Articles | Volume 26, issue 24 
            
                
                    
            
            
            https://doi.org/10.5194/hess-26-6311-2022
                    © Author(s) 2022. This work is distributed under 
the Creative Commons Attribution 4.0 License.
                the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/hess-26-6311-2022
                    © Author(s) 2022. This work is distributed under 
the Creative Commons Attribution 4.0 License.
                the Creative Commons Attribution 4.0 License.
Simulating carbon and water fluxes using a coupled process-based terrestrial biosphere model and joint assimilation of leaf area index and surface soil moisture
Sinan Li
                                            Key Laboratory of Digital Earth Science, Aerospace Information
Research Institute, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Beijing 100094, China
                                        
                                    
                                            College of Resources and Environment, University of Chinese Academy
of Sciences, No. 19A Yuquan Road, Beijing 100049, China
                                        
                                    Li Zhang
CORRESPONDING AUTHOR
                                            
                                    
                                            Key Laboratory of Digital Earth Science, Aerospace Information
Research Institute, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Beijing 100094, China
                                        
                                    
                                            International Research Center of Big Data for Sustainable
Development Goals, Beijing 100094, China
                                        
                                    Jingfeng Xiao
CORRESPONDING AUTHOR
                                            
                                    
                                            Earth Systems Research Center, Institute for the Study of Earth,
Oceans, and Space, University of New Hampshire, Durham, New Hampshire 03824, USA
                                        
                                    Rui Ma
                                            School of Remote Sensing and Information Engineering, Wuhan
University, Wuhan 430079, China
                                        
                                    Xiangjun Tian
                                            International Center for Climate and Environment Sciences (ICCES),
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing
100029, China
                                        
                                    Min Yan
                                            Key Laboratory of Digital Earth Science, Aerospace Information
Research Institute, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Beijing 100094, China
                                        
                                    
                                            International Research Center of Big Data for Sustainable
Development Goals, Beijing 100094, China
                                        
                                    Related authors
No articles found.
Liang Feng, Paul I. Palmer, Luke Smallman, Jingfeng Xiao, Paolo Cristofanelli, Ove Hermansen, John Lee, Casper Labuschagne, Simonetta Montaguti, Steffen M. Noe, Stephen M. Platt, Xinrong Ren, Martin Steinbacher, and Irène Xueref-Remy
                                    Atmos. Chem. Phys., 25, 13053–13076, https://doi.org/10.5194/acp-25-13053-2025, https://doi.org/10.5194/acp-25-13053-2025, 2025
                                    Short summary
                                    Short summary
                                            
                                                The year 2023 saw unexpectedly large global atmospheric CO2 growth. Satellite data reveal a role for increased tropical emissions. Larger emissions over eastern Brazil can be explained by warmer temperatures, which has led to exceptional drought, while hydrological changes play more of a role in emission increases elsewhere in the tropics. Broadly, we find that this situation continues into 2024.
                                            
                                            
                                        Xufeng Wang, Tao Che, Jingfeng Xiao, Tonghong Wang, Junlei Tan, Yang Zhang, Zhiguo Ren, Liying Geng, Haibo Wang, Ziwei Xu, Shaomin Liu, and Xin Li
                                    Earth Syst. Sci. Data, 17, 1329–1346, https://doi.org/10.5194/essd-17-1329-2025, https://doi.org/10.5194/essd-17-1329-2025, 2025
                                    Short summary
                                    Short summary
                                            
                                                In this study, carbon flux and auxiliary meteorological data are post-processed to create an analysis-ready dataset for 34 sites across six ecosystems in the Heihe River basin. Overall, 18 sites have multi-year observations, while 16 were observed only during the 2012 growing season, totaling 1513 site months. This dataset can be used to explore carbon exchange, assess ecosystem responses to climate change, support upscaling studies, and evaluate carbon cycle models.
                                            
                                            
                                        Yi Liu, Jingfeng Xiao, Xing Li, and Yue Li
                                    Hydrol. Earth Syst. Sci., 29, 1241–1258, https://doi.org/10.5194/hess-29-1241-2025, https://doi.org/10.5194/hess-29-1241-2025, 2025
                                    Short summary
                                    Short summary
                                            
                                                This work demonstrates that multi-source satellite-based water and carbon fluxes can capture critical soil moisture at a large spatial scale. In particular, grassland and clay with critical soil moisture higher than average soil moisture may be in a state of water limitation for long periods. Increased water demand could expose western grassland to more vulnerability.
                                            
                                            
                                        Mana Gharun, Ankit Shekhar, Jingfeng Xiao, Xing Li, and Nina Buchmann
                                    Biogeosciences, 21, 5481–5494, https://doi.org/10.5194/bg-21-5481-2024, https://doi.org/10.5194/bg-21-5481-2024, 2024
                                    Short summary
                                    Short summary
                                            
                                                In 2022, Europe's forests faced unprecedented dry conditions. Our study aimed to understand how different forest types respond to extreme drought. Using meteorological data and satellite imagery, we compared 2022 with two previous extreme years, 2003 and 2018. Despite less severe drought in 2022, forests showed a 30 % greater decline in photosynthesis compared to 2018 and 60 % more than 2003. This suggests an alarming level of vulnerability of forests across Europe to more frequent droughts.
                                            
                                            
                                        Shanlei Sun, Zaoying Bi, Jingfeng Xiao, Yi Liu, Ge Sun, Weimin Ju, Chunwei Liu, Mengyuan Mu, Jinjian Li, Yang Zhou, Xiaoyuan Li, Yibo Liu, and Haishan Chen
                                    Earth Syst. Sci. Data, 15, 4849–4876, https://doi.org/10.5194/essd-15-4849-2023, https://doi.org/10.5194/essd-15-4849-2023, 2023
                                    Short summary
                                    Short summary
                                            
                                                Based on various existing datasets, we comprehensively considered spatiotemporal differences in land surfaces and CO2 effects on plant stomatal resistance to parameterize the Shuttleworth–Wallace model, and we generated a global 5 km ensemble mean monthly potential evapotranspiration (PET) dataset (including potential transpiration PT and soil evaporation PE) during 1982–2015. The new dataset may be used by academic communities and various agencies to conduct various studies.
                                            
                                            
                                        Xinyan Liu, Tao He, Shunlin Liang, Ruibo Li, Xiongxin Xiao, Rui Ma, and Yichuan Ma
                                    Earth Syst. Sci. Data, 15, 3641–3671, https://doi.org/10.5194/essd-15-3641-2023, https://doi.org/10.5194/essd-15-3641-2023, 2023
                                    Short summary
                                    Short summary
                                            
                                                We proposed a data fusion strategy that combines the complementary features of multiple-satellite cloud fraction (CF) datasets and generated a continuous monthly 1° daytime cloud fraction product covering the entire Arctic during the sunlit months in 2000–2020. This study has positive significance for reducing the uncertainties for the assessment of surface radiation fluxes and improving the accuracy of research related to climate change and energy budgets, both regionally and globally.
                                            
                                            
                                        Brendan Byrne, Junjie Liu, Yonghong Yi, Abhishek Chatterjee, Sourish Basu, Rui Cheng, Russell Doughty, Frédéric Chevallier, Kevin W. Bowman, Nicholas C. Parazoo, David Crisp, Xing Li, Jingfeng Xiao, Stephen Sitch, Bertrand Guenet, Feng Deng, Matthew S. Johnson, Sajeev Philip, Patrick C. McGuire, and Charles E. Miller
                                    Biogeosciences, 19, 4779–4799, https://doi.org/10.5194/bg-19-4779-2022, https://doi.org/10.5194/bg-19-4779-2022, 2022
                                    Short summary
                                    Short summary
                                            
                                                Plants draw CO2 from the atmosphere during the growing season, while respiration releases CO2 to the atmosphere throughout the year, driving seasonal variations in atmospheric CO2 that can be observed by satellites, such as the Orbiting Carbon Observatory 2 (OCO-2). Using OCO-2 XCO2 data and space-based constraints on plant growth, we show that permafrost-rich northeast Eurasia has a strong seasonal release of CO2 during the autumn, hinting at an unexpectedly large respiration signal from soils.
                                            
                                            
                                        Rui Ma, Jingfeng Xiao, Shunlin Liang, Han Ma, Tao He, Da Guo, Xiaobang Liu, and Haibo Lu
                                    Geosci. Model Dev., 15, 6637–6657, https://doi.org/10.5194/gmd-15-6637-2022, https://doi.org/10.5194/gmd-15-6637-2022, 2022
                                    Short summary
                                    Short summary
                                            
                                                Parameter optimization can improve the accuracy of modeled carbon fluxes. Few studies conducted pixel-level parameterization because it requires a high computational cost. Our paper used high-quality spatial products to optimize parameters at the pixel level, and also used the machine learning method to improve the speed of optimization. The results showed that there was significant spatial variability of parameters and we also improved the spatial pattern of carbon fluxes.
                                            
                                            
                                        Jing Fang, Xing Li, Jingfeng Xiao, Xiaodong Yan, Bolun Li, and Feng Liu
                                        Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2021-452, https://doi.org/10.5194/essd-2021-452, 2022
                                    Revised manuscript not accepted 
                                    Short summary
                                    Short summary
                                            
                                                The dataset provided the vegetation photosynthetic phenology instead of traditional phenology to represent plant seasonal activities. This dataset had the latest period (2001–2020) and a fine spatial resolution (0.05 degree). Our phenology metrics revealed the spatial-temporal patterns of the multiple growing seasons in the Northern Hemisphere. The dataset will facilitate various research such as developing models, evaluating phenology shifts, and monitoring climate change worldwide.
                                            
                                            
                                        Fei Jiang, Hengmao Wang, Jing M. Chen, Weimin Ju, Xiangjun Tian, Shuzhuang Feng, Guicai Li, Zhuoqi Chen, Shupeng Zhang, Xuehe Lu, Jane Liu, Haikun Wang, Jun Wang, Wei He, and Mousong Wu
                                    Atmos. Chem. Phys., 21, 1963–1985, https://doi.org/10.5194/acp-21-1963-2021, https://doi.org/10.5194/acp-21-1963-2021, 2021
                                    Short summary
                                    Short summary
                                            
                                                We present a 6-year inversion from 2010 to 2015 for the global and regional carbon fluxes using only the GOSAT XCO2 retrievals. We find that the XCO2 retrievals could significantly improve the modeling of atmospheric CO2 concentrations and that the inferred interannual variations in the terrestrial carbon fluxes in most land regions have a better relationship with the changes in severe drought area or leaf area index, or are more consistent with the previous estimates about drought impact.
                                            
                                            
                                        Cited articles
                        
                        Albergel, C., Rüdiger, C., Pellarin, T., Calvet, J.-C., Fritz, N., Froissard, F., Suquia, D., Petitpa, A., Piguet, B., and Martin, E.: From near-surface to root-zone soil moisture using an exponential filter: an assessment of the method based on in-situ observations and model simulations, Hydrol. Earth Syst. Sci., 12, 1323–1337, https://doi.org/10.5194/hess-12-1323-2008, 2008. 
                    
                
                        
                        Albergel, C., Calvet, J.-C., Mahfouf, J.-F., Rüdiger, C., Barbu, A. L., Lafont, S., Roujean, J.-L., Walker, J. P., Crapeau, M., and Wigneron, J.-P.: Monitoring of water and carbon fluxes using a land data assimilation system: a case study for southwestern France, Hydrol. Earth Syst. Sci., 14, 1109–1124, https://doi.org/10.5194/hess-14-1109-2010, 2010. 
                    
                
                        
                        Albergel, C., Zheng, Y., Bonan, B., Dutra, E., Rodríguez-Fernández, N., Munier, S., Draper, C., de Rosnay, P., Muñoz-Sabater, J., Balsamo, G., Fairbairn, D., Meurey, C., and Calvet, J.-C.: Data assimilation for continuous global assessment of severe conditions over terrestrial surfaces, Hydrol. Earth Syst. Sci., 24, 4291–4316, https://doi.org/10.5194/hess-24-4291-2020, 2020. 
                    
                
                        
                        AmeriFlux: AmeriFlux Eddy Covariance Data [data set], https://ameriflux.lbl.gov/login/?redirect_to=/data/download-data/, last access: 4 October 2021. 
                    
                
                        
                        Anav, A., Friedlingstein, P., Beer, C., Ciais, P., Harper, A., Jones, C.,
Murray-Tortarolo, G., Papale, D., Parazoo, N. C., and Peylin,
P.: Spatiotemporal patterns of terrestrial gross primary production: A
review, Rev. Geophys., 53, 785–818, 2015. 
                    
                
                        
                        Bateni, S. M., Entekhabi, D., Margulis, S., Castelli, F., and Kergoat, L.,:
Coupled estimation of surface heat fluxes and vegetation dynamics from
remotely sensed land surface temperature and fraction of photosynthetically
active radiation, Water Resour. Res., 50, 8420–8440,
https://doi.org/10.1002/2013WR014573, 2014. 
                    
                
                        
                        Blyverket, J., Hamer, P. D., Bertino, L., Albergel, C., Fairbairn, D., and
Lahoz, W. A.: An Evaluation of the EnKF vs. EnOI and the Assimilation of
SMAP, SMOS and ESA CCI Soil Moisture Data over the Contiguous US, Remote Sens., 11, 478, https://doi.org/10.3390/rs11050478, 2019. 
                    
                
                        
                        Bonan, B., Albergel, C., Zheng, Y., Barbu, A. L., Fairbairn, D., Munier, S., and Calvet, J.-C.: An ensemble square root filter for the joint assimilation of surface soil moisture and leaf area index within the Land Data Assimilation System LDAS-Monde: application over the Euro-Mediterranean region, Hydrol. Earth Syst. Sci., 24, 325–347, https://doi.org/10.5194/hess-24-325-2020, 2020. 
                    
                
                        
                        Bonan, G. B., Williams, M., Fisher, R. A., and Oleson, K. W.: Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil–plant–atmosphere continuum, Geosci. Model Dev., 7, 2193–2222, https://doi.org/10.5194/gmd-7-2193-2014, 2014. 
                    
                
                        
                        Brocca, L., Tullo, T., Melone, F., Moramarco, T., and Morbidelli,
R.: Catchment scale soil moisture spatial–temporal variability, J. Hydrol., 422, 63–75, 2012. 
                    
                
                        
                        Burgin, M. S., Colliander, A., Njoku, E. G., Chan, S. K., Cabot, F., Kerr,
Y. H., Bindlish, R., Jackson, T. J., Entekhabi, D., and Yueh, S. H.: A
comparative study of the SMAP passive soil moisture product with existing
satellite-based soil moisture products, IEEE T. Geosci. Remote, 55, 2959–2971, 2017. 
                    
                
                        
                        Caires, S. and Sterl, A.: Validation of ocean wind and wave data using
triple collocation, J. Geophys. Res.-Oceans, 108, 3098, https://doi.org/10.1029/2002JC001491, 2003. 
                    
                
                        
                        Chan, S. K., Bindlish, R., O'Neill, P. E., Njoku, E., Jackson, T., Colliander, A., Chen, F., Burgin, M., Dunbar, S., and Piepmeier, J.: Assessment of the SMAP passive soil moisture
product, IEEE T. Geosci. Remote, 54, 4994–5007, 2016. 
                    
                
                        
                        Cui, C., Xu, J., Zeng, J., Chen, K.-S., Bai, X., Lu, H., Chen, Q., and
Zhao, T.: Soil moisture mapping from satellites: An intercomparison of SMAP,
SMOS, FY3B, AMSR2, and ESA CCI over two dense network regions at different
spatial scales, Remote Sens., 10, 33, https://doi.org/10.3390/rs10010033, 2018. 
                    
                
                        
                        Desai, A. R., Moore, D. J., Ahue, W. K., Wilkes, P. T., De Wekker, S. F., Brooks, B. G., Campos, T. L., Stephens, B. B., Monson, R. K., and Burns, S. P.: Seasonal pattern of regional carbon balance in the central Rocky Mountains from surface and airborne
measurements, J. Geophys. Res.-Biogeo., 116, G04009, https://doi.org/10.1029/2011JG001655, 2011. 
                    
                
                        
                        Entekhabi, D., Njoku, E. G., O'Neill, P. E., Kellogg, K. H., Crow, W. T.,
Edelstein, W. N., Entin, J. K., Goodman, S. D., Jackson, T. J., and Johnson,
J.: The soil moisture active passive (SMAP) mission, P. IEEE, 98, 704–716, 2010. 
                    
                
                        
                        Etheridge, D. M., Steele, L., Langenfelds, R. L., Francey, R. J., Barnola,
J. M., and Morgan, V.: Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn, J. Geophys. Res.-Atmos., 101, 4115–4128, 1996. 
                    
                
                        
                        Evensen, G.: Sampling strategies and square root analysis schemes for the
EnKF, Ocean Dynam., 54, 539–560, 2004. 
                    
                
                        
                        Exbrayat, J. F., Bloom, A. A., Carvalhais, N., Fischer, R., Huth, A., MacBean, N., and Williams, M.: Understanding the Land
Carbon Cycle with Space Data: Current Status and Prospects, Surv. Geophys., 40, 735–755, https://doi.org/10.1007/s10712-019-09506-2, 2019. 
                    
                
                        
                        Fang, H. and Liang, S.: A hybrid inversion method for mapping leaf area
index from MODIS data: Experiments and application to broadleaf and
needleleaf canopies, Remote Sens. Environ., 94, 405–424, 2005. 
                    
                
                        
                        Fang, H., Beaudoing, H. K., Rodell, M., Teng, W. L., and Vollmer, B. E.:
Global Land data assimilation system (GLDAS) products, services and
application from NASA hydrology data and information services center
(HDISC), in: ASPRS 2009 Annual Conference, 1 January 2009, Baltimore, Maryland, 8–13, Document ID: 20090005038, 2009. 
                    
                
                        
                        Fang, H., Baret, F., Plummer, S., and Schaepman-Strub, G.: An overview of
global leaf area index (LAI): Methods, products, validation, and
applications, Rev. Geophys., 57, 739–799, 2019. 
                    
                
                        
                        Feng, F., Chen, J., Li, X., Yao, Y., Liang, S., Liu, M., Zhang, N., Guo, Y.,
Yu, J., and Sun, M.: Validity of five satellite-based latent heat flux
algorithms for semi-arid ecosystems, Remote Sens., 7, 16733–16755, 2015. 
                    
                
                        
                        Friedl, M. A., Sulla-Menashe, D., Tan, B., Schneider, A., Ramankutty, N.,
Sibley, A., and Huang, X.: MODIS Collection 5 global land cover: Algorithm
refinements and characterization of new datasets, Remote Sens. Environ., 114, 168–182, 2010. 
                    
                
                        
                        Gokmen, M., Vekerdy, Z., Verhoef, A., Verhoef, W., Batelaan, O., and Van
der Tol, C.: Integration of soil moisture in SEBS for improving
evapotranspiration estimation under water stress conditions, Remote Sens. Environ., 121, 261–274, 2012. 
                    
                
                        
                        Gonsamo, A. and Chen, J. M.: Evaluation of the GLC2000 and NALC2005 land
cover products for LAI retrieval over Canada, Can. J. Remote Sens., 37, 302–313, 2011. 
                    
                
                        
                        Haxeltine, A. and Prentice, I. C.: BIOME3: An equilibrium terrestrial
biosphere model based on ecophysiological constraints, resource
availability, and competition among plant functional types, Global Biogeochem. Cy., 10, 693–709, 1996. 
                    
                
                        
                        Hayes, D. J., Turner, D. P., Stinson, G., McGuire, A. D., Wei, Y., West, T. O., Heath, L. S., De Jong, B., McConkey, B. G., and Birdsey, R. A.: Reconciling estimates of the contemporary North American carbon balance among
terrestrial biosphere models, atmospheric inversions, and a new approach for
estimating net ecosystem exchange from inventory-based data, Glob. Change Biol., 18, 1282–1299, 2012. 
                    
                
                        
                        He, L., Chen, J. M., Liu, J., Bélair, S., and Luo, X.: Assessment of
SMAP soil moisture for global simulation of gross primary production, J. Geophys. Res.-Biogeo., 122, 1549–1563, 2017. 
                    
                
                        
                        He, X., Xu, T., Bateni, S. M., Ki, S. J., Xiao, J., Liu, S., Song, L., and He, X.: Estimation of Turbulent Heat Fluxes and Gross Primary
Productivity by Assimilating Land Surface Temperature and Leaf Area Index,
Water Res., 57, e2020WR028224, https://doi.org/10.1029/2020WR028224, 2021. 
                    
                
                        
                        Huang, C., Li, Y., Gu, J., Lu, L., and Li, X.: Improving estimation of
evapotranspiration under water-limited conditions based on SEBS and MODIS
data in arid regions, Remote Sens., 7, 16795–16814, 2015. 
                    
                
                        
                        Ines, A. V., Das, N. N., Hansen, J. W., and Njoku, E. G.: Assimilation of
remotely sensed soil moisture and vegetation with a crop simulation model
for maize yield prediction, Remote Sens. Environ., 138, 149–164, 2013. 
                    
                
                        
                        Jacquette, E., Al Bitar, A., Mialon, A., Kerr, Y., Quesney, A., Cabot, F.,
and Richaume, P.: SMOS CATDS level 3 global products over land, in: Remote Sensing for Agriculture, Ecosystems, and Hydrology XII (p. 78240K), International Society for Optics and Photonics, https://doi.org/10.1117/12.865093, 2010. 
                    
                
                        
                        Kaminski, T., Scholze, M., Vossbeck, M., Knorr, W., Buchwitz, M., and
Reuter, M.: Constraining a terrestrial biosphere model with remotely sensed
atmospheric carbon dioxide, Remote Sens. Environ., 203, 109–124, 2017. 
                    
                
                        
                        Kato, T., Knorr, W., Scholze, M., Veenendaal, E., Kaminski, T., Kattge, J., and Gobron, N.: Simultaneous assimilation of satellite and eddy covariance data for improving terrestrial water and carbon simulations at a semi-arid woodland site in Botswana, Biogeosciences, 10, 789–802, https://doi.org/10.5194/bg-10-789-2013, 2013. 
                    
                
                        
                        Keeling, C. D., Whorf, T. P., Wahlen, M., and Van der Plichtt, J.:
Interannual extremes in the rate of rise of atmospheric carbon dioxide since
1980, Nature, 375, 666–670, 1995. 
                    
                
                        
                        Keller, M., Schimel, D. S., Hargrove, W. W., and Hoffman, F. M.: A continental strategy for the National Ecological Observatory Network, Front. Ecol. Environ., 6, 282–284, 2008. 
                    
                
                        
                        Kganyago, M., Mhangara, P., Alexandridis, T., Laneve, G., Ovakoglou, G.,
and Mashiyi, N.: Validation of sentinel-2 leaf area index (LAI) product
derived from SNAP toolbox and its comparison with global LAI products in an
African semi-arid agricultural landscape, Remote Sens. Lett., 11, 883–892, 2020. 
                    
                
                        
                        Khan, M. S., Liaqat, U. W., Baik, J., and Choi, M.: Stand-alone uncertainty
characterization of GLEAM, GLDAS and MOD16 evapotranspiration products using
an extended triple collocation approach, Agr. Forest Meteorol., 252, 256–268, 2018. 
                    
                
                        
                        Kim, H., Parinussa, R., Konings, A. G., Wagner, W., Cosh, M. H., Lakshmi, V.,
Zohaib, M., and Choi, M.: Global-scale assessment and combination of SMAP
with ASCAT (active) and AMSR2 (passive) soil moisture products, Remote Sens. Environ., 204, 260–275, 2018. 
                    
                
                        
                        Koster, R. D., Crow, W. T., Reichle, R. H., and Mahanama, S. P.: Estimating
basin-scale water budgets with SMAP soil moisture data, Water Resour. Res., 54, 4228–4244, 2018. 
                    
                
                        
                        Law, B., Falge, E., Gu, L. V., Baldocchi, D., Bakwin, P., Berbigier, P.,
Davis, K., Dolman, A., Falk, M., and Fuentes, J.: Environmental controls
over carbon dioxide and water vapor exchange of terrestrial vegetation, Agr. Forest Meteorol., 113, 97–120, 2002. 
                    
                
                        
                        Li, C., Tang, G., and Hong, Y.: Cross-evaluation of ground-based, multi-satellite and reanalysis precipitation products: Applicability of the Triple Collocation method across Mainland China, J. Hydrol., 562, 71–83, 2018. 
                    
                
                        
                        Li, S., Wang, G., Sun, S., Chen, H., Bai, P., Zhou, S., Huang, Y., Wang, J.,
and Deng, P.: Assessment of multi-source evapotranspiration products over
china using eddy covariance observations, Remote Sens., 10, 1692, https://doi.org/10.3390/rs10111692, 2018. 
                    
                
                        
                        Li, S., Zhang, L., Ma, R., Yan, M., and Tian, X.: Improved ET assimilation
through incorporating SMAP soil moisture observations using a coupled
process model: A study of US arid and semiarid regions, J. Hydrol., 590, 125402, https://doi.org/10.1016/j.jhydrol.2020.125402, 2020. 
                    
                
                        
                        Li, X. and Xiao, J.: A global, 0.05-degree product of solar-induced
chlorophyll fluorescence derived from OCO-2, MODIS, and reanalysis data, Remote Sens., 11, 517, https://doi.org/10.3390/rs11050517, 2019. 
                    
                
                        
                        Liang, S., Zhao, X., Liu, S., Yuan, W., Cheng, X., Xiao, Z., Zhang, X., Liu,
Q., Cheng, J., and Tang, H.: A long-term Global LAnd Surface Satellite
(GLASS) data-set for environmental studies, Int. J. Digit. Earth, 6, 5–33, 2013. 
                    
                
                        
                        Lievens, H., Tomer, S. K., Al Bitar, A., De Lannoy, G. J., Drusch, M.,
Dumedah, G., Franssen, H.-J. H., Kerr, Y. H., Martens, B., and Pan, M.: SMOS
soil moisture assimilation for improved hydrologic simulation in the Murray
Darling Basin, Australia, Remote Sens. Environ., 168, 146–162, 2015. 
                    
                
                        
                        Ling, X.-L., Fu, C.-B., Yang, Z.-L., and Guo, W.-D.: Comparison of different sequential assimilation algorithms for satellite-derived leaf area index using the Data Assimilation Research Testbed (version Lanai), Geosci. Model Dev., 12, 3119–3133, https://doi.org/10.5194/gmd-12-3119-2019, 2019. 
                    
                
                        
                        Liu, L., Gudmundsson, L., Hauser, M., Qin, D., Li, S., and Seneviratne,
S. I.: Soil moisture dominates dryness stress on ecosystem production
globally, Nat. Commun., 11, 1–9, 2020. 
                    
                
                        
                        Liu, Y., Xiao, J., Ju, W., Zhu, G., Wu, X., Fan, W., Li, D., and Zhou, Y.:
Satellite-derived LAI products exhibit large discrepancies and can lead to
substantial uncertainty in simulated carbon and water fluxes, Remote Sens. Environ., 206, 174–188, 2018. 
                    
                
                        
                        Ma, R., Zhang, L., Tian, X., Zhang, J., Yuan, W., Zheng, Y., Zhao, X., and
Kato, T.: Assimilation of remotely-sensed leaf area index into a dynamic
vegetation model for gross primary productivity estimation, Remote Sens., 9, 188, https://doi.org/10.3390/rs9030188, 2017. 
                    
                
                        
                        MacBean, N., Peylin, P., Chevallier, F., Scholze, M., and Schürmann, G.: Consistent assimilation of multiple data streams in a carbon cycle data assimilation system, Geosci. Model Dev., 9, 3569–3588, https://doi.org/10.5194/gmd-9-3569-2016, 2016. 
                    
                
                        
                        Martens, B., Miralles, D. G., Lievens, H., van der Schalie, R., de Jeu, R. A. M., Fernández-Prieto, D., Beck, H. E., Dorigo, W. A., and Verhoest, N. E. C.: GLEAM v3: satellite-based land evaporation and root-zone soil moisture, Geosci. Model Dev., 10, 1903–1925, https://doi.org/10.5194/gmd-10-1903-2017, 2017. 
                    
                
                        
                        Miernecki, M., Wigneron, J.-P., Lopez-Baeza, E., Kerr, Y., De Jeu, R., De
Lannoy, G. J., Jackson, T. J., O'Neill, P. E., Schwank, M., and Moran, R. F.:
Comparison of SMOS and SMAP soil moisture retrieval approaches using
tower-based radiometer data over a vineyard field, Remote Sens. Environ., 154, 89–101, 2014. 
                    
                
                        
                        Miralles, D. G., Jiménez, C., Jung, M., Michel, D., Ershadi, A., McCabe, M. F., Hirschi, M., Martens, B., Dolman, A. J., Fisher, J. B., Mu, Q., Seneviratne, S. I., Wood, E. F., and Fernández-Prieto, D.: The WACMOS-ET project – Part 2: Evaluation of global terrestrial evaporation data sets, Hydrol. Earth Syst. Sci., 20, 823–842, https://doi.org/10.5194/hess-20-823-2016, 2016. 
                    
                
                        
                        Mitchell, H. L., Houtekamer, P. L., and Pellerin, G.: Ensemble size, balance,
and model-error representation in an ensemble Kalman filter, Mon. Weather Rev., 130, 2791–2808, 2002. 
                    
                
                        
                        Mu, Q., Zhao, M., Heinsch, F. A., Liu, M., Tian, H., and Running, S. W.:
Evaluating water stress controls on primary production in biogeochemical and
remote sensing based models, J. Geophys. Res.-Biogeo., 112, G01012, https://doi.org/10.1029/2006JG000179, 2007. 
                    
                
                        
                        Müller, C., von Bloh, W., and Gieseke, R.: Open source distribution of the computer simulation model LPJmL, GitHub [code], https://github.com/PIK-LPJmL/LPJmL (last access: 14 December 2022), 2019. 
                    
                
                        
                        New, M., Hulme, M., and Jones, P.: Representing twentieth-century
space–time climate variability. Part II: Development of 1901–96 monthly
grids of terrestrial surface climate, J. Climate, 13, 2217–2238, 2000. 
                    
                
                        
                        Nijssen, B. and Lettenmaier, D. P.: Effect of precipitation sampling error
on simulated hydrological fluxes and states: Anticipating the Global
Precipitation Measurement satellites, J. Geophys. Res.-Atmos., 109, D02103, https://doi.org/10.1029/2003JD003497, 2004. 
                    
                
                        
                        O'Carroll, A. G., Eyre, J. R., and Saunders, R. W.: Three-way error analysis
between AATSR, AMSR-E, and in situ sea surface temperature observations, J. Atmos. Ocean. Tech., 25, 1197–1207, 2008. 
                    
                
                        
                        O'Neill, P., Entekhabi, D., Njoku, E., and Kellogg, K.: The NASA soil
moisture active passive (SMAP) mission: Overview, in: 2010 IEEE International Geoscience and Remote Sensing Symposium, 3 December 2010, Honolulu, HI, USA, IEEE, 3236–3239, https://doi.org/10.1109/IGARSS.2010.5652291, 2010. 
                    
                
                        
                        Pan, H., Chen, Z., de Wit, A., and Ren, J.: Joint Assimilation of Leaf Area Index and Soil Moisture from Sentinel-1 and Sentinel-2 Data into the WOFOST Model for Winter Wheat Yield Estimation, Sensors, 19, 3161, https://doi.org/10.3390/s19143161, 2019. 
                    
                
                        
                        Pardo, N., Sánchez, M. L., Timmermans, J., Su, Z., Pérez, I. A., and
García, M. A.: SEBS validation in a Spanish rotating crop, Agr. Forest Meteorol., 195, 132–142, 2014. 
                    
                
                        
                        Pastorello, G., Trotta, C., Canfora, E., et al.: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data, Sci. Data, 7, 225, https://doi.org/10.1038/s41597-020-0534-3, 2020 (data available at: https://fluxnet.org/data/fluxnet2015-dataset/, last access: 14 December 2022). 
                    
                
                        
                        Petropoulos, G. P., Ireland, G., and Barrett, B.: Surface soil moisture
retrievals from remote sensing: Current status, products and future trends, Phys. Chem. Earth A/B/C, 83, 36–56, 2015. 
                    
                
                        
                        Peylin, P., Bacour, C., MacBean, N., Leonard, S., Rayner, P., Kuppel, S., Koffi, E., Kane, A., Maignan, F., Chevallier, F., Ciais, P., and Prunet, P.: A new stepwise carbon cycle data assimilation system using multiple data streams to constrain the simulated land surface carbon cycle, Geosci. Model Dev., 9, 3321–3346, https://doi.org/10.5194/gmd-9-3321-2016, 2016. 
                    
                
                        
                        Pipunic, R., Walker, J., and Western, A.: Assimilation of remotely sensed
data for improved latent and sensible heat flux prediction: A comparative
synthetic study, Remote Sens. Environ., 112, 1295–1305, 2008. 
                    
                
                        
                        Purdy, A. J., Fisher, J. B., Goulden, M. L., Colliander, A., Halverson, G., Tu, K., and Famiglietti, J. S.: SMAP soil moisture improves global
evapotranspiration, Remote Sens. Environ., 219, 1–14, 2018. 
                    
                
                        
                        Rahman, A., Zhang, X., Houser, P., Sauer, T., and Maggioni, V.: Global
Assimilation of Remotely Sensed Leaf Area Index: The Impact of Updating More
State Variables Within a Land Surface Model, Front. Water, 3, 789352,
https://doi.org/10.3389/frwa.2021.789352, 2022a. 
                    
                
                        
                        Rahman, A., Maggioni, V., Zhang, X., Houser, P., Sauer, T., and Mocko, D. M.: The Joint Assimilation of Remotely Sensed Leaf Area Index and Surface Soil
Moisture into a Land Surface Model, Remote Sens. 14, 437,
https://doi.org/10.3390/rs14030437, 2022b. 
                    
                
                        
                        Reichle, R. H. and Koster, R. D.: Bias reduction in short records of
satellite soil moisture, Geophys. Res. Lett., 31, L19501, https://doi.org/10.1029/2004GL020938, 2004. 
                    
                
                        
                        Reichle, R. H., De Lannoy, G. J., Liu, Q., Koster, R. D., Kimball, J. S., Crow, W. T., Ardizzone, J. V., Chakraborty, P., Collins, D. W., and Conaty, A. L.: Global assessment of the SMAP level-4 surface and root-zone soil moisture product using assimilation diagnostics, J. Hydrometeorol., 18, 3217–3237, 2017. 
                    
                
                        
                        Rienecker, M. M., Suarez, M. J., Gelaro, R., Todling, R., Bacmeister, J., Liu, E., Bosilovich, M. G., Schubert, S. D., Takacs, L., and Kim, G.-K.: MERRA: NASA's modern-era retrospective analysis for research and applications, J. Climate, 24, 3624–3648, 2011. 
                    
                
                        
                        Rüdiger, C., Albergel, C., Mahfouf, J. F., Calvet, J. C., and Walker,
J. P.: Evaluation of the observation operator Jacobian for leaf area index
data assimilation with an extended Kalman filter, J. Geophys. Res.-Atmos., 115, D09111, https://doi.org/10.1029/2009JD012912, 2010. 
                    
                
                        
                        Running, S. W., Nemani, R. R., Heinsch, F. A., Zhao, M., Reeves, M., and
Hashimoto, H.: A continuous satellite-derived measure of global terrestrial
primary production, Bioscience, 54, 547–560, 2004. 
                    
                
                        
                        Scholze, M., Buchwitz, M., Dorigo, W., Guanter, L., and Quegan, S.: Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon cycle data assimilation systems, Biogeosciences, 14, 3401–3429, https://doi.org/10.5194/bg-14-3401-2017, 2017. 
                    
                
                        
                        Seneviratne, S. I., Corti, T., Davin, E. L., Hirschi, M., Jaeger, E. B.,
Lehner, I., Orlowsky, B., and Teuling, A. J.: Investigating soil
moisture–climate interactions in a changing climate: A review, Earth-Sci. Rev., 99, 125–161, 2010. 
                    
                
                        
                        Serraj, R., Allen, L. H., and Sinclair, T. R.: Soybean leaf growth and gas exchange response to drought under carbon dioxide enrichment, Glob. Change Biol., 5.3, 283–291, https://doi.org/10.1046/j.1365-2486.1999.00222.x, 1999. 
                    
                
                        
                        Sitch, S., Smith, B., Prentice, I. C., Arneth, A., Bondeau, A., Cramer, W.,
Kaplan, J. O., Levis, S., Lucht, W., and Sykes, M. T.: Evaluation of
ecosystem dynamics, plant geography and terrestrial carbon cycling in the
LPJ dynamic global vegetation model, Glob. Change Biol., 9, 161–185, 2003. 
                    
                
                        
                        Stoffelen, A.: Toward the true near-surface wind speed: Error modeling and
calibration using triple collocation, J. Geophys. Res.-Oceans, 103, 7755–7766, 1998. 
                    
                
                        
                        Sun, P., Wu, Y., Xiao, J., Hui, J., Hu, J., Zhao, F., Qiu, L., and Liu, S.:
Remote sensing and modeling fusion for investigating the ecosystem
water-carbon coupling processes, Sci. Total Environ., 697, 134064, https://doi.org/10.1016/j.scitotenv.2019.134064, 2019. 
                    
                
                        
                        Taylor, K. E.: Summarizing multiple aspects of model performance in a single
diagram, J. Geophys. Res.-Atmos., 106, 7183–7192, 2001. 
                    
                
                        
                        Tian, X. and Feng, X.: A non-linear least squares enhanced POD-4DVar
algorithm for data assimilation, Tellus A, 67, 25340, https://doi.org/10.3402/tellusa.v67.25340, 2015. 
                    
                
                        
                        Tian, X., Xie, Z., Dai, A., Shi, C., Jia, B., Chen, F., and Yang, K.: A
dual-pass variational data assimilation framework for estimating soil
moisture profiles from AMSR-E microwave brightness temperature, J. Geophys. Res.-Atmos., 114, D16102, https://doi.org/10.1029/2008JD011600, 2009. 
                    
                
                        
                        Tian, X., Xie, Z., Dai, A., Jia, B., and Shi, C.: A microwave land data
assimilation system: Scheme and preliminary evaluation over China, J. Geophys. Res.-Atmos., 115, D21113, https://doi.org/10.1029/2010JD014370, 2010. 
                    
                
                        
                        Tian, X., Xie, Z., and Sun, Q.: A POD-based ensemble four-dimensional
variational assimilation method, Tellus A, 63, 805–816, 2011. 
                    
                
                        
                        Tian, X., Xie, Z., Liu, Y., Cai, Z., Fu, Y., Zhang, H., and Feng, L.: A joint data assimilation system (Tan-Tracker) to simultaneously estimate surface CO2 fluxes and 3-D atmospheric CO2 concentrations from observations, Atmos. Chem. Phys., 14, 13281–13293, https://doi.org/10.5194/acp-14-13281-2014, 2014. 
                    
                
                        
                        Twine, T. E., Kustas, W., Norman, J., Cook, D., Houser, P., Meyers, T.,
Prueger, J., Starks, P., and Wesely, M.: Correcting eddy-covariance flux
underestimates over a grassland, Agr. Forest Meteorol., 103, 279–300, 2000. 
                    
                
                        
                        Wang, L., Zhu, H., Lin, A., Zou, L., Qin, W., and Du, Q.: Evaluation of the
latest MODIS GPP products across multiple biomes using global eddy
covariance flux data, Remote Sens., 9, 418, https://doi.org/10.3390/rs9050418, 2017. 
                    
                
                        
                        Waring, R. H. and Running, S. W.: Forest ecosystems: analysis at multiple scales, Academic Press, San Diego, USA, ISBN 978-0-12-370605-8, 2010. 
                    
                
                        
                        Wieder, W., Boehnert, J., Bonan, G. B., and Langseth, M.: Regridded Harmonized World Soil Database v1.2. ORNL DAAC, Oak Ridge, Tennessee, USA, https://doi.org/10.3334/ORNLDAAC/1247, 2014. 
                    
                
                        
                        Wu, M., Scholze, M., Voßbeck, M., Kaminski, T., and Hoffmann, G.:
Simultaneous Assimilation of Remotely Sensed Soil Moisture and FAPAR for
Improving Terrestrial Carbon Fluxes at Multiple Sites Using CCDAS, Remote
Sens., 11, 27, https://doi.org/10.3390/rs11010027, 2019. 
                    
                
                        
                        Wutzler, T. and Carvalhais, N.: Balancing multiple constraints in model‐data integration: Weights and the parameter block approach, J. Geophys. Res.-Biogeo., 119, 2112–2129, 2014. 
                    
                
                        
                        Xiao, J., Chevallier, F., Gomez, C., Guanter, L., Hicke, J. A., Huete, A. R.,
Ichii, K., Ni, W., Pang, Y., and Rahman, A. F.: Remote sensing of the
terrestrial carbon cycle: A review of advances over 50 years, Remote Sens. Environ., 233, 111383, https://doi.org/10.1016/j.rse.2019.111383, 2019. 
                    
                
                        
                        Xiao, Z., Liang, S., Wang, J., Chen, P., Yin, X., Zhang, L., and Song, J.:
Use of general regression neural networks for generating the GLASS leaf area
index product from time-series MODIS surface reflectance, IEEE T. Geosci. Remote, 52, 209–223, 2013. 
                    
                
                        
                        Xiao, Z., Liang, S., Wang, J., Xiang, Y., Zhao, X., and Song, J.:
Long-time-series global land surface satellite leaf area index product
derived from MODIS and AVHRR surface reflectance, IEEE T. Geosci. Remote, 54, 5301–5318, 2016. 
                    
                
                        
                        Xiao, Z., Liang, S., and Jiang, B.: Evaluation of four long time-series
global leaf area index products, Agr. Forest Meteorol., 246, 218–230, 2017. 
                    
                
                        
                        Xie, Y., Wang, P., Sun, H., Zhang, S., and Li, L.: Assimilation of Leaf Area
Index and Surface Soil Moisture With the CERES-Wheat Model for Winter Wheat
Yield Estimation Using a Particle Filter Algorithm, IEEE J. Sel. Top. Appl.
Earth Obs. Remote Sens., 10, 1303–1316, 2017. 
                    
                
                        
                        Xie, Z.: Monthly groundwater table depth, soil moisture, evapotranspiration dataset with high spatial resolution over the Heihe River Basin (1981–2013), National Tibetan Plateau Data Center [data set], https://doi.org/10.11888/Hydro.tpdc.270888, 2017. 
                    
                
                        
                        Xu, T., He, X., Bateni, S. M., Auligne, T., Liu, S., Xu, Z., Zhou, J., and Mao, K.: Mapping regional turbulent heat fluxes via variational assimilation of land surface temperature data from polar orbiting satellites, Remote Sens. Environ., 221, 444–461, https://doi.org/10.1016/j.rse.2018.11.023, 2019. 
                    
                
                        
                        Xu, T., Chen, F., He, X., Barlage, M., Zhang, Z., Liu, S., and He,
X.: Improve the Performance of the Noah-MP-Crop Model by Jointly
Assimilating Soil Moisture and Vegetation Phenology Data, J. Adv. Model. Earth Syst., 13, e2020MS002394, https://doi.org/10.1029/2020MS002394, 2021. 
                    
                
                        
                        Yan, M., Tian, X., Li, Z., Chen, E., Wang, X., Han, Z., and Sun, H.:
Simulation of forest carbon fluxes using model incorporation and data
assimilation, Remote Sens., 8, 567, https://doi.org/10.3390/rs8070567, 2016. 
                    
                
                        
                        Yang, W., Wang, Y., Liu, X., Zhao, H., Shao, R., and Wang, G.: Evaluation
of the rescaled complementary principle in the estimation of evaporation on
the Tibetan Plateau, Sci. Total Environ., 699, 134367, https://doi.org/10.1016/j.scitotenv.2019.134367, 2020. 
                    
                
                        
                        Yang, X., Yong, B., Ren, L., Zhang, Y., and Long, D.: Multi-scale
validation of GLEAM evapotranspiration products over China via ChinaFLUX ET
measurements, Int. J. Remote Sens., 38, 5688–5709, 2017. 
                    
                
                        
                        Yilmaz, M. T. and Crow, W. T.: Evaluation of assumptions in soil moisture
triple collocation analysis, J. Hydrometeorol., 15, 1293–1302, 2014. 
                    
                
                        
                        Yuan, W., Liu, S., Yu, G., Bonnefond, J.-M., Chen, J., Davis, K., Desai,
A. R., Goldstein, A. H., Gianelle, D., and Rossi, F.: Global estimates of
evapotranspiration and gross primary production based on MODIS and global
meteorology data, Remote Sens. Environ., 114, 1416–1431, 2010.  
                    
                
                        
                        Zhang, D.-H., Li, X.-R., Zhang, F., Zhang, Z.-S., and Chen, Y.-L.: Effects
of rainfall intensity and intermittency on woody vegetation cover and deep
soil moisture in dryland ecosystems, J. Hydrol., 543, 270–282, 2016. 
                    
                
                        
                        Zhang, F. and Weng, Y. :Predicting hurricane intensity and associated
hazards: A five-year real-time forecast experiment with assimilation of
airborne Doppler radar observations, B. Am. Meteorol. Soc., 96, 25–33, 2015. 
                    
                
                        
                        Zhang, L., Xiao, J., Zheng, Y., Li, S., and Zhou, Y.: Increased carbon
uptake and water use efficiency in global semi-arid
ecosystems, Environ. Res. Lett., 15, 034022, https://doi.org/10.1088/1748-9326/ab68ec, 2020. 
                    
                
                        
                        Zhang, R., Kim, S., and Sharma, A.: A comprehensive validation of the SMAP
Enhanced Level-3 Soil Moisture product using ground measurements over varied
climates and landscapes, Remote Sens. Environ., 223, 82–94, 2019. 
                    
                
                        
                        Zhao, L., Xia, J., Xu, C.-y., Wang, Z., Sobkowiak, L., and Long, C.:
Evapotranspiration estimation methods in hydrological models, J. Geogr. Sci., 23, 359–369, 2013. 
                    
                
                        
                        Zou, L., Zhan, C., Xia, J., Wang, T., and Gippel, C. J.: Implementation of
evapotranspiration data assimilation with catchment scale distributed
hydrological model via an ensemble Kalman filter, J. Hydrol., 549, 685–702, 2017. 
                    
                Short summary
            Accurate estimation for global GPP and ET is important in climate change studies. In this study, the GLASS LAI, SMOS, and SMAP datasets were assimilated jointly and separately in a coupled model. The results show that the performance of joint assimilation for GPP and ET is better than that of separate assimilation. The joint assimilation in water-limited regions performed better than in humid regions, and the global assimilation results had higher accuracy than other products.
            Accurate estimation for global GPP and ET is important in climate change studies. In this study,...