Hongjie Xie

The University of Texas at San Antonio | UTSA · Department of Geological Sciences

In the summer of 2010, atmosphere–ice–ocean interaction was studied aboard the icebreaker R/V Xuelong during the Chinese National Arctic Research Expedition (CHINARE), in the sea ice zone of the Pacific Arctic sector between 150° W and 180° W up to 88.5° N. The expedition lasted from 21 July to 28 August and comprised of ice observations and measur...

Sea ice thicknesses derived from NASA's Ice, Cloud, and Land Elevation Satellite (ICESat) altimetry data are examined using two different approaches, buoyancy and empirical equations, and at two spatial scales—ICESat footprint size (70 m diameter spot) and Advanced Microwave Scanning Radiometer (AMSR-E) pixel size (12.5 km by 12.5 km) for the Belli...

In this study, ICESat altimetry data are used to provide precise lake elevations of the Tibetan Plateau (TP) during the period of 2003–2009. Among the 261 lakes examined ICESat data are available on 111 lakes: 74 lakes with ICESat footprints for 4–7years and 37 lakes with footprints for 1–3years. This is the first time that precise lake elevation d...

Atmospheric circulation has significant impacts on sea ice drifting patterns and mass balance, as wind drag induces pressure ridges and leads on the sea ice surface. In this study, the spatiotemporal distributions of these dynamic sea ice deformation features in the Ross Sea are examined using ICESat‐2 (IS2) ATL10 freeboard data (2019–2022). The te...

Monitoring Antarctic icebergs helps us understand the interaction between ocean, atmosphere, and sea ice in the Southern Ocean. Although gigantic icebergs have been the objects of many remote sensing studies, medium icebergs in the Southern Ocean have been rarely monitored or traced. In this study, we develop an iceberg detection and tracking tool...

The ICESat-2 (IS2) ATL07 sea ice height product provides precise and accurate measurements of sea ice height for the polar regions. Although the original ATL07 product classifies the sea ice surface into snow-covered ice and open water (dark leads and specular leads), it has two critical issues: (1) it does not distinguish thin ice (gray ice) from...

Global warming is an urgent issue that is generating catastrophic environmental changes, such as the melting of sea ice and glaciers, particularly in the polar regions. The melting pattern and retreat of polar sea ice cover is an essential indicator of global warming. The Sentinel-2 satellite (S2) captures high-resolution optical imagery over the p...

Geoscience is now facing the huge potential enabled by the cyberinfrastructure, sensor network, big data, cloud computing, and data science. In this new era, what skills should geoscientists know and what actions can they take to foster new research topics? Are there already successful stories of data science in geosciences and what are the experie...

Accelerated extratropical glacier retreat of the last decades in the Andean region seems to be a response to atmospheric warming and associated disruption in precipitation patterns, retreat of glaciers poses a major threat to water resources availability as well as a potential geohazard risk, therefore, glacier status tracking is highly important....

Accelerated extratropical glacier retreat of the last decades in the Andean region seems to be a response to atmospheric warming and represents a major climate challenge, Nowadays we are able to monitor volume change by computing and analyzing glacier geodetic mass balance. In this study, we focus on the Sierra del Brujo (34°30’S) in Central Chile,...

The fine spatial resolution of the ICESat-2 (IS2) satellite altimeter allows monitoring the evolution of sea ice thickness with detailed dynamic information (e.g. ridges and leads). In this study, we first assess the ability of IS2 to estimate thermodynamic ice growth and dynamic thickening during the ice-growing season in the central Arctic Ocean....

Plain Language Summary Sea ice variations can reflect global climate change since sea ice has a very strong cyclical process of growing/expanding and melting/shrinking when the seasons change. Sea ice elevation has been monitored by satellite‐borne laser altimetry, namely Ice, Cloud and Land Elevation Satellite‐2 (ICESat) (2003–2009) and ICESat‐2 (...

Sentinel-1 C-band synthetic aperture radar (SAR) images can be used to observe the drift of icebergs over the Southern Ocean with around 1–3 d of temporal resolution and 10–40 m of spatial resolution. The Google Earth Engine (GEE) cloud-based platform allows processing of a large quantity of Sentinel-1 images, saving time and computational resource...

NASA’s ICESat-2 has been providing sea ice freeboard measurements across the polar regions since October 2018. In spite of the outstanding spatial resolution and precision of ICESat-2, the spatial sparsity of the data can be a critical issue for sea ice monitoring. This study employs a geostatistical approach (i.e., ordinary kriging) to characteriz...

Sentinel-1 C-band synthetic aperture radar (SAR) images can be used to observe the drift of icebergs over the Southern Ocean with around 1–3 days of temporal resolution and 10–40 m of spatial resolution. The Google Earth Engine (GEE) cloud-based platform allows processing of a large quantity of Sentinel-1 images, saving time and computational resou...

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Geohazards associated with the dynamics of the liquid and solid water of the Earth’s hydrosphere, such as floods and glacial processes, may pose significant risks to populations, activities and properties [...]

The measurement of sea ice elevation above sea level or the “freeboard” depends upon an accurate retrieval of the local sea level. The local sea level has been previously retrieved from altimetry data alone by the lowest elevation method, where the percentage of the lowest elevations over a particular segment length scale was used. Here, we provide...

As part of the Polynyas and Ice Production in the Ross Sea (PIPERS) project, the IcePod system onboard the LC-130 aircraft based at McMurdo Station was flown over the Ross Sea, Antarctica in November 2016 and 2017, with the purpose of repeating the same lines that NASA’s Operation IceBridge (OIB) aircraft flew over in 2013. We resampled the lidar d...

The changing distributions of sea ice thickness in different regions around Antarctica are important metrics of climate variability, but estimates have large uncertainties. Here, we analyze laser altimetry data from ICESat and IceBridge to generate a record of total freeboard and sea ice thickness in the Amundsen‐Bellingshausen and Weddell seas dur...

The surface flooding of Antarctic sea ice in summer covers 50% or more of the sea-ice area in the major summer ice packs, the western Weddell and the Bellingshausen-Amundsen Seas. Two CRREL ice mass-balance buoys were deployed on the Amundsen Sea pack in late December 2010 from the icebreaker Oden, bridging the summer period (January–February 2011)...

The angular and spectral kernel-driven (ASK) model distinguishes soil and vegetation spectral features by the component spectra and is a promising model which combines multisensor data for inversion. However, its global application is limited by the component spectra. This article proposes parameterization of the ASK component spectra of soil and l...

High sea ice production (SIP) generates high-salinity water, thus, influencing the global thermohaline circulation. Estimation from passive microwave data and heat flux models have indicated that the Ross Ice Shelf polynya (RISP) may be the highest SIP region in the Southern Oceans. However, the coarse spatial resolution of passive microwave data l...

The carbon-nitrogen (C:N) ratio plays a crucial role in regulation of the nutrient utilization efficiency and growth rate of plants. However, challenges are faced when hyperspectral data are directly used to estimate the C:N ratio due to the lack of corresponding sensitive feature bands. This study aims to explore the feasibility of using important...

Sea ice acts as both an indicator and an amplifier of climate change. High spatial resolution (HSR) imagery is an important data source in Arctic sea ice research for extracting sea ice physical parameters, and calibrating/validating climate models. HSR images are difficult to process and manage due to their large data volume, heterogeneous data so...

A number of satellite altimeters have been used to measure Arctic sea ice freeboard and to study its changes over the past decades (1992-present). In order to produce long-term time series of sea ice freeboard data set, it is essential to investigate the difference and consistency between different satellite-based sea ice freeboard data sets. Hence...

Since a new laser altimeter of ICESat-2 data was released in 2018, the data have been accumulated for a year. With its improved resolution compared to the previous ICESat mission, it is expected to estimate sea ice properties in polar region more accurately. However, one of the biggest limits of ICESat-2 laser altimeter data is that the photon coun...

NASA's Operation IceBridge mission flew over the Ross Sea, Antarctica (20 and 27 November 2013) and collected data with Airborne Topographic Mapper (ATM) and Digital Mapping System (DMS). Using the DMS and reflectivity of ATM L1B, leads are detected to define local sea level height. The total freeboard is then obtained and converted to ice thicknes...

As a fundamental climate state variable, sea ice thickness (SIT) has exhibited a declining trend over the past five decades. Here, we present a quantitative comparison of three CryoSat-2 (CS-2) SIT products from the Alfred-Wegener-Institute (AWI), the National Snow and Ice Data Centre (NSIDC), and the European Space Agency (ESA) during the growth s...

Test quality of glider mounted AD2CP current observations in the Northwestern Mediterranean (Ligurian) Sea using WMOP currents as a reference

High sea ice production (SIP) causes high-salinity water formation, influencing the global thermohaline circulation. Based on passive microwave data and a heat flux model, the Ross Ice Shelf polynya (RISP) region has been reported as the highest SIP region in the Southern Ocean. However, there are two limitations in previous methods: (1) the coarse...

Plain Language Summary The Tibetan Plateau contains many lakes that are changing in depth and size due to the climate warming that has been particularly rapid in this region. Because of the lack of water level gauges in this remote area, satellites provide the only practical tool of monitoring these lakes' changes. A new altimetry satellite, Ice, C...

In the published article [1], the authors realized some errors in the affiliation and email address of Yang Hong, and thus wish to make the following revisions: Add the Affiliation 5 “School of Civil Engineering and Environmental Science, University of Oklahoma, Norman, OK 73019, USA” for Yang Hong Change the email address of Yang Hong to yanghong@...

Surface soil moisture is a key variable in the exchange of water and energy between the land surface and the atmosphere, and critical to meteorology, hydrology, and ecology. The Tibetan Plateau (TP), known as “The third pole of the world” and “Asia’s water towers”, exerts huge influences on and sensitive to global climates. In this situation, longe...

Accurate and effective modeling of grassland aboveground biomass (AGB) is an important basic task in monitoring and management of grassland and livestock interaction in pastoral areas. In this study, three machine learning methods, multi-layer perceptron network (MLP), support vector regression, and random forest regression (RF) are assessed for mo...

Presents corrections to above named paper.

The applicability of hyperspectral remote sensing models for forage nitrogen (N) retrieval during different growth periods is limited. This study aims to develop a multivariate model feasible for estimating the forage N for the growth periods (June to November) in an alpine grassland ecosystem. The random forest (RF) algorithm is employed to determ...

The availability of lake bathymetry maps is imperative for estimating lake water volumes and their variability, which is a sensitive indicator of climate. It is difficult, if not impossible, to obtain bathymetric measurements from all of the thousands of lakes across the globe due to costly labor and/or harsh topographic regions. In this study, we...

Global water cycle dynamics involve the exchange of water and energy matter among the atmosphere, hydrosphere, geosphere, cryosphere, and biosphere. This Special Issue encompasses a number of contributions in satellite and airborne sensors applications in hydrology and water cycle.

Global horizontal irradiance (i.e., shortwave downward solar radiation received by a horizontal surface on the ground) is an important geophysical variable for climate and energy research. Since solar radiation is attenuated by clouds, its variability is intimately associated with the variability of cloud properties. The spatial distribution of clo...

Lake surface water temperature (LSWT) is of vital importance for hydrological and meteorological studies. The LSWT ground measurements in the Tibetan Plateau (TP) were quite scarce because of its harsh environment. Thermal infrared remote sensing is a reliable way to calculate historical LSWT. In this study, we present the first and longest 35-year...

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

The continuous rise in summer temperature and consequent glacier wastage have led to a significant loss of frozen water resources in the mountain headwaters of the major river systems in Central Asia. High mountain lakes in the headwaters of the Syr Darya River serve as sensitive indicators of climate change in the region. In this study, lakes in t...

Flash flood, one of the most devastating weather-related hazards in the world, has become more and more frequent in past decades. For the purpose of flood mitigation, it is necessary to understand the distribution of flash flood risk. In this study, artificial intelligence (Least squares support vector machine: LSSVM) and classical canonical method...

The accurate and effective retrieval of forage phosphorus (P) content can provide significant information for the management of pastoral agriculture and grazing livestock. In this study, we constructed 39 models to estimate the forage P of alpine grassland in the east of Tibetan Plateau based on hyperspectral remote sensing and multiple factors (to...

Since the main attenuation of solar irradiance reaching the earth’s surface is due to clouds, it has been hypothesized that global horizontal irradiance attenuation and its temporal variability at a given location could be characterized simply by cloud properties at that location. This hypothesis is tested using global horizontal irradiance measure...

Snow cover over the Qinghai-Tibetan Plateau (QTP) plays an important role in climate, hydrological, and ecological systems. Currently, passive microwave remote sensing is the most efficient way to monitor snow depth on global and regional scales; however, it presents a serious overestimation of snow cover over the QTP and has difficulty describing...

Monitoring changes in grassland cover is essential in assessment of grassland health as well as the effects of anthropogenic interventions and global climate change on grassland ecosystems. Remote sensing is an effective approach for providing rapid and dynamic monitoring of vegetation cover over large grassland areas. In this study, four types of...

The Tibetan Plateau (TP) plays a significant role in the Earth's climate system. This letter examines the nighttime lake surface water temperature (LSWT) of 374 lakes (≥10 km² each) over the TP for the past 15 years (2001–2015). An overall warming trend (0.037 °C/year) is found and it is consistent with the warming air temperature (0.036 °C/year) o...

National Oceanography and Atmosphere Administration's Advanced Very High Resolution Radiometer (AVHRR) (1970s–present, ∼1 km) and China's GaoFen-1 (GF-1) image series (2013–present, ∼16 m), can both provide extremely useful information of land use and land cover, due to the long history and, wide scanning width of AVHRR and the high resolution of G...

Water is one of the most critical natural resources that maintain the ecosystem and support people’s daily life. Pressures on water resources and disaster management are rising primarily due to the unequal spatial and temporal distribution of water resources and pollution, and also partially due to our poor knowledge about the distribution of water...

Grassland cover and its temporal changes are key parameters in the estimation and monitoring of ecosystems and their functions, especially via remote sensing. However, the most suitable model for estimating grassland cover and the differences between models has rarely been studied in alpine meadow grasslands. In this study, field measurements of gr...

Climate change and human activities are two key factors that affect grassland ecosystem. Accurately estimating the effects of these two factors on grassland dynamics and understanding the driving forces of the dynamics are important in controlling grassland degradation. In this study, the potential Net Primary productivity (NPPP) and the difference...

The Arctic sea-ice extent has shown a declining trend over the past 30 years. Ice coverage reached historic minima in 2007 and again in 2012. This trend has recently been assessed to be unique over at least the last 1450 years. In the summer of 2010, a very low sea-ice concentration (SIC) appeared at high Arctic latitudes—even lower than that of su...

Estimates of solar irradiance at the earth's surface from satellite observations are useful for planning both the deployment of distributed photovoltaic systems and their integration into electricity grids. In order to use surface solar irradiance from satellites for these purposes, validation of its accuracy against ground observations is needed....

Effective and accurate monitoring of grassland above-ground biomass (AGB) is important for pastoral agriculture planning and management. In this study, we combined 1433 AGB field measurements and remotely sensed data with the goal of establishing a suitable model for estimating grassland AGB in the Three-River Headwaters Region (TRHR) of China, whi...

In this study, three previously proposed echo waveform retracking techniques are assessed for their performances in measuring lead and sea ice elevations from Cryosat-2 (CS-2) SAR L1b data. These derived CS-2 sea ice elevations and freeboards are compared with those from seven Operation IceBridge (OIB) flights, dedicated as the CS-2 underflights du...

Snow albedo feedback is one of the most crucial feedback processes that control equilibrium climate sensitivity, which is a central parameter for better prediction of future climate change. However, persistent large discrepancies and uncertainties are found in snow albedo feedback estimations. Remotely sensed snow cover products, atmospheric reanal...