Invited newsletter and book chapter
  1. Chen, Y. and K. Yang, 2013: Land Surface Process Study and Modeling in Drylands and High-Elevation Regions (Chapter 4), in Land Surface Observation, Modeling and Data Assimilation, World Scientific Publishing Co. Pte. Ltd., 91-124.

    Drylands and high-elevation regions have sensitive responses to global changes. Land–atmosphere interactions in these regions also play an essential role in atmospheric circulation. However, some key processes of land–atmosphere interactions in these regions remain to be understood. In this chapter, we introduce existing problems of land surface modeling in drylands and high-elevation regions (mainly with reference to the Tibetan Plateau) and the efforts to resolve these issues, including the following three aspects.


  2. Chen, Y. and K. Yang, 2011: Parameterizing thermal roughness length is crucial for dryland energy budget modeling, GEWEX News, 21(1), 5-6.

    This newsletter indicates that parameterizing thermal roughness length is crucial for modeling surface temperature and energy budget in arid regions.The revised Noah LSM with a novel z0h scheme that was developed based on experimental data analysis can simulate surface temperature and sensible heat fluxes simultaneously. See details in Chen et al. (2010, JHM).

    指出热粗糙度参数化对在干旱地区模拟地表温度和能量预算的重要性。基于实验数据,改进了的Noah LSM能够很好地模拟地表温度和感热通量。相关研究已发表于Chen et al. (2010, JHM)。

  3. Yang, K., 2009: Diurnal variations of thermal roughness length and its importance for land surface modeling in dry regions, AsiaFlux Newsletter, 30, 10-14.

    This newsletter indicates that diurnal variations of thermal roughness length, a key parameter in estimating surface heat flux, are a widely existing phenomenon. Considering the variations is crucial modeling land surface processes for dry lands. A series of publications are Yang et al. (2009, HESS), Chen et al. (2010, JHM), and Chen et al. (2011, JGR).

    通过1998年至今的一系列试验,发现对地表热通量估计极其重要的热力粗糙度具有明显的日变化。我们证明对改日变化的合理参数化对干旱区陆面过程模拟具有决定性意义。相关研究已发表于Yang et al. (2009, HESS), Chen et al. (2010, JHM), 以及 Chen et al. (2011, JGR).

  4. Yang, K., M. Rasmy, S. Rauniyar, and T. Koike, 2006: Inter-comparisons of prediction skill of operational GCMs and a land data assimilation system, CEOP Newsletter, 10, 3-5.

    CEOP integrated high-resolution and high-accuracy in situ data, satellite products, and model output. This newsletter summarizes some preliminary results of global comparisons between four GCMs and in situ data and pointed out the models’ deficiencies. A full report may be found in Yang et al. (2007, JMSJ).

    CEOP集成了全球大量的高分辨率高精度野外台站数据、卫星数据和模拟数据。我们总结了应用野外台站数据评估模型性能的研究成果。相关研究已发表于Yang et al. (2007, JMSJ)。

Journal papers
  1. Ding, B., K. Yang, W. Yang, X. He, Y. Chen, Lazhu, X. Guo, L. Wang, H. Wu, and T. Yao, 2017: Development of a Water and Enthalpy Budget-based Glacier mass balance Model (WEB-GM) and its preliminary validation, Water Resour. Res., 53, 3146–3178, doi:10.1002/2016WR018865.

    A Water and Enthalpy Budget-based Glacier mass balance Model (WEB-GM) is developed. Enthalpy, rather than temperature, is used in the energy balance equations to simplify the computation and improve the simulation accuracy. A new parameterization for albedo estimation and state-of-the-art parameterizations for rainfall/snowfall type identification and surface turbulent heat flux calculations are implemented in the model. The evaluation at the Parlung No. 4 Glacier shows that the model can reproduce the glacier ablation depth, surface albedo, surface temperature, sensible heat flux, and latent heat flux with high accuracy. Comparing with a traditional glacier energy balance model, this enthalpy-based model shows a superior capacity in simulation accuracy


  2. Li, C., H. Lu, K. Yang, J. Wright, L. Yu, Y. Chen, X. Huang, and S. Xu, 2017: Evaluation of the Common Land Model (CoLM) from the Perspective of Water and Energy Budget Simulation: Towards Inclusion in CMIP6, Atmosphere, 8(141), 1-31, doi:10.3390/atmos8080141.

    We compared simulations of the CoLM2014, CoLM2005, and CLM4.5 against global diagnostic data and observations of energy and water cycle. The CoLM2014 is improved relative to CoLM2005, and is comparable to CLM4.5 with respect to many aspects of the energy and water budgets. The CoLM2014 is suitable for inclusion in Chinese GCMs, which will increase the diversity of LSMs considered during CMIP6


  3. Zheng, D., R. Velde, Z. Su, J. Wen, X. Wang, and K. Yang, 2017: Evaluation of Noah Frozen Soil Parameterization for Application to a Tibetan Meadow Ecosystem, J. Hydrometeorol., 18(6), 1749-1763, doi:10.1175/JHM-D-16-0199.1.

    Soil temperature and unfrozen water in an alpine meadow can be significantly improved through modifying several parameters in Noah model


  4. Bao, H., T. Koike, K. Yang, L. Wang, M. Shrestha, and P. Lawford, 2016: Development of an enthalpy-based frozen soil model and its validation in a cold region in China, J. Geophys. Res. Atmos., 121(10), 5259-5280, doi:10.1002/2015JD024451.

    An enthalpy-based frozen soil model was developed for stable and efficient simulations of water and energy transfer in cold regions.


  5. Lazhu, K. Yang, J. Wang, Y. Lei, Y. Chen, L. Zhu, B. Ding, and J. Qin, 2016: Quantifying evaporation and its decadal change for Lake Nam Co, central Tibetan Plateau, J. Geophys. Res. Atmos., 121(16), 7578-7591, doi:10.1002/2015JD024523.

    We found annual evaporation of Lake Nam Co is about 830 mm, which is far less than potential evaporation; the evaporation increased since 1998, which suppressed the recent lake expansion.


  6. Li, X., K. Yang, and Y. Zhou, 2016: Progress in the study of oasis-desert interactions, Agric. For. Meteorol., 230-231, 1-7, doi:10.1016/j.agrformet.2016.08.022.

    This is an overview of oasis-desert interaction studies available in the literature and our current understanding of the limitations and challenges of these studies. Future foci can be multiple-scale, high-accuracy observing matrices and seamless simulations from mesoscale circulations to large eddies, which are crucial for understanding small-scale structures of energy and water exchange and their connection with oasis-desert interaction.


  7. Wang, L., X. Li, Y. Chen, K. Yang, D. Chen, J. Zhou, W. Liu, J. Qi, and J. Huang, 2016: Validation of the global land data assimilation system based on measurements of soil temperature profiles, Agric. For. Meteorol., 218-219, 288-297, doi:10.1016/j.agrformet.2016.01.003.

    GLDAS-CLM1.0 generally shows too large diurnal and seasonal cycles in soil temperature for global grasslands. This overestimation is mainly caused by overestimation of the ground heat flux, due to inappropriate thermal conductivity parameterization scheme. This scheme produces too large values of the conductivity.


  8. Wang, X., S. Yi, Q. Wu, K. Yang, and Y. Ding, 2016: The role of permafrost and soil water in distribution of alpine grassland and its NDVI dynamics on the Qinghai-Tibetan Plateau, Global Planet. Change, 147, 40-53, doi:10.1016/j.gloplacha.2016.10.014.

    By using soil moisture and temperature data derived from microwave data assimilation, we found NDVI change in alpine meadow is determined by soil temperature, whereas NDVI change in alpine steppe is determined by both soil moisture and temperature. Nevertheless, soil moisture and temperature can only explain <50% of the variance of the NDVI trend in the alpine grasslands.


  9. Yang, K., Lazhu, Y. Chen, L. Zhao, J. Qin, H. Lu, W. Tang, M. Han, B. Ding, and N. Fang, 2016: Land surface model calibration through microwave data assimilation for improving soil moisture simulations, J. Hydrol., 533, 266–276, doi:10.1016/j.jhydrol.2015.12.018.

    A satellite data-based method for land surface model calibration is presented to improve soil moisture simulation. The effectiveness of this new method is demonstrated in three grasslands of the Tibetan Plateau and the Mongolian Plateau. The method may be applied to other regions.


  10. Guo, X., H. Liu, and K. Yang, 2015: On the Application of the Priestley–Taylor Relation on Sub-daily Time Scales, Bound.-Layer Meteor., 156(3), 489-499, doi:10.1007/s10546-015-0031-y.

    Based on turbulent heat flux observations over a reservoir and a glacier, we investigate the sub-daily variations in the Priestley–Taylor parameter for saturated surfaces. The results indicate that the heat transfer direction (upward or downward) significantly affects the performance of the Priestley–Taylor relation at sub-daily scale.


  11. Shen, M., S. Piao, S. Jeong, L. Zhou, Z. Zeng, P. Ciais, D. Chen, M. Huang, C. Jin, L. Li, Y. Li, R. Myneni, K. Yang, G. Zhang, and , 2015: Evaporative cooling over the Tibetan Plateau induced by vegetation growth, Proc. Natl. Acad. Sci., 112(30), 9299-9304, doi:10.1073/pnas.1504418112.

    In the Arctic, previous studies have shown that enhanced vegetation growth decreases albedo and amplifies warming. In contrast, on the Tibetan Plateau, increased vegetation activity may attenuate daytime warming by enhancing evapotranspiration (ET), a cooling process.


  12. Chen, X., Z. Su, Y. Ma, K. Yang, and B. Wang, 2013: Estimation of surface energy fluxes under complex terrain of Mt. Qomolangma over the Tibetan Plateau, Hydrol. Earth Syst. Sci., 17, 1607-1618, doi:10.5194/hess-17-1607-2013.

    Excess resistance parameterization developed by Yang et al. (2008) was introduced into the Surface Energy Balance System (SEBS) developed by Su et al. (2002) to improve the estimation of heat transfer over bare soil surfaces. Better performance was shown for typical land surfaces (bare soil, sparse canopy, dense canopy, and snow surface) on the Tibetan Plateau.

    Yang et al. (2008)发展的传热附加阻力参数化方案被引入Su et al. (2002)发展的SEBS中,通过在青藏高原的各种下垫面(裸地、稀疏植被、浓密植被、雪面)的观测资料对比,表明可以提高湍流热通量的计算精度。

  13. Chen, Y., K. Yang, W. Tang, J. Qin, and L. Zhao, 2012: Parameterizing soil organic carbon's impacts on soil porosity and thermal parameters for Eastern Tibet grasslands, Sci. China Ser. D, 55(6), 1001-1011, doi:10.1007/s11430-012-4433-0.

    This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. A new parameterization is developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases. The measured data can be provided upon request.


  14. Song, Y., J. Wang, K. Yang, M. Ma, X. Li, Z. Zhang, and X. Wang, 2012: A revised surface resistance parameterisation for estimating latent heat flux from remotely sensed data, Int. J. Appl. Earth Obs. Geoinf., 17, 76-84, doi:10.1016/j.jag.2011.10.011.

    With the support of Watershed Allied Telemetry Experimental Research (WATER) project, a biophysics-based surface resistance model was revised to account for the effect of water stress and temperature on crop evapotranspiration.


  15. Chen, Y., K. Yang, J. He, J. Qin, J. Shi, J. Du, and Q. He, 2011: Improving land surface temperature modeling for dry land of China, J. Geophys. Res. Atmos., 116, D20104, doi:10.1029/2011JD015921.

    This paper presents two improvements of Noah land surface modeling for China’s drylands: (1) The replacement of the model’s thermal roughness length (z0h) scheme with a new one, and (2) developing new forcing data for China. The two improvements reduced the biases in surface temperature by about 6 K on average.

    介绍了Noah模型对中国干旱半干旱区地表过程模拟的两个改进:(1)用一个新的热力学粗糙度(z0h)方案替换了Noah模型中的原有方案;(2)使用了新发展的ITPCAS驱动数据。结果显示: Noah模型中的高达6K的地表温度平均偏差基本消除。

  16. Guo, X., K. Yang, L. Zhao, W. Yang, S. Li, M. Zhu, T. Yao, and Y. Chen, 2011: Critical Evaluations of Scalar Roughness Length Parameterizations over a Melting Valley Glacier, Bound.-Layer Meteor., 139(2), 307-332, doi:10.1007/s10546-010-9586-9.

    Based on quality-controlled measurements over a melting valley glacier on the Tibetan Plateau, three parameterization schemes of the scalar roughness length are evaluated. One of them is recommended.


  17. Chen, Y., K. Yang, D. Zhou, J. Qin, and X. Guo, 2010: Improving the Noah Land Surface Model in Arid Regions with an Appropriate Parameterization of the Thermal Roughness Length, J. Hydrometeorol., 54(6), 989-1006, doi:10.1175/2010JHM1185.1.

    Daytime land surface temperatures in arid and semiarid regions are typically not well simulated in current land surface models (LSMs); the unreasonable presentation of thermal roughness length (z0h) is found to be the reason. Noah model was revised based on an evaluation of six z0h schemes. The revised model can well simulate surface temperature and sensible heat flux simultaneously. The revised model benefits from the successful modeling of the diurnal variation of z0h, which the original model cannot produce.


  18. Lu, L., S. Liu, Z. Xu, K. Yang, X. Cai, L. Jia, and J. Wang, 2009: The Characteristics and Parameterization of Aerodynamic Roughness Length over Heterogeneous Surfaces, Adv. Atmos. Sci., 26(1), 180-190, doi:10.1007/s00376-009-0180-3.

    This paper calculated aerodynamic roughness length (z0m) over several land surfaces with experimental data from Xiaotangshan. The results show that z0m is direction-dependent, mainly due to the heterogeneity of the size and spatial distribution of the roughness elements inside the source area along different wind directions. Furthermore, a heuristic parameterization of the z0m for heterogeneous surfaces is proposed.


  19. Ma, Y., Y. Wang, R. Wu, Z. Hu, K. Yang, M. Li, W. Ma, L. Zhong, F. Sun, X. Chen, Z. Zhu, S. Wang, and H. Ishikawa, 2009: Recent advances on the study of atmosphere-land interaction observations on the Tibetan Plateau, Hydrol. Earth Syst. Sci., 13, 1103-1111, doi:10.5194/hess-13-1103-2009.

    The Tibetan Observation and Research Platform (TORP) are introduced. The recent observed characteristics of land fluxes, atmospheric and soil variables, the structure of the ABL and the turbulent characteristics were summarized.


  20. Yang, K., Y. Chen, and J. Qin, 2009: Some practical notes on the land surface modeling in the Tibetan Plateau, Hydrol. Earth Syst. Sci., 13, 687-701, doi:10.5194/hess-13-687-2009.

    This study evaluated performance of three land surface models (LSMs) for the Tibetan Plateau. Two modeling deficiencies identified are the underestimation of the topsoil soil moisture of alpine grassland (due to failure to represent the soil organic matter induced soil stratification) and the underestimation of the ground-air temperature gradient in alpine deserts (due to inappropriate excess resistance parameterization). New advances in SiB2 was presented.


  21. Yang, K., T. Koike, H. Ishikawa, J. Kim, X. Li, H. Liu, S. Liu, Y. Ma, and J. Wang, 2008: Turbulent Flux Transfer over Bare-Soil Surfaces: Characteristics and Parameterization, J. Appl. Meteor. Climatol., 40(1), 276-290, doi:10.1175/2007JAMC1547.1.

    This paper presented a comprehensive analysis on characteristics of heat transfer over bare-soil surfaces in arid and semi-arid regions and an extensive evaluation of several schemes in the literature. It is found that diurnal variations of the parameter kB-1 [=ln(z0m/z0h)] is a common phenomenon, with higher values during the day and lower values at night. This diurnal variation is particularly evident on the Tibetna Plateau surfaces. A scheme that can produce the diurnal variation of kB-1 generally performs satisfactorily.


  22. Yang, K. and J. Wang, 2008: A temperature prediction-correction method for estimating surface soil heat flux from soil temperature and moisture data, Sci. China Ser. D, 51(5), 721-729, doi:10.1007/s11430-008-0036-1.

    A new method is developed to estimate soil heat flux from soil temperature and moisture observations. The new method does not require the soil thermal conductivity, and the results obtained with it are not very sensitive to the availability of temperature data in the topsoil.


  23. Ma, Y., M. Song, H. Ishikawa, K. Yang, T. Koike, L. Jia, M. Menenti, and Z. Su, 2007: Estimation of the regional evaporative fraction over the Tibetan Plateau area by using Landsat-7 ETM data and the field observations, J. Meteor. Soc. Japan, 85A, 295-309, doi:10.2151/jmsj.85A.295.

    This study proposed a parameterization methodology based on Landsat-7 ETM data and filed observations and tested it for deriving an evaporative fraction over a heterogeneous landscape. This methodology has been applied to the experimental area of CAMP/Tibet.

    提出并验证了一种基于Landsat-7 ETM和地面观测资料估算复杂下垫面的蒸发比的方法。该方法被用于CAMP/Tibet实验区。

  24. Yang, K. and T. Koike, 2005: Comments on "Estimating Soil Water Contents from Soil Temperature Measurements by Using an Adaptive Kalman Filter", J. Appl. Meteorol., 44(4), 546-550, doi:10.1175/JAM2215.1.

    This note pointed out that estimating soil water content from soil temperature measurements can be risky. Soil thermal diffusivity is not monotonically dependent on soil water content, and thus, such a estimation may result in multiple solutions.


  25. Yang, K., T. Koike, B. Ye, and L. Bastidas, 2005: Inverse analysis of the role of soil vertical heterogeneity in controlling surface soil state and energy partition, J. Geophys. Res. Atmos., 110, D08101, doi:10.1029/2004JD005500.

    For the first time, this study addressed the importance of soil vertical stratification in the land-atmosphere interactions on the central and eastern Tibetan Plateau. The soil stratification was caused due to slow decomposition of organic matters. The topsoils, therefore, contain dense vegetation roots and soil organic matters, which significantly change the soil thermal and hydraulic properties.


  26. Yang, K., T. Koike, H. Ishikawa, and Y. Mao, 2004: Analysis of the surface energy budget at a site of GAME/Tibet using a single-source model, J. Meteor. Soc. Japan, 82(1), 131-153, doi:10.2151/jmsj.82.131.

    The surface energy balance closure in rainy season was investigated for a site (Anduo) on the Tibetan Plateau. We pointed out that the measured latent heat flux was untrustable due to an instrumental limitation. A single-source land surface model was developed that can be used to simulate land fluxes on the Plateau sparse-vegetation surfaces.


  27. Yang, K., T. Koike, and D. Yang, 2003: Surface flux parameterization in the Tibetan Plateau, Bound.-Layer Meteor., 106(2), 245-262, doi:10.1023/A:1021152407334.

    This study pointed out that the thermal roughness lengths on the Tibetan Plateau surfaces have outstanding diurnal variations. An optimization approach was proposed to estimate aerodynamic roughness length that varies with vegetation growing.


  28. Yang, K., T. Koike, H. Fujii, K. Tamagawa, and N. Hirose, 2002: Improvement of surface flux parameterizations with a turbulence-related length, Quart. J. Roy. Meteor. Soc., 128(584), 2073-2088, doi:10.1256/003590002320603548.

    A new parameterization scheme for surface turbulent flux estimation was developed to consider the diurnal variations of thermal roughness length by introducing a turbulence-related length. This scheme is widely applicable to surfaces covered by bare soil or short vegetation.


  29. Yang, K., N. Tamai, and T. Koike, 2001: Analytical solution of surface layer similarity equation, J. Appl. Meteorol., 40(9), 1647-1653, doi:10.1175/1520-0450(2001)040<1647:ASOSLS>2.0.CO;2.

    This paper derived the exact solution of the stability parameter equation for a stable surface layer and proposes an approximate analytical solution for an unstable surface layer. The solution can improve the computational efficiency of flux parameterization and is applicable in a wide range of z/z0 (50-104) and z0/zT (from less than 1 to greater than 104).

    提出了获得稳定边界层条件下精确解和不稳定条件下近似解析解的方法。该方法能提高参数化方法计算湍流通量的效率,可适用于不同下垫面条件(z/z0大于50小于104,以及z0/zT 从小于1到大于104)。