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航空 发表于 2011-10-27 16:04:13

Vaisala windshear detection solution

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航空 发表于 2011-10-27 16:04:29

Vaisala windshear
detection solution
Juhani Polvinen
Vaisala Airports
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Agenda
Wind shear in general
 Terrain-induced wind shear
 Microbursts
 LLWAS
Windprofiler integration
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Why Is Wind Shear Detection
Important?
 If Low Level Wind Shear is encountered close to the ground
during aircraft take-off or landing procedures, it can be very
dangerous
 the change in velocity or direction can drastically alter lift,
indicated airspeed (IAS), and thrust requirements
 Can exceed aircraft climb capabilities
 US wind shear related Incidents between 1964 and 1985
 Over 25 US airline accidents
 625 fatalities
 200 injuries
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Low Level Wind Shear Is a Major Safety
Hazard at Airport!
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Low Level Wind Shear
 Causes of wind shear:
Terrain effects
Convective weather
Fronts
Temperature inversion
Wake vortices
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Terrain wind shear
Hills, mountains
 Land-sea interaction
 Interaction between general and local wind fields
Very difficult to forecast without good measurements
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Terrain wind shear, day-night variations
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Terrain wind shear, day-night variations
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Terrain wind shear, day-night variations
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Terrain wind shear, case Juneau
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How to Measure Terrain wind shear?
Wind profiler is an excellent tool for terrain wind shear
detection
Doppler weather radar can also detect terrain wind shear, but
sometimes ground clutter is a problem
Usually combination of several systems is needed
 LLWAS system can not be used for terrain wind shear
detection
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Downburst
Microburst characteristics:
– Downdraft
– Intense localized downdraft exceeding 720 feet per minute at 300
feet, AGL
– Can exceed aircraft climb capabilities (all classes of aircraft)
–Windshear resulting from large downdrafts
– Result from large downdrafts striking the ground and spreading out
horizontally
– Winds can change direction by as much as 180 degrees and reach
velocities of 100 knots as far as 16 km ahead of the storm
– May increase as much as 50% between the surface and 1500 feet.
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Downburst
Courtesy of NCAR
Downdraft
While the pilot
compensates for the
headwind by dipping
the nose, the aircraft
enters a downdraft.
A headwind slows and
lifts the aircraft above its
normal flight path.
A tailwind dangerously
reduces the aircraft’s
speed.
The glide path of a
normal landing.
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Downburst
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How to Measure Downbursts?
Wind Profiler
 One point measurement
 No Horisontal shear
 Verical wind shear
Doppler Radar
 Mainly in rain
 Resolution, time lag
 Excellent in combination with LLWAS
 Lidar
 Does not work in rain
 Expensive
 Anemometers
 Horisontal shear
 Fast response time
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How to Measure Fronts and
Temperature inversion
Wind profiler is an excellent tool for detecting Fronts and
Temperature inversions
Doppler radar is also good sensor for detecting Fronts and
Temperature inversions but clear air causes some problems
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Wind Shear Values
Vaisala will:
• Consult and design the ideal
windshear alert solution (technical
and services).
• Ensure professional project
management, delivery, training and
installation of the technical solution.
• Ensure reliable lifecycle support
Customer gets:
• Increased awareness on wind shear
phenomenon and its implications
• Professional opinion of what is the
correct solution
• Alerts implying hazardous take-off
and landing conditions
• Professional support (technical
solution and competence levels)
Impact:
• Airlines: Safer landings without surprises due to low-level wind shear
• Airport: Optimal, motivated and useful investments
• Airport: Increased safety for take-offs and landings
• Airport: More efficient take-off and landing operations
• Airport: Increased revenue for the airport through increased attractiveness to the
airlines
• ATC: Less (personal) risk taking in directing flights
• Technical maintenance: Maintenance of system with reasonable effort
• Technical maintenance: Keeping up with the system knowledge
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Windshear Solution Concept
How to mitigate the windshear challenge at airports
1. Ensure that the identified windshear challenge is real
2. Study and specify the airport specific solution for optimal
performance
3. Design the site specific technical solution and needed lifecycle
services
4. Implement and commission the system and train all user
groups
5. Maintain the system and support the users to ensure the
continuous performance
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Solution Concept Framework
Requirements definition
and consulting
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Technical realization of
the solution
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Requirements definition
and consulting
 Ensure the existence of low-level windshear by studying the
weather conditions at the airport
 Specify the optimal wind site locations and measurement
mast heights by studying the topology and obstructions
 Specify the system and interfaces by investigating the
existing infrastructure
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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Solution design
 Together with the customer
 create the detailed technical design of the system and needed
interfaces
 define the needed services to ensure optimal performance over
the systems life-cycle
 create the implementation project plan
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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Solution delivery
 Implement and test the system ensuring that all requirements
are met
 Train all user groups and commission the system in order to
secure a smooth ramp-up of the operations
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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Life-cycle services
Maximize availability of information by:
 performing preventive maintenance (e.g. corrosion inspection,
battery replacement)
 verifying the solution performance (e.g. survey possible new
obstructions, review data and error logs, pilot reports)
 upgrading the software for regulatory compliance and better
performance
 Ensure minimum downtime (less then 24 hours) by e.g.:
 providing fast response time help desk
 optimized on-site spare stock
 providing on-site repair services
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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Support elements
Organize workshop or seminar in order to:
 give insight into the atmospheric phenomena behind low-level
windshear
 discuss the implications of windshear for airport operations and
aviation safety
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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One possible technical
realization
of the solution
Requirements definition and consulting
Requirements definition and consulting
Solution design
Solution design
Solution deli ver y
Solution deli ver y
Life-cycle ser vices
Life-cycle ser vices
Support el ements
Support el ements
Technical realization of the solution
Technical realization of the solution
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LLWAS
Wind data is analyzed in accordance with a wind shear
algorithm developed by NCAR for FAA
The algorithm employed by Vaisala LLWAS system is the
latest Phase III algorithm and is patented by NCAR
Vaisala is a licensee for that patented algorithm
 The algorithm is a module running on a AviMet system platform
 AviMet platform features like hot-standby duplication, displays and
workstation concept are available
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LLWAS Algorithm
 A network of anemometers in and around the airport provide direct
wind measurements.
Wind data between sensors are analyzed to determine if there is
wind divergence (aircraft performance decreasing shear) or
convergence (aircraft performance increasing shear) in the
network.
 The intensity, location, and type of shear are calculated and the
standardized warnings are generated.
 Output is specific to every aircraft operation and runway heading.
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LLWAS
 Low level wind shear and microburst conditions are assessed by
processing wind data collected from an array or network of wind
sensors.
 Number of wind sites is typically 8-16
 Wind sites consists normally of:
– 20-30 meter masts
– WAS425 ultrasonic sensor
– Radio Modem
– Solar panel with battery
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LLWAS
Two- kilometer
times two
kilometer grid
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LLWAS Siting, Shenzen
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LLWAS Siting, Dalian
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LLWAS Siting
LLWAS siting has been done in China for:
Shenzhen
Dalian
Chanchun
Beijing
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New AviMet displays
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FAA Wind Shear Terminology and Alert
Criteria
 ”Wind Shear With Loss”
 If the estimated IAS loss is between 15 and 30 knots, over 4 km of
flight
 “Microburst”
 If the estimated IAS loss is 30 knots or greater, over 4 km
 “Wind Shear With Gain”
 If a convergence zone is detected with a wind shear of 15 knots
(IAS gain) or greater
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Vaisala wind field analysis
Wind Profiler LLWAS
AWOS
Winds
Weather
radar
Airport wind information
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Vaisala wind field analysis
Airport wind information
Other users Pilots
Forecaster ATC
OOthtehreur suesresrs
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AviMet Wind Profiler displays
Highlights
 Integrates LLWAS horizontal wind field and WP vertical wind
field for 3D wind shear alerts
 LLWAS and WP information is easy to use and offer
integrated user interface
Offers the horizontal and vertical wind information needed for
ATC operations and meteorologists
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AviMet Wind Profiler displays
1. Alert when wind difference between two height levels
exceed pre-set limit
2. Alert for cross-wind and headwind vertical wind
shear separately
3. Alerts on temporal changes on vertical windshear
4. Turbulence alerts
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AviMet Wind Profiler displays
Alert when wind difference between two height levels
exceed pre-set limit
 Important feature for vertical wind shear detection.
 Both the high-low altitude levels and the wind difference amount
are user configurable through password protected UI.
 The wind difference amount is calculated as vector difference.
 Five vertical shear warning layers. These layers can overlap totally
or partially.
 There is a timer for each eventual warning so that a user can set
the warning duration.
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AviMet Wind Profiler displays
 Alert for cross-wind and headwind vertical wind shear
separately
Capability to alert user if wind difference between two height
levels exceed pre-set limit
Option to separately alert for cross-wind and headwind
vertical wind shear
 The alert height levels can be set in configuration
 The alert thresholds can be set in configuration
 The alert strings shown in alert displays follow closely the
LLWAS alert displays "runway; windshear type; windshear
strength; windshear height"
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AviMet Wind Profiler displays
 Runway: Runway ID and direction
 A: Approach
 D:Departure
 Windshear type:
 VERTICAL WIND SHEAR
 VERTICAL CROSS WIND SHEAR
 VERTICAL HEAD WIND SHEAR
 altitude: The altitude between the lower and higher limits
calculation, used when difference is small
 altitude levels: The lower and higher limits of the shear calculation, used when
the difference is bigger
 windshear strength: Total, head or cross wind shear amount.
 For cross wind shear, L stands for left wind at first level if access (higher in
approach, lower in departure).
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AviMet Wind Profiler displays
 Example: R22A VERTICAL WIND SHEAR 800FT 20KT
Here the wind shear is the total difference vector at 800FT
 Example for cross oriented shear:
R22A VERTICAL CROSS WIND SHEAR 800FT L20KT+
 It should be noted that the shear is reversed for planes
landing or taking off. So for landing aircraft the previous
example becomes:
 Example: R04D VERTICAL CROSS WIND SHEAR 800FT
L20KTPage
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AviMet Wind Profiler displays
Alerts on temporal changes on vertical windshear
 An alert can be issued when vertical windshear has a strong temporal
tendency.
 Temporal windshear alerts act as predictive alerts for windshear alerts.
 As the wind profiler normally averages the data for about 10 minutes, that time
interval is also used for temporal change interval.
 The windshear alerts overrides temporal windshear alerts if they are
happening simultaneously.
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AviMet Wind Profiler displays
 Turbulence alerts
 As wind profiler is also capable to detect turbulence, alerts for turbulence
layers are created.
 The ICAO turbulence definition is used for classification.
 The ICAO turbulence definition:
 Very low – below 0.05g – Light oscillations
 Low – 0.05 to 0.2g – Choppy; slight, rapid, rhythmic bumps or cobblestoning
 Moderate – 0.2 to 0.5g – Strong intermittent jolts
 Severe – 0.5 to 1.5g – Aircraft handling made difficult
 Very severe – above 1.5g – Increasing handling difficulty, structural damage
possible.
 It should be noted that this classification is approximated, as windprofiler can
not measure turbulence effects for aircraft.
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LLWAS and Wind Profiler
 Main displays
 Standard meteorological windbarb height-time display with
wind speed color coding
 Alert display following the LLWAS alert display format
 Visual alert display with color coding
 Wind shear versus height graph
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WP Visual alert display with color
coding
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Head/crosswind display
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Combined Alert display, LLWAS integration
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Wind barb display, LLWAS integration

lht520yy 发表于 2012-2-1 16:44:42

/crosswind display
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Combined Alert display, LLWAS integration
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Wind barb display, LLWAS integration

ingooooo 发表于 2018-9-24 18:12:15

好好学习一下，感谢分享。

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