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8/11/2019 Henton Et Al an Updated Canadian GPS Velocity Field Using NRCans Precise Point Positioning PPP Software Plans and Preliminary Results
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An updated Canadian GPS velocity field using NRCansPrecise Point Positioning (PPP) Software
Plans and preliminary results
J. Henton 1, M. Craymer 2, M. Piraszewski 2 and E. Lapelle 2
1 Geodetic Survey Division, Natural Resources Canada (Sidney, BC)2 Geodetic Survey Division, Natural Resources Canada (Ottawa, ON)
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National-Scale PPP Processing Introduction & Rationale
Scope of Processing Effort
Preliminary Results
Summary of Plans Acknowledgements
Examples of Other NRCan Applications for PPP Results
(Successes, Opportunities, Challenges)
Presentation Outline
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In an effort to continuously improve and refine previouscontinental-scale GPS velocity fields for Canada (inparticular), we process data from nearly all continuousGPS (cGPS) sites in Canada, the northern portions of theUS including Alaska, Greenland as well as a set of global
sites used to define the reference frame.
In addition, repeated high accuracy campaign surveys ofthe Canadian Base Network (CBN) are included in ouranalyses.
Results from NRCans PPP software will be integratedwith cGPS & CBN solutions for increased redundancy.
Introduction
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Contribute to the NAREF initiative
Generate a national Canadian velocity grid forinterpolation to any point
Support national and regional NRCan studies ofgeophysical processes
Rationale
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NORTH AMERICAN REFERENCE FRAME (NAREF) OBJECTIVES
IAG Sub-commission 1.3c(Regional Reference Frames for North America)
To densify the ITRF reference frame in North America
Consolidate regional networks into a continental one
Integrate into ITRF via IGS global network
Produce coordinate solutions Weekly solutions/combinations Cumulative solutions with velocity estimates
Rationale NAREF Initiative
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High accuracy cGPS sites in Canada, northern US (Great
Lakes) & Alaska, and Greenland; Data spanning 2000 (TBC) to current
Processing with Bernese 5.2 & NRCan PPP (using latestIGS satellite products);
Global IGS sites included to define reference frame; Cumulative solution (coordinates and velocities)produced using NRCans updated SINEX_COMBINEsoftware;
Using ITRF-published set of time series discontinuities
for ITRF sites Examine time series of all sites for additional
discontinuities
Scope of Processing Effort - Continuous GPS (I)
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Scope of Processing Effort - Continuous GPS (II)
CBN Sites
RF Sites
Based upon
previous GSB
(GSD Bernese
v5.0) Solution &
Combination:
568 sites
20002011.29
589 weekly
solutions
New effort willinclude more
cGPS sites.
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Scope of Processing Effort - Continuous GPS (III)
Global RF Sites
Based uponprevious GSB
(GSD Bernese
v5.0) Solution &
Combination:
117 global IGSsites used to
define reference
frame (RF).
New effort will
be updated toinclude current
IGS RF sites.
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Repeated survey campaigns of the Canadian Base
Network (CBN) Network of stable pillar monuments
Forced centering antenna mounts
Covers mainly southern half of Canada (sparser in north)
Multiple (3-4) 24 hr occupations of each site
60 survey campaigns from 1994 to current 1st national campaign 1994 2000 (no 1998)
2nd national campaign 2001(east) 2002(west)
3rd national campaign 2005(east) 2006(west) 4th national campaign 2010(east) 2011(west)
Many smaller campaigns occupied a few CBN sites
Scope of Processing Effort - Episodic GPS (I)
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CBN Sites
RF Sites
CBN Site - 94K0016LES-DE-LA-MADELEINE
(Qubec)
CBN Site - 87K1003PORT-CARTIER (PILIER A)
(Qubec)
Scope of Processing Effort - Episodic GPS (II)
Use identical
procedures &
softwares as
for continuous
processing;
Stack daily
solutions into
campaign
solutions
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Results: Vertical Rates (Previous Combination)
GSB & CBN
solutions (rates& coordinates
both aligned
and integrated
with ITRF2008
GIA signal isapparent across
Canada.
Also, signals
from western
plate margindeformation
processes are
present.
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Results: Regional Preliminary PPP Vertical Rates
[from: James et al (2012), 2012 AGU Fall Meeting]
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Results: Regional Comparison of Vertical Velocities
Plot Courtesy of Andrea Darlington (NRCan & UVic)
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We have begun to process GPS data with NRCansPrecise Point Positioning (PPP) software using the mostcurrent IGS orbits, precise clocks and absolute antennacalibrations together with the Vienna Mapping Function(VMF1) for the tropospheric model.
The PPP software is efficient for processing large arraysand preliminary rate results have proven comparable tothose from Bernese (v5.0).
Soon, we will initiate PPP processing (and integratedsolutions) for all GSB & CBN sites to provide completeredundancy for the Bernese (v5.2) results.
Summary General Plans for National PPP Processing
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Evaluate other processing and analysis products (e.g.):
VMF1 products from University of New Brunswick (UNB) Atmospheric pressure loading (and other loading) corrections
Implement procedures to produce PPP networkcoordinate files using GSDs updated SINEX software
Begin integration with new GSB solutions (and NAREF?)
Automate search for discontinuities in all time series
Generate cumulative (coordinate & rate) solutions Using updated SINEX_COMBINE software
Routine cumulative solutions (rather than as-needed)
Summary Specific (Near) Future Plans
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Provincial geodetic agencies for providing access to their cGPS
data;
GSD and provincial geodetic agencies for installation of highlystable CBN monumentation;
GSD field survey personnel for consistently providing highlyaccurate GPS survey campaigns;
Franois Lahaye (GSD) for support with PPP software(on behalf of the PPP development team);
Rmi Ferland (GSD) for SINEX combination software and support;
Andrea Darlington (GSC & UVic) for preliminary PPP analyses.
Acknowledgements
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Regional RSL Studies: GPS Vertical Rates (PPP)
Land subsidence inNova Scotia, with
transition to uplift at
the mouth of St.
Lawrence River
Pattern is consistent
with paleo-sea-levelrecord, and with
models of postglacial
rebound (PGR)
from: James et al (2012),
2012 AGU Fall Meeting
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Regional RSL Studies: Tide Gauge Trends
[from: James et al (2012), 2012 AGU Fall Meeting]
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Regional RSL Studies: Eustatic Sea-level Change
Tide Gauge Trend
minus GPS Trend
Average observed
sea-level change is
1.8 0.7 mm/yr
(tg analysis ends 2006)
(Weighted average2.0 mm/yr)
IPCC AR4 20th century
global estimate is
1.8 0.5 mm/yr
Success: Comparison
gives confidence in GPS
uplift rates.
[from: James et al (2012), 2012 AGU Fall Meeting]
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Cascadia ETS Studies - Introduction
Image Courtesy of Herb Dragert (NRCan)
Deep Slip Event
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Cascadia ETS Studies Signal from Strainmeter Site
Borehole strainmeters (BSM) provide a continuous precise deformation signal.
However the distribution of these instruments is more limited than GPS sites and
they can be affected by large non-tectonic signals (e.g. drift & hydrological loading).
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Cascadia ETS Studies Signal from GPS Site
Challenge: To better constrain the timing of ETS migration, can we achieve
precise sub-daily positions through PPP?
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Earthquake Monitoring Studies
For the Thoku earthquake (and aftershocks) NRCans carrier-phase correction
service HPGPSC is used to simulate real-time epoch-by-epoch positions.
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Earthquake Monitoring Studies Offsets I
Elastic model deformation from a simplified Nootka Fault Zone strike-slip earthquake (Mw = 7.35)
ELIZ
E = -0.046m
N = -0.309m
U = -0.020m
NTKA
E = 0.281m
N = -0.025m
U = 0.023m
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ELIZ
E = -2.342m
N = -2.599m
U = -0.934m
NTKA
E = -0.386m
N = -0.164m
U = -0.108m
Elastic model deformation from a simplified Explorer Plate subduction earthquake (Mw = 8.15)
Earthquake Monitoring Studies Offsets II