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27 results on '"Langhorst, Theodore"'

1. River Morphology

Author

Yang, Xiao, Langhorst, Theodore, Pavelsky, Tamlin M., Cardille, Jeffrey A., editor, Crowley, Morgan A., editor, Saah, David, editor, and Clinton, Nicholas E., editor

Published
2024
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4. Quantification of wetland vegetation communities features with airborne AVIRIS-NG, UAVSAR, and UAV LiDAR data in Peace-Athabasca Delta

Author

Wang, Chao, Pavelsky, Tamlin M., Kyzivat, Ethan D., Garcia-Tigreros, Fenix, Podest, Erika, Yao, Fangfang, Yang, Xiao, Zhang, Shuai, Song, Conghe, Langhorst, Theodore, Dolan, Wayana, Kurek, Martin R., Harlan, Merritt E., Smith, Laurence C., Butman, David E., Spencer, Robert G.M., Gleason, Colin J., Wickland, Kimberly P., Striegl, Robert G., and Peters, Daniel L.

Published
2023
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6. Global Cloud Biases in Optical Satellite Remote Sensing of Rivers.

Author

Langhorst, Theodore, Andreadis, Konstantinos M., and Allen, George H.

Subjects
*REMOTE sensing, *REMOTE-sensing images, *CLOUDINESS, *MULTISENSOR data fusion, *OPTICAL sensors
Abstract

Satellite imagery provides a global perspective for studying river hydrology and water quality, but clouds remain a fundamental limitation of optical sensors. Explicit studies of this problem were limited to specific locations or regions. In this study, we characterize the global severity of this limitation by analyzing 22 years of daily satellite cloud cover data and modeled river discharge for a global sample 21,642 river reaches of diverse sizes and climates. Our results show that the bias in observed river discharge is highly organized in space, particularly affecting Tropical and Arctic rivers. Given the fundamental nature of this cloud limitation, optical satellites will always provide a biased representation of river conditions. We discuss several strategies to mitigate bias, including modeling, data fusion, and temporal averaging, yet these methods introduce their own challenges and uncertainties. Plain Language Summary: This study examines how optical satellite imagery, which is vital for understanding rivers worldwide, is hindered by clouds specifically when observing rivers. We analyzed 22 years of daily data covering 21,642 sections of rivers of various sizes and climates. Our findings reveal that cloud cover significantly biases the distribution of river discharges we observe, especially for Tropical and Arctic rivers. This means that satellite images do not represent river conditions accurately. Our research provides the first comprehensive analysis of its extent and impact. Ultimately, while satellite technology continues to improve, clouds remain a challenge in obtaining precise river data, highlighting the need for innovative solutions. Key Points: We evaluated the impact of cloud cover on satellite optical remote sensing across a global sample of river reachesDirect optical satellite observations can present a highly biased, and geographically variable, view of river conditionsSeasonal relationships of clouds and discharge predict the ability of optical satellites to observe the distribution of river discharge [ABSTRACT FROM AUTHOR]

Published
2024
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9. Increased scale and accessibility of sediment transport research in rivers through practical, open-source turbidity and depth sensors

Author

Langhorst, Theodore, primary, Pavelsky, Tamlin, additional, Eidam, Emily, additional, Cooper, Lillian, additional, Davis, Julianne, additional, Spellman, Katie, additional, Clement, Sarah, additional, Arp, Christopher, additional, Bondurant, Allen, additional, Friedmann, Elisa, additional, and Gleason, Colin, additional

Published
2023
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10. Athabasca River Avulsion Underway in the Peace‐Athabasca Delta, Canada

Author

Wang, Bo, primary, Smith, Laurence C., additional, Gleason, Colin, additional, Kyzivat, Ethan D., additional, Fayne, Jessica V., additional, Harlan, Merritt E., additional, Langhorst, Theodore, additional, Feng, Dongmei, additional, Eidam, Emily, additional, Munoz, Sebastian, additional, Davis, Julianne, additional, Pavelsky, Tamlin M., additional, and Peters, Daniel L., additional

Published
2023
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12. The Importance of Lake Emergent Aquatic Vegetation for Estimating Arctic‐Boreal Methane Emissions

Author

Kyzivat, Ethan D., primary, Smith, Laurence C., additional, Garcia‐Tigreros, Fenix, additional, Huang, Chang, additional, Wang, Chao, additional, Langhorst, Theodore, additional, Fayne, Jessica V., additional, Harlan, Merritt E., additional, Ishitsuka, Yuta, additional, Feng, Dongmei, additional, Dolan, Wayana, additional, Pitcher, Lincoln H, additional, Wickland, Kimberly P., additional, Dornblaser, Mark M., additional, Striegl, Robert G., additional, Pavelsky, Tamlin M., additional, Butman, David E., additional, and Gleason, Colin J., additional

Published
2022
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14. The Importance of Lake Emergent Aquatic Vegetation for Estimating Arctic-Boreal Methane Emissions

Author

Kyzivat, Ethan, primary, Smith, Laurence, additional, Garcia Tigeros, Fenix, additional, Huang, Chang, additional, Wang, Chao, additional, Langhorst, Theodore, additional, Fayne, Jessica V, additional, Harlan, Merritt, additional, Ishitsuka, Yuta, additional, Feng, Dongmei, additional, Dolan, Wayana, additional, Pitcher, Lincoln H, additional, Pavelsky, Tamlin M, additional, Butman, David, additional, Wickland, Kimberly P, additional, Dornblaser, Mark M, additional, Striegl, Robert, additional, and Gleason, Colin Joseph, additional

Published
2022
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15. Mapping Flow‐Obstructing Structures on Global Rivers

Author

Yang, Xiao, primary, Pavelsky, Tamlin M., additional, Ross, Matthew R. V., additional, Januchowski‐Hartley, Stephanie R., additional, Dolan, Wayana, additional, Altenau, Elizabeth H., additional, Belanger, Michael, additional, Byron, Danesha, additional, Durand, Michael, additional, Van Dusen, Ian, additional, Galit, Hailey, additional, Jorissen, Michiel, additional, Langhorst, Theodore, additional, Lawton, Eric, additional, Lynch, Riley, additional, Mcquillan, Katie Ann, additional, Pawar, Sayali, additional, and Whittemore, Aaron, additional

Published
2022
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16. The Importance of Lake Littoral Zones for Estimating Arctic-Boreal Methane Emissions

Author

Kyzivat, Ethan, primary, Smith, Laurence, additional, Garcia Tigeros, Fenix, additional, Huang, Chang, additional, Wang, Chao, additional, Langhorst, Theodore, additional, Fayne, Jessica V, additional, Harlan, Merritt, additional, Ishitsuka, Yuta, additional, Feng, Dongmei, additional, Dolan, Wayana, additional, Pitcher, Lincoln H, additional, Pavelsky, Tamlin M, additional, Butman, David, additional, Wickland, Kimberly P, additional, Dornblaser, Mark M, additional, Striegl, Robert, additional, and Gleason, Colin Joseph, additional

Published
2021
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19. Mapping flow-obstructing structures on global rivers

Author

Yang, Xiao, primary, Pavelsky, Tamlin M, additional, Ross, Matthew Richard Voss, additional, Januchowski-Hartley, Stephanie R, additional, Dolan, Wayana, additional, Altenau, Elizabeth Humphries, additional, Belanger, Michael, additional, Byron, Danesha, additional, Durand, Michael, additional, Dusen, Ian Van, additional, Galit, Hailey, additional, Jorissen, Michiel, additional, Langhorst, Theodore, additional, Lawton, Eric, additional, Lynch, Riley, additional, Mcquillan, Katie Ann, additional, Pawar, Sayali K, additional, and Whittemore, Aaron, additional

Published
2021
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20. Advancing Field-Based GNSS Surveying for Validation of Remotely Sensed Water Surface Elevation Products

Author

Pitcher, Lincoln H., Smith, Laurence C., Cooley, Sarah W., Zaino, Annie, Carlson, Robert, Pettit, Joseph, Gleason, Colin J., Minear, J. Toby, Fayne, Jessica V., Willis, Michael J., Hansen, Jasmine S., Easterday, Kelly J., Harlan, Merritt E., Langhorst, Theodore, Topp, Simon N., Dolan, Wayana, Kyzivat, Ethan D., Pietroniro, Al, Marsh, Philip, Yang, Daqing, Carter, Tom, Onclin, Cuyler, Hosseini, Nasim, Wilcox, Evan, Moreira, Daniel, Berge-Nguyen, Muriel, Cretaux, Jean-Francois, Pavelsky, Tamlin M., Pitcher, Lincoln H., Smith, Laurence C., Cooley, Sarah W., Zaino, Annie, Carlson, Robert, Pettit, Joseph, Gleason, Colin J., Minear, J. Toby, Fayne, Jessica V., Willis, Michael J., Hansen, Jasmine S., Easterday, Kelly J., Harlan, Merritt E., Langhorst, Theodore, Topp, Simon N., Dolan, Wayana, Kyzivat, Ethan D., Pietroniro, Al, Marsh, Philip, Yang, Daqing, Carter, Tom, Onclin, Cuyler, Hosseini, Nasim, Wilcox, Evan, Moreira, Daniel, Berge-Nguyen, Muriel, Cretaux, Jean-Francois, and Pavelsky, Tamlin M.

Abstract

To advance monitoring of surface water resources, new remote sensing technologies including the forthcoming Surface Water and Ocean Topography (SWOT) satellite (expected launch 2022) and its experimental airborne prototype AirSWOT are being developed to repeatedly map water surface elevation (WSE) and slope (WSS) of the world’s rivers, lakes, and reservoirs. However, the vertical accuracies of these novel technologies are largely unverified; thus, standard and repeatable field procedures to validate remotely sensed WSE and WSS are needed. To that end, we designed, engineered, and operationalized a Water Surface Profiler (WaSP) system that efficiently and accurately surveys WSE and WSS in a variety of surface water environments using Global Navigation Satellite Systems (GNSS) time-averaged measurements with Precise Point Positioning corrections. Here, we present WaSP construction, deployment, and a data processing workflow. We demonstrate WaSP data collections from repeat field deployments in the North Saskatchewan River and three prairie pothole lakes near Saskatoon, Saskatchewan, Canada. We find that WaSP reproducibly measures WSE and WSS with vertical accuracies similar to standard field survey methods [WSE root mean squared difference (RMSD) ∼8 cm, WSS RMSD ∼1.3 cm/km] and that repeat WaSP deployments accurately quantify water level changes (RMSD ∼3 cm). Collectively, these results suggest that WaSP is an easily deployed, self-contained system with sufficient accuracy for validating the decimeter-level expected accuracies of SWOT and AirSWOT. We conclude by discussing the utility of WaSP for validating airborne and spaceborne WSE mappings, present 63 WaSP in situ lake WSE measurements collected in support of NASA’s Arctic-Boreal and Vulnerability Experiment, highlight routine deployment in support of the Lake Observation by Citizen Scientists and Satellites project, and explore WaSP utility for validating a novel GNSS interferometric reflectometry LArge Wave Warn

Published
2020

21. Advancing Field-Based GNSS Surveying for Validation of Remotely Sensed Water Surface Elevation Products

Author

Pitcher, Lincoln H., primary, Smith, Laurence C., additional, Cooley, Sarah W., additional, Zaino, Annie, additional, Carlson, Robert, additional, Pettit, Joseph, additional, Gleason, Colin J., additional, Minear, J. Toby, additional, Fayne, Jessica V., additional, Willis, Michael J., additional, Hansen, Jasmine S., additional, Easterday, Kelly J., additional, Harlan, Merritt E., additional, Langhorst, Theodore, additional, Topp, Simon N., additional, Dolan, Wayana, additional, Kyzivat, Ethan D., additional, Pietroniro, Al, additional, Marsh, Philip, additional, Yang, Daqing, additional, Carter, Tom, additional, Onclin, Cuyler, additional, Hosseini, Nasim, additional, Wilcox, Evan, additional, Moreira, Daniel, additional, Berge-Nguyen, Muriel, additional, Cretaux, Jean-Francois, additional, and Pavelsky, Tamlin M., additional

Published
2020
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23. Boreal Wetland Mapping by UAV to Upscale Greenhouse Gas Emissions

Author

Kyzivat, Ethan, primary, Smith, Laurence, additional, Gleason, Colin, additional, Pavelsky, Tamlin, additional, Langhorst, Theodore, additional, Fayne, Jessica, additional, Kuhn, Catherine, additional, Harlan, Merritt, additional, Ishitsuka, Yuta, additional, Feng, Dongmei, additional, Striegl, Robert, additional, Wickland, Kimberly, additional, Dornblaser, Mark, additional, Butman, David, additional, and Garcia-Tigreros, Fenix, additional

Published
2020
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24. OpenOBS: Open‐source, low‐cost optical backscatter sensors for water quality and sediment‐transport research.

Author

Eidam, Emily F., Langhorst, Theodore, Goldstein, Evan B., and McLean, McKenzie

Subjects
OPTICAL sensors, WATER quality, TOTAL suspended solids, WATER quality monitoring, SUSPENDED sediments, ENVIRONMENTAL management
Abstract

Optical backscatter sensors (OBSs) are commonly used to measure the turbidity, or light obscuration, of water in fresh and marine environments and various industrial applications. These turbidity data are commonly calibrated to yield total suspended solids (TSS) or suspended sediment concentration (SSC) measurements for water quality, sediment transport, and diverse other research and environmental management applications. Commercial sensors generally cost > $1000–3000. Here we leveraged simple, low‐cost microprocessors, electronics, and housing components to design and construct open‐source OBSs for < $150 per unit. The circuit relies on a photodiode to sense backscattered light, two stages of signal amplification, and a high‐resolution analog‐to‐digital converter to read the detected signal. The instrument and logger utilize inexpensive, custom‐printed circuit boards with through‐hole soldering mounts; micro‐SD card reader and real‐time clock modules; and PVC housings with commercial end caps and epoxy‐potted diode emitter and receiver. All parts are readily and publicly available, and minimal experience in soldering and coding is required to build and deploy the sensor. In lab and field tests, standard deviations were comparable to those measured by commercial sensors (~ 2–3% of the mean for suspended muds and 20–30% for suspended sands). These open‐source sensors represent a useful advance in inexpensive sensing technology with broad applications across scientific and environmental management disciplines. [ABSTRACT FROM AUTHOR]

Published
2022
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25. ANTICIPATED IMPROVEMENTS TO RIVER SURFACE ELEVATION PROFILES FROM THE SURFACE WATER AND OCEAN TOPOGRAPHY MISSION

Author

Langhorst, Theodore

Abstract

Existing publicly available digital elevation models (DEMs) provide global-scale data but are often not precise enough for studying processes that depend on small-scale topographic features in rivers. The upcoming Surface Water and Ocean Topography (SWOT) satellite mission is planned to launch in 2021 and will provide surface water elevation and inundation extent at high resolution for most of the Earth surface. We present a novel noise reduction method for multitemporal river water surface elevation profiles that combines a truncated singular value decomposition and a slope-constrained least-squares estimator. We use simulated SWOT data of 85-145 km sections of the Po, Sacramento, and Tanana Rivers to show that 3-12 months of simulated SWOT data can produce elevation profiles with mean absolute errors of 5.38-12.55 cm at 100-200 m along-stream resolution. Last, we consider case studies in geomorphology and ecology to demonstrate the scientific value of more accurate water surface elevation profiles.

Published
2019
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26. A High-Resolution Airborne Color-Infrared Camera Water Mask for the NASA ABoVE Campaign

Author

Kyzivat, Ethan D., primary, Smith, Laurence C., additional, Pitcher, Lincoln H., additional, Fayne, Jessica V., additional, Cooley, Sarah W., additional, Cooper, Matthew G., additional, Topp, Simon N., additional, Langhorst, Theodore, additional, Harlan, Merritt E., additional, Horvat, Christopher, additional, Gleason, Colin J., additional, and Pavelsky, Tamlin M., additional

Published
2019
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