New Dataset Based on Multi-Source Land Surface Flux Data and Its Application in the East Asian Summer Monsoon Boundary Area
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摘要: 夏季风影响过渡区是陆面能量交换与区域气候相互作用显著的热点区域。然而,目前缺乏适用于该区域的高精度长期通量数据集,这限制了陆面水热交换与气候相互作用的研究。如何融合目前已有的多源通量资料进行重构建以及应用显得十分必要。本研究综合包括中国北方协同观测试验和中国通量网的多种下垫面通量观测以及多种格点资料,试图重构中国夏季风影响过渡区的陆面能量通量数据集。在筛选具有优良下垫面代表性站点并考察模拟和观测散点分布规律的基础上,利用多元回归模型构建了一套适用于夏季风影响过渡区并且受观测资料约束的月平均感热、潜热和净辐射数据集。交叉验证结果表明构建的数据集相对于几种原始格点数据集精度有一定提高,最大程度上消除了原始格点资料的系统偏差。进一步分析表明在地表能量平衡分量中,陆面湍流通量对夏季风的响应更为显著,并且夏季风影响过渡区陆面湍流热通量对夏季风持续时间呈现对数分布的年际变化规律;当夏季风处于低持续影响状态时陆面湍流热通量年际变化更为显著,偏弱的夏季风系统可能导致陆面过程对气候变化更强的影响。本文基于多源通量数据融合构建的新数据集可以为气候变化研究提供数据支撑,同时增加了对陆面过程与季风系统相互作用的认识。Abstract: The EASM (East Asian summer monsoon) boundary area is active with intense interaction between the land surface process and the regional climate. However, the lack of high-quality long-term flux datasets for this region limits the study of the interaction among the land surface water, heat exchange, and climate. It is necessary to reconstruct a new dataset based on the currently available multiple flux data and then apply it in climate research. In this study, the datasets of land surface energy fluxes in the EASM boundary area in China were reconstructed by integrating the field observations conducted over northern China and several gridded datasets. Based on the selection of sites with good underlying representative surface and the investigation of the scattering distribution of simulations and observations, a set of monthly average sensible heat, latent heat, and net radiation datasets was generated using a multiple regression model. The cross-validation results showed that the accuracy of the constructed dataset was improved compared with several original gridded datasets, and the systematic deviation of the original lattice data was maximally eliminated. Further analysis suggests that among the surface energy balance components, the response of land surface turbulent flux to summer monsoon was more significant, and the interannual variation of the land surface turbulent heat flux with the summer monsoon duration in the EASM boundary area showed logarithmic distribution. The turbulent heat fluxes presented more significant interannual variations, as the summer monsoon was in a low persistent state. A weaker summer monsoon system may lead to a stronger impact of land surface processes on climate change. The new dataset based on multi-source flux data fusion can support climate change research and further clarify the interaction between land surface processes and monsoon climate.
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Key words:
- EASM (East Asian summer monsoon) /
- Boundary area /
- Land surface flux /
- Dataset /
- Summer monsoon duration
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图 1 夏季风影响过渡区内所选观测站点的地理分布。红线代表夏季风活动的南北边缘,蓝色实框、蓝色空三角形和红色实圆点分别代表草原站、农田站和裸地/荒漠站
Figure 1. Geographical distribution of observation sites in EASM (East Asian summer monsoon) boundary area. Red lines represent the north and south edge of summer monsoon. Blue solid frames, blue hollow triangles, and red solid dots represent grassland, cropland, and bare land/desert sites, respectively
图 3 以站点为圆心、不同距离为半径的圆形区域内观测站点所属下垫面类型所占比例:(a)裸地/戈壁;(b)草原;(c)农田;(d)森林。Spt和Zhy分别代表沙坡头和张掖站,Yuz、Nma、Aro、Tyu、Xil和Dsu分别代表榆中、奈曼、阿柔、通榆、锡林格勒和东苏站,Pli、Jzh、Qya、Miy、Chw、Yke和Dxi分别代表平凉、锦州、庆阳、密云、长武、盈科和定西站,Dyk代表大野口站
Figure 3. Percentage of land cover types at measurement sites within the circular area with different radii for (a) bare land/desert, (b) grassland, (c) cropland, and (d) forest. Spt and Zhy represent Shapotou and Zhangye sites, respectively; Yuz, Nma, Aro, Tyu, Xil, and Dsu represent Yuzhong, Naiman, Arou, Tongyu, Xilingele, and Dongsu sites, respectively; Pli, Jzh, Qya, Miy, Chw, Yke, and Dxi represent Pingliang, Jinzhou, Qingyang, Miyun, Changwu, Yingke, and Dingxi sites, respectively; Dyk represents Dayekou site
图 4 草地(蓝色圆圈)、农田(绿色方框)、裸地/荒漠(红色实心圆点)三种下垫面类型净辐射通量(左)、感热通量(中)、潜热通量(右)的模拟值与观测值的散点分布
Figure 4. The scatter distributions of net radiation fluxes (NRF, left), sensible heat fluxes (SHF, middle), latent heat fluxes (LHF, right) from simulation (Sim) and observations (Obs) for grassland (blue circles), farmland (green squares), and bare land/desert (solid red points)
图 5 新构建的(a)净辐射通量、(b)感热通量和(c)潜热通量数据集与观测值的散点图,RMSE、R、N分别表示格点资料的均方根误差、格点资料与观测资料的线性相关系数、样本数
Figure 5. Scatter plots of newly constructed (a) net radiation fluxes (Rn), (b) sensible heat fluxes (HS), and (c) latent heat fluxes (HL) datasets and observations, RMSE, R, N represent the root mean square error of grid datasets, linear correlation coefficients between grid data and observation, sample number, respectively
图 6 不同格点资料(a)净辐射通量、(b)感热通量和(c)潜热通量均方差的相关偏差项、标准差偏差项和平均值偏差项贡献分布
Figure 6. The distributions of contributions from correlation deviation term, standard deviation term, and mean bias term of the mean square error (MSE) in (a) net radiation fluxes, (b) sensible heat fluxes, and (c) latent heat fluxes for different grid datasets
图 8 夏季风影响过渡区(a、b)净辐射通量、(c、d)感热通量和(e、f)潜热通量的夏季气候平均(左,单位:W m−2)和年际变率(右,单位:W m−2)空间分布
Figure 8. Spatial distributions of summer climate mean (left, units: W m−2) and interannual variability (right, units: W m−2) of (a, b) net radiation fluxes, (c, d) sensible heat fluxes, and (e, f) latent heat fluxes in the EASM boundary area
图 9 夏季风影响过渡区(a)西部和(b)东部区域湍流热通量(左侧纵坐标)、夏季风持续时间指数(右侧纵坐标)年际变化以及(c)西部和(d)东部湍流热通量和夏季风持续时间指数的散点分布
Figure 9. Interannual variations of turbulent heat fluxes (left y-axis) and duration index of summer monsoon (right y-axis) in (a) west and (b) east regions of the EASM boundary area. Scatter distributions between turbulent heat fluxes and duration index of summer monsoon for (c) west and (d) east regions of the EASM boundary area
表 1 使用资料简介
Table 1. Introduction of data used in the study
数据类型 名称 机构名称 空间分辨率 时间分辨率 时间长度 再分析资料 NCEP/DOE NCEP/DOE T62 (200 km) 6 h 1979年1月至今 JRA-25 JMA T106 (110 km) 3 h 1979年1月至2014年2月 ERA-Int ECMWF 1.5°×1.5° 6 h 1979年1月至今 MERRA NASA 0.5°×0.67° 1 h 1979年1月至今 离线陆面模式数据集 GLDAS2-NOAH NASA 1°×1° 3 h 1979年1月至2010年12月 陆面观测 中国北方陆面过程观测 中国科学院大气物理研究所/
地理科学与资源所16个站点 30 min 详见表2 表 2 所选观测站点基本情况
Table 2. Basic information on selected observation sites
站点名称 纬度 经度 下垫面类型 观测时段 沙坡头 37.45°N 104.95°S 荒漠 2008年7~9月;2009年7~9月 张掖 38.86°N 100.41°S 裸地 2008年7~9月;2009年7~9月 长武 35.2°N 107.67°S 农田 2008年7~9月;2009年7~9月 定西 35.56°N 104.59°S 旱作农田 2008年7~9月;2009年7~9月 锦州 41.15°N 121.2°S 农田(玉米) 2008年7~9月;2009年7~9月 密云 40.63°N 117.32°S 农田/果林 2008年7~9月;2009年7~9月 平凉 35.53°N 106.94°S 农田 2009年7月至2010年12月 庆阳 35.66°N 107.84°S 农田(小麦) 2009年5月至2010年12月 盈科 38.86°N 100.58°S 绿洲农田(玉米) 2008年7~9月;2009年7~9月 大野口 38.53°N 100.25°S 常绿针叶林 2008年7~9月;2009年7~9月 阿柔 38.04°N 100.46°S 亚高山草甸 2008年7~9月;2009年7~9月 东苏 44.09°N 113.57°S 荒漠化草原 2008年7~9月;2009年7~9月 奈曼 42.93°N 120.7°S 荒漠化草原 2008年7~9月;2009年7~9月 通榆 44.88°N 122.88°S 退化草原 2003年1月至2008年12月 榆中 35.95°N 104.13°S 草原 2007年1月至2010年12月 锡林格勒 44.13°N 116.32°S 草原 2004年1月至2008年12月 表 3 5种格点资料的误差统计情况
Table 3. Errors statistics of five gridded data
资料名称 净辐射通量Rn 感热通量HS 潜热通量HL RMSE/W m−2 Bias/W m−2 R RMSE/W m−2 Bias/W m−2 R RMSE/W m−2 Bias/W m−2 R NCEP/DOE 34.06 12.46 0.90 32.93 9.23 0.69 20.76 11.45 0.79 JRA-25 23.76 3.08 0.92 18.77 4.48 0.76 14.67 2.21 0.85 ERA-Int 20.40 −0.78 0.93 12.66 4.98 0.83 15.16 3.40 0.86 MERRA 24.45 10.55 0.92 22.21 14.85 0.77 15.47 3.50 0.86 GLDAS2-NOAH 27.97 19.94 0.93 32.92 26.31 0.63 17.22 1.04 0.80 注:RMSE、Bias、R分别表示格点资料的均方根误差、系统误差以及格点资料与观测资料的线性相关系数。 表 4 三种陆面通量多元回归模型的截距和回归系数
Table 4. Interception and regression coefficients of three multiple regression models for land surface fluxes
陆面
通量截距/
W m−2回归系数 NCEP/
DOEJRA-25 ERA-Int MERRA GLDAS2-
NOAHRn −8.1894 −0.4522 0.2826 0.6218 0.2019 0.3943 HS 5.1904 −0.1113 0.0596 0.594 0.1396 0.0093 HL 2.854 −0.1512 0.2401 0.2057 0.3972 0.191 表 5 构建数据集与原始格点数据交叉验证的均方根误差(RMSE_CV)
Table 5. Root mean square error of cross-validation (RMSE-CV) between constructed and original gridded datasets
数据集 交叉验证的均方根误差 Rn/W m−2 HS/W m−2 HL/W m−2 构建数据集 22.1 9.4 13.8 NCEP/DOE 34.1 32.9 20.8 JRA-25 23.8 18.8 14.7 ERA-Int 20.4 12.7 15.2 MERRA 24.5 22.2 15.5 GLDAS2-NOAH 28.0 32.9 17.2 注:黑色字体数字表示一列中最小的两个数。 -
[1] Betts A K, Ball J H, Beljaars A C M, et al. 1996. The land surface-atmosphere interaction: A review based on observational and global modeling perspectives [J]. J. Geophys. Res., 101(D3): 7209−7225. doi: 10.1029/95JD02135 [2] Chen Y Y, Yang K, Tang W J, et al. 2012. Parameterizing soil organic carbon’s impacts on soil porosity and thermal parameters for eastern Tibet grasslands [J]. Sci. China: Earth Sci., 55(6): 1001−1011. doi: 10.1007/s11430-012-4433-0 [3] da Rocha H R, Manzi A O, Cabral O M, et al. 2009. Patterns of water and heat flux across a biome gradient from tropical forest to savanna in Brazil [J]. J. Geophys. Res., 114(G1): G00B12. doi: 10.1029/2007JG000640 [4] Decker M, Zeng X B. 2009. Impact of modified Richards equation on global soil moisture simulation in the Community Land Model (CLM3.5) [J]. J. Adv. Model. Earth Syst., 1(3): 5. doi: 10.3894/JAMES.2009.1.5 [5] Decker M, Brunke M A, Wang Z, et al. 2012. Evaluation of the reanalysis products from GSFC, NCEP, and ECMWF using flux tower observations [J]. J. Climate, 25(6): 1916−1944. doi: 10.1175/JCLI-D-11-00004.1 [6] 丁一汇, 司东, 柳艳菊, 等. 2018. 论东亚夏季风的特征、驱动力与年代际变化 [J]. 大气科学, 42(3): 533−558. doi: 10.3878/j.issn.1006-9895.1712.17261Ding Y H, Si D, Liu Y J, et al. 2018. On the characteristics, driving forces and inter-decadal variability of the East Asian summer monsoon [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 42(3): 533−558. doi: 10.3878/j.issn.1006-9895.1712.17261 [7] Finnigan J J, Clement R, Malhi Y, et al. 2003. A re-evaluation of long-term flux measurement techniques. Part I: Averaging and coordinate rotation [J]. Bound.-Layer Meteorol., 107(1): 1−48. doi: 10.1023/A:1021554900225 [8] Fisher J B, Tu K P, Baldocchi D D. 2008. Global estimates of the land–atmosphere water flux based on monthly AVHRR and ISLSCP-II data, validated at 16 FLUXNET sites [J]. Remote Sens. Environ., 112(3): 901−919. doi: 10.1016/j.rse.2007.06.025 [9] Foken T, Wimmer F, Mauder M, et al. 2006. Some aspects of the energy balance closure problem [J]. Atmos. Chem. Phys., 6(12): 4395−4402. doi: 10.5194/acp-6-4395-2006 [10] Foken T. 2008. The energy balance closure problem: An overview [J]. Ecol. Appl., 18(6): 1351−1367. doi: 10.1890/06-0922.1 [11] 符淙斌, 马柱国. 2008. 全球变化与区域干旱化 [J]. 大气科学, 32(4): 752−760. doi: 10.3878/j.issn.1006-9895.2008.04.05Fu C B, Ma Z G. 2008. Global change and regional aridification [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 32(4): 752−760. doi: 10.3878/j.issn.1006-9895.2008.04.05 [12] Gupta H V, Kling H, Yilmaz K K, et al. 2009. Decomposition of the mean squared error and NSE performance criteria: Implications for improving hydrological modelling [J]. J. Hydrol., 377(1-2): 80−91. doi: 10.1016/j.jhydrol.2009.08.003 [13] 胡豪然, 钱维宏. 2007. 东亚夏季风北边缘的确认 [J]. 自然科学进展, 17(1): 57−65. doi: 10.3321/j.issn:1002-008X.2007.01.009Hu H R, Qian W H. 2007. Identifying the northernmost summer monsoon location in East Asia [J]. Prog. Nat. Sci. (in Chinese), 17(1): 57−65. doi: 10.3321/j.issn:1002-008X.2007.01.009 [14] 胡隐樵, 高由禧, 王介民, 等. 1994. 黑河实验(HEIFE)的一些研究成果 [J]. 高原气象, 13(3): 225−236. doi: 10.3321/j.issn:1000-0534.1994.03.019Hu Y Q, Gao Y X, Wang J M, et al. 1994. Some achievements in scientific research during HEIFE [J]. Plateau Meteor. (in Chinese), 13(3): 225−236. doi: 10.3321/j.issn:1000-0534.1994.03.019 [15] 黄菲, 李栋梁, 汤绪, 等. 2009. 用过程透雨量确定的东亚夏季风北边缘特征 [J]. 应用气象学报, 20(5): 530−538. doi: 10.3969/j.issn.1001-7313.2009.05.003Huang F, Li D L, Tang X, et al. 2009. Determination on the north boundary of summer monsoon in East Asian with soaking rainfall [J]. Journal of Applied Meteorological Science (in Chinese), 20(5): 530−538. doi: 10.3969/j.issn.1001-7313.2009.05.003 [16] 姜大膀, 田芝平. 2013. 21世纪东亚季风变化: CMIP3和CMIP5模式预估结果 [J]. 科学通报, 58(8): 707−716. doi: 10.1007/s11434-012-5533-0Jiang D B, Tian Z P. 2013. East Asian monsoon change for the 21st century: Results of CMIP3 and CMIP5 models [J]. Chinese Science Bulletin (in Chinese), 58(8): 707−716. doi: 10.1007/s11434-012-5533-0 [17] Jiménez C, Prigent C, Mueller B, et al. 2011. Global intercomparison of 12 land surface heat flux estimates [J]. J. Geophys. Res., 116(D2): D02102. doi: 10.1029/2010JD014545 [18] Jung M, Reichstein M, Bondeau A. 2009. Towards global empirical upscaling of FLUXNET eddy covariance observations: Validation of a model tree ensemble approach using a biosphere model [J]. Biogeosciences, 6(10): 2001−2013. doi: 10.5194/bg-6-2001-2009 [19] Jung M, Reichstein M, Ciais P, et al. 2010. Recent decline in the global land evapotranspiration trend due to limited moisture supply [J]. Nature, 467(7318): 951−954. doi: 10.1038/nature09396 [20] 柯宗建, 张培群, 董文杰, 等. 2009. 最优子集回归方法在季节气候预测中的应用 [J]. 大气科学, 33(5): 994−1002. doi: 10.3878/j.issn.1006-9895.2009.05.10Ke Z J, Zhang P Q, Dong W J, et al. 2009. An application of optimal subset regression in seasonal climate prediction [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 33(5): 994−1002. doi: 10.3878/j.issn.1006-9895.2009.05.10 [21] Koster R D, Dirmeyer P A, Guo Z C, et al. 2004. Regions of strong coupling between soil moisture and precipitation [J]. Science, 305(5687): 1138−1140. doi: 10.1126/science.1100217 [22] Kumar S, Merwade V. 2011. Evaluation of NARR and CLM3.5 outputs for surface water and energy budgets in the Mississippi River basin [J]. J. Geophys. Res., 116(D8): D08115. doi: 10.1029/2010JD014909 [23] 李栋梁, 邵鹏程, 王慧, 等. 2013. 中国东亚副热带夏季风北边缘带研究进展 [J]. 高原气象, 32(1): 305−314. doi: 10.7522/j.issn.1000-0534.2012.00030Li D L, Shao P C, Wang H, et al. 2013. Advances in research of the north boundary belt of East Asia subtropical summer monsoon in China [J]. Plateau Meteor. (in Chinese), 32(1): 305−314. doi: 10.7522/j.issn.1000-0534.2012.00030 [24] Li H Y, Fu C B, Guo W D. 2017. An integrated evaluation of land surface energy fluxes over China in seven reanalysis/modeling products [J]. J. Geophys. Res., 122(16): 8543−8566. doi: 10.1002/2016JD026166 [25] 李杉, 符淙斌. 2015. 中美半干旱区长期地表通量序列的构建及检验 [J]. 气象科学, 35(1): 1−8. doi: 10.3969/2013jms.0041Li S, Fu C B. 2015. Reconstruction and validation of a long-term surface flux sequence in the semi-arid region of China and North America [J]. Journal of the Meteorological Sciences (in Chinese), 35(1): 1−8. doi: 10.3969/2013jms.0041 [26] 李正泉, 于贵瑞, 温学发, 等. 2004. 中国通量观测网络(ChinaFLUX)能量平衡闭合状况的评价 [J]. 中国科学D: 地球科学, 34(S2): 46−56.Li Z Q, Yu G R, Wen X F, et al. 2004. Energy balance closure at ChinaFLUX sites [J]. Science in China (Earth Sciences), 34(S2): 46−56. [27] 林祥, 钱维宏. 2012. 全球季风和季风边缘研究 [J]. 地球科学进展, 27(1): 26−34.Lin X, Qian W H. 2012. Review of the global monsoon and monsoon marginal zones [J]. Adv. Earth Sci. (in Chinese), 27(1): 26−34. [28] 吕达仁, 陈佐忠, 陈家宜, 等. 2002. 内蒙古半干旱草原土壤—植被—大气相互作用(IMGRASS)综合研究 [J]. 地学前缘, 9(2): 295−306. doi: 10.3321/j.issn:1005-2321.2002.02.007Lü D R, Chen Z Z, Chen J Y, et al. 2002. Composite study on Inner Mongolia semi-arid grassland soil–vegetation–atmosphere interaction (IMGRASS) [J]. Earth Sci. Front. (in Chinese), 9(2): 295−306. doi: 10.3321/j.issn:1005-2321.2002.02.007 [29] Onogi K, Tsutsui J, Koide H, et al. 2007. The JRA-25 reanalysis [J]. J. Meteor. Soc. Japan, 85: 369−432. doi: 10.2151/jmsj.85.369 [30] 欧廷海, 钱维宏. 2006. 东亚季风边缘带上的植被变化 [J]. 地球物理学报, 49(3): 698−705. doi: 10.3321/j.issn:0001-5733.2006.03.012Ou T H, Qian W H. 2006. Vegetation variations along the monsoon boundary zone in East Asia [J]. Chinese J. Geophys. (in Chinese), 49(3): 698−705. doi: 10.3321/j.issn:0001-5733.2006.03.012 [31] Roberts J B, Robertson F R, Clayson C A, et al. 2012. Characterization of turbulent latent and sensible heat flux exchange between the atmosphere and ocean in MERRA [J]. J. Climate, 25(3): 821−838. doi: 10.1175/jcli-d-11-00029.1 [32] Rodell M, Houser P R, Jambor U, et al. 2004. The global land data assimilation system [J]. Bull. Amer. Meteor. Soc., 85(3): 381−394. doi: 10.1175/BAMS-85-3-381 [33] Seneviratne S I, Corti T, Davin E L, et al. 2010. Investigating soil moisture–climate interactions in a changing climate: A review [J]. Earth-Science Reviews, 99(3-4): 125−161. doi: 10.1016/j.earscirev.2010.02.004 [34] Sheffield J, Wood E F, Munoz-Arriola F. 2010. Long-term regional estimates of evapotranspiration for Mexico based on downscaled ISCCP data [J]. J. Hydrometeor., 11(2): 253−275. doi: 10.1175/2009jhm1176.1 [35] Shi Q Q, Liang S L. 2014. Surface-sensible and latent heat fluxes over the Tibetan Plateau from ground measurements, reanalysis, and satellite data [J]. Atmos. Chem. Phys., 14(11): 5659−5677. doi: 10.5194/acp-14-5659-2014 [36] Shi Q Q, Liang S L. 2013. Characterizing the surface radiation budget over the Tibetan Plateau with ground-measured, reanalysis, and remote sensing data set. 1: Methodology [J]. J. Geophys. Res., 118(17): 9642−9657. doi: 10.1002/jgrd.50720 [37] 史正涛. 1996. 中国季风边缘带自然灾害的区域特征 [J]. 干旱区资源与环境, 10(4): 1−7.Shi Z T. 1996. Regional characters of natural disaster in marginal monsoon belt of China [J]. J. Arid Land Resour. Environ. (in Chinese), 10(4): 1−7. [38] Simmons A, Uppala S, Dee D, et al. 2006. ERA-Interim: New ECMWF reanalysis products from 1989 onwards [J]. ECMWF Newsl., 110: 25−35. [39] Steinfeld G, Letzel M O, Raasch S, et al. 2007. Spatial representativeness of single tower measurements and the imbalance problem with eddy-covariance fluxes: Results of a large-eddy simulation study [J]. Bound.-Layer Meteor., 123(1): 77−98. doi: 10.1007/s10546-006-9133-x [40] Stephens G L, Li J L, Wild M, et al. 2012. An update on Earth’s energy balance in light of the latest global observations [J]. Nature Geoscience, 5(10): 691−696. doi: 10.1038/ngeo1580 [41] 汤绪, 陈葆德, 梁萍, 等. 2009. 有关东亚夏季风北边缘的定义及其特征 [J]. 气象学报, 67(1): 83−89. doi: 10.3321/j.issn:0577-6619.2009.01.009Tang X, Chen B D, Liang P, et al. 2009. Definition and features of the north edge of Asian summer monsoon [J]. Acta Meteor. Sinica (in Chinese), 67(1): 83−89. doi: 10.3321/j.issn:0577-6619.2009.01.009 [42] Tramontana G, Jung M, Schwalm C R, et al. 2016. Predicting carbon dioxide and energy fluxes across global FLUXNET sites with regression algorithms [J]. Biogeosciences, 13(14): 4291−4313. doi: 10.5194/bg-13-4291-2016 [43] Trenberth K E, Stepaniak D P. 2004. The flow of energy through the Earth’s climate system [J]. Quart. J. Roy. Meteor. Soc., 130(603): 2677−2701. doi: 10.1256/qj.04.83 [44] Twine T E, Kustas W P, Norman J M, et al. 2000. Correcting eddy-covariance flux underestimates over a grassland [J]. Agric. For. Meteor., 103(3): 279−300. doi: 10.1016/s0168-1923(00)00123-4 [45] 王澄海, 王蕾迪. 2010. 西北半干旱区感、潜热通量特征及近50年来的变化趋势 [J]. 高原气象, 29(4): 849−854.Wang C H, Wang L D. 2010. Characteristics of sensible and latent heat fluxes in semi-arid region of northwest China and change trend in recent 50 years [J]. Plateau Meteor. (in Chinese), 29(4): 849−854. [46] Wang K C, Liang S L. 2008. An improved method for estimating global evapotranspiration based on satellite determination of surface net radiation, vegetation index, temperature, and soil moisture [J]. J. Hydrometeor., 9(4): 712−727. doi: 10.1175/2007JHM911.1 [47] Yang K, Koike T, Ishikawa H, et al. 2008. Turbulent flux transfer over bare-soil surfaces: Characteristics and parameterization [J]. J. Appl. Meteor. Climatol., 47(1): 276−290. doi: 10.1175/2007JAMC1547.1 [48] Yao Y J, Liang S L, Li X L, et al. 2016. Assessment and simulation of global terrestrial latent heat flux by synthesis of CMIP5 climate models and surface eddy covariance observations [J]. Agricultural and Forest Meteorology, 223: 151−167. doi: 10.1016/j.agrformet.2016.03.016 [49] 曾剑, 张强, 王胜. 2011. 中国北方不同气候区晴天陆面过程区域特征差异 [J]. 大气科学, 35(3): 483−494. doi: 10.3878/j.issn.1006-9895.2011.03.09Zeng J, Zhang Q, Wang S. 2011. Regional differences in the characteristics of clear-sky land surface processes in distinct climatic zones over northern China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 35(3): 483−494. doi: 10.3878/j.issn.1006-9895.2011.03.09 [50] 曾剑, 张强, 王春玲. 2016. 东亚夏季风边缘摆动区陆面能量时空分布规律及其与气候环境的关系 [J]. 气象学报, 74(6): 876−888. doi: 10.11676/qxxb2016.064Zeng J, Zhang Q, Wang C L. 2016. Spatial–temporal pattern of surface energy fluxes over the East Asian summer monsoon edge area in China and its relationship with climate [J]. Acta Meteor. Sinica (in Chinese), 74(6): 876−888. doi: 10.11676/qxxb2016.064 [51] Zeng J, Zhang Q. 2019. A humidity index for the summer monsoon transition zone in East Asia [J]. Climate Dyn., 53(9): 5511−5527. doi: 10.1007/s00382-019-04876-0 [52] 张强, 胡向军, 王胜, 等. 2009. 黄土高原陆面过程试验研究 (LOPEX) 有关科学问题 [J]. 地球科学进展, 24(4): 363−371. doi: 10.3321/j.issn:1001-8166.2009.04.002Zhang Q, Hu X J, Wang S, et al. 2009. Some technological and scientific issues about the experimental study of land surface processes in Chinese Loess Plateau (LOPEX) [J]. Adv. Earth Sci. (in Chinese), 24(4): 363−371. doi: 10.3321/j.issn:1001-8166.2009.04.002 [53] 张强, 黄菁, 张良. 2013. 黄土高原区域气候暖干化对地表能量交换特征的影响 [J]. 物理学报, 62(13): 139202. doi: 10.7498/aps.62.139202Zhang Q, Huang J, Zhang L. 2013. Warming and drying climate over Loess Plateau area in China and its effect on land surface energy exchange [J]. Acta Phys. Sinica (in Chinese), 62(13): 139202. doi: 10.7498/aps.62.139202 [54] Zhang Q, Zeng J, Zhang L Y. 2012. Characteristics of land surface thermal-hydrologic processes for different regions over North China during prevailing summer monsoon period [J]. Sci. China Earth Sci., 55(11): 1872−1880. doi: 10.1007/s11430-012-4373-8 [55] Zhang H L, Zhang Q, Yue P, et al. 2016. Aridity over a semiarid zone in northern China and responses to the East Asian summer monsoon [J]. J. Geophys. Res., 121(23): 13901−13918. doi: 10.1002/2016JD025261 [56] 张强, 岳平, 张良, 等. 2019. 夏季风过渡区的陆—气相互作用: 述评与展望 [J]. 气象学报, 77(4): 758−773. doi: 10.11676/qxxb2019.038Zhang Q, Yue P, Zhang L, et al. 2019. Land–Atmosphere over the summer monsoon transition zone in China: A review and prospects [J]. Acta Meteor. Sinica (in Chinese), 77(4): 758−773. doi: 10.11676/qxxb2019.038 [57] Zhang Q, Lin J J, Liu W C, et al. 2019. Precipitation seesaw phenomenon and its formation mechanism in the eastern and western parts of Northwest China during the flood season [J]. Sci. China: Earth Sci., 62(12): 2083−2098. doi: 10.1007/s11430-018-9357-y [58] 周兵, 赵翠光, 赵声蓉. 2006. 多模式集合预报技术及其分析与检验 [J]. 应用气象学报, 17(S1): 104−109. doi: 10.3969/j.issn.1001-7313.2006.z1.015Zhou B, Zhao C G, Zhao S R. 2006. Multi-model ensemble forecast technology with analysis and verification of the results [J]. Journal of Applied Meteorological Science (in Chinese), 17(S1): 104−109. doi: 10.3969/j.issn.1001-7313.2006.z1.015 [59] Zhou C L, Wang K C. 2016. Evaluation of surface fluxes in ERA-interim using flux tower data [J]. J. Climate, 29(4): 1573−1582. doi: 10.1175/JCLI-D-15-0523.1 [60] Zuo H C, Xiao X, Yang Q D, et al. 2012. On the atmospheric movement and the imbalance of observed and calculated energy in the surface layer [J]. Sci. China Earth Sci., 55(9): 1518−1532. doi: 10.1007/s11430-012-4378-3 -