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1 Graduate Program in Earth and Space Science, York University, Toronto, Ontario 2 Environment Canada, Cloud Physics and Severe Weather Research Section,

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Presentation on theme: "1 Graduate Program in Earth and Space Science, York University, Toronto, Ontario 2 Environment Canada, Cloud Physics and Severe Weather Research Section,"— Presentation transcript:

1 1 Graduate Program in Earth and Space Science, York University, Toronto, Ontario 2 Environment Canada, Cloud Physics and Severe Weather Research Section, Toronto, Ontario Yi (Emily) Zhou 1, George Isaac 2, 1, Peter Taylor 1

2 1. Introduction 2. Low level wind shear criteria 3. Method of interpolation 4. AMDAR low level wind shear analysis 5. Frequency of low level wind shear 6. Case study 7. Summary Low Level Wind Shear at Pearson Airport

3 1. Introduction Low level wind shear : change of horizontal wind direction and/or speed with height ((U/z, where U is horizontal wind) Dangerous: increase/decrease of head wind (tail wind), hence an increase /decrease of lifting force, causing the aircraft to fly above or below its intended flight path. A survey conducted by the International Civil Aviation Organization showed that from 1964 to 1983, low level windshear caused at least 28 large transport aircraft accidents in the world that together resulted in over 500 fatalities and 200 injuries.

4 Tasks Study low level wind shear from models out put (GEM-15 Regional, GEM-2.5 LAM and RUC-13) Analysis of low level wind shear from AMDAR (Aircraft Meteorological Data Reports) wind profile data for Pearson Airport Case study Data: From CAN-Now Archive Files: Pearson M300 Data ( to ) GEM-15 Regional ( to ) GEM-2.5 LAM ( to ) RUC-13 model data ( to ) AMDAR data in netCDF from pftp.madis- data.noaa.gov ( to )

5 2. Low level wind shear criteria According to MANAIR 2.6.7(MANAIR - manual of standards and procedures for aviation weather forecasts), the vertical non convective low level wind shear criteria are listed as: Wind vector change greater than 25 knots within 500 ft AGL. Wind vector change greater than 40 knots within 1000 ft AGL. Wind vector change greater than 50 knots within 1500 ft AGL. A PIREP indicates a loss or gain of indicated airspeed of 20 knots or more, within 1500 ft AGL. When any of the above guidelines are met, then the low level wind shear achieves the criterion, and this wind shear is classed as a wind shear case.

6 Low Level Wind Shear Criteria Non metric unitmetric unit HeightCriteriaHeightCriteria feetktsmm/s 1st 500 ft st 1000ft st 1500ft Low level wind shear criteria

7 3. Methods of Interpolation Purpose of interpolation: to obtain particular 500ft, 1000ft, and 1500ft height wind Methods: Cubic spline method Linear method Comparison 2 methods:

8 3. Methods of Interpolation

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10 Comparison 2 methods: linear is better for interpolating AMDAR data and RUC data than Cubic spline. For interpolating GEM-15 Regional and GEM-2.5 LAM, the two methods have roughly the same results. Reason: uneven end points distance of AMDAR and RUC. Method Chosen: Linear 3. Methods of Interpolation

11 4. AMDAR wind shear analysis Wind shear cases monthly distribution

12 Wind shear cases time distribution 4. AMDAR wind shear analysis Local Time?

13 Wind shear cases distribution in different levels 4. AMDAR wind shear analysis

14 5. Frequency of low level wind shear within 500ft above ground level Wind Shear Criterion: 12.8m/s

15 5. Frequency of low level wind shear Within 1000ft above ground level Wind Shear Criterion: 20.56m/s

16 5. Frequency of low level wind shear Within 1500ft above ground level Wind Shear Criterion: 25.7m/s

17 5. Frequency of low level wind shear Conclusion: within 500, 1000 feet height above ground level, the GEM-15 Regional has the best capability for low level wind shear forecasting, the second is GEM-2.5 LAM. For 1500 feet height above ground level, RUC is the best one. Low level wind shears predicted from models are lower than those observed.

18 Coarse time Gaint time 1 st 500ft Shear m/s 1 st 1000ft Shear m/s 1 st 1500ft Shear m/s 2008Dec :03: Dec :30: Dec :14: Dec :08: Case study 1.From OBS 2. From LAM DateValidTime 1 st 500ft Shear m/s 1 st 1000ft Shear m/s 1 st 1500ft Shear m/s _lam.tar.gz :05Z _lam.tar.gz :30Z _lam.tar.gz :05Z _lam.tar.gz :05Z91113

19 DateValidTime 1 st 500ft Shear m/s 1 st 1000ft Shear m/s 1 st 1500ft Shear m/s _reg.tar.gz :00Z _reg.tar.gz :30Z _reg.tar.gz :00Z _reg.tar.gz :00Z Case study 1.From REG 2. From RUC DateForecast and ValidTime 1 st 500ft Shear m/s 1 st 1000ft Shear m/s 1 st 1500ft Shear m/s ruc.tar.gz ruc2.t11z.p grb13f02.grib2.txt ruc.tar.gz ruc2.t11z.p grb13f03.grib2.txt ruc.tar.gz ruc2.t16z.p grb13f02.grib2.txt3814

20 6. Case study Hourly Surface Data Report (December 27, 2008) Sfc wind from models Time TempTd RH Wind dir Wind Spd LAM Wind SPD REG Wind SPD RUC Wind SPD LST UTC °C % 10's degm/s 6:00 11: :00 12: :00 13: :00 14: :00 15: :00 16: :00 17: SFC OBS From:

21 6. Case study Event overview From: 07AM, EST, Dec 27, 2008

22 6. Case study Event overview Data from : collection.pl?model_sys=narr&model_name=narr-a&grid_name=221 NARR DATA

23 6. Case study Event overview

24 6. Case study

25 M300 DATA AMDAR DATA CYYZ(Dn) Dec08 Descent sounding from 140° into Toronto Intl, ON (CYYZ) lasting 30 min, and covering 46 nautical miles (Aircraft #7189) P_altmbt/tdw_dir/w_spdTimeBng/Rng (ft)(°C)(kts)(UTC)(nm) / °/ °/ / °/ °/ / °/ °/ / °/ / °/ °/ / °/ °/ / °/ °/ / °/ °/ / °/ °/ / °/ / °/ °/008 Data from: COARSETIMEGAINTTIME PROFILE TIME WINSPEED m/s ktsWINDIR 2008Dec :03: Dec :30: Dec :14: Dec :08:

26 6. Case study AMDAR profile From:

27 6. Case study Conclusion Front passage passing station Close to surface ground, an inversion layer exists RH>90% Surface wind is small; above surface, wind speed increase quickly

28 7 Summary Linear interpolation method is better for interpolating particular height wind. Wind shear cases exhibit features: 1. more cases happen in autumn and winter; 2. cases occur mostly during night or morning (local time); 3. most wind shear happen within 1 st 500ft AGL. Within 500 and 1000 ft, GEM Regional has the best capability for low level wind shear forecasting, the second is LAM. For 1500 ft AGL, RUC is better. Frontal passage passing station, strong low level T inversion support low level wind shear development.

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