henton et al an updated canadian gps velocity field using nrcan’s precise point positioning ppp...

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



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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.



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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

henton et al an updated canadian gps velocity field using nrcan’s precise point positioning ppp...

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