scholarly journals The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 634
Author(s):  
Jiahe Lang ◽  
Yaoming Ma ◽  
Zhaoguo Li ◽  
Dongsheng Su
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Climate Warming ◽  
Significant Feature ◽  
The Tibetan Plateau ◽  
Lake Surface ◽  
Rate Of Increase ◽  
The Impact ◽  
Ice Phenology

Increasing air temperature is a significant feature of climate warming, and is cause for some concern, particularly on the Tibetan Plateau (TP). A lack of observations means that the impact of rising air temperatures on TP lakes has received little attention. Lake surfaces play a unique role in determining local and regional climate. This study analyzed the effect of increasing air temperature on lake surface temperature (LST), latent heat flux (LE), sensible heat flux (H), and ice phenology at Lake Nam Co and Lake Ngoring, which have mean depths of approximately 40 m and 25 m, respectively, and are in the central and eastern TP, respectively. The variables were simulated using an adjusted Fresh-water Lake (FLake) model (FLake_α_ice = 0.15). The simulated results were evaluated against in situ observations of LST, LE and H, and against LST data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) for 2015 to 2016. The simulations show that when the air temperature increases, LST increases, and the rate of increase is greater in winter than in summer; annual LE increases; H and ice thickness decrease; ice freeze-up date is delayed; and the break-up date advances. The changes in the variables in response to the temperature increases are similar at the two lakes from August to December, but are significantly different from December to July.

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.

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.

scholarly journals Improved parameterization of snow albedo in Noah coupled with Weather Research and Forecasting: applicability to snow estimates for the Tibetan Plateau

2021 ◽  
Vol 25 (9) ◽  
pp. 4967-4981
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 ◽  
Weather Research And Forecasting ◽  
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 interaction 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 Weather Research and Forecasting (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 root mean square error (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.

scholarly journals Numerical study on the response of the largest lake in China to climate change

2019 ◽  
Vol 23 (4) ◽  
pp. 2093-2109 ◽  
Author(s):  
Dongsheng Su ◽  
Xiuqing Hu ◽  
Lijuan Wen ◽  
Shihua Lyu ◽  
Xiaoqing Gao ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Flux ◽  
Tibetan Plateau ◽  
Surface Temperature ◽  
Air Temperature ◽  
Longwave Radiation ◽  
Shortwave Radiation ◽  
Qinghai Lake ◽  
Observation Data ◽  
Lake Surface

Abstract. Lakes are sensitive indicators of climate change. There are thousands of lakes on the Tibetan Plateau (TP), and more than 1200 of them have an area larger than 1 km2; they respond quickly to climate change, but few observation data of lakes are available. Therefore, the thermal condition of the plateau lakes under the background of climate warming remains poorly understood. In this study, the China regional surface meteorological feature dataset developed by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences (ITPCAS), MODIS lake surface temperature (LST) data and buoy observation data were used to evaluate the performance of lake model FLake, extended by simple parameterizations of the salinity effect, for brackish lake and to reveal the response of thermal conditions, radiation and heat balance of Qinghai Lake to the recent climate change. The results demonstrated that the FLake has good ability in capturing the seasonal variations in the lake surface temperature and the internal thermal structure of Qinghai Lake. The simulated lake surface temperature showed an increasing trend from 1979 to 2012, positively correlated with the air temperature and the downward longwave radiation while negatively correlated with the wind speed and downward shortwave radiation. The simulated internal thermodynamic structure revealed that Qinghai Lake is a dimictic lake with two overturn periods occurring in late spring and late autumn. The surface and mean water temperatures of the lake significantly increased from 1979 to 2012, while the bottom temperatures showed no significant trend, even decreasing slightly from 1989 to 2012. The warming was the strongest in winter for both the lake surface and air temperature. With the warming of the climate, the later ice-on and earlier ice-off trend was simulated in the lake, significantly influencing the interannual and seasonal variability in radiation and heat flux. The annual average net shortwave radiation and latent heat flux (LH) both increase obviously while the net longwave radiation and sensible heat flux (SH) decrease slightly. Earlier ice-off leads to more energy absorption mainly in the form of shortwave radiation during the thawing period, and later ice-on leads to more energy release in the form of longwave radiation, SH and LH during the ice formation period. Meanwhile, the lake–air temperature difference increased in both periods due to shortening ice duration.

scholarly journals Numerical study on the response of the largest lake in China to climate change

2018 ◽  
Author(s):  
Dongsheng Su ◽  
Xiuqing Hu ◽  
Lijuan Wen ◽  
Lin Zhao ◽  
Zhaoguo Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Surface Temperature ◽  
Air Temperature ◽  
Qinghai Lake ◽  
Observation Data ◽  
Lake Surface ◽  
Recent Climate ◽  
Downward Longwave Radiation ◽  
The Impact

Abstract. Lakes are sensitive indicators of climate change. There are thousands of lakes on the Tibetan Plateau (TP), more than 1200 of them having an area larger than 1 km2, but few observation data of lakes are available. Therefore, the thermal condition of the plateau lakes under the background of climate warming remain poorly understood. In this study, the China Meteorological Forcing Dataset developed by Institute of Tibetan Plateau Research, Chinese Academy of Sciences (ITPCAS), MODIS Land Surface Temperature (LST) data and buoy observation data were used to reveal the response of thermal conditions of Qinghai Lake to the recent climate change and to analyze the applicability of Freshwater Lake Model (FLake) to Qinghai Lake. Despite some deviations caused by model simplifications and uncertain forcing data, FLake demonstrated a good ability in capturing the seasonal variations of the lake surface temperature and the internal thermal structure of Qinghai Lake. The simulated lake surface temperature demonstrated a positive trend from 1979 to 2012, positively correlated with the air temperature and the downward longwave radiation, while negatively correlated with the wind speed and with the solar radiation but failing to pass the significance test. The simulated internal thermodynamic structure revealed that, if the impact of salinity is not considered, the Qinghai Lake is a dimictic lake with two overturn periods occurring in late spring and late autumn respectively. The surface and mean water temperatures significantly increased from 1979 to 2012, while the bottom temperatures showed no significant trend, even decreasing slightly from 1989 to 2012. The warming was the strongest in winter for both LST and air temperature. With the warming of the climate, the earlier ice break-up and later ice-on were simulated, having a strong effect on lake-air temperature differences in January and May.

Improved parameterization of albedo in WRF + Noah in snow events simulation in the Tibetan Plateau

2021 ◽  
Author(s):  
Lian Liu ◽  
Massimo Menenti ◽  
Yaoming Ma ◽  
Weiqiang Ma
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
Numerical Experiments ◽  
Parameterization Scheme ◽  
Cold Bias ◽  
Surface Model ◽  
Good Prospect ◽  
The Tibetan Plateau ◽  
The Impact ◽  
Resolution Simulation

<p>Snowfall and the subsequent evolution of the snowpack have a large effect on surface energy balance and water cycle, among which albedo is a major driver. However, the current widely used Noah land surface model does not describe snow albedo correctly, although it keeps snow-related variables i.e. snow cover and age into account. In our study, the impact of an improved albedo parameterization scheme in WRF coupled with Noah was investigated. In the improved albedo scheme, albedo was parameterized as functions of snow depth and age which was developed using remote sensing retrievals of albedo.</p><p>Numerical experiments were conducted to model a severe snow event in March 2017. The performance of WRF coupled with Noah applying the improved albedo scheme was compared with that of applying the default albedo scheme and with that of WRF coupled with CLM applying CLM’s complex albedo scheme. First, the improved albedo scheme largely reduces the WRF coupled with Noah default albedo overestimation in the southeastern Tibetan Plateau, remarkably reducing the large cold bias estimates by 0.7 ℃ air temperature RMSE. Second, the improved albedo scheme gives the highest correlationship between the satellite-derived and the model estimated albedo, contributing to achieve the SWE spatial pattern, heavy snow belt and maximum SWE estimates in eastern Tibetan Plateau. Third, the fine resolution simulation, such as 5 km (1 km), significantly reduces the eastern SWE overestimation by 29% (49%).</p><p>In order to investigate the applicability of the improved albedo scheme in snow events simulation in the Tibetan Plateau, 16 numerical experiments were conducted to simulate 8 snow events by using WRF coupling with Noah default and improved albedo schemes. The assessment demonstrates that the improved albedo scheme significantly reduces the air temperature underestimation, and reduces the air temperature RMSE by 0.5 - 1 ℃ for both 5 km and 1 km resolution simulations. It is expected that the improved albedo parameterization scheme will have a good prospect in high resolution simulation of snow events in the Tibetan Plateau.</p>

Accelerated Changes of Environmental Conditions on the Tibetan Plateau Caused by Climate Change

2011 ◽  
Vol 24 (24) ◽  
pp. 6540-6550 ◽  
Author(s):  
Lei Zhong ◽  
Zhongbo Su ◽  
Yaoming Ma ◽  
Mhd. Suhyb Salama ◽  
José A. Sobrino
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Land Surface ◽  
Asian Monsoon ◽  
Sensible Heat Flux ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Land Surface Parameters

Abstract Variations of land surface parameters over the Tibetan Plateau have great importance on local energy and water cycles, the Asian monsoon, and climate change studies. In this paper, the NOAA/NASA Pathfinder Advanced Very High Resolution Radiometer (AVHRR) Land (PAL) dataset is used to retrieve the land surface temperature (LST), the normalized difference vegetation index (NDVI), and albedo, from 1982 to 2000. Simultaneously, meteorological parameters and land surface heat fluxes are acquired from the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) dataset and the Global Land Data Assimilation System (GLDAS), respectively. Results show that from 1982 to 2000 both the LST and the surface air temperature increased on the Tibetan Plateau (TP). The rate of increase of the LST was 0.26±0.16 K decade−1 and that of the surface air temperature was 0.29 ± 0.16 K decade−1, which exceeded the increase in the Northern Hemisphere (0.054 K decade−1). The plateau-wide annual mean precipitation increased at 2.54 mm decade−1, which indicates that the TP is becoming wetter. The 10-m wind speed decreased at about 0.05±0.03 m s−1 decade−1 from 1982 to 2000, which manifests a steady decline of the Asian monsoon wind. Due to the diminishing ground–air temperature gradient and subdued surface wind speed, the sensible heat flux showed a decline of 3.37 ± 2.19 W m−2 decade−1. The seasonal cycle of land surface parameters could clearly be linked to the patterns of the Asian monsoon. The spatial patterns of sensible heat flux, latent heat flux, and their variance could also be recognized.

Estimating daily 1-km surface air temperature from satellite all-weather land surface temperature over the Tibetan Plateau

2020 ◽  
Author(s):  
Xin Wen ◽  
Ji Zhou ◽  
Xiaodong Zhang ◽  
Jin Ma
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Climate Warming ◽  
Land Surface ◽  
Surface Air Temperature ◽  
Thermal Infrared ◽  
The Tibetan Plateau

<p>Over the past several decades, global climate change, particularly the rising temperature has caused public concerns. In the context of climate warming, many environmental and water problems such as decreasing runoff, shrinking glaciers and permafrost, vegetation degradation and desertification can be attributed to rapid climate change. Surface air temperature (SAT) plays a key role in land-atmospheric interactions and is an important parameter for climate change studies. Traditional SAT data are collected by ground meteorological observation. Nevertheless, such traditional measurements at ground stations cannot capture the spatial variations of SAT, especially over complicated areas such as the Tibetan Plateau, where meteorological stations are with large elevation variability and unreasonable spatial distribution. In contrast, satellite remote sensing provides an direct observation of land surface temperature (LST) and, thus, also provides an possible way to obtain SAT since LST and SAT are generally closely related to each other. The scientific communities have developed various methods to estimate SAT from LST through statistical or physical models. The widely used satellite LST, however, is derived from satellite thermal infrared remote sensing and thus, significantly affected by the clouds.</p><p>In this study, we report an examination of the estimation of daily 1-km SAT from the all-weather satellite LST over the Tibetan Plateau. The estimation of SAT is based on a noval method that dynamicall integrates the newly published 1-km all-weather LST data by merging satellite thermal infrared and microwave remote sensing observations based on the random forest. The matchups of the ground measured SAT at stations and the corresponding all-weather LST were separated into the training set and valiation set. In addition, independent SAT measured at experimental ground sites were used to evaluate the SAT method. Results indicate that reasonably integrating multiple LST terms provides daily average all-weather SAT with satisfactory accuracies over the Tibetan Plateau. The estimated SAT based on the proposed method has ignorable systematic error and low root-mean squared error when validated with ground measured SAT under all-weather conditions. Further comparison demonstrates that the SAT estimate agree well with other SAT estimated from satellite thermal infrared LST under cloud-free condition. In addition, the SAT method has the potential to be generalized and extended to various complicated areas. With this method, the daily 1-km SAT for the entire Tibetan Plateau from 2003 to 2018 were produced. This dataset is of great value to examine recent climate warming trend and the land-atmospheirc interactions in the entire Tibetan Plateau.</p>

scholarly journals Analysis of ice phenology of lakes on the Tibetan Plateau from MODIS data

2012 ◽  
Vol 6 (3) ◽  
pp. 1739-1779
Author(s):  
J. Kropáček ◽  
F. Chen ◽  
S. Hoerz ◽  
V. Hochschild
Keyword(s):  
Tibetan Plateau ◽  
Ice Cover ◽  
Optical Data ◽  
Water Volume ◽  
The Tibetan Plateau ◽  
Large Lakes ◽  
Local Conditions ◽  
Break Up ◽  
The Impact ◽  
Ice Phenology

Abstract. Much attention has recently been paid to the impact of climate change at the Tibetan Plateau. This remote and harsh region includes a large system of endorheic (closed basin) lakes. Ice phenology i.e. the timing of freeze-up and break-up and the duration of the ice cover may provide valuable information about climate variations in this region. The ice phenology of 59 large lakes on the Tibetan Plateau was derived from Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day composite data for the period from 2001 to 2010. Duration of the ice cover appears to have a high variability in the studied region due to both climate and local factors. Mean values for the duration of ice cover were calculated for four groups of lakes defined as distinct geographic regions. In each group several lakes showed anomalies in ice cover duration in the studied period. Possible reasons for such anomalous behavior are discussed. Furthermore, many lakes do not freeze up completely during some seasons. This was confirmed by inspection of high resolution optical data. Mild winter seasons, large water volume and/or high salinity are the most likely explanations. Trends in the ice cover duration derived by linear regression for all the studied lakes show a high variation in space. A correlation of ice phenology variables with parameters describing climatic and local conditions showed a high thermal dependency of the ice regime. It appears that the freeze onset and water clean of ice day appear to be more thermally determined than freeze-up and break-up dates in case of the studied lakes.

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