实际蒸散发(ET)模拟试验;结合原位观测等多源参照数据,从多个时空尺度评估4套大气强迫数据在NPP和ET模拟中的表现。相较于原位观测的NPP和ET,4组试验模拟的NPP和ET的决定系数分别在0.58-0.84以及0.59-0.87之间,其中基于GSWP3和ITPCAS驱动的模拟表现更佳。在区域尺度上,基于CRUNCEP驱动的模拟结果相较于参照NPP和ET偏差最大。基于GSWP3驱动的模拟在青藏高原NPP、ET的量级及变化趋势方面都表现最为优异。基于ITPCAS驱动数据模拟的青藏高原ET在1982-2010年间的增加趋势显著高于参照ET和其他3组模拟结果,表明ITPCAS可能并不适用于青藏高原ET的长期变化研究。总体而言,GSWP3大气驱动数据总体表现最优,适合用于驱动CLM4.5开展青藏高原碳水过程的长期模拟研究。本研究结果可为提高陆面模式在高寒区碳水模拟的准确性提供参考。
基金
supported by the National Key Research and Development Program of China(2022YFC3201702)
the National Natural Science Foundation of China(42201146,U2240226)
the Science and Technology Project of Sichuan Province(2022NSFSC1001)
Fundamental Research Funds for The Central Universities(YJ2021133).
