Open Water Data Research Articles

A Spatiotemporal Enhanced SMAP Freeze/Thaw Product (1980–2020) over China and Its Preliminary Analyses

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 on Convolutional Long Short-Term Memory networks (ConvLSTM) to expand the SMAP-enhanced L3 landscape freeze/thaw product (SMAP_E_FT) temporally. In the algorithm, the Freeze/Thaw Earth System Data Record product (ESDR_FT) is sucked in the ConvLSTM and fused with SMAP_E_FT at the decision level. Eight predictor datasets, i.e., soil temperature, snow depth, soil moisture, precipitation, terrain complexity index, area of open water data, latitude and longitude, are used to train the ConvLSTM. Direct validation using six dense observation networks located in the Genhe, Maqu, Naqu, Pali, Saihanba, and Shandian river shows that the fusion product (ConvLSTM_FT) effectively absorbs the high accuracy characteristics of ESDR_FT and expands SMAP_E_FT with an overall average improvement of 2.44% relative to SMAP_E_FT, especially in frozen seasons (averagely improved by 7.03%). The result from indirect validation based on categorical triple collocation also shows that ConvLSTM_FT performs stable regardless of land cover types, climate types, and terrain complexity. The findings, drawn from preliminary analyses on ConvLSTM_FT from 1980 to 2020 over China, suggest that with global warming, most parts of China suffer from different degrees of shortening of the frozen period. Moreover, in the Qinghai–Tibet region, the higher the permafrost thermal stability, the faster the degradation rate.

The hydrodynamic performance analysis of a submarine with new pump-jet propulsor

A new type of pump-jet propulsor (PJP) was designed and installed on the DARPA Suboff. The installation position of this new PJP is different from the traditional PJP, which gives more possibilities to improve the comprehensive performance of submarine. The duct of PJP has been automatically modeled based on pumped rotor, stator and hull shape. The rotor of PJP has been modeled as an actuator disc based on body force method coupled with the experimental open water data. The hydrodynamic performance analysis was applied on the self-propulsion point, and the self-propulsion characteristics were estimated by the thrust identity method. Moreover, the pressure and velocity distribution for different duct geometric parameters have been compared and discussed. The results indicate that the size of the duct has an impact on the generation of negative pressure zone and the wake distribution. When the geometric parameters of duct are equal to r = 0.75R, L = 3.5D and H = 0.8D, the overall performance is superior. The new pump jet destroys the circumferential correlation of the duct vortex and accelerates the dissipation of the vortex.

Social barriers to open (water) data

AbstractAlthough the proliferation of open water data platforms and initiatives in recent years is a laudable phenomenon, there is little empirical evidence indicating whether and to what extent these efforts are generating anticipated benefits of improved transparency, citizen participation, innovation, and water resource decision making. Relatedly, water resource researchers have devoted little attention to identifying and accounting for barriers that may be limiting open water data efforts from realizing their potential. The premise of this overview is that (a) open water data efforts could be improved with a better understanding of the non‐technical challenges and that (b) water researchers interested in open water data would benefit from delving into the emerging body of research in public policy, information science, and other disciplines on open data barriers more broadly. However, the research on open data barriers has neglected water sustainability issues. In light of this asymmetry, the aim of this overview is to foster interdisciplinary engagement on this topic by introducing the water resource community to this literature via a discussion of key social barriers to open data. Additionally, I hope to motivate water resource researchers to develop a two‐way interdisciplinary engagement by making original research contributions to this larger literature.This article is categorized under: Engineering Water Science of Water > Methods Human Water > Water Governance Human Water > Water as Imagined and Represented

A semi-empirical multi-degree of freedom body force propeller model

Efficient and accurate modelling of a self-propelled vessel in a large amplitude seaway with CFD-based numerical methods is a challenging task and is prohibitively expensive for most designers and engineers. Viscous CFD methods can accurately model viscous effects, but the small numerical time step required to analyze the rotating propeller leads to a large computational cost. A method for efficiently and accurately modelling the six degree of freedom force on the propeller is required to feasibly model a self propelled vessel maneuvering in a high amplitude seaway. This paper outlines the framework for developing an unsteady body force propeller model for unsteady conditions. The purpose of this study is to train a semi-empirical algorithm to accurately prescribe the unsteady body force to model the propeller. The MOERI Container ship propeller is analyzed with RANS CFD. Open water data is compared to the RANS CFD results of a steady Moving Reference Frame approach. Unsteady surge and propeller revolution rate are applied to a transient rotating mesh model in open water and behind condition. The predictions of the algorithm match well with the CFD results.

Inter-comparing and improving land surface temperature estimates from passive microwaves over the Jiangsu province of the People’s Republic of China

ABSTRACT In the recent years, the FengYun-3B passive microwave observations (FY3B) have been used to study global and regional soil moisture estimates, and land surface temperature (LST) has been an important input in the retrieval model. Previous studies proposed a linear model to derive LST from Ka-band brightness temperatures (H09 approach) which were routinely masked based on open water data. This study aimed to further understand microwave emission under such challenging open water conditions and developed the first data-driven approach to correct for such open water conditions. The H09 was first applied to the FY3B observations, and then inter-compared against MODIS (Moderate-resolution Imaging Spectro-radiometer), MERRA (Modern Era Retrospective analysis for Research and Applications) and ground observations over the Jiangsu province in the People’s Republic of China. Several freshwater bodies are located within this region, and the Pacific Ocean bounds at the east, this makes it an excellent region for the study of open water impact on the passive microwave observations. As in previous studies, the quality of the FY3B LST based on the H09 approach dropped over the regions with high open water. While the MERRA and MODIS LST products maintained an average correlation of about 0.95, the FY3B LST product had an average correlation of 0.85 with drops to about 0.65 over the open water regions. Additional comparisons also revealed biases over the open water regions within the passive microwave product. An open water metric, which is based on the percentage of a pixel and its surrounding pixels covered by water was developed to quantify the impact of open water. Based on a pixel-wise linear relationship between the MERRA LST and FY3B Ka-band brightness temperature, spatially variable slopes and intercepts were obtained as a function of open water to produce a correction for open water in the H09 which leads to the HG18 approach. Validations with both the MODIS LST product and the ground observations showed that there was a significant reduction in both the absolute bias (MODIS: 2 K, in situ: 10 K) and the standard errors (MODIS: 0.8 K, in situ: 1 K) using the HG18 approach. This opens up a new window towards further improving and understanding LST retrievals from passive microwave products.

Investigation of self-propulsion of DARPA Suboff by RANS method

In this study, the resistance and self-propulsion analyses of the benchmark DARPA Suboff with E1619 propeller have been done using Computational Fluid Dynamics (CFD) method. Single phase analyses have been carried out by assuming 3-D, turbulent, incompressible and steady flow, thus the governing equations (RANS Equations) have been discretized with finite volume method (FVM). First, verification and validation studies have been carried out in order to determine the optimum grid numbers for resistance analyses of bare and appended forms, and then for open water propeller analyses. The numerical studies have been done by taking the propeller-hull interaction into consideration by two methods for different velocities. First, the propeller has been modeled as an actuator disc based on body force method coupled with the experimental open water data. The propeller itself has later been modeled behind the hull with a rotating region. Performance analyses have been carried out at the self-propulsion points determined by these two methods. Self-propulsion characteristics have been estimated using thrust identity method. Finally, a comprehensive investigation of wake has been carried out by comparing the present results with those of other studies and the applicability of CFD on self-propulsion prediction of the underwater vehicles has been discussed.

Featured Collection Introduction: Open Water Data Initiative

Featured Collection Introduction: Open Water Data Initiative

Open Water Data in Space and Time

AbstractAn Open Water Data Initiative has been established by the federal government to enhance water information sharing across the United States (U.S.) using standardized web services for geospatial and temporal data. In a parallel effort, the National Weather Service has established a new National Water Center on the Tuscaloosa campus of the University of Alabama, at which a new National Water Model starts operations in June 2016, to continually simulate and forecast streamflow discharge throughout the continental U.S. These two developments support the interoperability of streamflow and hydrologic information in time and space from modeled and observed sources through the use of open standards to share water information.

Air‐sea exchange of carbon dioxide in the Southern Ocean and Antarctic marginal ice zone

AbstractDirect carbon dioxide flux measurements using eddy covariance from an icebreaker in the high‐latitude Southern Ocean and Antarctic marginal ice zone are reported. Fluxes were combined with the measured water‐air carbon dioxide partial pressure difference (ΔpCO2) to compute the air‐sea gas transfer velocity (k, normalized to Schmidt number 660). The open water data showed a quadratic relationship between k (cm h−1) and the neutral 10 m wind speed (U10n, m s−1), kopen = 0.245 U10n2 + 1.3, in close agreement with decades old tracer‐based results and much lower than cubic relationships inferred from previous open ocean eddy covariance studies. In the marginal ice zone, the effective gas transfer velocity decreased in proportion to sea ice cover, in contrast with predictions of enhanced gas exchange in the presence of sea ice. The combined open water and marginal ice zone results affect the calculated magnitude and spatial distribution of Southern Ocean carbon flux.

The USGS Water Availability and Use Science Program: Needs, Establishment, and Goals of a Water Census

AbstractMany reports have recognized the need for a national water census for the United States and have called upon the U.S. Geological Survey to undertake this challenge. For example, the National Science and Technology Council stated: “The United States has a strong need for an ongoing census of water that describes the status of our Nation's water resource at any point in time and identifies trends over time.” Responding to the need for this information, the U.S. Congress established the SECURE Water Act. The directives are to provide a more accurate assessment of the status of the water resources of the United States; determine the quantity of water available for beneficial uses; identify long‐term trends in water availability; assist in determination of the quality of the water resources; and develop the basis for an improved ability to forecast the availability of water for future economic, energy production, and environmental uses. This article provides summary and new information on the process and progress on work to estimate water budget components nationwide, involvement of stakeholder interests, efforts to examine water‐use characteristics throughout the Nation, studies of water availability in geographically focused areas and the initiation of methods to provide open access to existing and new water resources information contributing to Open Water Data Initiative (OWDI) efforts and objectives.

An Analysis of Water Data Systems to Inform the Open Water Data Initiative

AbstractImproving access to data and fostering open exchange of water information is foundational to solving water resources issues. In this vein, the Department of the Interior's Assistant Secretary for Water and Science put forward the charge to undertake an Open Water Data Initiative (OWDI) that would prioritize and accelerate work toward better water data infrastructure. The goal of the OWDI is to build out the Open Water Web (OWW). We therefore considered the OWW in terms of four conceptual functions: water data cataloging, water data as a service, enriching water data, and community for water data. To describe the current state of the OWW and identify areas needing improvement, we conducted an analysis of existing systems using a standard model for describing distributed systems and their business requirements. Our analysis considered three OWDI‐focused use cases—flooding, drought, and contaminant transport—and then examined the landscape of other existing applications that support the Open Water Web. The analysis, which includes a discussion of observed successful practices of cataloging, serving, enriching, and building community around water resources data, demonstrates that we have made significant progress toward the needed infrastructure, although challenges remain. The further development of the OWW can be greatly informed by the interpretation and findings of our analysis.

Supporting Diverse Data Providers in the Open Water Data Initiative: Communicating Water Data Quality and Fitness of Use

AbstractShared, trusted, timely data are essential elements for the cooperation needed to optimize economic, ecologic, and public safety concerns related to water. The Open Water Data Initiative (OWDI) will provide a fully scalable platform that can support a wide variety of data from many diverse providers. Many of these will be larger, well‐established, and trusted agencies with a history of providing well‐documented, standardized, and archive‐ready products. However, some potential partners may be smaller, distributed, and relatively unknown or untested as data providers. The data these partners will provide are valuable and can be used to fill in many data gaps, but can also be variable in quality or supplied in nonstandardized formats. They may also reflect the smaller partners' variable budgets and missions, be intermittent, or of unknown provenance. A challenge for the OWDI will be to convey the quality and the contextual “fitness” of data from providers other than the most trusted brands. This article reviews past and current methods for documenting data quality. Three case studies are provided that describe processes and pathways for effective data‐sharing and publication initiatives. They also illustrate how partners may work together to find a metadata reporting threshold that encourages participation while maintaining high data integrity. And lastly, potential governance is proposed that may assist smaller partners with short‐ and long‐term participation in the OWDI.

Progress on water data integration and distribution: a summary of select US Geological Survey data systems

Critical water-resources issues ranging from flood response to water scarcity make access to integrated water information, services, tools, and models essential. Since 1995 when the first water data web pages went online, the US Geological Survey has been at the forefront of water data distribution and integration. Today, real-time and historical streamflow observations are available via web pages and a variety of web service interfaces. The Survey has built partnerships with Federal and State agencies to integrate hydrologic data providing continuous observations of surface and groundwater, temporally discrete water-quality data, groundwater well logs, aquatic biology data, water availability and use information, and tools to help characterize the landscape for modeling. In this paper, we summarize the status and design patterns implemented for selected data systems. We describe how these systems contribute to a US Federal Open Water Data Initiative and present some gaps and lessons learned that apply to global hydroinformatics data infrastructure.

Spatial analysis of environment and population at risk of natural gas fracking in the state of Pennsylvania, USA

Hydraulic fracturing, also known as fracking, has been increasing exponentially across the United States, which holds the largest known shale gas reserves in the world. Studies have found that the high-volume horizontal hydraulic fracturing process (HVHFP) threatens water resources, harms air quality, changes landscapes, and damages ecosystems. However, there is minimal research focusing on the spatial study of environmental and human risks of HVHFP, which is necessary for state and federal governments to administer, regulate, and assess fracking. Integrating GIS and spatial kernel functions, we study the presently operating fracking wells across the state of Pennsylvania (PA), which is the main part of the current hottest Marcellus Shale in US. We geographically process the location data of hydraulic fracturing wells, 2010 census block data, urbanized region data, railway data, local road data, open water data, river data, and wetland data for the state of PA. From this we develop a distance based risk assessment in order to understand the environmental and urban risks. We generate the surface data of fracking well intensity and population intensity by integrating spatial dependence, semivariogram modeling, and a quadratic kernel function. The surface data of population risk generated by the division of fracking well intensity and population intensity provide a novel insight into the local and regional regulation of hydraulic fracturing activities in terms of environmental and health related risks due to the proximity of fracking wells.

Validation of RANS predictions of open water performance of a highly skewed propeller with experiments

Abstract The paper presents a validation study of a RANS prediction of open water characteristics of a highly skewed propeller in full range advance-ratio. Computational results are compared with open water data, and extensively validated at one loading with paint test, cavitation inception test and PIV measurements. Except at two extreme off-design loads, the difference between prediction and measurement is less than 3% for K T and less than 5% for K Q at a wide range of advance ratios. While this can be considered as good agreement with experiment for K T and K Q, an attempt is made to critically analyze the predicted flow detail and some possible deficiency of the existing RANS method is discussed. Part of the work was carried out within the EU-funded research project “LEADING EDGE 2 2 Leading Edge: Prediction of Leading Edge and Tip Flow for the Design of Quiet and Efficient Screw Propellers (Contract No: G3RD-CT-2002-00818). ”.

Meteorological Forcing and Water Level Fluctuations on Lake Erie

Analyses of both overtake wind and water level data in Lake Erie are presented for the summer periods of 1979 and 1980. The new data sets are compared to the more conventional land-based data and, where appropriate, to the results of several numerical models. Differences between land-based and open-water data are particularly significant on the shorter time scales of a few hours to several days in length (for winds and less than a few hours in the case of water levels). In practical applications of Lake Erie meteorological forcing functions these differences are shown to be important to such problems as storm surge forecasting. Thus, further research into the relation between land-based and lake-based forcing is recommended.

Hydrophone Calibrator

A system to provide rapid, reliable, economical calibration of small hydrophones is described. The system is designed for production testing and field use in the frequency range of 100 cps to 3 kc. The hydrophone is placed in an open-ended column of water which is excited by an electrodynamic driver. Acoustic pressure in the tube is calculated from system parameters and compared to measured results for various types of hydrophones. Results agree with open-water data within ±1.0 db.