1. Quantifying the impact of the wind climate for Amsterdam Int. Airport Andrew Stepek Dirk Wolters Xueli Wang Ine Wijnant 11-09-2012 Andrew.Stepek@knmi.nl

2. EMS-ECAC 2012 2 Content PROBLEM: Influence weather on take-off and landing Research question METHOD: Trends in wind climate? Cross and tail wind frequencies RESULTS CONCLUSIONS

3. EMS-ECAC 2012 3 Influence weather on take-off and landing Preference list Minimum noise pollution: Take-off to / landing from North or South-Southwest Gordijn et al. 2007 Limiting factors Weather (safety first) Runway maintenance Time of day (Buitenveldert not at night) Preference 1

4. EMS-ECAC 2012 4 Research question ? 1971-present observations representative for climate in 2011/2018 ? Is there a trend in wind climate (speed & direction)? Are cross and tail wind frequencies changing? Noise pollution forecasts (5-10 years ahead ≈ 2018) Operational planning (1 year ahead ≈ 2011) Observations from 1971-present (wind, cloud base, visibility) Preference list +

5. EMS-ECAC 2012 5 Content PROBLEM: Influence weather on take-off and landing Research question METHOD: Trends in wind climate? Cross and tail wind frequencies RESULTS CONCLUSIONS

6. EMS-ECAC 2012 6 Trends in wind climate? Trend = Change geostrophic (upper) wind (1) + change in surface wind as a result of changes in local (2) and/or regional roughness (3)

7. EMS-ECAC 2012 7 Trends in wind climate? Trend = Change geostrophic (upper) wind (1) + change in surface wind as a result of changes in local (2) and/or regional roughness (3) Aberdeen (Scotland) Thyboron (Denmark) Armagh (Ireland) De Bilt (Netherlands) Aberdeen_Amargh_De Bilt: 1868-2000 Aberdeen_Thyboron_De Bilt: 1874-2007

8. EMS-ECAC 2012 8 Trends in wind climate? Trend = Change geostrophic (upper) wind (1) + change in surface wind as a result of changes in local (2) and/or regional roughness (3) Aberdeen (Scotland) Thyboron (Denmark) Armagh (Ireland) De Bilt (Netherlands) Aberdeen_Amargh_De Bilt: 1868-2000 Aberdeen_Thyboron_De Bilt: 1874-2007

9. EMS-ECAC 2012 9 Trends in wind climate? Trend = Change geostrophic (upper) wind (1) + change in surface wind as a result of changes in local (2) and/or regional roughness (3) Remove year to year variations of geostrophic wind from yearly average potential wind to get trend as a result of changes in regional roughness

10. EMS-ECAC 2012 10 Trends in wind climate? Two scenarios no trend (Aber-Arm) decreasing trend (Aber-Thy) of 0.8% per decade Yearly average potential wind with year to year variations in geostrophic wind removed

11. EMS-ECAC 2012 11 Trends in wind climate? Two scenarios no trend (Aber-Arm) decreasing trend (Aber-Thy) of 0.8% per decade So these trends are: caused by change in regional roughness used to extrapolate to the future Yearly average potential wind with year to year variations in geostrophic wind removed

12. EMS-ECAC 2012 12 Cross and tail wind frequencies Cross wind frequency = % of hours that component of average wind speed to runway > 20 kts Tail wind frequency = % of hours that component of average wind speed // to runway from behind aircraft > 7 kts 2007 Boeing E-3A Crosswind landing (Wikipedia) Cross wind Tail wind Gust instead of average wind speed if gust > average + 10 kts

13. EMS-ECAC 2012 13 Cross/tail wind frequencies 2011 & 2018 (no trend) We need hourly wind speed, wind direction and gust data to calculate cross and tail wind frequencies. Available: hourly wind dataset 1971-1995 Data before 1971 useless: only gusts > 25 kts stored Data after 1995 useless: stored in whole m/s (1 m/s = 1.9439 kts) which leads to errors up to 10% in tailwind frequencies Present climate (2011) operational planning Hourly data 1971-1995 Future climate (2018) noise prediction

14. EMS-ECAC 2012 14 Cross wind freq. 2011 & 2018 (decreasing trend) Calculate 1969-2011 average wind speed which is representative for the wind climate around 1990 Apply -0.8%/decade trend from 1990 to 2011/2018 Use linear relationships in graph to determine corresponding 2011/2018 cross wind frequencies for all runways Cross-wind: significant linear relationship could be found for all runways

15. EMS-ECAC 2012 15 Tail wind freq. 2011 & 2018 (decreasing trend) Significant linear trend for runways 04, 06, 09, 36: determine tail wind frequencies assuming -0.8%/decade in annual average wind speed No significant trend for runways 18,22,24,27: take average tail wind frequencies from hourly values 1971-1995 (should be treated as max freq)

16. EMS-ECAC 2012 16 Percentiles Wind speeds vary significantly from year to year: use percentiles 50%: common years 10%: “calm” years (low freq) 90%: “windy” years (high freq)

17. EMS-ECAC 2012 17 Content PROBLEM: Influence weather on take-off and landing Research question METHOD: Trends in wind climate? Cross and tail wind frequencies RESULTS CONCLUSIONS

18. EMS-ECAC 2012 18 Noth-south runways (18/36): Common years (50% of years): cross wind frequency ≤ 7.6% Cross wind frequency varies from max 4.9% of the time in extremely low frequency years to max 8.9% in extremely high frequency years Calm years (10%) Windy years (90%) Common years (50%) Interm. years (30%) Interm. years (70%) No trend: 1971-1995 represents 2011 & 2018

19. EMS-ECAC 2012 19 Decreasing trend: future climate (2018) Calm years (10%) Common years (50%) Interm. years (30%) Interm. years (70%) Windy years (90%) Year to year variation of cross and tail wind frequencies 5 times bigger than decrease of median frequencies caused by decreasing trend between 1971- 1995 and 2011/2018

20. EMS-ECAC 2012 20 Conclusions The most likely scenario is a decreasing trend of cross and tail wind frequencies, but no change is also possible Compared to 1971-1995, decrease in median cross wind frequency is 5-13% (2011) and 7-16% (2018) depending on the runway Decrease in median tail wind frequency is 4-7% (2011/2018) Year to year variation of cross and tail wind frequencies 5 times bigger than decrease of median frequencies caused by decreasing trend between 1971-1995 and 2011/2018

21. EMS-ECAC 2012 21 24-8-2012 Cross wind 45 kts Lajes Azores (Paulo Santos, Daily mail) Dziękuję bardzo!