Turbulent flux modelling with a simple 2-layer soil model and extrapolated surface temperature applied at Nam Co Lake basin on the Tibetan Plateau

Abstract. This paper introduces a surface model with two soil-layers for use in a high-resolution circulation model that has been modified with an extrapolated surface temperature, to be used for the calculation of turbulent fluxes. A quadratic temperature profile based on the layer mean and base temperature is assumed in each layer and extended to the surface. The model is tested at two sites on the Tibetan Plateau near Nam Co Lake during four days during the 2009 Monsoon season. In comparison to a two-layer model without explicit surface temperature estimate, there is a greatly reduced delay in diurnal flux cycles and the modelled surface temperature is much closer to observations. Comparison with a SVAT model and eddy covariance measurements shows an overall reasonable model performance based on RMSD and cross correlation comparisons between the modified and original model. A potential limitation of the model is the need for careful initialisation of the initial soil temperature profile, that requires field measurements. We show that the modified model is capable of reproducing fluxes of similar magnitudes and dynamics as the more complex methods chosen as reference.

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Long-Term Changes of Lake Level and Water Budget in the Nam Co Lake Basin, Central Tibetan Plateau

Journal of Hydrometeorology ◽

10.1175/jhm-d-13-093.1 ◽

2014 ◽

Vol 15 (3) ◽

pp. 1312-1322 ◽

Cited By ~ 39

Author(s):

Yanhong Wu ◽

Hongxing Zheng ◽

Bing Zhang ◽

Dongmei Chen ◽

Liping Lei

Keyword(s):

Climate Change ◽

Tibetan Plateau ◽

Water Budget ◽

Lake Level ◽

Lake Basin ◽

The Tibetan Plateau ◽

Nam Co ◽

Long Term Changes ◽

Nam Co Lake

Abstract Long-term changes in the water budget of lakes in the Tibetan Plateau due to climate change are of great interest not only for the importance of water management, but also for the critical challenge due to the lack of observations. In this paper, the water budget of Nam Co Lake during 1980–2010 is simulated using a dynamical monthly water balance model. The simulated lake level is in good agreement with field investigations and the remotely sensed lake level. The long-term hydrological simulation shows that from 1980 to 2010, lake level rose from 4718.34 to 4724.93 m, accompanied by an increase of lake water storage volume from 77.33 × 109 to 83.66 × 109 m3. For the net lake level rise (5.93 m) during the period 1980–2010, the proportional contributions of rainfall–runoff, glacier melt, precipitation on the lake, lake percolation, and evaporation are 104.7%, 56.6%, 41.7%, −22.2%, and −80.9%, respectively. A positive but diminishing annual water surplus is found in Nam Co Lake, implying a continuous but slowing rise in lake level as a hydrological consequence of climate change.

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Precipitation Dominates Long-Term Water Storage Changes in Nam Co Lake (Tibetan Plateau) Accompanied by Intensified Cryosphere Melts Revealed by a Basin-Wide Hydrological Modelling

Remote Sensing ◽

10.3390/rs12121926 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1926

Author(s):

Xiaoyang Zhong ◽

Lei Wang ◽

Jing Zhou ◽

Xiuping Li ◽

Jia Qi ◽

...

Keyword(s):

Tibetan Plateau ◽

Water Storage ◽

Hydrological Processes ◽

Lake Basin ◽

Water Runoff ◽

The Tibetan Plateau ◽

Nam Co ◽

Glacier Melting ◽

Nam Co Lake

Lakes on the Tibetan Plateau (TP) have changed dramatically as a result of climate change during recent decades. Studying the changes in long-term lake water storage (LWS) is of great importance for regional water security and ecosystems. Nam Co Lake is the second largest lake in the central TP. To investigate the long-term changes in LWS, a distributed cryosphere-hydrology model (WEB-DHM) driven by multi-source data was evaluated and then applied to simulate hydrological processes across the whole Nam Co Lake basin from 1980 to 2016. Firstly, a comparison of runoff (lake inflow), land surface temperature, and snow depth between the model simulations and observations or remote sensing products showed that WEB-DHM could accurately simulate hydrological processes in the basin. Meanwhile, the simulated daily LWS was in good agreement with satellite-derived data during 2000–2016. Secondly, long-term simulations showed that LWS increased by 9.26 km3 during 1980–2016, reaching a maximum in 2010 that was 10.25 km3 greater than that in 1980. During this period, LWS firstly decreased (1980–1987), then increased (1988–2008), and decreased again (2009–2016). Thirdly, the contributions of precipitation runoff, melt-water runoff, lake surface precipitation, and lake evaporation to Nam Co LWS were 71%, 33%, 24%, and -28%, respectively. Snow and glacier melting have significantly intensified during recent decades (2.96 m3 s−1/decade on average), contributing a mean proportion of 22% of lake inflows. These findings are consistent with the significant increasing trends of annual precipitation and temperature in the lake basin (25 mm/decade and 0.4 K/decade, respectively). We conclude that long-term variations in Nam Co LWS during 1980–2016 were largely controlled by precipitation; however, the contribution of precipitation runoff to total lake inflow has decreased while the contribution from warming-induced snow and glacier melting has significantly increased.

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Hydrothermal pattern of frozen soil in Nam Co lake basin, the Tibetan Plateau

Environmental Geology ◽

10.1007/s00254-008-1462-2 ◽

2008 ◽

Vol 57 (8) ◽

pp. 1775-1784 ◽

Cited By ~ 15

Author(s):

Keming Tian ◽

Jingshi Liu ◽

Shichang Kang ◽

Iain B. Campbell ◽

Fei Zhang ◽

...

Keyword(s):

Tibetan Plateau ◽

Frozen Soil ◽

Lake Basin ◽

The Tibetan Plateau ◽

Nam Co ◽

Nam Co Lake

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Observed and Simulated Lake Effect Precipitation Over the Tibetan Plateau: An Initial Study at Nam Co Lake

Journal of Geophysical Research Atmospheres ◽

10.1029/2018jd028330 ◽

2018 ◽

Vol 123 (13) ◽

pp. 6746-6759 ◽

Cited By ~ 10

Author(s):

Yufeng Dai ◽

Lei Wang ◽

Tandong Yao ◽

Xiangyu Li ◽

Lingjing Zhu ◽

...

Keyword(s):

Tibetan Plateau ◽

Initial Study ◽

The Tibetan Plateau ◽

Nam Co ◽

Lake Effect ◽

Nam Co Lake

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Evaporation variability of Nam Co Lake in the Tibetan Plateau and its role in recent rapid lake expansion

Journal of Hydrology ◽

10.1016/j.jhydrol.2016.03.030 ◽

2016 ◽

Vol 537 ◽

pp. 27-35 ◽

Cited By ~ 54

Author(s):

Ning Ma ◽

Jozsef Szilagyi ◽

Guo-Yue Niu ◽

Yinsheng Zhang ◽

Teng Zhang ◽

...

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Nam Co ◽

Nam Co Lake

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Black Carbon: The Concentration and Sources Study at the Nam Co Lake, the Tibetan Plateau from 2015 to 2016

Atmosphere ◽

10.3390/atmos11060624 ◽

2020 ◽

Vol 11 (6) ◽

pp. 624 ◽

Cited By ~ 1

Author(s):

Feiteng Wang ◽

Xin Zhang ◽

Xiaoying Yue ◽

Mengyuan Song ◽

Guoshuai Zhang ◽

...

Keyword(s):

Tibetan Plateau ◽

Black Carbon ◽

Animal Manure ◽

Average Concentration ◽

Tourism Industry ◽

Atmospheric Environment ◽

The Tibetan Plateau ◽

Nam Co ◽

Long Distance ◽

Nam Co Lake

We measured black carbon (BC) with a seven-wavelength aethalometer (AE-31) at the Nam Co Lake (NCL), the hinterland of the Tibetan Plateau (TP) from May 2015 to April 2016. The daily average concentration of BC was 145 ± 85 ng m−3, increasing by 50% since 2006. The seasonal variation of BC shows higher concentrations in spring and summer and lower concentrations in autumn and winter, dominated by the adjacent sources and meteorological conditions. The diurnal variation of BC showed that its concentrations peaked at 9:00–16:00 (UTC + 8), significantly related to local human activities (e.g., animal-manure burning and nearby traffic due to the tourism industry). The concentration-weighted trajectory (CWT) analysis showed that the long-distance transport of BC from South Asia could also be a potential contributor to BC at the NCL, as well as the biomass burning by the surrounding residents. The analyses of the absorption coefficient and absorption Ångström exponent show the consistency of sourcing the BC at the NCL. We suggest here that urgent measures should be taken to protect the atmospheric environment at the NCL, considering the fast-increasing concentrations of BC as an indicator of fuel combustion.

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Evaluating and improving simulations of diurnal variation in land surface temperature with the Community Land Model for the Tibetan Plateau

PeerJ ◽

10.7717/peerj.11040 ◽

2021 ◽

Vol 9 ◽

pp. e11040

Author(s):

Xiaogang Ma ◽

Jiming Jin ◽

Lingjing Zhu ◽

Jian Liu

Keyword(s):

Thermal Conductivity ◽

Tibetan Plateau ◽

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Soil Layer ◽

Surface Model ◽

The Tibetan Plateau ◽

Soil Thermal Conductivity ◽

Community Land Model

This study evaluated and improved the ability of the Community Land Model version 5.0 (CLM5.0) in simulating the diurnal land surface temperature (LST) cycle for the whole Tibetan Plateau (TP) by comparing it with Moderate Resolution Imaging Spectroradiometer satellite observations. During daytime, the model underestimated the LST on sparsely vegetated areas in summer, whereas cold biases occurred over the whole TP in winter. The lower simulated daytime LST resulted from weaker heat transfer resistances and greater soil thermal conductivity in the model, which generated a stronger heat flux transferred to the deep soil. During nighttime, CLM5.0 overestimated LST for the whole TP in both two seasons. These warm biases were mainly due to the greater soil thermal inertia, which is also related to greater soil thermal conductivity and wetter surface soil layer in the model. We employed the sensible heat roughness length scheme from Zeng, Wang & Wang (2012), the recommended soil thermal conductivity scheme from Dai et al. (2019), and the modified soil evaporation resistance parameterization, which was appropriate for the TP soil texture, to improve simulated daytime and nighttime LST, evapotranspiration, and surface (0–10 cm) soil moisture. In addition, the model produced lower daytime LST in winter because of overestimation of the snow cover fraction and an inaccurate atmospheric forcing dataset in the northwestern TP. In summary, this study reveals the reasons for biases when simulating LST variation, improves the simulations of turbulent fluxes and LST, and further shows that satellite-based observations can help enhance the land surface model parameterization and unobservable land surface processes on the TP.

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Ostracod-based environmental reconstruction over the last 8,400 years of Nam Co Lake on the Tibetan plateau

Hydrobiologia ◽

10.1007/s10750-010-0149-3 ◽

2010 ◽

Vol 648 (1) ◽

pp. 157-174 ◽

Cited By ~ 28

Author(s):

Liping Zhu ◽

Ping Peng ◽

Manping Xie ◽

Junbo Wang ◽

Peter Frenzel ◽

...

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Environmental Reconstruction ◽

Nam Co ◽

Nam Co Lake

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Simulation and Analysis of the Water Balance of the Nam Co Lake Using SWAT Model

Water ◽

10.3390/w11071383 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1383

Author(s):

Muhammad Adnan ◽

Shichang Kang ◽

Guoshuai Zhang ◽

Muhammad Saifullah ◽

Muhammad Naveed Anjum ◽

...

Keyword(s):

Water Balance ◽

Swat Model ◽

Regional Scale ◽

Rapid Change ◽

Lake Basin ◽

Glacier Mass Balance ◽

The Tibetan Plateau ◽

Nam Co ◽

Glacier Melt ◽

Nam Co Lake

Rapid change of alpine lakes in the Tibetan Plateau (TP) is a clear manifestation of regional-scale climate variability that can be investigated by quantifying the regional hydrological cycle. The degree-day model (DDM) coupled with the Soil and Water Assessment Tool (SWAT) model were used to quantify the water budget of the Nam Co Lake over the period of 2007 to 2013. Driven by local observed meteorological data, the coupled model was successfully validated with the observed lake levels (with R2 = 0.65, NSE = 0.61, and PBIAS = −2.26). Analysis of the water balance revealed that rapid enlargement of the Nam Co Lake was primarily associated with precipitation increase while glacier melt played its role as the potential secondary driver in lake expansion. However, temporal analysis of lake expansion displayed that supremacy of precipitation and glacier melt interchanged between the years. It was found that average annual relative contributions of the precipitation, including direct precipitation on the lake, and glacier melt to the lake were 57% (or 667 mm), and 43% (or 502 mm), respectively. Besides, it was observed that annual values of actual evapotranspiration (ET) from the lake, glaciated, and non-glaciated subbasins were 615 mm, 280 mm, and 234 mm respectively. The average annual glacier mass balance (GMB) of the Nam Co basin was −150.9 millimeter water equivalent (mm w.e.). The relatively high amount of glacier melt was a consequence of the substantial increase in annual temperature in the lake basin. This work is of importance for understanding the rapid water cycle in the TP under global warming. Moreover, this work will also be helpful in monitoring and sustaining the local ecosystem and infrastructure, which is under risk due to rapid lake expansion as a result of climate change in the TP.

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