Post on 14-Apr-2022
Assessment of HF Radar for Significant Wave Height
Determination
Desmond Power
VP, Remote Sensing, C-CORE
Agenda
• Study Rationale
• Technology Overview
• Technology Assessment for CNLOPB
• Proposed ‘Go Forward’
Study Rationale
• Sikorsky S-92A rated to Sea State 6 (4-6m)
• No flights above SS6
• Sea state measurements available at rigs and on-shore
• No sea state measurement between platforms and shore
– Networks of wave buoys are rather impractical considering the required areal coverage
– Is there an alternative technology?
HF Radar Technology
• Crombie observed peaks in HF radio wave echoes in 1955
– Observed Doppler shift in the radar echo
– Concluded it was from ocean gravity waves
• Studies in the 1970s showed relationship between radio signal backscatter and characteristics of gravity wave
• Surface currents, surface winds and surface waves could be derived
Study Objectives
• Investigate HF radar technology for measuring wave heights
• Demonstrate that technology works
– Can it work over the extended range required, >300km?
– Can it measure Sea State 6 and beyond?
• Use existing facility to baseline the capability
– What is the system configuration?
– What are the power levels?
– Where should the system be installed?
– What type of information can be supplied?
HF Radar Technology Overview
The Signal
(from University of Hamburg)
Doppler Spectrum
Doppler Frequency
No
rmal
ize
d P
ow
er S
pe
ctra
l De
nsi
ty
HF Radars are known for Current Mapping Capability
C-CORE Research (Howell and Walsh, 1993) from Canadian Atlantic Storms Program (CASP, 1986)
Cape Race, Cape Bonavista DND Radars
200 meter contour
HF ROSA
• High Frequency Radar Ocean Surface Applications
• Objective: Real time knowledge of ocean surface conditions
• Argentia test site looks into Placentia Bay
• Project Partners – MUN Faculty of
Engineering
– MUN Physics and Physical Oceanography
– Northern Radar Inc
HF ROSA 2012 Field Program Placentia Bay
HF ROSA 2012 Field Program Placentia Bay
Transmit Antenna Array
Receive Antenna Array
Currents from HF ROSA
Waves from HF ROSA
Technology Assessment
Sample WERA/Northern Radar Radar Spectra from Placentia Bay
11.7 km 59.7 km
Waves from HF ROSA
Buoy Measured Waves: 2.53 m
Buoy Measured Waves: 1.28 m
Significant wave heights from the radar are within about ±0.25 m of the buoy readings
Radar is here
Maximum Range Analysis
• 13.385 MHz
– 10 Watts
– SWH = 2.3 m
– Range = 60 km
– Measured Second Order has 10 dB SNR
• Can radar measure Sea State 6?
• What is radar range at Sea State 6?
• Use 7.7 metres as benchmark (~30% above SS6)
Maximum Range Analysis
• 13.385 MHz
– 100 Watts
– 7.7 m waves
– Modeled Second Order has 10 dB SNR
• 150 km when winds are along the radar look
• 110 km when winds are across the radar look
• 10 MHz
– 100 Watts
– 7.7 m waves
– Modeled Second Order has 10 dB SNR
• 170 km when winds are along the radar look
• 120 km when winds are across the radar look
Coverage for 150km Radars
~150 km
~150 km
HF Oceanographic Radar
• Recommend operating in 10 MHz Frequency Range
• Antennas
– Receive antenna ~6m high guyed monopole
– Array of 12 elements
– Shore based 165 m long
– Production platform based ~100 m (7 elements), mounted underneath topsides
• 100 Watt transmitter
Coastline Concept
TX Array
RX Array
Platform Concept
Phase 2 Objectives
• Install a single dedicated shore-based HF Radar facility
• Facilitate access to data in near-real-time
• Operate facility for one year
• Demonstrate the performance of the radar – Does it give the information you need
• Reliably
• Timely
• Accurately
– Is this better than what we had?
– Does this system introduce other problems?
• Interface with industry to integrate wave height data
• Make recommendations for a system that covers the full flight path from shore to platforms (Phase 3)
Prospective Site – Bear Cove Point
Prospective Site – White Hills