scholarly journals Evaluation of Noah-MP Land-Model Uncertainties over Sparsely Vegetated Sites on the Tibet Plateau

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 458
Author(s):  
Guo Zhang ◽  
Fei Chen ◽  
Yueli Chen ◽  
Jianduo Li ◽  
Xindong Peng
Keyword(s):  
Heat Flux ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Tibetan Plateau ◽  
Sensible Heat Flux ◽  
Limiting Factors ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
Annual Total ◽  
The Impact

The water budget and energy exchange over the Tibetan Plateau (TP) region play an important role on the Asian monsoon. However, it is not well presented in the current land surface models (LSMs). In this study, uncertainties in the Noah with multiparameterization (Noah-MP) LSM are assessed through physics ensemble simulations in three sparsely vegetated sites located in the central TP. The impact of soil organic matter on energy flux and water cycles, along with the influence of uncertainties in precipitation are explored using observations at those sites during the third Tibetan Plateau Experiment from 1August2014 to31July2015. The greatest uncertainties are in the subprocesses of the canopy resistance, soil moisture limiting factors for evaporation, runoff (RNF) and ground water, and surface-layer parameterization. These uncertain subprocesses do not change across the different precipitation datasets. More precipitation can increase the annual total net radiation (Rn), latent heat flux (LH) and RNF, but decrease sensible heat flux (SH). Soil organic matter enlarges the annual total LH by ~26% but lessens the annual total Rn, SH, and RNF by ~7%, 7%, and 39%, respectively. Its effect on the LH and RNF at the Nagqu site, which has a sand soil texture type, is greater than that at the other two sites with sandy loam. This study highlights the importance of precipitation uncertainties and the effect of soil organic matter on the Noah-MP land-model simulations. It provides a guidance to improve the Noah-MP LSM further and hence the land-atmosphere interactions simulated by weather and climate models over the TP region.

Evaluation of Noah-MP land-model uncertainties over sparsely vegetated sites on the Tibet Plateau

2020 ◽  
Author(s):  
Guo Zhang ◽  
Fei Chen ◽  
Yueli Chen ◽  
Jianduo Li
Keyword(s):  
Heat Flux ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Tibetan Plateau ◽  
Sandy Soil ◽  
Lower Boundary ◽  
Sensitivity Analyses ◽  
Tibet Plateau ◽  
Surface Model ◽  
Annual Total

<p>Uncertainties in the Noah with multiparameterization (Noah-MP) land surface model are assessed through physics ensemble simulations in four sparsely vegetated sites located in the central and western Tibetan Plateau. The simulated hydrological components are evaluated using observations at those sites during the third Tibetan Plateau Experiment from August 1st, 2014 to August 1st, 2015. By using natural selection, the crucial subprocesses impacting the hydrological component simulations are identified. The effects of precipitation uncertainties and soil organic matter on the energy fluxes and water cycles are analyzed through a set of sensitivity experiments based on an optimal scheme set. The uncertainty analyses indicate that the greatest uncertainties are in the subprocesses of runoff (RNF) and groundwater, surface-layer parameterization and frozen soil permeability, along with the subprocesses of snow surface albedo and the lower boundary of soil temperature for the bare ground site but the subprocesses of the canopy resistance and soil moisture limiting factors for evaporation for the three alpine grassland sites. The sensitivity analyses reveal that more precipitation can increase the annual total net radiation (Rn), latent heat flux (LE) and RNF but decrease sensible heat flux (SH). Compared to the insufficient precipitation, the relatively small increase in precipitation results in the LE increase during the growing season at the Amdo and Baingoin sites but an RNF increase at the Nagqu site (sandy soil). However, when more precipitation was added, a greater proportion of the added water was distributed to the RNF at the Nagqu site and to the soil liquid water at the Amdo and Baingoin sites. The organic soil increases the annual total LE but reduces the annual total Rn, SH, and RNF. The effect of the soil organic matter on the LE and RNF at the Nagqu site (sandy soil), is greater than that at the other three sites (sandy loam soil).</p>

scholarly journals Method Development for Estimating Sensible Heat Flux over the Tibetan Plateau from CMA Data

2009 ◽  
Vol 48 (12) ◽  
pp. 2474-2486 ◽  
Author(s):  
Kun Yang ◽  
Jun Qin ◽  
Xiaofeng Guo ◽  
Degang Zhou ◽  
Yaoming Ma
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Method Development ◽  
Sensible Heat Flux ◽  
Atmospheric Stability ◽  
Surface Energy Budget ◽  
New Method ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Hourly Data

Abstract To clarify the thermal forcing of the Tibetan Plateau, long-term coarse-temporal-resolution data from the China Meteorological Administration have been widely used to estimate surface sensible heat flux by bulk methods in many previous studies; however, these estimates have seldom been evaluated against observations. This study at first evaluates three widely used bulk schemes against Tibet instrumental flux data. The evaluation shows that large uncertainties exist in the heat flux estimated by these schemes; in particular, upward heat fluxes in winter may be significantly underestimated, because diurnal variations of atmospheric stability were not taken into account. To improve the estimate, a new method is developed to disaggregate coarse-resolution meteorological data to hourly according to statistical relationships derived from high-resolution experimental data, and then sensible heat flux is estimated from the hourly data by a well-validated flux scheme. Evaluations against heat flux observations in summer and against net radiation observations in winter indicate that the new method performs much better than previous schemes, and therefore it provides a robust basis for quantifying the Tibetan surface energy budget.

Elevation-dependent sensible heat flux trend over the Tibetan Plateau and its possible causes

2018 ◽  
Vol 52 (7-8) ◽  
pp. 3997-4009 ◽  
Author(s):  
Lihua Zhu ◽  
Gang Huang ◽  
Guangzhou Fan ◽  
Xia Qü ◽  
Zhibiao Wang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Sensible Heat Flux ◽  
The Tibetan Plateau ◽  
Sensible Heat

Changes in soil organic matter stability with depth in two alpine ecosystems on the Tibetan Plateau

Geoderma ◽  
2019 ◽  
Vol 351 ◽  
pp. 153-162 ◽  
Author(s):  
Yanhui Hou ◽  
Ying Chen ◽  
Xiao Chen ◽  
Keyi He ◽  
Biao Zhu
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Alpine Ecosystems

scholarly journals Surface-sensible and latent heat fluxes over the Tibetan Plateau from ground measurements, reanalysis, and satellite data

2014 ◽  
Vol 14 (11) ◽  
pp. 5659-5677 ◽  
Author(s):  
Q. Shi ◽  
S. Liang
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Vegetation Index ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Future Research ◽  
The Tibetan Plateau ◽  
Mean Square Errors

Abstract. Estimations from meteorological stations over the Tibetan Plateau (TP) indicate that since the 1980s the surface-sensible heat flux has been decreasing continuously, and modeling studies suggest that such changes are likely linked to the weakening of the East Asian Monsoon through exciting Rossby wave trains. However, the spatial and temporal variations in the surface-sensible and latent heat fluxes over the entire TP remain unknown. This study aims to characterize the spatial and seasonal variability of the surface-sensible and latent heat fluxes at 0.5° over the TP from 1984 to 2007 by synthesizing multiple data sources including ground measurements, reanalysis products, and remote-sensing products. The root mean square errors (RMSEs) from cross validation are 14.3 Wm−2 and 10.3 Wm−2 for the monthly fused sensible and latent heat fluxes, respectively. The fused sensible and latent heat-flux anomalies are consistent with those estimated from meteorological stations, and the uncertainties of the fused data are also discussed. The associations among the fused sensible and latent heat fluxes and the related surface anomalies such as mean temperature, temperature range, snow cover, and normalized difference vegetation index (NDVI) in addition to atmospheric anomalies such as cloud cover and water vapor show seasonal dependence, suggest that the land–biosphere–atmosphere interactions over the TP could display nonuniform feedbacks to the climate changes. It would be interesting to disentangle the drivers and responses of the surface-sensible and latent heat-flux anomalies over the TP in future research from evidences of modeling results.

Indian irrigation effects on precipitation over the Tibetan Plateau

2020 ◽  
Author(s):  
Yaqiong Lu ◽  
Shan Lin
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Climate Model ◽  
Regional Climate ◽  
Sensible Heat Flux ◽  
Summer Precipitation ◽  
Back Trajectory ◽  
The Tibetan Plateau ◽  
Irrigation Effects

<p>Indian agriculture equipped the most intensive irrigation worldwide and still maintains an increasing trend of irrigation due to the decreasing of Indian summer monsoon rainfall. Irrigation could largely increase soil moisture and evapotranspiration while cooling air temperature. Several researches showed that Indian irrigation did not significantly contribute to local precipitation, so will the Indian irrigation affect the adjacent regions, such as the Tibetan Plateau is unclear. Here, we set up 10-years simulations for two nested domains (30-10km) over the South-East Asia to quantify the irrigation effects with a coupled dynamic crop model and regional climate model (WRF4.0-CLM4Crop). Besides the numeric simulations, we adopted a water vapor back trajectory tracking method to track where the evaporation from the irrigated land fall as precipitation. Our preliminary results showed that Indian irrigation did not significantly affects temperature, sensible heat flux, and latent heat flux over the Tibetan Plateau, but the water vapor from Indian irrigation contributed to 10% of the summer precipitation on the Tibetan Plateau.</p>

scholarly journals Spatio-Temporal Trends of Surface Energy Budget in Tibet from Satellite Remote Sensing Observations and Reanalysis Data

2021 ◽  
Vol 13 (2) ◽  
pp. 256
Author(s):  
Usman Mazhar ◽  
Shuanggen Jin ◽  
Wentao Duan ◽  
Muhammad Bilal ◽  
Md. Arfan Ali ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Energy Budget ◽  
Sensible Heat Flux ◽  
Reanalysis Data ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Spatio Temporal

Being the highest and largest land mass of the earth, the Tibetan Plateau has a strong impact on the Asian climate especially on the Asian monsoon. With high downward solar radiation, the Tibetan Plateau is a climate sensitive region and the main water source for many rivers in South and East Asia. Although many studies have analyzed energy fluxes in the Tibetan Plateau, a long-term detailed spatio-temporal variability of all energy budget parameters is not clear for understanding the dynamics of the regional climate change. In this paper, satellite remote sensing and reanalysis data are used to quantify spatio-temporal trends of energy budget parameters, net radiation, latent heat flux, and sensible heat flux over the Tibetan Plateau from 2001 to 2019. The validity of both data sources is analyzed from in situ ground measurements of the FluxNet micrometeorological tower network, which verifies that both datasets are valid and reliable. It is found that the trend of net radiation shows a slight increase. The latent heat flux increases continuously, while the sensible heat flux decreases continuously throughout the study period over the Tibetan Plateau. Varying energy fluxes in the Tibetan plateau will affect the regional hydrological cycle. Satellite LE product observation is limited to certain land covers. Thus, for larger spatial areas, reanalysis data is a more appropriate choice. Normalized difference vegetation index proves a useful indicator to explain the latent heat flux trend. Despite the reduction of sensible heat, the atmospheric temperature increases continuously resulting in the warming of the Tibetan Plateau. The opposite trend of sensible heat flux and air temperature is an interesting and explainable phenomenon. It is also concluded that the surface evaporative cooling is not the indicator of atmospheric cooling/warming. In the future, more work shall be done to explain the mechanism which involves the complete heat cycle in the Tibetan Plateau.

scholarly journals Improved parameterization of snow albedo in WRF + Noah. Part II: Applicability to snow estimates for the Tibetan Plateau

2021 ◽  
Author(s):  
Lian Liu ◽  
Yaoming Ma ◽  
Massimo Menenti ◽  
Rongmingzhu Su ◽  
Nan Yao ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Land Surface ◽  
Snow Depth ◽  
Sensible Heat Flux ◽  
Parameterization Scheme ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Snow Albedo

Abstract. Snow albedo is important to the land surface energy balance and to the water cycle. During snowfall and subsequent snowmelt, snow albedo is usually parameterized as functions of snow related variables in land surface models. However, the default snow albedo scheme in the widely used Noah land surface model shows evident shortcomings in land-atmosphere interactions estimates during snow events on the Tibetan Plateau. Here, we demonstrate that our improved snow albedo scheme performs well after including snow depth as an additional factor. By coupling the WRF and Noah models, this study comprehensively evaluates the performance of the improved snow albedo scheme in simulating eight snow events on the Tibetan Plateau. The modeling results are compared with WRF run with the default Noah scheme and in situ observations. The improved snow albedo scheme significantly outperforms the default Noah scheme in relation to air temperature, albedo and sensible heat flux estimates, by alleviating cold bias estimates, albedo overestimates and sensible heat flux underestimates, respectively. This in turn contributes to more accurate reproductions of snow event evolution. The averaged RMSE relative reductions (and relative increase in correlation coefficients) for air temperature, albedo, sensible heat flux and snow depth reach 27 % (5 %), 32 % (69 %), 13 % (17 %) and 21 % (108 %) respectively. These results demonstrate the strong potential of our improved snow albedo parameterization scheme for snow event simulations on the Tibetan Plateau. Our study provides a theoretical reference for researchers committed to further improving the snow albedo parameterization scheme.

Sign in / Sign up

Export Citation Format

Share Document