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The Green's function approach is well‐established and widely used for modeling the surface mass loading displacements. Global mean Green's functions (MGFs) are commonly applied without considering local variations of the crustal structure. Derived from the modified layered Earth structure, the local Green's functions (LGFs) are theoretically beneficial to generate more accurate deformation, since they consider interior information of the local crust. This paper analyzed the differences among MGFs from Gutenberg–Bullen A model and two sets of LGFs derived from modified PREM Earth models consolidating with two crust models TEA12 and CRUST1.0, hereafter called PREMTEA and PREMCRU, respectively. Utilizing MGFs and two sets of LGFs, we modeled the corresponding 3D atmospheric loading displacements for 984 ITRF2014 stations and compared them with the ITRF2014 residuals. The results show that LGFs from PREMTEA and PREMCRU perform well in further promoting scatter reduction for ∼72%, ∼56%, and ∼85% of stations for the Up, East and North components, respectively. The improvements for the North components are significant (up to 3.6%). In particular, stations in the east coastal areas of North America and the west edge of Greenland exhibit further promoting scatter reduction for the East components (up to ∼2.5%), while those located in west coastline of North America show better performance for the North components. Nevertheless, there are significant anomalies in northern Europe for PREMCRU, the mutation margin of which should be carefully considered when using a resolution higher than 1°. In the area around station MORP (358.31°W, 55.21°N, sited at coastline of Britain), we suggest using PREMTEA model. Plain Language Summary: In any location worldwide, we employ a consistent set of numbers, known as load Green's functions that characterize the elastic properties of the Earth, to model the deformation caused by mass transfer on Earth's surface, which is referred to as surface mass loading effects. Most research and data products adopt same set of global mean Green's functions for any location on Earth, which neglects the differences in elastic properties of various regions of the Earth, leading to modeling errors to some extent. This study aims to optimize the modeling using local load Green's functions, with the objective of obtaining results that are more theoretically valuable. "Local" means that the Green's functions for each site are derived from an Earth model that takes into account the local crustal structure. The modeled atmospheric loading displacements exhibit enhanced alignment with GNSS position time series. This, in turn, further elucidates that deformations can be more attributed to atmospheric loading. Moreover, the model shows improved performance in the horizontal components when compared to the vertical components. Key Points: Local load Green's Functions enable a more precise modeling of loading displacements than global mean Green's FunctionsThe modeled atmospheric loading displacements based on Local Green's Functions can improve scatter reduction of GNSS position time seriesTwo sets of local load Green's Functions, based on CRUST1.0 model and TEA12 model, are compared. We recommend TEA12 for European region [ABSTRACT FROM AUTHOR]

The adverse effect of the ionospheric scintillation on Global Navigation Satellite System (GNSS) requires scintillation monitoring on a global scale. Ionospheric Scintillation Monitoring Receivers (ISMR) are usually adopted to monitor scintillation, while they are not suitable for global monitoring due to the 50 Hz data collecting rate, which restricts the distribution. This paper proposes a new method to extract the phase scintillation index from each GNSS carrier with 1s‐sampling‐interval, mainly based on the cycle slip detection, the geodetic detrending and the wavelet transform, in which the optimal symmetry parameter and the time‐bandwidth product are determined with trial calculation. Taken the σϕ ${\sigma }_{\phi }$ index provided by ISMR as the reference, 1‐year observations are utilized to evaluate the scintillation monitoring performance of the extracted index regarding the correlation of the magnitude in each observation arc, the detected daily scintillation occurrence rate, the diurnal variation pattern of the ionospheric scintillation, the correlation between the scintillation occurrence rate and the space weather parameter, and the complementary cumulative distribution of the magnitudes. Compared to the performance of Rate of Total electron content Index, a higher consistency can be achieved between the extracted index and the σϕ ${\sigma }_{\phi }$ index, indicating the rationality of applying the proposed method in monitoring scintillations. The extracted scintillation index can be expected to introduce geodetic receivers operating at 1s‐sampling‐interval into the field of ionospheric scintillation monitoring on a global scale. Plain Language Summary: Small scale structures in the ionosphere will interfere with the amplitude and phase of the Global Navigation Satellite System (GNSS) signals passing through them. This phenomenon is called ionospheric scintillation, which can affect the positioning navigation and timing services of GNSS, calling for the need of monitoring ionospheric scintillations on a global scale. A special type of receiver, called Ionospheric Scintillation Monitoring Receiver (ISMR), is usually needed in ionosphere monitoring. However, due to the high sampling rate and price, the distribution of ISMR is limited, making it impossible to realize large‐scale ionospheric scintillation monitoring using only ISMR. In order to solve this problem, this paper proposes a new method to extract the scintillation index from the widely distributed geodetic receivers. Although the existing Rate of Total electron content Index (ROTI) can also use geodetic receivers for ionospheric scintillation monitoring, experiments based on long‐period observations collected in the Arctic region of the North America show that the extracted scintillation index can be more accurate than ROTI and the scintillation information on each carrier can be provided. The extracted scintillation index provides a basis for realizing global ionospheric scintillation monitoring and modeling in the future. Key Points: A new method is proposed to extract the scintillation index by applying cycle slip detection, geodetic detrending and wavelet transformThe scintillation index can be extracted from each carrier of the 1s‐sampling‐interval Global Navigation Satellite System observationsThe extracted scintillation index can provide a consistent performance in monitoring scintillation as that given by Ionospheric Scintillation Monitoring Receiver [ABSTRACT FROM AUTHOR]

This manuscript presents the analysis of data from multiple ground‐ and space‐based sensors in the North American region before, during, and after the 12 October 2021 geomagnetic storm. Total electron content (TEC) and electron density data show the formation and equatorward propagation of a mid‐latitude trough at ∼50°N followed by the appearance of a wider depletion region (∼15° in latitude) at lower latitudes. During the recovery phase on the 13th, the equatorward edge of this depletion region settled at around 30° latitude and exhibited a steep density gradient. By the 14th, this sharp boundary had disappeared. Near this edge on the 13th, small‐scale irregularities formed. The impact of these was observed within Global Positioning System data as elevated rate of TEC index (ROTI) and presented as strong 35 MHz scintillations of cosmic radio sources as well as spread‐F within ionograms from multiple digisonde systems. GPS and 35‐MHz data demonstrated that the irregularity region was narrowly confined (≲5° wide) near the edge of the depletion region. The 35‐MHz scintillation data also showed that the irregularities were moving relatively slowly at ∼7 m s−1, likely toward the southeast. Density and velocity measurements demonstrated that the conditions near the depletion boundary were highly favorable to the gradient drift instability (GDI) with the one‐dimensional growth rate estimated to be ∼0.01 s−1. Since these conditions persisted for many hours, this growth rate was more than sufficient for the GDI to be considered the primary driver of irregularity formation in this case. Plain Language Summary: Earth's ionosphere, the ionized portion of the upper atmosphere, is a dynamic environment, often beset with irregularities and disturbances that interfere with radio frequency signals that travel through it. In this regard, mid‐latitudes are usually quite tame relative to the equatorial and polar regions. However, when significant geomagnetic disturbances, or "storms," occur, this normally placid region can become anything but. This paper presents the results of a study that examines the impact of a storm over North America, using several space‐ and ground‐based sensors. Of particular interest is the formation of a density depletion region during the recovery period following the onset of the storm. Multiple sensors show evidence of this depletion and still others show a preponderance of small‐scale irregularities (as small as a few kilometers) near its southern boundary. A holistic analysis indicates that these irregularities are consistent with a turbulent cascade moving relatively slowly, likely toward the south or southeast. Conditions near the depletion edge were observed to be conducive with the so‐called gradient drift instability. This is known to be a primary driver of irregularity formation within other settings, and appears to be the culprit in this case as well. Key Points: A multitude of ground‐ and space‐based sensors were used to study a storm‐induced mid‐latitude ionospheric depletion over North AmericaIrregularities at the equatorward edge of the depletion at ∼30°N were detected with radio frequency systems from a few MHz to 1.5 GHzSpace‐based in situ and remote sensing data point to the gradient drift instability as the most likely driver of irregularity formation [ABSTRACT FROM AUTHOR]

This paper reports the first high‐resolution 4‐dimensional ionospheric disturbance caused by hurricane Matthew on 7 October 2016. The temporal as well as vertical and horizontal variations of the concentric traveling ionospheric disturbances (CTIDs) were reconstructed using 3‐dimensional computerized ionospheric tomography (3DCIT) technology, based upon the Global Navigation Satellite System data from the dense receiver network over North America. The frequency range of disturbances was determined by spectrum analysis, and a Butterworth band‐pass filter was used to de‐trend the total electron content (TEC) sequences to determine TIDs. A remarkable CTID segment was detected at a distance of 1,000–1,500 km from the hurricane eye at ∼5:40–6:10 UT on 7 October 2016, moving westward with the horizontal phase velocity of ∼153.4 m/s, the period of ∼30 min and the horizontal wavelength of ∼276.1 km. The positive and negative wavefronts dominated the CITD at different times during the event. From 4:00 to 8:00 UT, the altitudinal variation of the CTIDs in electron density exhibited clear downward phase progression predominately in the range of 150–400 km altitudes; however, the percentage of electron density disturbances was larger below 250 km. The inverted cone‐like geometry of CTID wavefronts was presented. The vertical phase velocities of the CTIDs ∼1,100 km away from the hurricane eye in the northwest direction near 88°W, 34°N were ∼203.7–277.8 m/s, and at the same location, the horizontal phase velocities at 300 km altitude were ∼149.1–181.5 m/s, slightly larger than those at 200 km altitude (∼145.1–178.5 m/s). Key Points: The propagation features of concentric traveling ionospheric disturbances (CTID) caused by Hurricane Matthew on 7 October 2016 were analyzedFirst 4‐dimensional CTIDs caused by hurricane were reconstructed using ionospheric tomographyThe horizontal phase velocities at different altitudes and the vertical phase velocities of the ionospheric disturbances were estimated [ABSTRACT FROM AUTHOR]

Medium‐scale Traveling Ionospheric Disturbances (MSTIDs) are prominent and ubiquitous features of the mid‐latitude ionosphere, and are observed in Super Dual Auroral Radar Network (SuperDARN) and high‐resolution Global Navigational Satellite Service (GNSS) Total Electron Content (TEC) data. The mechanisms driving these MSTIDs are an open area of research, especially during geomagnetic storms. Previous studies have demonstrated that nightside MSTIDs are associated with an electrodynamic instability mechanism like Perkins, especially during geomagnetically quiet conditions. However, dayside MSTIDs are often associated with atmospheric gravity waves. Very few studies have analyzed the mechanisms driving MSTIDs during strong geomagnetic storms at mid‐latitudes. In this study, we present mid‐latitude MSTIDs observed in de‐trended GNSS TEC data and SuperDARN radars over the North American sector, during a geomagnetic storm (peak Kp reaching 9) on 7–8 September 2017. In SuperDARN, MSTIDs were observed in ionospheric backscatter with Line of Sight (LOS) velocities exceeding 800 m/s. Additionally, radar LOS velocities oscillated with amplitudes reaching ±500 m/s as the MSTIDs passed through the fields‐of‐view. In detrended TEC, these MSTIDs produced perturbations reaching ∼50 percent of background TEC magnitude. The MSTIDs were observed to propagate in the westward/south‐westward direction with a time period of ∼15 min. Projecting de‐trended GNSS TEC data along SuperDARN beams showed that enhancements in TEC were correlated with enhancements in SuperDARN SNR and positive LOS velocities. Finally, SuperDARN LOS velocities systematically switched polarities between the crests and the troughs of the MSTIDs, indicating the presence of polarization electric fields and an electrodynamic instability process during these MSTIDs. Key Points: Medium‐scale Traveling Ionospheric Disturbance (MSTID) signatures were observed in Global Navigational Satellite Service Total Electron Content and Super Dual Auroral Radar Network (SuperDARN) ionospheric backscatter during a strong geomagnetic stormMSTID characteristics were broadly consistent between the data sets, with periods of 10–20 min and phase speeds of ∼800 m/sSuperDARN Line of Sight velocities systematically switched polarities between MSTID crests and troughs, indicating polarization electric fields [ABSTRACT FROM AUTHOR]

An updated global climatology of blanketing sporadic E (Es) is developed from a combined data set of Global Positioning System (GPS) radio occultation (RO) and ground‐based ionosonde soundings over the period of September 2006–January 2019. A total of 46 sites and 3.2 million total soundings from the Global Ionosphere Radio Observatory network in combination with 3.0 million occultations from the Constellation Observing System for Meteorology, Ionosphere, and Climate constellation are used to calculate global occurrence rates (ORs) for two blanketing frequency thresholds: all blanketing sporadic‐E with no limit on intensity (all‐Es) and moderate‐Es with fbEs ≥ 3 MHz. Following the GPS‐RO to ionosonde comparison by Carmona et al. (2022), https://doi.org/10.3390/rs14030581 the all‐Es rates are calculated using ionosonde data and an amplitude‐based S4 threshold for the GPS‐RO data while the moderate‐Es rates use a primarily phase‐based technique. Occurrence rates are separated by intensity, season, month, and solar local time for quiet geomagnetic conditions. Overall, the general geomagnetic trends agree with previous Es climatologies and the ORs peak near 50% for all‐Es and 25% for moderate‐Es measured in the mid‐latitudes during local summer in the late afternoon. Low ORs are observed near the South Atlantic Anomaly and North America, and a general asymmetry is observed between hemispheres with higher ORs in the Northern Hemisphere. High‐latitude and late morning blanketing Es are found to be stronger but less frequent with rates nearly equal to the moderate‐Es mid‐latitude maximums. Plain Language Summary: A global climatology for sporadic‐E occurrence is developed using a combination of GPS radio occultation and ionosonde measurements for two intensity thresholds. The global OR trends generally follow the results of many previous studies with peaks in the mid‐latitudes of the local summer hemisphere during late afternoon. However, the OR magnitudes differ from previous studies as the inclusion of ionosonde data provides a "ground‐truth" to determine the best Global positioning satellite radio occultation technique for a given intensity threshold. From this, peak occurrence rates of nearly 50% are observed for sporadic‐E with no lower limit on intensity, and 25% for moderate intensity blanketing sporadic‐E. Key Points: An updated global sporadic‐E climatology is presented for two intensity thresholds using a combination of global positioning satellite radio occultation and ionosonde observationsPeak rates of 50% for blanketing Es with no intensity threshold and 25% for moderate‐Es are observed in mid‐latitudes during local summerGlobal trends are similar for both thresholds with high‐latitude sporadic‐E shown to be stronger but less frequent [ABSTRACT FROM AUTHOR]

Interference competition occurs when two species have similar resource requirements and one species is dominant and can suppress or exclude the subordinate species. Wolves (Canis lupus) and coyotes (C. latrans) are sympatric across much of their range in North America where white‐tailed deer (Odocoileus virginianus) can be an important prey species. We assessed the extent of niche overlap between wolves and coyotes using activity, diet, and space use as evidence for interference competition during three periods related to the availability of white‐tailed deer fawns in the Upper Great Lakes region of the USA. We assessed activity overlap (Δ) with data from accelerometers onboard global positioning system (GPS) collars worn by wolves (n = 11) and coyotes (n = 13). We analyzed wolf and coyote scat to estimate dietary breadth (B) and food niche overlap (α). We used resource utilization functions (RUFs) with canid GPS location data, white‐tailed deer RUFs, ruffed grouse (Bonasa umbellus) and snowshoe hare (Lepus americanus) densities, and landscape covariates to compare population‐level space use. Wolves and coyotes exhibited considerable overlap in activity (Δ = 0.86–0.92), diet (B = 3.1–4.9; α = 0.76–1.0), and space use of active and inactive RUFs across time periods. Coyotes relied less on deer as prey compared to wolves and consumed greater amounts of smaller prey items. Coyotes exhibited greater population‐level variation in space use compared to wolves. Additionally, while active and inactive, coyotes exhibited greater selection of some land covers as compared to wolves. Our findings lend support for interference competition between wolves and coyotes with significant overlap across resource attributes examined. The mechanisms through which wolves and coyotes coexist appear to be driven largely by how coyotes, a generalist species, exploit narrow differences in resource availability and display greater population‐level plasticity in resource use. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed velocities based on the Global Positioning System (GPS) with respect to both North American and Caribbean plate reference frames. Relative motion between the Caribbean and North American plates; Data acquisition through the GPS; Geological and tectonic implications.

Presents a study on the motion of the Sierra Nevada block and some tectonic implications for the Basin and Range province in the North American Cordillera based on global positioning system data. Vertical motion, data quality, monument noise and local effects; Rigidity of the Sierra Nevada block; Block rotation and `missing' rotation; Deformation in the Basin and Range province.