The diurnal cycle of Integrated Water Vapor (IWV) plays a key role in radiation, convection, and land–atmosphere interactions, yet its global characteristics and representation in atmospheric reanalysis products remain insufficiently quantified. Using a decade of GNSS observations from more than 6,000 stations, this study characterizes the global IWV diurnal variability and assesses the performance of ERA5 in reproducing these signals. GNSS IWV exhibits a coherent diurnal cycle dominated by the S₁ (24 h) harmonic, with annual-mean amplitudes decreasing from 3 kg m⁻² in the tropics to near zero at high latitudes, a global mean of 0.40 kg m⁻², and peak times clustered around 17.4 local time; the semidiurnal S₂ (12 h) component is weaker but similarly systematic. In contrast, ERA5 exhibits sharp artificial discontinuities at the transition times (09–10 and 21–22 UTC) of its 12-hour assimilation windows, affecting 54

The diurnal cycle of tropospheric Zenith Total Delays (ZTD) is critical for refining tropospheric models and understanding key geophysical and atmospheric processes. The fifth European Centre for Medium‐Range Weather Forecasts reanalysis ERA5, with its unique 1‐hr temporal resolution, provides valuable data for these purposes. However, we identified obvious discontinuities in ERA5‐derived ZTD at 09:00 and 21:00 UTC. A comparison with 10‐year GNSS data from 6,437 stations showed that 32.8% of the stations experienced discontinuities in mean diurnal anomalies of ERA5 ZTD, with an average magnitude of 2.2 mm, far exceeding the 0.3 mm hour‐to‐hour variations observed by GNSS. The discontinuities are more pronounced in summer and are primarily due to errors in ERA5's humidity modeling, with a few pressure‐related issues limited to Antarctica. The discontinuity is attributed to the transition between ERA5's 12‐hr assimilation windows and suggest that other ERA5 variables may also be impacted, warranting caution in ERA5‐based diurnal cycle studies.

The Chesapeake Bay region (defined as longitudes − 78° to -74° and latitudes 36.5° to 40°) experiences the highest rates of relative sea-level rise (RSLR) on the Atlantic Coast. Regional land subsidence influences RSLR, however quantified rates of vertical land motions (VLM) are inconsistent in published solutions. For 5 years from 2019 to 2023, new Global Navigation Satellite System (GNSS) campaign data were collected at over 60 sites across the Chesapeake Bay region annually. These data were processed and combined with continuous GNSS data (120 stations) from the region covering the same time-period using GAMIT-GLOBK to produce 3D velocities and their associated uncertainties. We use the Robust Network Imaging algorithm to interpolate GNSS-derived VLM to produce a new regional VLM solution of the Chesapeake Bay region. We find that land subsidence is ubiquitous throughout the region with rates varying from − 2.97 to -0.40 mm/yr. In major cities across the Chesapeake Bay region, VLM rates are − 1.1 ± 1.6 mm/yr (1-sigma) for Washington DC, -0.8 ± 1.4 mm/yr for Baltimore, MD, -2.4 ± 0.5 mm/yr for Ocean City, MD, and − 2.3 ± 1.0 mm/yr for Hampton, VA. When we compare our VLM rates with a geodetic-based solution from 1974, we observe meaningful shifts in the locations and rates of maximum subsidence. The results of this work underscore that regular monitoring of VLM and can be used to improve projections of relative sea-level changes as well as the associated coastal hazards for communities in the Chesapeake Bay region.

With more continuous Global Navigation Satellite System (cGNSS) network stations becoming available around the world and with improved data processing techniques, it is possible to observe and model subtle motions in the Earth’s crust that were previously undetectable. Critical to studying these subtle motions is understanding the contributions of various signals mixed into the cGNSS time-series, for example non-tidal atmospheric and ocean loading (NTAOL) and hydrologic loading. We investigate the effect that atmospheric and surface mass loading has on the stochastic properties of GPS time series around the Great Lakes (GL) region of the U.S. and Canada. This region is ideal for studying these effects because it is covered by a dense network of GPS stations and it is known to be affected by significant hydrological loading due to water level changes in the GL. We use readily available NTAOL and hydrologic loading models to remove these signals from the cGNSS time-series and track the variance changes in the residual time-series in order to quantify the effect of each loading component. In order to assess whether the loading models fully capture the full magnitude of displacement we also perform common mode filtering in order to extract the remaining spatially correlated signal. We estimate the stochastic parameters (white noise amplitude, power law amplitude and spectral index) and compare between the raw, loading corrected, and filtered loading corrected time series in order to evaluate the contribution of the different loading signals to the time series noise properties. The outcomes of this study will help validate existing loading models and where improvement may be needed. Results will also support GNSS data providers in assessing the quality of available GNSS stations for use in scientific and surveying applications.

Abstract Various types of Global Navigation Satellite System (GNSS) data are used for a wide range of applications. When modeled correctly, millimeter precision daily GNSS position time‐series yield velocities and other derived products that can be used for investigations of lithospheric processes and properties. In this review paper, we describe the specific types of GNSS data and data products that are valuable for studies of the lithosphere, such as coseismic offsets, post‐seismic decay in time‐series, seasonal signals, secular velocities, and strain rates, and how those data are derived. We also discuss the applications of several types of GNSS data and data products. We provide open access resources for precision GNSS daily position time‐series, quality secular velocity solutions, and daily GNSS RINEX files for researchers interested in processing their own data.

Accurate positioning using the Global Positioning System relies on accurate modeling of tropospheric delay. Estimated tropospheric delay must vary sufficiently to capture true variations; otherwise, systematic errors propagate into estimated positions, particularly the vertical. However, if the allowed delay variation is too large, the propagation of data noise into all parameters is amplified, reducing precision. Here we investigate the optimal choice of tropospheric constraints applied in the GipsyX software, which are specified by values of random walk process noise. We use the variability of 5-min estimated positions as a proxy for tropospheric error. Given that weighted mean 5-min positions closely replicate 24-h solutions, our ultimate goal is to improve 24-h positions and other daily products, such as precise orbit parameters. The commonly adopted default constraint for the zenith wet delay (ZWD) is 3 mm/√(hr) for 5-min data intervals. Using this constraint, we observe spurious wave-like patterns of 5-min vertical displacement estimates with amplitudes 100 mm coincident with Winter Storm Ezekiel of November 27, 2019, across the central/eastern USA. Loosening the constraint suppresses the spurious waves and reduces 5-min vertical displacement variability while improving water vapor estimates. Further improvement can be achieved when optimizing constraints regionally, or for each station. Globally, results are typically optimized in the range of 6–12 mm/√(hr). Generally, we at least recommend loosening the constraint from the current default of 3 mm/√(hr) to 6 mm/√(hr) for ZWD every 300 s. Constraint values must be scaled by √(x/300) for alternative data intervals of x seconds.

The Walker Lane (WL) in the western Great Basin (GB) is an active plate boundary system accommodating 10%-20% of the relative tectonic motion between the Pacific and North American plates. Its neotectonic framework is structurally complex, having hundreds of faults with various strikes, rakes, and crustal blocks with vertical axis rotation. Faults slip rates are key parameters needed to quantify seismic hazard in such tectonically active plate boundaries but modeling them in complex areas like the WL and GB is challenging. We present a new modeling strategy for estimating fault slip rates in complex zones of active crustal deformation using data from GPS networks. The technique does not rely on prior estimates of slip rates from geologic studies, and only uses data on the surface trace location, dip, and rake. The iterative framework generates large numbers of block models algorithmically from the fault database to obtain many estimates of slip rates for each fault. This reduces bias from subjective choices about how discontinuous faults connect and interact to accommodate strain. Each model iteration differs slightly in block boundary configuration, but all models honor geodetic and fault data, regularization, and are kinematically self-consistent. The approach provides several advantages over bespoke models, including insensitivity to outlier data, realistic uncertainties, explicit mapping of off-fault deformation, and slip rates that are more objective and independent of geologic slip rates. Comparisons to the U.S. National Seismic Hazard Model indicate that similar to 80% of our geodetic slip rates agree with their geologic slip rates to within uncertainties. The Walker Lane (WL) is a complex zone of faults in the western Great Basin of the western United States that experiences frequent earthquakes driven by active plate tectonics. Ground networks of very sensitive GPS stations deployed over the last few decades have collected data showing where the ground deforms most quickly, and hence where earthquakes are more likely to occur. Data on how fast faults slip over time is used to inform the public about the distribution and intensity of the seismic hazard. In this study we present improved data and modeling that resolve with unprecedented detail the rates, patterns, and styles of active crustal motion, resulting in better estimates of fault slip rates in the WL. This work brings the picture of earthquake potential derived from GPS networks into sharper focus, provides new information about how plate tectonics works, and will lead to more accurate estimates of seismic hazard that can help reduce the loss of life and property from earthquakes. We estimate Walker Lane fault slip rates using a dense filtered and gridded geodetic velocity field and a robust multi-block model approach The geodetic slip rates are independent of geologic slip rates, but 80% agree with them to within uncertainties The method images off-fault deformation and vertical axis rotations providing more insight into how crustal motion drives earthquakes

The predominant approach for modeling faults in the Earth's crust represents them as elastic dislocations, extending downdip into the lower crust, where the faults slip continuously. The resulting surface deformation features strain accumulation concentrated across locked faults during the interseismic period. An alternative model proposes faults confined to the elastic crust, with surface deformation driven by a wide zone of distributed shear underneath. Using high-precision GPS data, we analyze deformation profiles across the Walker Lane (WL), USA. The WL is a transtensional region of complex faulting, which delineates the western edge of the Basin and Range province and accommodates a significant portion of the Pacific-North American plate boundary deformation budget. Despite a dense geodetic network surveyed collectively for nearly 20 years, horizontal velocities reveal no evidence of localized strain rate accumulation across fault surface expressions. Instead, deformation within the shear zone is uniformly linear, suggesting that the surface velocities reflect distributed shear within the ductile crust rather than discrete fault deformation. This implies no downdip fault extension below the seismogenic layer. The shear zone, bound by the Sierra Nevada crest in the west, is 172±6 km wide in the northernmost WL narrowing to 116±4 km in the central WL. This study's conclusion challenges the assumption of the presence of dislocations in the lower crust when estimating geodetic slip rates, suggesting that slip rates are instead controlled by the fault's position and orientation within the shear zone. This has important implications for quantifying seismic hazards in regions with complex fault systems.

We developed a high-quality global integrated water vapour (IWV) dataset from 12 552 ground-based global positioning system (GPS) stations in 2020. It consists of 5 min GPS IWV estimates with a total number of 1 093 591 492 data points. The completeness rates of the IWV estimates are higher than 95 % at 7253 (58 %) stations. The dataset is an enhanced version of the existing operational GPS IWV dataset provided by the Nevada Geodetic Laboratory (NGL). The enhancement is reached by employing accurate meteorological information from the fifth generation of European ReAnalysis (ERA5) for the GPS IWV retrieval with a significantly higher spatiotemporal resolution. A dedicated data screening algorithm is also implemented. The GPS IWV dataset has a good agreement with in situ radiosonde observations at 182 collocated stations worldwide. The IWV biases are within ±3.0 kg m−2 with a mean absolute bias (MAB) value of 0.69 kg m−2. The standard deviations (SD) of IWV differences are no larger than 3.4 kg m−2. In addition, the enhanced IWV product shows substantial improvements compared to NGL's operational version, and it is thus recommended for high-accuracy applications, such as research of extreme weather events and diurnal variations of IWV and intercomparisons with other IWV retrieval techniques. Taking the radiosonde-derived IWV as reference, the MAB and SD of IWV differences are reduced by 19.5 % and 6.2 % on average, respectively. The number of unrealistic negative GPS IWV estimates is also substantially reduced by 92.4 % owing to the accurate zenith hydrostatic delay (ZHD) derived by ERA5. The dataset is available at https://doi.org/10.5281/zenodo.6973528 (Yuan et al., 2022).

ABSTRACTCrustal deformation in the central Basin and Range between the Colorado plateau and the Eastern California Shear Zone is active but slow, making it a challenge to assess how strain is distributed and crustal motion transferred. However, knowledge of strain rates is very important, particularly for addressing the seismic hazard for both the Las Vegas urban area and the site of the proposed Yucca Mountain nuclear waste repository, in southern Nevada. Global Positioning System (GPS) data provide important constraints, particularly now that the GPS network in the area has substantially expanded in recent years. However, because deformation is slow, it is important to mitigate any transient tectonic and nontectonic signals to obtain the most accurate long-term interseismic motion and robust estimation of strain rates. We use data from all GPS stations in the region including both long-running continuous and semicontinuous stations. We model and remove postseismic displacements at these stations using source parameters for 41 events, dating back to the 1700 Cascadia megathrust earthquake, which contribute significantly to the deformation field within the central Basin and Range. We also remove correlated noise from the time series with the common-mode component imaging technique. We find that removal of both the postseismic transients and common-mode noise substantially reduces the uncertainties and spatial variation in the velocities. We find east–west extension across the Las Vegas Valley of 0.5–0.6 mm/yr. The interseismic strain rate field, calculated with the final velocities, reveals higher strain rates through southern Nevada than in previous studies, with rates within Las Vegas Valley of 8.5±2.4×10−9 yr−1. Our results also confirm shear along the Pahranagat shear zone, but the estimated amplitude is strongly affected by postseismic relaxation.

The WHOLESCALE (Water and Hole Observations Leverage Effective Stress Calculations and Lessen Expenses) project is aiming to simulate the spatial distribution and temporal evolution of stress throughout the geothermal system at San Emidio, Nevada, United States, via a thermo-hydro-mechanical reservoir model. Focal mechanisms for microseismic events during a temporary shutdown of the geothermal power plant in 2016 were analyzed through linear stress-inversion methods to infer the in-situ reservoir stress state. This analysis was supplemented by other geophysical and geological data, including focal mechanisms from regional earthquakes, slickenlines on exposed fracture surfaces, wellbore stress indicators observed in the surrounding region, and secular strain rate measurements. From the inferences of in-situ reservoir stress, 78 different realizations of stress models were generated over reasonable ranges for the values of maximum compressive horizontal stress (SHmax) azimuth and ratios of principal stress magnitudes. Evaluation of slip tendencies on fault planes determined for the micro -seismic events for each realization of the initial stress model suggests the reservoir stress state as transtensional with an SHmax azimuth between N and N30 circle E.

We use GPS data to image vertical crustal velocities in the vicinity of the Great Plains physiographic province of the United States. In the southern Great Plains, we find crustal uplift of up to 2 mm/year in an area approximately 670 km × 280 km. This signal is spatially correlated with the area of greatest groundwater decline in the southern High Plains aquifer. To determine the uplift mechanism and its possible relation to aquifer depletion, we investigate changes in aquifer water content. Gravity data coupled with an elastic model show the uplift rate is consistent with hydrological unloading from anthropogenic aquifer depletion exacerbated by severe drought. Our model that encompasses two regions of greatest groundwater decline indicates a water volume loss of −5.1 km3/year is sufficient to match the observed signal. In other large aquifers, vertical crustal motions associated with groundwater depletion are often dominated by near‐field subsidence. Our results challenge the perception that vertical motions driven by aquifer depletion necessarily equate to near‐field subsidence. In the High Plains system, depletion causes near‐field uplift because of the combination of mass removal and the style of geologic reservoir. As current climate change models predict aggravated drought conditions in the southern Great Plains in the coming decades, we expect to see an increasing rate of uplift caused by groundwater depletion unless there is offsetting recharge or changes in water resource management.

We present a suite of strain rate models for the western United States based on geologic and geodetic data. The geologic data consist of Quaternary fault-slip rates and the geodetic data consists of a new compilation of Global Positioning System (GPS) velocities derived from continuous, semicontinuous, and campaign measurements. We remove postseismic deformation from the GPS time series in order for our geodetic strain rate model to best capture the interseismic strain accumulation rate. We present models based on either geologic or geodetic data, but also create a hybrid model. Although there are some differences between the models, the large-scale features are the same, with the noticeable exception for the Pacific Northwest where interseismic strain is naturally more distributed than the long-term strain release. We also present a map of earthquake rate densities based on mainshocks, and the result has similar spatial features similar to the strain rate models (at least in the southwestern United States). We perform a general correlation analysis between strain rate and seismicity rate (south of Cascadia) and find a change in linearity between seismicity and strain rates from slow to faster deforming areas with seismicity rates relatively lower for the latter. The extent of that change depends a bit on assumptions made on the declustering and completeness of the catalog, but the finding of a change in slope is robust across the different strain rate models. Linearity for all areas is only expected when Gutenberg–Richter parameters and parameters involved in the conversion from strain to moment rate are uniform across the study area. We discuss these qualifications, but find no single satisfactory explanation for our observation. Moreover, when considering a rather short time and space, theoretical considerations of sampling from a power-law distribution actually predict there to be a power law instead of a linear relationship, generally consistent with our observation.

Relative sea-level rise is a major coastal hazard affecting about half the population of the United States.The Chesapeake Bay is characterized by the fastest rate of sea-level rise along the Atlantic coast of North America, in part because of land subsidence.Previous studies have quantified a range of land subsidence rates in the Chesapeake Bay (˜1-4 mm/yr) from various measurement techniques that contribute to high rates of relative sea-level rise.In this study, we present progress towards developing a new vertical land motion map for the Chesapeake Bay region to provide more robust constraints on estimates of relative sea-level rise.We are using a combination of GNSS observations and InSAR interferograms.Available continuous GNSS data in the region that span November 2014 -September 2020 are processed with GAMIT-GLOBK to align temporally with available Sentinel-1 InSAR satellite data.We are using an approach that combines the two geodetic observations to provide a new solution of vertical land motions for the Chesapeake Bay.Additionally, this project is collecting new campaign GNSS observations across the Chesapeake Bay each fall for 5 years, beginning in 2019.We will also present about the 2020 and planned 2021 campaign GNSS observations, which will ultimately be incorporated into our new map of vertical land motions for the region.The impacts of this work will be improved flooding and inundation hazard maps, as well as updated projections for municipal flood mitigation planning that will be created using the new dataset.

Accurate spatial models of tectonic plates and geological terranes are important for analyzing and interpreting a wide variety of geoscientific data and developing compositional and physical models of the lithosphere. We present a global compilation of active plate boundaries and geological provinces in a shapefile format with interpretive attributes (e.g., crust type, plate type, province type, last orogeny). The initial plate and province boundaries are constructed from a combination of published global and regional models that we refine using a variety of geoscientific constraints including, but not limited to, relative GPS motions, earthquakes, mapped faults, potential field characteristics, and geochronology. These new plate model show improved correlation to observed earthquake and volcano occurrences within deformation zones and microplates, compared to existing models, capturing 73 and 80% of these criteria, respectively. Deformation zones and microplates only account for 16% of Earth's surface area. We estimate 57.5% of the Earth's surface is covered by oceanic crust, which is a slight increase relative to the most recent seafloor age model. The model of last orogenies agrees well with peaks in the globally summed geochronology data. There is room for improvement in future editions of our global plate and geologic provinces model where basins, ice, or lack of geological data fidelity obscure bedrock geology, particularly in the eastern Central Asian Orogenic Belt, much of Africa, East Antarctica, and eastern Australia. Additionally, some province types—orogens, shields, and cratons that are homogenized within our global scheme—can likely be partitioned into smaller terranes with more precise geodynamic attributes. Despite some of these shortcomings, the digital maps presented here form a self-consistent data standard for adding spatial metadata to geoscientific databases. The database is available on GitHub where the geoscience community can provide updates to improve the models and their contemporaneity as new knowledge is acquired. The files are also released in formats suitable for use in Generic Mapping Tools and GoogleEarth.

We estimate the rates and patterns of vertical land motion (VLM) on all locations on Earth's land surface using GPS Imaging. The solution is based on a large database of uniformly processed GPS data from solutions that are aligned to the International Terrestrial Reference Frame. We provide global maps and estimates of VLM at all tide gauges of the Permanent Service for Mean Sea Level to better constrain the difference between geocentric and relative sea level rise. To enable critical assessment of the VLM estimate, the temporal and spatial contributions to rate uncertainty and variability are generated and included for every gauge. Seasonality and trends of uplift are assessed and found to be strongly correlated with observations from gravity data suggesting that loading from the terrestrial hydrosphere is a dominant driver of non‐glacial isostatic adjustment (non‐GIA) VLM. Although stations are dominantly concentrated at subsiding parts of continents, GPS Imaging geographically balances VLM signals, correcting for bias associated with network distribution. This allows us to make a global assessment of the budget of uplift and subsidence attributable to GIA and non‐GIA sources. We show that the surface motion of the continents is on average upward, implying that the unobserved areas (composed of the ocean basins and ice‐covered areas) move on average downward with respect to Earth center. However, after correcting for the GIA the reverse is true, and observed areas subside on average implying that the unobserved areas undergo net non‐GIA‐related uplift.

Although Earth's surface motion is well known, the flow field in the underlying mantle is not. Mantle flow is typically calculated on the basis of inferred density variations, and flow directions can also be reflected in seismically observed anisotropy, but those observations leave ambiguity on the depth and direction of the deformation. Anisotropy orientations in East Asia, outside Tibet, have been interpreted in various ways and have often been linked to deformation in the asthenosphere related to absolute plate motion and/or mantle wedge deformation. Here, we re-analyze published seismic anisotropy data and find that orientations outside Tibet can be much better explained when considering absolute plate motion (APM) of the Earth's surface in addition to coherent sub-asthenospheric mantle flow, than when comparing orientations to APM alone. The direction and magnitude of the required sub-asthenospheric flow depend on the absolute reference frame used for the surface velocities, but when considering an APM frame with an intermediate global net-rotation we find an eastward flow of 1-2 cm/yr. This flow is faster than the surface motion, and generally in the same direction, from which we conclude that the mantle leads the plate motion. Our inferred flow is similar to those independently calculated based on buoyancy forces driven by density variations, most notably the high density anomalies associated with the western Pacific subduction zones, but possibly also the upwelling underneath Africa. Additionally, based on our predicted sub-asthenospheric flow and absolute motion of the lithosphere, we predict asthenospheric-based XKS orientations underneath all of east Asia and find it to differ significantly with observed XKS orientations where either the lithosphere is thick and/or strain rate is high, which suggests that at those places observed XKS orientations reflect the integrated deformation in both asthenosphere and lithosphere.

We distinguish between two models of solid Earth's viscous response to unloading of the Laurentide ice sheet over the past 26,000 years. The upper mantle viscosity in both models is 0.5 x 1021 Pa s. The viscosity of the top 700 km of the lower mantle (670 –1370 km) in model L17 is 13 x 1021 Pa s, eight times larger than the value of 1.6 x 1021 Pa s in ICE-6G_D (VM5a). In ICE-6G_D (VM5a), viscous relaxation of solid Earth was rapid 8,000 years ago and is slow today, with present-day uplift at the Laurentide ice center being 12 mm/yr. In L17, solid Earth relaxed more slowly 8,000 years ago but is faster today, with present uplift of the ice center at 20 mm/yr. The significant difference is not due to different ice histories given that total ice loss in L17 is just 12% less than in ICE-6G_D. We determine a comprehensive set of GPS uplift rates for North America that is more accurate than in prior studies due to (1) more sites and a longer data time history, (2) removal of elastic loading produced by increase in Great Lakes water, and (3) technical advances in GPS positioning that have significantly reduced the dispersion in position estimates. We find uplift at the ice center to be about 12 mm/yr, supporting low value of the viscosity of the top 700 km of the lower mantle in ICE-6G_D (VM5a), but ruling out the high value in L17.