Liu Shaomin

Beijing Normal University | bnu · Faculty of Geographical Science

Oases and deserts generally act as a landscape matrix and mosaic in arid and semiarid regions. The significant difference in thermal and dynamic characteristics between an oasis and desert surface will result in oasis–desert interaction. Specifically, this refers to the interaction between an oasis and desert system via the exchange of momentum, en...

Soil moisture (SM) and soil freeze/thaw (FT) are two relatively active surface parameters that are significant to the sustainable development of the water-land-air-plant-human nexus. Over time, regional or global SM and FT datasets with different spatial resolutions have been developed. In response to the requirements of multiscale product validati...

The uncertainty of ground truth values at the pixel scale obtained via upscaling directly affects the credibility of remote sensing product validation. This paper provides an in-depth analysis of the sources of uncertainty in ground truth evapotranspiration (ET) at the pixel scale. This uncertainty is quantitatively evaluated, and the methods for i...

The inhibition of foliar respiration by light is a crucial yet often overlooked component in estimating ecosystem respiration. However, current estimations of the light inhibition of ecosystem respiration are biased by ignoring the effects of moisture factors. We developed a novel physics‐constrained machine learning method to quantify the extent o...

Soil moisture (SM) is intricately connected to various components of the Earth's system and plays a critical role in human survival and development. Although significant efforts have been made in soil moisture retrieval and validation, the monitoring and assessment of high-precision, high-resolution SM networks remain limited. This study focuses on...

The eddy covariance (EC) technique is currently the most widely used method for measuring carbon exchange between terrestrial ecosystems and the atmosphere at the ecosystem scale. Using this technique, a regional carbon flux network comprising a total of 34 sites has been established in the Heihe River Basin (HRB) in Northwest China. This network h...

Study region: Heihe River Basin (HRB), Northwest China. Study focus: The study proposes an analytical scheme to identify trend, periodicity, and scale-correlation in climate, water, land, and vegetation resources over the past four decades using multivariate remote sensing data. New hydrological insights for the region: Heat and precipitation resou...

As a key component of the water cycle, evapotranspiration (ET) plays a critical role in agricultural management and climate prediction. While numerous long-term observation sites have been established in Europe and North America (data-rich regions), fewer short-term observation sites exist in South America and, particularly, in Africa (data-poor re...

Terrestrial water storage anomaly (TWSA) and groundwater storage anomaly (GWSA) data are of great importance for hydrological research and water resource management. However, products derived from the Gravity Recovery and Climate Experiment (GRACE) mission and its Follow-On mission (GRACE-FO) are constrained by the satellite design and variation in...

The climate of the Tibetan Plateau (TP) has experienced substantial changes in recent decades as a result of the location's susceptibility to global climate change. The changes observed across the TP are closely associated with regional land–atmosphere interactions. Current models and satellites struggle to accurately depict the interactions; there...

The soil freeze/thaw (FT) state has emerged as a critical role in the ecosystem, hydrological, and biogeochemical processes, but obtaining representative soil FT state datasets with a long time sequence, fine spatial resolution, and high accuracy remains challenging. Therefore, we propose a decision-level spatiotemporal data fusion algorithm based...

The Bowen ratio (β), which is the ratio of sensible heat (H) to latent heat (LE), reflects the energy balance and partitioning processes among soil, vegetation, and the atmosphere. Although the spatial patterns of β have been clearly delineated, the importance of vegetation in the spatial variation of β is frequently underestimated. Revealing the s...

Temperate grassland (TG) and alpine grassland (AG) are two distinct grassland types with different climatic backgrounds and adaptation patterns. Little is known about the universal and divergent responses of TGs and AGs to climate change, particularly with regard to the carbon (C) fluxes. The large-scale responses of the C fluxes in different grass...

Spatio-temporally continuous daily evapotranspiration (ET) is essential for characterizing water and energy exchange and scheduling efficient water management. ET has conventionally been generated using thermal infrared-based models, cloud contamination of satellite data could prohibit accurate estimates of spatial continuous daily ET. Although app...

Instrumentation packages for eddy covariance (EC) measurements have been developed for unoccupied aerial vehicles (UAVs) to measure the turbulent fluxes of latent heat (LE), sensible heat (H), and CO2 (Fc) in the atmospheric boundary layer. This study aims to evaluate the performance of this UAV-based EC system. First, the measurement precision (1σ...

The oasis-desert ecosystem is a unique landscape in arid/semi-arid regions, and the observation and research of its water vapor, heat, and carbon fluxes are of great significance to the stability and sustainable development of oases. This study focuses on the oasis-desert area of Zhangye City, Gansu Province, in the middle reaches of the Heihe Rive...

A thermal infrared (TIR) imager mounted on an unmanned aerial vehicle (UAV) has been widely used to obtain land surface temperature (LST) at very high-spatial resolutions. The TIR images are valuable for various applications, including mapping fine-scale surface evapotranspiration and monitoring crop water stress. However, UAV-borne uncooled TIR im...

High spatial resolution maps of evapotranspiration (ET) for precision agricultural irrigation, water resource management are increasingly important in the context of climate change. Here, we conducted extensive un-manned aerial vehicle (UAV) experiments in oasis-desert areas with three 2 km × 1 km regions during two growing seasons. The spatially d...

Obtaining in-situ land surface temperature (LST) with thermal infrared or longwave radiometers for validating satellite LST, namely the radiation-based method, is one of the most widely used approaches. Due to the rela­ tively short path lengths, the near-surface atmosphere contribution is generally ignored in radiation-based in-situ LST measuring...

The annual gross primary productivity (AGPP) is the basis of food production and carbon sequestration in terrestrial ecosystems. An accurate assessment of regional AGPP can provide a theoretical basis for analyzing the spatiotemporal variation of AGPP and ensuring regional food security and mitigating climate change trends. Based on Chinese Flux Ob...

Oases and deserts generally act as a landscape matrix and mosaic in arid/semiarid regions. The significant difference of thermal and dynamic characteristics between oasis and desert surface will result in oasis-desert interaction. That is, the interaction between oasis and desert system through the exchange of momentum, energy, water and carbon, wh...

The two-source energy balance model coupled with soil moisture (TSEB-SM) was evaluated against observations from a global set of 57 eddy covariance (EC) sites, part of the FLUXNET2015 dataset. In addition, modeled soil evaporation (E) and transpiration (T) were compared with the values obtained from the Transpiration Estimation Algorithm (TEA) and...

The energy and water vapor exchange between the land surface and atmospheric boundary layer plays a critical role in regional climate simulations. This paper implemented a hybrid data assimilation and machine learning framework (DA-ML method) into the Weather Research and Forecasting (WRF) model to optimize surface soil and vegetation conditions. T...

Accurately estimating the temperature sensitivity (Q 10) of ecosystem respiration (R e) is essential for understanding the climate-carbon cycle feedback in endorheic river basins. Singular spectrum analysis is considered to be an effective approach to estimate intrinsic (unconfounded) Q 10. However, its accuracy in minimizing confounding factors re...

Latent heat flux (LE) plays an essential role in the hydrological cycle, surface energy balance, and climate change, but the spatial resolution of site-scale LE extremely limits its application potential over a regional scale. To overcome the limitation, five transfer learning models were constructed based on artificial neural networks (ANNs), rand...

The eddy-covariance (EC) method has been widely used to measure sensible (H) and latent (LE) heat fluxes, however, it has limited spatial representativeness (hundreds of meters' scale). Optical-microwave scintillometers (OMS) can directly measure kilometer-scale H and LE, which can be used to validate satellite remote sensing products and model sim...

The crop coefficient is a key link between crop evapotranspiration (ETc) and reference evapotranspiration (ET0), which is important for agricultural water management and irrigation strategy. However, how to quantify seasonal variations in the single and dual crop coefficients (Kc and Kcb, respectively) remains a challenge. This study aimed to provi...

Quantifying and monitoring land surface evapotranspiration (ET) is an essential task for understanding the earth’s water, energy and carbon cycles. ET, specifically plant transpiration ( T ) is closely linked to the photosynthesis which is coupled through stomatal function. However, the mechanistic links between Sun-induced chlorophyll fluorescenc...

High spatial resolution maps of evapotranspiration (ET) for precision agricultural irrigation, water resource management are increasingly important in the context of climate change. Here, we conducted extensive un-manned aerial vehicle (UAV) experiments in oasis-desert areas with three 2 km × 1 km regions during two growing seasons. The spatially d...

The energy and moisture exchange between the land surface and atmospheric boundary layer plays a critical role in regional climate simulations. This paper implemented a hybrid data assimilation and machine learning framework (DA-ML method) into the Weather Research and Forecasting (WRF) model to optimize surface soil and vegetation conditions. The...

Accurate estimation of regional and global patterns of ecosystem respiration (ER) is crucial to improve the understanding of terrestrial carbon cycles and the predictive ability of the global carbon budget. However, large uncertainties still exist in regional and global ER estimation due to the drawbacks of modeling methods. Based on eddy covarianc...

Seasonal soil freeze/thaw (FT) state transition plays a critical role in the range of ecosystem, hydrological and biogeochemical processes. A thorough and large-scale validation of remote-sensed or model-based FT products is therefore quite important. Previous validation studies have applied categorical triple collocation (CTC) as a cross-validatio...

Watersheds are the basic unit of Earth's terrestrial systems and are therefore ideal units for the study of critical zones (CZs). However, grand challenges remain regarding the observation, modeling, and management of CZs and watershed systems. We synthesize the progress and breakthroughs associated with watershed science and CZ research in the Hei...

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuri...

Automatic registration of unmanned aerial vehicle (UAV) thermal infrared and visible (TIR&V) images is fundamental for subsequent applications. However, few studies address this issue due to significant radiation gap, shape gap, and texture gap among TIR&V images. The area-based methods are not able to satisfy the accuracy and robustness of locatio...

Evapotranspiration (ET) is a critical component of the water, carbon and energy cycles of the land surface. Remote sensing-based models provide the possibility of mapping ET from field to regional and even global scales. A key boundary condition of the Two-Source Energy Balance (TSEB) model for computing ET is land surface temperature (LST). The pr...

Land surface temperature (LST) derived from satellite thermal infrared (TIR) remote sensing is widely used in estimating land surface evapotranspiration (ET) through energy balance theory. However, as satellite TIR remote sensing is frequently affected by clouds, the derived LST with spatial missing makes it impossible to estimate seamless ET for l...

Validation of remotely sensed evapotranspiration (RS_ET) products is important because their accuracy is critical for various scientific applications. In this study, an integrated validation framework was proposed for evaluating RS_ET products with coarse spatial resolution extending from homogenous to heterogeneous land surfaces. This framework wa...

Soil moisture (SM) is an important land-surface parameter. Although microwave remote sensing is recognized as one of the most appropriate methods for retrieving SM, such retrievals often cannot meet the requirements of specific applications because of their coarse spatial resolution and spatiotemporal data gaps. A range of general models (GMs) for...

The two-source energy balance (TSEB) model using the land surface temperature (LST) as a key boundary has been used to estimate land surface evapotranspiration (ET) over various landcovers and environmental conditions. However, LST may not always provide an adequate boundary condition to simultaneously constrain the soil evaporation and plant trans...

Alpine grassland is the main ecosystem of the Tibetan Plateau (TP), thus accurate simulation of water and heat exchange in the grassland will significantly enhance the understanding of the land-atmosphere interaction process on the TP. In this study, we assessed and improved the ensemble numerical simulations of the community Noah land surface mode...

Accurate estimation of evapotranspiration (ET) is essential for understanding terrestrial energy, water, andcarbon cycles. This study proposes a hybrid model integrating in-situ and remote sensing-derived soil moisture(SM) observations and remote sensing leaf area index (LAI) with the Noah-MP model. The ensemble Kalman filter (EnKF) approach update...

Satellite-based models have tremendous potential for monitoring crop production because satellite data can provide temporally and spatially continuous crop growth information at large scale. This study used a satellite-based vegetation production model (i.e., eddy covariance light use efficiency, EC-LUE) to estimate national winter wheat gross prim...

In this study, land surface temperature (LST) and leaf area index (LAI) observations are merged with a coupled two-source surface energy budget–vegetation dynamic model (TSEB–VDM) via a variational data assimilation (VDA) system to predict turbulent heat fluxes and gross primary productivity (GPP). The TSEB and VDM are coupled by relating photosynt...

A reliable accuracy is essential for the application of land surface temperature (LST) products. Current satellite retrieved LSTs are mainly validated over a few homogeneous sites. However, most of the existing ground sites are located in inhomogeneous areas: thus, their spatial representativeness on satellite pixel scales is unknown. In this situa...

It is of great significance for the validation of remotely sensed evapotranspiration (ET) products to solve the spatial-scale mismatch between site observations and remote sensing estimations. To overcome this challenge, this paper proposes a comprehensive framework for obtaining the ground truth ET at the satellite pixel scale (1 × 1 km resolution...

Here, four normalized difference water index (NDWI) variants, i.e., NDWI(860,970), NDWI(860,1240), NDWI(860,1640), and NDWI(1240,1640) are generated from the corn-oriented PROSAIL radiative transfer model. It is found that, instead of the linear relationship derived in previous studies, corn canopy water content (CWC) is best approximated as an exp...

Automatically registration of unmanned aerial vehicle (UAV) multispectral images is fundamental for subsequent applications. Although many studies exist for visible camera images and satellite multispectral image registration, studies for UAV are still rare. Under this context, this study firstly evaluates the performance of several widely used tra...

Accurate estimates of the spatiotemporal distribution of evapotranspiration (ET) are essential for understanding terrestrial energy, carbon and water cycles. Station-based observations are limited for their spatial coverage whereas satellite-derived ET products exhibit large discrepancies and uncertainties. Here we presented a Deep Neural Networks...

Vegetative windbreaks play an important role in reducing soil erosion and sand storms, which are widely applied in arid/semiarid regions. An optimal design of vegetative windbreaks is essential in aeolian engineering practice. In this study, three‐dimensional airflows around multiple arrangements of vegetative windbreaks were simulated using a modi...

The unavailability of thermal infrared satellite observations in cloudy conditions has limited the spatial distribution and temporal coverage of remotely sensed evapotranspiration (ET) data. As a result, a number of approaches have been developed to reconstruct remotely sensed daily ET data in cloudy-sky conditions. Despite the wide application of...

Unmanned aerial vehicle (UAV) thermal infrared (TIR) remote sensing is an important way to obtain land surface temperature (LST) with high spatial and temporal resolutions. Due to wide spectral response function (SRF) ranges of UAV thermal imagers, currently available LST retrieval methods suitable for satellite sensors may induce significant uncer...

The interactions between crops and the atmosphere significantly impact surface energy and hydrology budgets, climate, crop yield, and agricultural management. In this study, a multipass land data assimilation scheme (MLDAS) is proposed based on the Noah‐MP‐Crop model. The ensemble Kalman filter (EnKF) method is used to jointly assimilate the leaf a...

Partitioning of evapotranspiration (ET) into evaporation (E) and transpiration (T) is challenging but important to better understand the mechanisms of water loss from the ground surface to the atmosphere, especially in semiarid and arid regions. In this study, the underlying water use efficiency (uWUE) method is compared with hydrometric and remote...

The accurate estimation of the temperature sensitivity of ecosystem respiration (Q10) is important to understanding the terrestrial ecosystem carbon cycle, especially in northern high‐latitude regions (NHLs). Q10 estimated by the conventional approach at the annual scale is influenced by seasonal confounding effects. Based on singular spectrum anal...

Chinese download link: https://data.tpdc.ac.cn/zh-hans/data/118dfdff-c07d-449a-8947-8a2a19d768b0/ English download link: https://data.tpdc.ac.cn/en/data/118dfdff-c07d-449a-8947-8a2a19d768b0/ Cite as: MA Yanfei, LIU Shaomin. High-Temporal and Landsat-Like surface evapotranspiration in Heihe River Basin (2010-2016) (HiTLL ET V1.0). National Tibetan...

Drought, a natural hydrometeorological phenomenon, has been more frequent and more widespread due to climate change. Water availability strongly regulates the coupling (or trade-off) between carbon uptake via photosynthesis and water loss through transpiration, known as water-use efficiency (WUE). Understanding the effects of drought on WUE across...

Soil moisture (SM) is a fundamental environmental variable for characterizing climate, land surface and atmosphere. In recent years, several SM products have been developed based on remote sensing (RS), land surface model (LSM) or land data assimilation system (LDAS). However, little knowledge is available in understanding spatial patterns of the u...

Successfully applied in the carbon research area, sun-induced chlorophyll fluorescence (SIF) has raised the interest of researchers from the water research domain. However, current works focused on the empirical relationship between SIF and plant transpiration (T), while the mechanistic linkage between them has not been fully explored. Two mechanis...