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Monitoring paddy rice cultivation is essential for ensuring food security and for land resource management in agrarian countries of South Asia. In this study, we investigated the spatial and temporal variation of rice cultivated area and phenological metrics in Nepal between 2003 and 2018 using the time series MODIS data and PhenoRice algorithm. Comparisons of PhenoRice outputs with ancillary data show that implementation of PhenoRice with the MODIS data can be used for long-term change analysis of rice cultivation. Results on spatial distribution illustrate: rice cultivation is concentrated in the low elevation belt in the south; the cultivation begins earlier in the western region compared to the eastern region and begins earlier in the hilly region compared to the plains. The inter-annual trend analysis found a statistically significant decrease of rice cultivated area at the rate of 19.13 thousand hectares per year during the recent decade; the loss of rice fields was more prominent in the eastern plains while rice farming expanded in the mid-hills in the western region. Our study provides insights regarding timely and cost-efficient monitoring of rice farming at a large scale in the mountainous region.
Nirajan Luintel; Weiqiang Ma; Yaoming Ma; Binbin Wang; Jie Xu; Binod Dawadi; Bhogendra Mishra. Tracking the dynamics of paddy rice cultivation practice through MODIS time series and PhenoRice algorithm. Agricultural and Forest Meteorology 2021, 307, 108538 .
AMA StyleNirajan Luintel, Weiqiang Ma, Yaoming Ma, Binbin Wang, Jie Xu, Binod Dawadi, Bhogendra Mishra. Tracking the dynamics of paddy rice cultivation practice through MODIS time series and PhenoRice algorithm. Agricultural and Forest Meteorology. 2021; 307 ():108538.
Chicago/Turabian StyleNirajan Luintel; Weiqiang Ma; Yaoming Ma; Binbin Wang; Jie Xu; Binod Dawadi; Bhogendra Mishra. 2021. "Tracking the dynamics of paddy rice cultivation practice through MODIS time series and PhenoRice algorithm." Agricultural and Forest Meteorology 307, no. : 108538.
Over the past decades, human-induced climate change has led to a widespread wetting and warming of the Tibetan Plateau, affecting both ecosystems and the carbon cycling therein. Whether the observed climate changes stimulate carbon uptake via enhanced photosynthesis or carbon loss via enhanced soil respiration remains unclear. Here we present long term observations of carbon fluxes, meteorological variables and remotely sensed plant cover estimations from a central Tibetan alpine steppe ecosystem at Nam Co, the third largest lake on the Tibetan Plateau. Using modified Mann-Kendall trend tests, we found a significant increasing daily net carbon uptake of 0.5 g C m-2 decade-1, which can be explained by a widespread greening at the southern shore of lake Nam Co. The Plateau-wide changes in temperature and precipitation are locally expressed as an increasing diurnal temperature range during winter, higher water availability during spring, higher cloud cover during early summer and less water availability during late summer. While these changes differ over the course of the year, they tend to stimulate plant growth more than microbial respiration, leading to an increased carbon uptake during all seasons. This study indicates that during the 14 years study period, a higher amplitude in winter temperatures and an earlier summer monsoon promote carbon uptake in a central Tibetan alpine steppe ecosystem.
Felix NieberdingiD; Christian Wille; Yaoming MaiD; Yuyang Wang; Philipp MaurischatiD; Lukas LehnertiD; Torsten SachsiD. Winter daytime warming and shift in summer monsoon increase plant cover and net CO2 uptake in a central Tibetan alpine steppe ecosystem. 2021, 1 .
AMA StyleFelix NieberdingiD, Christian Wille, Yaoming MaiD, Yuyang Wang, Philipp MaurischatiD, Lukas LehnertiD, Torsten SachsiD. Winter daytime warming and shift in summer monsoon increase plant cover and net CO2 uptake in a central Tibetan alpine steppe ecosystem. . 2021; ():1.
Chicago/Turabian StyleFelix NieberdingiD; Christian Wille; Yaoming MaiD; Yuyang Wang; Philipp MaurischatiD; Lukas LehnertiD; Torsten SachsiD. 2021. "Winter daytime warming and shift in summer monsoon increase plant cover and net CO2 uptake in a central Tibetan alpine steppe ecosystem." , no. : 1.
The vertical motion of air is closely related to the amount of precipitation that falls in a particular region. The Tibetan Plateau and the North Pacific are important determinants of the East Asian climate. We use climate diagnosis and statistical analysis to study the vertical motion of the air over the North Pacific and Tibetan Plateau and the relationship between the vertical motion of air over them and the climate in East Asia. Here we show that there is a downward movement of air over the Tibetan Plateau during the winter, with a maximum velocity of downward movement at 500 hPa, whereas there is an upward movement of air with a maximum velocity of upward movement at 600 hPa during the summer. Precipitation in East Asia has a significant negative correlation (The correlation coefficient exceeds −0.463 and confidence level is greater than 99%) with the vertical motion of air over the Tibetan Plateau and the North Pacific during both the winter and summer. There is also a negative correlation of precipitation in the region south of the Yangtze River with the vertical motion of air over the Tibetan Plateau in winter, whereas the area of negative correlation to the vertical motion of air over the North Pacific in winter is located to the east of the Tibetan Plateau and the Yangtze–Huaihe river basin. The research results provide a climatic framework for the vertical motion of air over both the Tibetan Plateau and the North Pacific.
Rongxiang Tian; Yaoming Ma; Weiqiang Ma; Xiuyi Zhao; Duo Zha. Longer Time-Scale Variability of Atmospheric Vertical Motion over the Tibetan Plateau and North Pacific and the Climate in East Asia. Atmosphere 2021, 12, 630 .
AMA StyleRongxiang Tian, Yaoming Ma, Weiqiang Ma, Xiuyi Zhao, Duo Zha. Longer Time-Scale Variability of Atmospheric Vertical Motion over the Tibetan Plateau and North Pacific and the Climate in East Asia. Atmosphere. 2021; 12 (5):630.
Chicago/Turabian StyleRongxiang Tian; Yaoming Ma; Weiqiang Ma; Xiuyi Zhao; Duo Zha. 2021. "Longer Time-Scale Variability of Atmospheric Vertical Motion over the Tibetan Plateau and North Pacific and the Climate in East Asia." Atmosphere 12, no. 5: 630.
The contrasting responses of ice core δ18O records (δ18Oice) from the northern and southern Tibetan Plateau (TP) to the El Niño Southern Oscillation (ENSO) complicate δ18Oice‐based temperature reconstructions. These contrasting responses were explored using stable hydrogen isotopes in water vapor (δDv). We found that the interannual variation in δDv from the northern TP is influenced by midtropospheric moisture sources from the Indo‐Pacific Warm Pool, with enriched (depleted) δDv values in La Niña (El Niño) years due to enhanced (weakened) deep convection. In comparison, the interannual δDv variation in the southern TP is mainly influenced by low‐tropospheric moisture from the central Indian Continent, whose δDv is depleted (enriched) in La Niña (El Niño) years. These results demonstrate that moisture transported from different altitudes can lead to opposite isotopic signals of water vapor over the northern and southern TP and can be used to reconcile the contrasting responses of δ18Oice to ENSO.
Zhaowei Jing; Wusheng Yu; Andreas Schneider; Tobias Borsdorff; Jochen Landgraf; Stephen Lewis; Jingyi Zhang; Wenjun Tang; Yaoming Ma; Baiqing Xu; Dongmei Qu. Interannual Variation in Stable Isotopes in Water Vapor Over the Northern Tibetan Plateau Linked to ENSO. Geophysical Research Letters 2021, 48, 1 .
AMA StyleZhaowei Jing, Wusheng Yu, Andreas Schneider, Tobias Borsdorff, Jochen Landgraf, Stephen Lewis, Jingyi Zhang, Wenjun Tang, Yaoming Ma, Baiqing Xu, Dongmei Qu. Interannual Variation in Stable Isotopes in Water Vapor Over the Northern Tibetan Plateau Linked to ENSO. Geophysical Research Letters. 2021; 48 (8):1.
Chicago/Turabian StyleZhaowei Jing; Wusheng Yu; Andreas Schneider; Tobias Borsdorff; Jochen Landgraf; Stephen Lewis; Jingyi Zhang; Wenjun Tang; Yaoming Ma; Baiqing Xu; Dongmei Qu. 2021. "Interannual Variation in Stable Isotopes in Water Vapor Over the Northern Tibetan Plateau Linked to ENSO." Geophysical Research Letters 48, no. 8: 1.
The Tibetan Plateau (TP) is characterized by complex topography and heterogeneous surface cover, which makes it difficult to obtain accurate precipitation data at a regional scale. Therefore, it is important to use dense ground observations to evaluate satellite‐derived precipitation products. In this study, the top‐down‐based Global Precipitation Measurement Integrated MultisatellitE Retrievals (GPM IMERG) and bottom‐up‐based SM2RAIN‐ASCAT (SM2RASC) precipitation products were evaluated against 1584 unevenly distributed rain gauges over the TP from May to October 2015. Results show: (1) The overall performances of IMERG and SM2RASC are comparable at the daily scale, with a higher correlation coefficient (CC) for IMERG and lower root‐mean‐square error (RMSE) for SM2RASC. Regarding the precipitation detectability, IMERG outperforms SM2RASC; (2) Spatially, SM2RASC shows better performance than IMERG in grasslands, but IMERG outperforms SM2RASC in forest areas, due to the low quality of the soil moisture retrieved by satellite in the areas; (3) The accuracy of both SM2RASC and IMERG is closely correlated with altitude and rainfall intensity. The SM2RASC product estimates light to moderate rainfall (5‐25 mm/day) more accurately than the IMERG, but the IMERG product shows better performance for drizzle and heavy rainfall (> 25 mm/day). Due to relatively frequent fluctuations of the ASCAT soil moisture product, SM2RASC frequently reports false rainfall in dry conditions. This study demonstrates the good performance of the SM2RASC product over the TP and suggests that the impact of vegetation density and topography should be considered for improving the SM2RAIN algorithm. This article is protected by copyright. All rights reserved.
Yixi Fan; Ziqiang Ma; Yaoming Ma; Weiqiang Ma; Zhipeng Xie; Leiding Ding; Yizhe Han; Wei Hu; Rongmingzhu Su. Respective advantages of “top‐down” based GPM IMERG and “bottom‐up” based SM2RAIN‐ASCAT precipitation products over the Tibetan Plateau. Journal of Geophysical Research: Atmospheres 2021, 1 .
AMA StyleYixi Fan, Ziqiang Ma, Yaoming Ma, Weiqiang Ma, Zhipeng Xie, Leiding Ding, Yizhe Han, Wei Hu, Rongmingzhu Su. Respective advantages of “top‐down” based GPM IMERG and “bottom‐up” based SM2RAIN‐ASCAT precipitation products over the Tibetan Plateau. Journal of Geophysical Research: Atmospheres. 2021; ():1.
Chicago/Turabian StyleYixi Fan; Ziqiang Ma; Yaoming Ma; Weiqiang Ma; Zhipeng Xie; Leiding Ding; Yizhe Han; Wei Hu; Rongmingzhu Su. 2021. "Respective advantages of “top‐down” based GPM IMERG and “bottom‐up” based SM2RAIN‐ASCAT precipitation products over the Tibetan Plateau." Journal of Geophysical Research: Atmospheres , no. : 1.
Evapotranspiration (ET) is composed of soil evaporation (ETs), canopy transpiration (ETc) and canopy intercepted water evaporation (ETw), and it plays an indispensable role in the water and energy cycles of land surface processes. More accurate estimations of variations in ET are essential for natural hazard monitoring and water resource management. An improved algorithm for ETs with soil moisture and texture (SMT) and an optimized ETc based on the MOD16 model (MOD16‐STM) are proposed for the cold, arid and semiarid regions of the Tibetan Plateau (TP). The nonlinear relationships between the soil surface resistance (rss) and soil surface hydration state in different soil textures were redefined by using five flux tower measurements over the TP. The value of the mean potential stomatal conductance per unit leaf area (CL) used for ETc calculation in grasslands was optimized at 0.0038 (m s‐1). The MOD16‐STM was compared with the MOD16 and a soil water index‐based Priestley‐Taylor algorithm (SWI‐PT) at five independent sites. The results showed that the half‐hourly, daily, and monthly estimations from the MOD16‐STM were closer to observations than those from the other two models. The results indicated that the MOD16‐STM increased R2 by 0.2/0.05 and the index of agreement (IOA) by 0.37/0.23 and deceased RMSE by 43.89/42.77 W m‐2 and the absolute mean bias (|MB|) by 46.23/45.89 W m‐2, when compared to the results of the MOD16 at daily/monthly scales. The results suggested that the MOD16‐STM will produce more accurate ET estimates over the flux sites and has great potential for ET estimation and land surface model improvement for the TP region. This article is protected by copyright. All rights reserved.
Ling Yuan; Yaoming Ma; Xuelong Chen; Yuyang Wang; Zhaoguo Li. An enhanced MOD16 evapotranspiration model for the Tibetan Plateau during the unfrozen season. Journal of Geophysical Research: Atmospheres 2021, 1 .
AMA StyleLing Yuan, Yaoming Ma, Xuelong Chen, Yuyang Wang, Zhaoguo Li. An enhanced MOD16 evapotranspiration model for the Tibetan Plateau during the unfrozen season. Journal of Geophysical Research: Atmospheres. 2021; ():1.
Chicago/Turabian StyleLing Yuan; Yaoming Ma; Xuelong Chen; Yuyang Wang; Zhaoguo Li. 2021. "An enhanced MOD16 evapotranspiration model for the Tibetan Plateau during the unfrozen season." Journal of Geophysical Research: Atmospheres , no. : 1.
Precipitation is a key hydrometeorological variable for understanding surface energy partitioning and water budget over the Tibetan Plateau (TP). A substantial proportion of summer precipitation falls as rain. The effects of different land surface models (LSMs) on the TP's precipitation and their inner mechanisms remain unclear. Therefore, the assessments of different LSMs coupled with the Weather Research and Forecasting (WRF) model in precipitation simulation were investigated over the TP during June 28th to 29th of 2008. The simulated results were evaluated with the merged CMORPH precipitation dataset developed by the China Meteorological Administration (CMA). The assessment demonstrated that precipitation simulated by the CLM4, Noah‐MP and PX LSM schemes was wider and stronger compared with the merged CMORPH over the central and western TP but was underestimated over the eastern and southern regions. Generally, both CLM4 and Noah‐MP schemes exhibited higher forecasting quality and accuracy in simulating precipitation over the TP. The optimal precipitation simulation was achieved by applying the Noah‐MP scheme, with a lowest RMSE of 9.53 mm/day, mainly attributed to its corrections of overforecasting for precipitation that did not occur. Further mechanism analysis indicated that soil moisture‐energy flux‐precipitation feedback play an important role in different LSM schemes.This article is protected by copyright. All rights reserved.
Lei Zhong; Ziyu Huang; Yaoming Ma; Yunfei Fu; Mingxing Chen; Ming Ma; Jianqiu Zheng. Assessments of Weather Research and Forecasting Land Surface Models in Precipitation Simulation Over the Tibetan Plateau. Earth and Space Science 2021, 8, 1 .
AMA StyleLei Zhong, Ziyu Huang, Yaoming Ma, Yunfei Fu, Mingxing Chen, Ming Ma, Jianqiu Zheng. Assessments of Weather Research and Forecasting Land Surface Models in Precipitation Simulation Over the Tibetan Plateau. Earth and Space Science. 2021; 8 (3):1.
Chicago/Turabian StyleLei Zhong; Ziyu Huang; Yaoming Ma; Yunfei Fu; Mingxing Chen; Ming Ma; Jianqiu Zheng. 2021. "Assessments of Weather Research and Forecasting Land Surface Models in Precipitation Simulation Over the Tibetan Plateau." Earth and Space Science 8, no. 3: 1.
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.
Jiahe Lang; Yaoming Ma; Zhaoguo Li; Dongsheng Su. The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau. Water 2021, 13, 634 .
AMA StyleJiahe Lang, Yaoming Ma, Zhaoguo Li, Dongsheng Su. The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau. Water. 2021; 13 (5):634.
Chicago/Turabian StyleJiahe Lang; Yaoming Ma; Zhaoguo Li; Dongsheng Su. 2021. "The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau." Water 13, no. 5: 634.
This study focused on planetary boundary layer (PBL) growth in winter under the influence of the westerlies over the Rongbuk Valley on the north side of the central Himalayas. Two sunny November days in 2014 with different synoptic conditions in terms of large‐scale wind direction and speed were selected to investigate the ways in which large‐scale synoptic forcing affected the vertical structure of the PBL, atmospheric stability, surface wind field, and land surface energy fluxes. This was done by using radiosonde and in‐situ measurements, the ECMWF ERA5 reanalysis dataset, and a one‐dimensional model. The results revealed that the valley winds and PBL growth were strongly influenced by the variations of the westerlies, which prevail in this region during the winter. When the synoptic wind direction at the height of the mountain ridges was parallel to the axis of the valley and strong, the downward transmission of the westerlies to the valley floor (DTWTV) was strong, causing high near‐surface wind speeds and sensible heat flux values. These conditions, together with a deep residual layer, unstable atmosphere, and thermally driven local wind, produced an extremely deep PBL (9 km above sea level) in the early afternoon of 23 November. When the synoptic wind direction at the ridge height intersected the axis of the valley and was weak, the DTWTV was weak, and the PBL became relatively low on 28 November. These results demonstrate that the interaction between the topography and synoptic circulation plays a critical role in PBL growth. This article is protected by copyright. All rights reserved.
Yue Lai; Xuelong Chen; Yaoming Ma; Deliang Chen; Suolang Zhaxi. Impacts of the Westerlies on Planetary Boundary Layer Growth Over a Valley on the North Side of the Central Himalayas. Journal of Geophysical Research: Atmospheres 2021, 126, 1 .
AMA StyleYue Lai, Xuelong Chen, Yaoming Ma, Deliang Chen, Suolang Zhaxi. Impacts of the Westerlies on Planetary Boundary Layer Growth Over a Valley on the North Side of the Central Himalayas. Journal of Geophysical Research: Atmospheres. 2021; 126 (3):1.
Chicago/Turabian StyleYue Lai; Xuelong Chen; Yaoming Ma; Deliang Chen; Suolang Zhaxi. 2021. "Impacts of the Westerlies on Planetary Boundary Layer Growth Over a Valley on the North Side of the Central Himalayas." Journal of Geophysical Research: Atmospheres 126, no. 3: 1.
The northern slopes of Himalaya (NSH) have the highest average elevation in the world. It is difficult to assess how climate change has affected this region because only a few observations are available from the high terrain and harsh environment. This study investigates the long-term characteristics of temperature and precipitation in the NSH. Further, the association of these variations with atmospheric circulation patterns is also investigated. Our results indicated that the warming trend in this region is almost 1.5 times that of the TP region, 2 times that of China, and 3.5 times that of the world. Additionally, the warming rate of the NSH is more obvious than other regions in the Himalayas, which shows that different regions of the Himalayas have different sensitivity to climate change. Although the warming trend in the NSH region does not show obvious seasonal differences like the TP, the temperature increase rate in autumn and winter is still higher than that in spring and summer. The abrupt change point for the temperature increase in summer was about 5 years later than that in other seasons, indicating that the NSH region is more sensitive to climate warming in cooler seasons, which is similar to the western and northwestern Himalaya. Furthermore, the Southern Oscillation Index (SOI) displays significant relationships with the temperature in the NSH, meanwhile, the North Atlantic Oscillation index (NAO) and Western Pacific Subtropical High Intensity Index (WPI) also exist some correlations with seasonal temperature change. This indicating that the atmospheric circulation would also have affected the temperature increase in this region, especially in summer and winter. The changes in precipitation are only affected by the SOI during the monsoon season (June to September), indicating that ENSO influences precipitation changes through water vapor transmission. In contrast, the precipitation in the TP is correlated with NAO, SOI and WPI, which indicating the precipitation of the TP might be affected by multiple circulation systems.
Yizhe Han; Yaoming Ma; Zhongyan Wang; Zhipeng Xie; Genhou Sun; Binbin Wang; Weiqiang Ma; Rongmingzhu Su; Wei Hu; Yixi Fan. Variation characteristics of temperature and precipitation on the northern slopes of the Himalaya region from 1979 to 2018. Atmospheric Research 2021, 253, 105481 .
AMA StyleYizhe Han, Yaoming Ma, Zhongyan Wang, Zhipeng Xie, Genhou Sun, Binbin Wang, Weiqiang Ma, Rongmingzhu Su, Wei Hu, Yixi Fan. Variation characteristics of temperature and precipitation on the northern slopes of the Himalaya region from 1979 to 2018. Atmospheric Research. 2021; 253 ():105481.
Chicago/Turabian StyleYizhe Han; Yaoming Ma; Zhongyan Wang; Zhipeng Xie; Genhou Sun; Binbin Wang; Weiqiang Ma; Rongmingzhu Su; Wei Hu; Yixi Fan. 2021. "Variation characteristics of temperature and precipitation on the northern slopes of the Himalaya region from 1979 to 2018." Atmospheric Research 253, no. : 105481.
Snowstorms frequently occur in spring over the heterogeneous underlying surface of the Tibetan Plateau, causing both economic and societal damage. What the intensity of factors triggering snowstorms remains poorly understood. This study quantitatively diagnoses water vapor, the thermodynamic and dynamic conditions of a large-scale heavy snowfall event over the Tibetan Plateau using reanalysis data. Here we show, a cold vortex, the Southern Branch Trough and a meridional shear line are favorable synoptic systems. The snowfall is characterized by low-layer (− 8.3 × 10−7 g s−1 hPa−1 cm−2) and whole-layer (− 4.5 × 10−4 g s−1 cm−2) moisture convergence, low-level atmospheric convergence and high-level divergence (± 3 × 10−4 s−1), low-level positive vorticity (4.8 × 10−4 s−1) and strong vertical velocity (− 4 Pa s−1). Although the convectively-stable stratification acted to suppress snowfall, the abundant water vapor and strong orographic uplift of Himalayas and the downhill wind speed convergence overcome this to trigger the heavy snowfall event witnessed in March 2017. These diagnostic results are well consistent with those from WRF simulation. Our study acknowledges the importance of WRF in diagnostic analysis, deepens the understanding of evolution mechanisms and provides theoretical references for accurate forecasting of such events over the Tibetan Plateau. It would aid the development of effective strategies for sustainable livestock, and the mitigation and prevention of snow disasters in this region.
Lian Liu; Yaoming Ma; Nan Yao; Weiqiang Ma. Diagnostic analysis of a regional heavy snowfall event over the Tibetan Plateau using NCEP reanalysis data and WRF. Climate Dynamics 2021, 56, 2451 -2467.
AMA StyleLian Liu, Yaoming Ma, Nan Yao, Weiqiang Ma. Diagnostic analysis of a regional heavy snowfall event over the Tibetan Plateau using NCEP reanalysis data and WRF. Climate Dynamics. 2021; 56 (7-8):2451-2467.
Chicago/Turabian StyleLian Liu; Yaoming Ma; Nan Yao; Weiqiang Ma. 2021. "Diagnostic analysis of a regional heavy snowfall event over the Tibetan Plateau using NCEP reanalysis data and WRF." Climate Dynamics 56, no. 7-8: 2451-2467.
The local land–atmosphere coupling (LoCo) investigates the interactions between soil conditions, surface fluxes, planetary boundary layer (PBL) growth, and the formations of convective clouds and precipitation. Studying LoCo over the Tibetan Plateau (TP) is of great significance for understanding the TP's role in the Asian water tower. A series of real-case simulations, using the Weather Research and Forecasting (WRF) model with different combinations of land surface model (LSM) schemes and PBL schemes, has been carried out to investigate the LoCo characteristics over a typical underlying surface in the central TP in the rainy season. The LoCo characteristics in the study area are analyzed by applying a mixing diagram to the simulation results. The analysis indicates that the WRF simulations, using the Noah with BouLac, Mellor-Yamada Nakanishi and Niino Level-2.5 PBL (MYNN), and Yonsei University (YSU) produce closer results to the observation in terms of curves of Cp⋅θ and Lv⋅q, surface fluxes (Hsfc and LEsfc), entrainment fluxes (Hent, and LEent) at site BJ of Nagqu Station (BJ/Nagqu) than those using the Community Land Model (CLM) with BouLac, MYNN, and YSU. The frequency distributions of Hsfc, LEsfc, Hent, and LEent in the study area confirm this result. The spatial distributions of simulated Hsfc, LEsfc, Hent, and LEent, using WRF with Noah and BouLac, suggest that the spatial distributions of Hsfc and LEsfc in the study area are consistent with that of soil moisture, but the spatial distributions of Hent and LEent are quite different from that of soil moisture. A close examination of the relationship between entrainment fluxes and cloud water content (QCloud) reveals that the grids with small Hent and large LEent tend to have high QCloud and Hsfc, suggesting that high Hsfc is conducive to convective cloud formation, which leads to small Hent and large LEent. A sensitivity analysis of LoCo to the soil moisture at site BJ/Nagqu indicates that, on a sunny day, an increase in soil moisture leads to an increase in LEsfc but decreases in Hsfc, Hent, and LEent. The sensitivity of the relationship between simulated maximum daytime PBL height (PBLH) and mean daytime evapotranspiration (ET) in the study area to soil moisture indicates the rate at which the maximum daytime PBLH decreases with the mean ET increase as the initial soil moisture goes up. The analysis of simulated Hsfc, LEsfc, Hent, and LEent under different soil moisture conditions reveals that the frequency of Hent ranging from 80 to 240 W m−2 and the frequency of LEent ranging from −240 to −90 W m−2 both increase as the initial soil moisture increases. Coupled with the changes in QCloud, the changes in Hent and LEent as the initial soil moisture increases indicate that the rise in soil moisture leads to an increase in the cloud amount but a decrease in QCloud.
Genhou Sun; Zeyong Hu; Yaoming Ma; Zhipeng Xie; Jiemin Wang; Song Yang. Simulation analysis of local land atmosphere coupling in rainy season over a typical underlying surface in the Tibetan Plateau. Hydrology and Earth System Sciences 2020, 24, 5937 -5951.
AMA StyleGenhou Sun, Zeyong Hu, Yaoming Ma, Zhipeng Xie, Jiemin Wang, Song Yang. Simulation analysis of local land atmosphere coupling in rainy season over a typical underlying surface in the Tibetan Plateau. Hydrology and Earth System Sciences. 2020; 24 (12):5937-5951.
Chicago/Turabian StyleGenhou Sun; Zeyong Hu; Yaoming Ma; Zhipeng Xie; Jiemin Wang; Song Yang. 2020. "Simulation analysis of local land atmosphere coupling in rainy season over a typical underlying surface in the Tibetan Plateau." Hydrology and Earth System Sciences 24, no. 12: 5937-5951.
The Tibetan alpine steppe ecosystem covers an area of roughly 800 000 km2 and contains up to 3.3 % soil organic carbon in the uppermost 30 cm, summing up to 1.93 Pg C for the Tibet Autonomous Region only (472 037 km2). With temperatures rising 2 to 3 times faster than the global average, these carbon stocks are at risk of loss due to enhanced soil respiration. The remote location and the harsh environmental conditions on the Tibetan Plateau (TP) make it challenging to derive accurate data on the ecosystem–atmosphere exchange of carbon dioxide (CO2) and water vapor (H2O). Here, we provide the first multiyear data set of CO2 and H2O fluxes from the central Tibetan alpine steppe ecosystem, measured in situ using the eddy covariance technique. The calculated fluxes were rigorously quality checked and carefully corrected for a drift in concentration measurements. The gas analyzer self-heating effect during cold conditions was evaluated using the standard correction procedure and newly revised formulations (Burba et al., 2008; Frank and Massman, 2020). A wind field analysis was conducted to identify influences of adjacent buildings on the turbulence regime and to exclude the disturbed fluxes from subsequent computations. The presented CO2 fluxes were additionally gap filled using a standardized approach. The very low net carbon uptake across the 15-year data set highlights the special vulnerability of the Tibetan alpine steppe ecosystem to become a source of CO2 due to global warming. The data are freely available at https://doi.org/10.5281/zenodo.3733202 (Nieberding et al., 2020a) and https://doi.org/10.11888/Meteoro.tpdc.270333 (Nieberding et al., 2020b) and may help us to better understand the role of the Tibetan alpine steppe in the global carbon–climate feedback.
Felix Nieberding; Christian Wille; Gerardo Fratini; Magnus O. Asmussen; Yuyang Wang; Yaoming Ma; Torsten Sachs. A long-term (2005–2019) eddy covariance data set of CO2 and H2O fluxes from the Tibetan alpine steppe. Earth System Science Data 2020, 12, 2705 -2724.
AMA StyleFelix Nieberding, Christian Wille, Gerardo Fratini, Magnus O. Asmussen, Yuyang Wang, Yaoming Ma, Torsten Sachs. A long-term (2005–2019) eddy covariance data set of CO2 and H2O fluxes from the Tibetan alpine steppe. Earth System Science Data. 2020; 12 (4):2705-2724.
Chicago/Turabian StyleFelix Nieberding; Christian Wille; Gerardo Fratini; Magnus O. Asmussen; Yuyang Wang; Yaoming Ma; Torsten Sachs. 2020. "A long-term (2005–2019) eddy covariance data set of CO2 and H2O fluxes from the Tibetan alpine steppe." Earth System Science Data 12, no. 4: 2705-2724.
Net radiation is an important factor in studies of land–atmosphere processes, water resource management, and global climate change. This is particularly true for the Upper Blue Nile (UBN) basin, where significant parts of the basin are dry and evapotranspiration (ET) is a major mechanism for water loss. However, net radiation has not yet been appropriately parameterized in the basin. In this study, we estimated the instantaneous distribution of the net radiation flux in the basin using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the Terra satellite and Automatic Weather Station (AWS) data. Downward shortwave radiation and air temperature usually vary with topography, so we applied residual kriging spatial interpolation techniques to convert AWS data for point locations into gridded surface data. Simulated net radiation outputs were validated through comparison with independent field measurements. Validation results show that our method successfully reproduced the downward shortwave, upward shortwave, and net radiation fluxes. Using AWS data and residual kriging spatial interpolation techniques makes our results robust and comparable to previous works that used satellite data at a finer spatial resolution than MODIS. The estimated net shortwave, longwave, and total radiation fluxes were in close agreement with ground truth measurements, with mean bias (MB) values of − 14.84, 5.7, and 20.53 W m−2 and root mean square error (RMSE) values 83.43, 32.54, and 78.07 W m−2, respectively. The method presented here has potential applications in research focused on energy balance, ET estimation, and weather prediction for regions with similar physiographic features to those of the Nile basin.
Eyale Bayable Tegegne; Yaoming Ma; Xuelong Chen; Weiqiang Ma; Bingbing Wang; Zhangwei Ding; Zhikun Zhu. Estimation of the distribution of the total net radiative flux from satellite and automatic weather station data in the Upper Blue Nile basin, Ethiopia. Theoretical and Applied Climatology 2020, 143, 587 -602.
AMA StyleEyale Bayable Tegegne, Yaoming Ma, Xuelong Chen, Weiqiang Ma, Bingbing Wang, Zhangwei Ding, Zhikun Zhu. Estimation of the distribution of the total net radiative flux from satellite and automatic weather station data in the Upper Blue Nile basin, Ethiopia. Theoretical and Applied Climatology. 2020; 143 (1-2):587-602.
Chicago/Turabian StyleEyale Bayable Tegegne; Yaoming Ma; Xuelong Chen; Weiqiang Ma; Bingbing Wang; Zhangwei Ding; Zhikun Zhu. 2020. "Estimation of the distribution of the total net radiative flux from satellite and automatic weather station data in the Upper Blue Nile basin, Ethiopia." Theoretical and Applied Climatology 143, no. 1-2: 587-602.
In contrast to widespread glacier retreat evidenced globally, glaciers in the Karakoram region have exhibited positive mass balances and general glacier stability over the past decade. Snow and glacier meltwater from the Karakoram and the western Himalayas, which supplies the Indus River Basin, provide an essential source of water to more than 215 million people, either directly, as potable water, or indirectly, through hydroelectric generation and irrigation for crops. This study focuses on water resources in the Upper Indus Basin (UIB) which combines the ranges of the Hindukush, Karakoram and Himalaya (HKH). Specifically, we focus on the Gilgit River Basin (GRB) to inform more sustainable water use policy at the sub-basin scale. We employ two degree-day approaches, the Spatial Processes in Hydrology (SPHY) and Snowmelt Runoff Model (SRM), to simulate runoff in the GRB during 2001–2012. The performance of SRM was poor during July and August, the period when glacier melt contribution typically dominates runoff. Consequently, SPHY outperformed SRM, likely attributable to SPHY’s ability to discriminate between glacier, snow, and rainfall contributions to runoff during the ablation period. The average simulated runoff revealed the prevalent snowmelt contribution as 62%, followed by the glacier melt 28% and rainfall 10% in GRB. We also assessed the potential impact of climate change on future water resources, based on two Representative Concentration Pathways (RCP) (RCP 4.5 and RCP 8.5). We estimate that summer flows are projected to increase by between 5.6% and 19.8% due to increased temperatures of between 0.7 and 2.6 °C over the period 2039–2070. If realized, increased summer flows in the region could prove beneficial for a range of sectors, but only over the short to medium term and if not associated with extreme events. Long-term projections indicate declining water resources in the region in terms of snow and glacier melt.
Yasir Latif; Yaoming Ma; Weiqiang Ma; Sher Muhammad; Muhammad Adnan; Muhammad Yaseen; Rowan Fealy. Differentiating Snow and Glacier Melt Contribution to Runoff in the Gilgit River Basin via Degree-Day Modelling Approach. Atmosphere 2020, 11, 1023 .
AMA StyleYasir Latif, Yaoming Ma, Weiqiang Ma, Sher Muhammad, Muhammad Adnan, Muhammad Yaseen, Rowan Fealy. Differentiating Snow and Glacier Melt Contribution to Runoff in the Gilgit River Basin via Degree-Day Modelling Approach. Atmosphere. 2020; 11 (10):1023.
Chicago/Turabian StyleYasir Latif; Yaoming Ma; Weiqiang Ma; Sher Muhammad; Muhammad Adnan; Muhammad Yaseen; Rowan Fealy. 2020. "Differentiating Snow and Glacier Melt Contribution to Runoff in the Gilgit River Basin via Degree-Day Modelling Approach." Atmosphere 11, no. 10: 1023.
Lake evaporation can influence basin-wide hydrological cycles and is an important factor in loss of water resources in endorheic lakes of the Tibetan Plateau. Because of the scarcity of data, published lake evaporation values are inconsistent, and their spatial distribution has never been reported. Presenting a plausible hypothesis of energy balance during the ice-free seasons, we explored the multiyear (2003–2016) average ice phenology and evaporation amounts of 75 large dimictic lakes by using a combination of meteorological and satellite data. Evaporation amounts show large variability in spatial distribution, with a pattern of higher values in the south. Lakes with higher elevation, smaller area, and higher latitude are generally associated with a shorter ice-free season and lower evaporation. The total evaporated water amounts have values of approximately 29.4 ± 1.2 km3 year−1 for the 75 studied lakes and 51.7 ± 2.1 km3 year−1 for all plateau lakes included.
Binbin Wang; Yaoming Ma; Zhongbo Su; Yan Wang; Weiqiang Ma. Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau. Science Advances 2020, 6, eaay8558 .
AMA StyleBinbin Wang, Yaoming Ma, Zhongbo Su, Yan Wang, Weiqiang Ma. Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau. Science Advances. 2020; 6 (26):eaay8558.
Chicago/Turabian StyleBinbin Wang; Yaoming Ma; Zhongbo Su; Yan Wang; Weiqiang Ma. 2020. "Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau." Science Advances 6, no. 26: eaay8558.
Alpine meadow is one of the most widely distributed vegetation types on the Tibetan Plateau—the Earth’s Third Pole. Characterizing the carbon and water vapor fluxes in alpine meadow ecosystems is of particular importance for elucidating the mechanisms underlying the carbon budget and water cycle in high-altitude areas, especially under changing climatic conditions. Thus, the quantitative relationships between carbon and water fluxes and environmental drivers were examined based on a continuous eddy covariance (EC) dataset from 2013 to 2015 over the alpine Kobresia meadow on the northeastern Tibetan Plateau. The results show that (1) the net ecosystem CO2 exchange (NEE) was − 152.89 g C m−2 year−1, − 197.69 g C m−2 year−1, and − 160.09 g C m−2 year−1 from 2013 to 2015, respectively, suggesting that this alpine meadow ecosystem is a strong and consistent carbon sink. (2) Both the multiple stepwise regression analysis (MSRA) and the structural equation model (SEM) analysis confirmed the dominant role of Ts in controlling the carbon flux and that of Rn in controlling the water vapor flux. (3) The inherent water use efficiency (IWUE = GPP×VPD/ET) and underlying water use efficiency (uWUE = GPP×VPD0.5/ET), which incorporates the vapor pressure deficit (VPD) effect, better described the carbon-water coupling characteristics at daily and hourly scales than did the traditional water use efficiency (WUE = GPP/ET). These findings highlight the dominant climatic factors controlling CO2 and water vapor exchanges and contribute to our knowledge of the land surface-atmosphere exchange in alpine meadows on the Tibetan Plateau.
Yuyang Wang; Yaoming Ma; Haixia Li; Ling Yuan. Carbon and water fluxes and their coupling in an alpine meadow ecosystem on the northeastern Tibetan Plateau. Theoretical and Applied Climatology 2020, 142, 1 -18.
AMA StyleYuyang Wang, Yaoming Ma, Haixia Li, Ling Yuan. Carbon and water fluxes and their coupling in an alpine meadow ecosystem on the northeastern Tibetan Plateau. Theoretical and Applied Climatology. 2020; 142 (1-2):1-18.
Chicago/Turabian StyleYuyang Wang; Yaoming Ma; Haixia Li; Ling Yuan. 2020. "Carbon and water fluxes and their coupling in an alpine meadow ecosystem on the northeastern Tibetan Plateau." Theoretical and Applied Climatology 142, no. 1-2: 1-18.
While a number of machine learning (ML) models have been used to estimate RE, systematic evaluation and comparison of these models are still limited. In this study, we developed three traditional ML models and a deep learning (DL) model, stacked autoencoders (SAE), to estimate RE in northern China’s grasslands. The four models were trained with two strategies: training for all of northern China’s grasslands and separate training for the alpine and temperate grasslands. Our results showed that all four ML models estimated RE in northern China’s grasslands fairly well, while the SAE model performed best (R2 = 0.858, RMSE = 0.472 gC m−2 d−1, MAE = 0.304 gC m−2 d−1). Models trained with the two strategies had almost identical performances. The enhanced vegetation index and soil organic carbon density (SOCD) were the two most important environmental variables for estimating RE in the grasslands of northern China. Air temperature (Ta) was more important than the growing season land surface water index (LSWI) in the alpine grasslands, while the LSWI was more important than Ta in the temperate grasslands. These findings may promote the application of DL models and the inclusion of SOCD for RE estimates with increased accuracy.
Xiaobo Zhu; Honglin He; Mingguo Ma; Xiaoli Ren; Li Zhang; Fawei Zhang; Yingnian Li; Peili Shi; Shiping Chen; Yanfen Wang; Xiaoping Xin; Yaoming Ma; Yu Zhang; Mingyuan Du; Rong Ge; Na Zeng; Pan Li; Zhongen Niu; Liyun Zhang; Yan Lv; Zengjing Song; Qing Gu. Estimating Ecosystem Respiration in the Grasslands of Northern China Using Machine Learning: Model Evaluation and Comparison. Sustainability 2020, 12, 2099 .
AMA StyleXiaobo Zhu, Honglin He, Mingguo Ma, Xiaoli Ren, Li Zhang, Fawei Zhang, Yingnian Li, Peili Shi, Shiping Chen, Yanfen Wang, Xiaoping Xin, Yaoming Ma, Yu Zhang, Mingyuan Du, Rong Ge, Na Zeng, Pan Li, Zhongen Niu, Liyun Zhang, Yan Lv, Zengjing Song, Qing Gu. Estimating Ecosystem Respiration in the Grasslands of Northern China Using Machine Learning: Model Evaluation and Comparison. Sustainability. 2020; 12 (5):2099.
Chicago/Turabian StyleXiaobo Zhu; Honglin He; Mingguo Ma; Xiaoli Ren; Li Zhang; Fawei Zhang; Yingnian Li; Peili Shi; Shiping Chen; Yanfen Wang; Xiaoping Xin; Yaoming Ma; Yu Zhang; Mingyuan Du; Rong Ge; Na Zeng; Pan Li; Zhongen Niu; Liyun Zhang; Yan Lv; Zengjing Song; Qing Gu. 2020. "Estimating Ecosystem Respiration in the Grasslands of Northern China Using Machine Learning: Model Evaluation and Comparison." Sustainability 12, no. 5: 2099.
In this study, a decade long measurement of aerosol optical properties at two AERONET stations (Nam Co during 2006‐2016 and QOMS during 2009‐2017) in the Tibetan Plateau (TP), a region sensitive to climate change and human perturbation are presented. The baseline value of aerosol optical depth (AOD) was 0.029 and 0.027 at Nam Co and QOMS, respectively, which are comparable to or even lower than those at some Arctic and remote ocean locations. The seasonality of AOD values were the order of spring > summer > winter > autumn. Based on AOD and Angstrom Exponent (α), major aerosol types over the TP were further identified as continental background, biomass burning and dust. Although continental background aerosol was the main feature in remote areas of TP, biomass burning plumes frequently occurred, especially during spring (March‐April). In one of such biomass burning event in April 2014, MODIS observations demonstrated that intensive open fires occurred in South Asia, covering the foothills of Himalayas and Indo‐Gangetic Plain. The air mass back trajectories and CALIOP observations further revealed that biomass burning plume could be uplifted to higher altitudes and reach the Himalayas. Moreover, an occasional dust event detected in April 2008 over the TP, demonstrated that the dust from Taklamakan Desert may impact the main body of TP episodically, although the local dust from the inside of TP cannot be excluded and warrants further study.
Manisha Pokharel; Jie Guang; Bin Liu; Shichang Kang; Yaoming Ma; Brent N. Holben; Xiang'ao Xia; Jinyuan Xin; Kirpa Ram; Dipesh Rupakheti; Xin Wan; Guangming Wu; Hemraj Bhattarai; Chuanfeng Zhao; Zhiyuan Cong. Aerosol Properties Over Tibetan Plateau From a Decade of AERONET Measurements: Baseline, Types, and Influencing Factors. Journal of Geophysical Research: Atmospheres 2019, 124, 13357 -13374.
AMA StyleManisha Pokharel, Jie Guang, Bin Liu, Shichang Kang, Yaoming Ma, Brent N. Holben, Xiang'ao Xia, Jinyuan Xin, Kirpa Ram, Dipesh Rupakheti, Xin Wan, Guangming Wu, Hemraj Bhattarai, Chuanfeng Zhao, Zhiyuan Cong. Aerosol Properties Over Tibetan Plateau From a Decade of AERONET Measurements: Baseline, Types, and Influencing Factors. Journal of Geophysical Research: Atmospheres. 2019; 124 (23):13357-13374.
Chicago/Turabian StyleManisha Pokharel; Jie Guang; Bin Liu; Shichang Kang; Yaoming Ma; Brent N. Holben; Xiang'ao Xia; Jinyuan Xin; Kirpa Ram; Dipesh Rupakheti; Xin Wan; Guangming Wu; Hemraj Bhattarai; Chuanfeng Zhao; Zhiyuan Cong. 2019. "Aerosol Properties Over Tibetan Plateau From a Decade of AERONET Measurements: Baseline, Types, and Influencing Factors." Journal of Geophysical Research: Atmospheres 124, no. 23: 13357-13374.
Land surface heat fluxes consist of the net radiation flux, soil heat flux, sensible heat flux, and latent heat flux. The estimation of these fluxes is essential to the study of energy transfer in land–atmosphere systems. In this paper, Landsat 7 ETM+ SLC-on data were applied to estimate the land surface heat fluxes on the northern Tibetan Plateau using the SEBS (surface energy balance system) model, in combination with the calculation of field measurements at CAMP/Tibet (Coordinated Enhanced Observing Period (CEOP) Asia–Australia Monsoon Project on the Tibetan Plateau) automatic weather stations based on the combinatory method (CM) for comparison. The root mean square errors between the satellite estimations and the CM calculations for the net radiation flux, soil heat flux, sensible heat flux, and latent heat flux were 49.2 W/m2, 46.3 W/m2, 68.2 W/m2, and 54.9 W/m2, respectively. The results reveal that land surface heat fluxes all present significant seasonal variability. Apart from the sensible heat flux, the satellite-estimated net radiation flux, soil heat flux, and latent heat flux exhibited a trend of summer > spring > autumn > winter. In summer, spring, autumn, and winter, respectively, the median values of the net radiation flux (631.8 W/m2, 583.0 W/m2, 404.4 W/m2, 314.3 W/m2), soil heat flux (40.9 W/m2, 37.9 W/m2, 26.1 W/m2, 20.5 W/m2), sensible heat flux (252.7 W/m2, 219.5 W/m2, 221.4 W/m2, 204.8 W/m2), and latent heat flux (320.1 W/m2, 298.3 W/m2, 142.3 W/m2, 75.5 W/m2) exhibited distinct seasonal diversity. From November to April, the in situ sensible heat flux is higher than the latent heat flux; the opposite is true between June and September, leaving May and October as transitional months. For water bodies, alpine meadows and other main underlying surface types, sensible and latent heat flux generally present contrasting and complementary spatial distributions. Due to the 15–60 m resolution of the Landsat 7 ETM+ data, the distribution of land surface heat fluxes can be used as an indicator of complex underlying surface types over the northern Tibetan Plateau.
Nan Ge; Lei Zhong; Yaoming Ma; Meilin Cheng; Xian Wang; Mijun Zou; Ziyu Huang. Estimation of Land Surface Heat Fluxes Based on Landsat 7 ETM+ Data and Field Measurements over the Northern Tibetan Plateau. Remote Sensing 2019, 11, 2899 .
AMA StyleNan Ge, Lei Zhong, Yaoming Ma, Meilin Cheng, Xian Wang, Mijun Zou, Ziyu Huang. Estimation of Land Surface Heat Fluxes Based on Landsat 7 ETM+ Data and Field Measurements over the Northern Tibetan Plateau. Remote Sensing. 2019; 11 (24):2899.
Chicago/Turabian StyleNan Ge; Lei Zhong; Yaoming Ma; Meilin Cheng; Xian Wang; Mijun Zou; Ziyu Huang. 2019. "Estimation of Land Surface Heat Fluxes Based on Landsat 7 ETM+ Data and Field Measurements over the Northern Tibetan Plateau." Remote Sensing 11, no. 24: 2899.