scholarly journals The use of «native» wavelet transform for determining lateral density variation of the Volgo-Uralian subcraton

2021 ◽  
pp. 135-140
Author(s):  
I. N. Ognev ◽  
◽  
E. V. Utemov ◽  
D. K. Nurgaliev ◽  
◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Gravity Field ◽  
Regional Scale ◽  
Density Variation ◽  
Gravity Modeling ◽  
Regional Models ◽  
Residual Gravity ◽  
Satellite Gravimetry ◽  
Scale Models ◽  
Residual Gravity Anomaly

In the last two decades in conjunction with the development of satellite gravimetry, the techniques of regional-scale inverse and forward gravity modeling started to be more actively incorporated in the construction of crustal and lithospheric scale models. Such regional models are usually built as a set of layers and bodies with constant densities. This approach often leads to a certain difference between the initially used measured gravity field and a gravity field that is produced by the model. One of the examples of this kind of models is a recent lithospheric model of the Volgo-Uralian subcraton. In the current study, we are applying the method of «native» wavelet transform to the residual gravity anomaly for defining the possible lateral density variations within the lithospheric layers of Volgo-Uralia. Keywords: wavelet transform; gravity field inversion; forward gravity modeling; Volgo-Uralian subcraton; satellite gravimetry.

scholarly journals Two-scale multi-model ensemble: is a hybrid ensemble of opportunity telling us more?

2018 ◽  
Vol 18 (12) ◽  
pp. 8727-8744 ◽  
Author(s):  
Stefano Galmarini ◽  
Ioannis Kioutsioukis ◽  
Efisio Solazzo ◽  
Ummugulsum Alyuz ◽  
Alessandra Balzarini ◽  
...  
Keyword(s):  
Time Series ◽  
Air Quality ◽  
Surface Ozone ◽  
Regional Scale ◽  
Probability Of Detection ◽  
Daily Maximum ◽  
Regional Models ◽  
Global Models ◽  
Ensemble Performance ◽  
Scale Models

Abstract. In this study we introduce a hybrid ensemble consisting of air quality models operating at both the global and regional scale. The work is motivated by the fact that these different types of models treat specific portions of the atmospheric spectrum with different levels of detail, and it is hypothesized that their combination can generate an ensemble that performs better than mono-scale ensembles. A detailed analysis of the hybrid ensemble is carried out in the attempt to investigate this hypothesis and determine the real benefit it produces compared to ensembles constructed from only global-scale or only regional-scale models. The study utilizes 13 regional and 7 global models participating in the Hemispheric Transport of Air Pollutants phase 2 (HTAP2)–Air Quality Model Evaluation International Initiative phase 3 (AQMEII3) activity and focuses on surface ozone concentrations over Europe for the year 2010. Observations from 405 monitoring rural stations are used for the evaluation of the ensemble performance. The analysis first compares the modelled and measured power spectra of all models and then assesses the properties of the mono-scale ensembles, particularly their level of redundancy, in order to inform the process of constructing the hybrid ensemble. This study has been conducted in the attempt to identify that the improvements obtained by the hybrid ensemble relative to the mono-scale ensembles can be attributed to its hybrid nature. The improvements are visible in a slight increase of the diversity (4 % for the hourly time series, 10 % for the daily maximum time series) and a smaller improvement of the accuracy compared to diversity. Root mean square error (RMSE) improved by 13–16 % compared to G and by 2–3 % compared to R. Probability of detection (POD) and false-alarm rate (FAR) show a remarkable improvement, with a steep increase in the largest POD values and smallest values of FAR across the concentration ranges. The results show that the optimal set is constructed from an equal number of global and regional models at only 15 % of the stations. This implies that for the majority of the cases the regional-scale set of models governs the ensemble. However given the high degree of redundancy that characterizes the regional-scale models, no further improvement could be expected in the ensemble performance by adding yet more regional models to it. Therefore the improvement obtained with the hybrid set can confidently be attributed to the different nature of the global models. The study strongly reaffirms the importance of an in-depth inspection of any ensemble of opportunity in order to extract the maximum amount of information and to have full control over the data used in the construction of the ensemble.

Cross-Scale Assessment of Potential Habitat Shifts in a Rapidly Changing Climate

2014 ◽  
Vol 7 (3) ◽  
pp. 491-502 ◽  
Author(s):  
Catherine S. Jarnevich ◽  
Tracy R. Holcombe ◽  
Elizabeth M. Bella ◽  
Matthew L. Carlson ◽  
Gino Graziano ◽  
...  
Keyword(s):  
Regional Scale ◽  
Local Scale ◽  
Suitable Habitat ◽  
Climatic Data ◽  
Local Models ◽  
Regional Models ◽  
Changing Climate ◽  
Scale Models ◽  
Near Term

AbstractWe assessed the ability of climatic, environmental, and anthropogenic variables to predict areas of high-risk for plant invasion and consider the relative importance and contribution of these predictor variables by considering two spatial scales in a region of rapidly changing climate. We created predictive distribution models, using Maxent, for three highly invasive plant species (Canada thistle, white sweetclover, and reed canarygrass) in Alaska at both a regional scale and a local scale. Regional scale models encompassed southern coastal Alaska and were developed from topographic and climatic data at a 2 km (1.2 mi) spatial resolution. Models were applied to future climate (2030). Local scale models were spatially nested within the regional area; these models incorporated physiographic and anthropogenic variables at a 30 m (98.4 ft) resolution. Regional and local models performed well (AUC values > 0.7), with the exception of one species at each spatial scale. Regional models predict an increase in area of suitable habitat for all species by 2030 with a general shift to higher elevation areas; however, the distribution of each species was driven by different climate and topographical variables. In contrast local models indicate that distance to right-of-ways and elevation are associated with habitat suitability for all three species at this spatial level. Combining results from regional models, capturing long-term distribution, and local models, capturing near-term establishment and distribution, offers a new and effective tool for highlighting at-risk areas and provides insight on how variables acting at different scales contribute to suitability predictions. The combinations also provides easy comparison, highlighting agreement between the two scales, where long-term distribution factors predict suitability while near-term do not and vice versa.

scholarly journals Application of global models and satellite data for smaller-scale groundwater recharge studies

2016 ◽  
Author(s):  
Rogier Westerhoff ◽  
Paul White ◽  
Zara Rawlinson
Keyword(s):  
New Zealand ◽  
Satellite Data ◽  
Input Data ◽  
Large Scale ◽  
Regional Scale ◽  
Global Scale ◽  
Global Models ◽  
Scale Models ◽  
Boundary Issues ◽  
Rainfall Recharge

Abstract. Large-scale models and satellite data are increasingly used to characterise groundwater and its recharge at the global scale. Although these models have the potential to fill in data gaps and solve trans-boundary issues, they are often neglected in smaller-scale studies, since data are often coarse or uncertain. Large-scale models and satellite data could play a more important role in smaller-scale (i.e., national or regional) studies, if they could be adjusted to fit that scale. In New Zealand, large-scale models and satellite data are not used for groundwater recharge estimation at the national scale, since regional councils (i.e., the water managers) have varying water policy and models are calibrated at the local scale. Also, some regions have many localised ground observations (but poor record coverage), whereas others are data-sparse. Therefore, estimation of recharge is inconsistent at the national scale. This paper presents an approach to apply large-scale, global, models and satellite data to estimate rainfall recharge at the national to regional scale across New Zealand. We present a model, NGRM, that is largely inspired by the global-scale WaterGAP recharge model, but is improved and adjusted using national data. The NGRM model uses MODIS-derived ET and vegetation satellite data, and the available nation-wide datasets on rainfall, elevation, soil and geology. A valuable addition to the recharge estimation is the model uncertainty estimate, based on variance, covariance and sensitivity of all input data components in the model environment. This research shows that, with minor model adjustments and use of improved input data, large-scale models and satellite data can be used to derive rainfall recharge estimates, including their uncertainty, at the smaller scale, i.e., national and regional scale of New Zealand. The estimated New Zealand recharge of the NGRM model compare well to most local and regional lysimeter data and recharge models. The NGRM is therefore assumed to be capable to fill in gaps in data-sparse areas and to create more consistency between datasets from different regions, i.e., to solve trans-boundary issues. This research also shows that smaller-scale recharge studies in New Zealand should include larger boundaries than only a (sub-)aquifer, and preferably the whole catchment. This research points out the need for improved collaboration on the international to national to regional levels to further merge large-scale (global) models to smaller (i.e., national or regional) scales. Future research topics should, collaboratively, focus on: improvement of rainfall-runoff and snowmelt methods; inclusion of river recharge; further improvement of input data (rainfall, evapotranspiration, soil and geology); and the impact of recharge uncertainty in mountainous and irrigated areas.

scholarly journals Modeling inter-continental transport of ozone in North America with CAMx for the Air Quality Model Evaluation International Initiative (AQMEII) Phase 3

2017 ◽  
Author(s):  
Uarporn Nopmongcol ◽  
Zhen Liu ◽  
Till Stoeckenius ◽  
Greg Yarwood
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
North America ◽  
Regional Scale ◽  
Regional Models ◽  
Phase 3 ◽  
Global Models ◽  
The Us ◽  
Surface O3 ◽  
International Initiative

Abstract. Inter-continental ozone (O3) transport extends the geographic range of O3 air pollution impacts and makes local air pollution management more difficult. Phase 3 of the Air Quality Modeling Evaluation International Initiative (AQMEII-3) is examining the contribution of inter-continental transport to regional air quality by applying regional scale atmospheric models jointly with global models. We investigate methods for tracing O3 from global models within regional models. The CAMx photochemical grid model was used to track contributions from boundary condition (BC) O3 over a North America modeling domain for calendar year 2010 using a built-in tracer module called RTCMC. RTCMC can track BC contributions using chemically reactive tracers and also using inert tracers in which deposition is the only sink for O3. Lack of O3 destruction chemistry in the inert tracer approach leads to over estimation biases that can exceed 10 ppb. The flexibility of RTCMC also allows tracking O3 contributions made by groups of vertical BC layers. The largest BC contributions to seasonal average daily maximum 8-hour averages (MDA8) of O3 over the US are found to be from the mid-troposphere with small contributions from the upper troposphere-lower stratosphere. Contributions from the lower troposphere are shown to not penetrate very far inland. Higher contributions in the Western than the Eastern US, reaching an average of 57 ppb in Denver for the 30 days with highest MDA8 O3 in 2010, present a significant challenge to air quality management approaches based solely on local or US-wide emission reductions. The substantial BC contribution to MDA8 O3 in the Intermountain West means regional models are particularly sensitive to any biases and errors in the BCs. A sensitivity simulation with reduced BC O3 in response to 20 % lower emissions in Asia found a near linear relationship between the BC O3 changes and surface O3 changes in the Western US in all seasons and across the US in fall and winter. However, the surface O3 decreases are small: below 1 ppb in spring and below 0.5 ppb in other seasons.

A Gravity Investigation of the Pickwell Down Sandstone, North Devon

1967 ◽  
Vol 104 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Hamid Nassar Al-Sadi
Keyword(s):  
Bouguer Anomaly ◽  
Gravity Gradient ◽  
Near Surface ◽  
Red Sandstone ◽  
Residual Gravity ◽  
The North ◽  
Thrust Plane ◽  
Residual Gravity Anomaly ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

AbstractThe area to the north of Barnstaple (North Devon) was covered by a detailed gravity survey. The main gravity gradient of the Bouguer anomaly map (estimated to be 1·2 mgals per mile) confirmed the conclusions drawn by Bott et al. (1958), who attributed it to a basin of possibly Carboniferous sediments and/or Old Red Sandstone, about 4 miles thick, separated from the outcropping Devonian rocks by an assumed thrust plane.A negative residual gravity anomaly is located over the outcrop of the Pickwell Down Sandstone. Analyses of the anomaly show that it is caused by the southwards dipping belt of sandstone and that the angle of dip of the formation decreases with depth. At a depth of about 2 miles the formation becomes nearly horizontal. Alternatively, it may terminate against an assumed thrust plane underlying the whole outcropping Devonian.The aeromagnetic map of the area shows an elongated magnetic “high” following the outcrop of the Morte Slates. The anomaly is probably caused by near surface, highly magnetized rocks in association with the Morte Slates.

High-resolution gravity study of the Gray Fossil Site

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. B25-B32 ◽  
Author(s):  
J. L. Whitelaw ◽  
K. Mickus ◽  
M. J. Whitelaw ◽  
J. Nave
Keyword(s):  
High Resolution ◽  
Gravity Anomaly ◽  
Drill Hole ◽  
Structural Features ◽  
Gravity Measurement ◽  
Gray Fossil Site ◽  
Residual Gravity ◽  
Residual Gravity Anomaly ◽  
Fossil Site ◽  
Anomaly Map

The Gray Fossil Site, Washington County, Tennessee, has produced a remarkable Mio-Pliocene fauna and flora with no known correlative in the Appalachian region. After its discovery in 2000, a series of auger holes were drilled by the Tennessee Department of Transportation (TDOT) to determine the areal extent of the site. Drilling indicated that the fossils occurred in fill material within a paleokarst basin, but the distribution of boreholes does not permit details of sinkhole topography, and therefore its formation and fill history, to be adequately resolved. To better image the sinkhole basin, a high-resolution gravity survey, which included 1104 gravity measurement stations, was conducted. These data were used to create complete Bouguer and residual gravity anomaly maps and a 3D density model via inversionmethods. The residual gravity anomaly map compares favorably with 29 TDOT auger holes drilled to basement, but contains significantly more detail. The residual gravity anomaly map reveals the presence of seven separate sinkholes. However, 3D inverse modeling constrained by drill-hole depths and density data indicates that there are 11 separate sinkholes formed within the Knox Group carbonates. These sinkholes, which range between 20 and [Formula: see text] in depth, are aligned along northwest and northeast trending linear features that correlate to structural features formed during the Appalachian orogenies. It is possible that the overall sinkhole basin formed as the result of partial coalescence of multiple sinkhole structures controlled by a joint system and that the sinkholes then acted as a natural trap for the Gray Fossil Site fauna and flora.

Sign in / Sign up

Export Citation Format

Share Document