AIRGrav AIRGrav Stefan Elieff Sander Geophysics Sander Geophysics - - PowerPoint PPT Presentation

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AIRGrav AIRGrav Stefan Elieff Sander Geophysics Sander Geophysics - - PowerPoint PPT Presentation

Apr 15, 2023 224 likes •921 views

MEETING THE CHALLENGES OF MEETING THE CHALLENGES OF DIFFICULT ENVIRONMENTS WITH DIFFICULT ENVIRONMENTS WITH AIRGrav AIRGrav Stefan Elieff Sander Geophysics Sander Geophysics Sander Geophysics Founded in 1956 - currently 160 employees,

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Sander Geophysics

MEETING THE CHALLENGES OF MEETING THE CHALLENGES OF DIFFICULT ENVIRONMENTS WITH DIFFICULT ENVIRONMENTS WITH

AIRGrav AIRGrav

Stefan Elieff Sander Geophysics

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Sander Geophysics

Sander Geophysics

 Founded in 1956 - currently 160 employees, 16 aircraft  Head office at Ottawa International Airport, Canada  World-wide operations – fixed-wing and helicopter  High resolution airborne geophysics – petroleum, mineral, environmental

− Magnetic − Gamma ray spectrometry − Gravimetry − LIDAR Laser Scanning − EM

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Sander Geophysics

Worldwide Operations

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Sander Geophysics

Mauritanian Sahara Desert

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Sander Geophysics

Jungles of Papua New Guinea Jungles of Papua New Guinea

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Empty Quarter, Saudi Arabia Empty Quarter, Saudi Arabia

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Ice Sheets and Glaciers of Antarctica Ice Sheets and Glaciers of Antarctica

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Difficult Environments Difficult Environments

Stakes are higher: c Stakes are higher: costs, logistics, limited time

  • sts, logistics, limited time

window for operations window for operations Fly often Fly often

– Wide range of conditions Wide range of conditions – Reliable equipment Reliable equipment

Fly efficiently Fly efficiently

– All sensors collecting optimal data All sensors collecting optimal data – Optimal data throughout flight Optimal data throughout flight

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Sander Geophysics

SGL SGL AIRGrav AIRGrav AIRBORNE GRAVITY AIRBORNE GRAVITY

System design: System design:

– Three accelerometers (x y z) on a three axis Three accelerometers (x y z) on a three axis gyro stabilized platform gyro stabilized platform – Dual frequency GPS Dual frequency GPS receivers receivers – Gravity = inertial accelerations – GPS Gravity = inertial accelerations – GPS accelerations accelerations

Excellent tolerance of aircraft motion Excellent tolerance of aircraft motion

– Maintains accuracy in turbulence and while Maintains accuracy in turbulence and while following terrain (flying drape) following terrain (flying drape) – Short lead-ins to lines (about 1 minute) Short lead-ins to lines (about 1 minute)

High resolution and accuracy High resolution and accuracy

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Sander Geophysics

Turbulence

  • Hot, low altitude
  • No significant

impact on gravity until turbulence extremes

  • Other factors (ie

GPS) dominant

Influence of Turbulence - Sahara Desert Surveys

Relative turbulence for each line Relative noise estimate

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Sander Geophysics

Drape

  • Instrument height limits (laser, spectrometer)
  • Loss of resolution (attenuation with height)
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Sander Geophysics

20 40 60 80

  • 30
  • 25
  • 20
  • 15
  • 10
  • 5

Effect of altitude on airborne gravity data resolution

150 m 300 m 1500 m

Distance from start of line (km) Gravity (mGal)

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Sander Geophysics

EARLIER ANTARCTIC AIRBORNE GRAVITY EARLIER ANTARCTIC AIRBORNE GRAVITY

Science surveys since late 1970s Science surveys since late 1970s

Successful, but with Successful, but with shortcomings shortcomings

  • Limited resolution & accuracy

Limited resolution & accuracy

  • Long lead-ins to lines

Long lead-ins to lines

  • Inability to acquire accurate data

Inability to acquire accurate data while following terrain (drape) while following terrain (drape)

Prevents broader application in Prevents broader application in Antarctic research Antarctic research

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IPY – AGAP PROJECT IPY – AGAP PROJECT

International Polar Year International Polar Year 2007-2008 2007-2008

Lamont-Doherty Earth Lamont-Doherty Earth Observatory of Columbia Observatory of Columbia University (LDEO) University (LDEO)

leading U.S. airborne leading U.S. airborne portion of the AGAP portion of the AGAP project project

– A Antarctica's ntarctica's – Ga Gamburtsev mburtsev – P Province rovince

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Science Goals: Science Goals:

  • Map the hidden

Map the hidden Gamburtsev Mountains Gamburtsev Mountains buried under ice (over buried under ice (over 4 km thick in places) 4 km thick in places)

  • History of ice sheet – the

History of ice sheet – the cradle of formation? cradle of formation?

  • Tectonic history of

Tectonic history of Antarctica Antarctica

  • Locate places to drill for

Locate places to drill for the oldest ice cores the oldest ice cores

  • Subglacial lakes

Subglacial lakes

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IPY - AGAP: GRAVITY METER? IPY - AGAP: GRAVITY METER?

  • Use commercial

Use commercial gravity meter from gravity meter from exploration industry? exploration industry?

  • Need to test suitability

Need to test suitability for polar research for polar research and Antarctic and Antarctic environment first... environment first...

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Sander Geophysics

IPY - AGAP: GRAVITY METER? IPY - AGAP: GRAVITY METER?

Calgary & Eureka tests Calgary & Eureka tests Summer 2007 Summer 2007

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IPY - AGAP: GRAVITY METER IPY - AGAP: GRAVITY METER

SGL's AIRGrav system SGL's AIRGrav system selected for use in selected for use in Antarctica for AGAP Antarctica for AGAP

Comparison of AIRGrav and Comparison of AIRGrav and GT-1A airborne gravimeters GT-1A airborne gravimeters for research applications. for research applications. Michael Studinger, Robin Michael Studinger, Robin Bell, and Nick Frearson, Bell, and Nick Frearson, Geophysics Geophysics,Vol. 73, No. 6 ,Vol. 73, No. 6 November-December 2008 November-December 2008

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Sander Geophysics

IPY - AGAP: 2008-2009 FIELD SEASON IPY - AGAP: 2008-2009 FIELD SEASON

  • LDEO:

LDEO: magnetic, ice magnetic, ice penetrating penetrating radar, laser radar, laser scanner scanner

  • SGL: gravity,

SGL: gravity, aircraft aircraft attitude attitude

  • Kenn Borek Air:

Kenn Borek Air: Twin Otter Twin Otter

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Williams 'Field', McMurdo, Antarctica Williams 'Field', McMurdo, Antarctica Kenn Borek Twin Otter C-FSJB Kenn Borek Twin Otter C-FSJB

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AGAP Airborne Science Team AGAP Airborne Science Team BAS Twin Otter VP-FBL BAS Twin Otter VP-FBL

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Sander Geophysics

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Sander Geophysics

AGAP-South Field Camp

  • Extremely

Extremely remote – 600 km from South Pole, 1500 km from McMurdo

  • -25ºC to -35ºC (plus wind chill)
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Sander Geophysics

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AGAP-South Field Camp

  • Actual altitude: 3500m (11,500 ft)
  • Physiological altitude: up to 14,000 ft
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  • Antarctica – a moving ice sheet
  • GPS base stations are not stationary
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  • 0.08
  • 0.06
  • 0.04
  • 0.02

0.00 0.02 0.04 0.06 0.08

  • 0.08
  • 0.06
  • 0.04
  • 0.02

0.00 0.02 0.04 0.06 0.08

AGAP-S GPS Reference Station Motion

UPS X Offset (m) UPS Y Offset (m)

AGAP-South 5 mm per day movement

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AGAP-South Operations

  • Logistical / Operational challenges
  • Delays getting camp operational
  • Fuel supply
  • Weather
  • Aircraft snags
  • Short flying 'season'
  • Must take advantage of every flying opportunity
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AGAP-South Operations

  • 53 flights: 55,000lkm of data between 22nd

December 2008 and 17th January 2009

  • Most productive period:
  • 21 flights in 6 days
  • Round the clock flying: 4 flights per day, 22

hours per day, 4,000+ km per day.

  • 40% of the survey completed during this period
  • AIRGrav system – no delays, no downtime,

through entire survey

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Gamburtsev Mountains as imaged by AIRGrav. Similar in size and character to the European Alps

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Two days ago...first AGAP research paper published.

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British Antarctic Survey (BAS)

  • Traditional L&R airborne gravity meter modified by ZLS
  • Flew northern area from AGAP-North camp
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AGAP Performance Comparison

AIRGrav AIRGrav

  • Flown drape (benefits

grav, mag, laser)

  • 3.5km lead-ins
  • 3500m resolution
  • 1 mGal crossover

errors BAS L&R BAS L&R

  • Flown constant height

(no laser instrument)

  • 15-20km lead-ins
  • 8000m resolution
  • 3.5 mGal crossover

errors

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Continued Continued LDEO / SGL LDEO / SGL collaboration collaboration

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NASA IceBridge NASA IceBridge

  • Multi-year, multi-instrument,

Multi-year, multi-instrument, multi-aircraft campaign multi-aircraft campaign

  • Monitor ice at Earth's poles

Monitor ice at Earth's poles

  • Bridging the gap between

Bridging the gap between ICESat (ended 2009) and ICESat (ended 2009) and ICESat 2 (launch 2015?) ICESat 2 (launch 2015?)

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DC-8 in Antarctic and Arctic DC-8 in Antarctic and Arctic P-3 in Arctic P-3 in Arctic

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IceBridge Radar & Laser IceBridge Radar & Laser

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Role of airborne gravity Role of airborne gravity

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Role of airborne gravity Role of airborne gravity

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Role of airborne gravity Role of airborne gravity

Source: NRCan

  • Sea ice surface rises, no open leads...

Thicker ice or geoid?

  • Horizontal gravity components from AIRGrav
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IceBridge Antarctica 2009

Based in Punta Arenas, Based in Punta Arenas, Chile Chile 21 missions (17 planned) 21 missions (17 planned) 155,305 flight 155,305 flight kilometres kilometres 227.4 flight hours 227.4 flight hours

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IceBridge Arctic 2010

  • NASA DC8 and P3
  • Based in Thule and

Kangerlussuaq, Greenland

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IceBridge Antarctica 2010

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NASA IceBridge Extremes

  • Long flights: duration up to 12.5 hours

Long flights: duration up to 12.5 hours

  • Long distances: up to 9000 km

Long distances: up to 9000 km

  • Long differential GPS baselines: over 4000 km

Long differential GPS baselines: over 4000 km

  • Altitude range: 150-12,000 m (500' – 40,000')

Altitude range: 150-12,000 m (500' – 40,000')

  • Speed range: 270-450 knots (140-230 m/s)

Speed range: 270-450 knots (140-230 m/s)

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Extremely large survey aircraft... Extremely large survey aircraft...

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IceBridge DC8 & P3: Multi-instrument platforms IceBridge DC8 & P3: Multi-instrument platforms

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Multi-instrument = conflicting requirements Multi-instrument = conflicting requirements

Laser scanner –

  • ften highest

priority

  • Many lines flown

with constant course changes, curved paths

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Multi-instrument = conflicting requirements Multi-instrument = conflicting requirements

Straight flight Constant turns

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Multi-instrument = conflicting requirements Multi-instrument = conflicting requirements

  • Impact on 'low priority' AIRGrav data:

Impact on 'low priority' AIRGrav data:

  • Increased noise (filtering kept constant)

Increased noise (filtering kept constant)

  • Decrease resolution (filtering strengthened to

Decrease resolution (filtering strengthened to maintain accuracy) maintain accuracy)

  • Unlikely any usable data would be recovered by other

Unlikely any usable data would be recovered by other gravity instruments gravity instruments

  • Reduced accuracy / resolution compares well against

Reduced accuracy / resolution compares well against traditional instruments flown in ideal conditions traditional instruments flown in ideal conditions

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Sander Geophysics

  • No re-flights, no significant delays possible

No re-flights, no significant delays possible

  • Instrument must be available to fly whenever

Instrument must be available to fly whenever required required AGAP and IceBridge 2008-2010 AGAP and IceBridge 2008-2010

  • 116 survey flights in Twin Otter, DC8, and P3

116 survey flights in Twin Otter, DC8, and P3

  • >99% success rate. Only 1 flight with lost

>99% success rate. Only 1 flight with lost gravity data (in-flight computer failure) gravity data (in-flight computer failure)

IceBridge flights with AIRGrav continue... IceBridge flights with AIRGrav continue...

Multi-instrument = conflicting requirements Multi-instrument = conflicting requirements

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Pine Island Glacier, Antarctica

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Sander Geophysics

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Sander Geophysics

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Pine Island Glacier

NASA Earth Observatory

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ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS

Michael Studinger Michael Studinger (NASA) (NASA) Nick Frearson Nick Frearson (LDEO) (LDEO) Robin Bell Robin Bell (LDEO) (LDEO) ...plus many others from Lamont-Doherty Earth Observatory of Columbia University & NASA

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ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS

Sander Geophysics Sander Geophysics

Field crews... AGAP: Dan Geue, Martin Bates IceBridge: Kevin Charles, Sean O'Rourke, Eric Renaud ...and many others at SGL

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Thank you Thank you

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Incredible views out the window...

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Logistical Logistical

challenges...

challenges...