Characterizing regimes of strong terrain-induced winds in the vicinity of the Hong Kong International Airport Alexander Gohm, Lukas Umek, Victoria Fetz Institute for Meteorology and Geophysics, University of Innsbruck ICAM 2013, Kranjska Gora, Slovenia 03 June 2013 Introduction Goals and Methods Results Conclusions Appendix Hong Kong International Airport (HKIA) Regimes of strong terrain-induced winds at HKIA 2/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Hong Kong International Airport (HKIA) Regimes of strong terrain-induced winds at HKIA 3/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Hong Kong International Airport (HKIA) Regimes of strong terrain-induced winds at HKIA 4/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Hong Kong International Airport (HKIA) Regimes of strong terrain-induced winds at HKIA 5/78 Alexander Gohm I No systematic study that relates upstream conditions to various flow regimes I Shallow water model (SWM) is an easy and suitable tool for such a systematic study I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) I Requirement for the SWM: two layer structure I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) Regimes of strong terrain-induced winds at HKIA 6/78 Alexander Gohm I Shallow water model (SWM) is an easy and suitable tool for such a systematic study I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) I Requirement for the SWM: two layer structure I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) I No systematic study that relates upstream conditions to various flow regimes Regimes of strong terrain-induced winds at HKIA 7/78 Alexander Gohm I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) I Requirement for the SWM: two layer structure I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) I No systematic study that relates upstream conditions to various flow regimes I Shallow water model (SWM) is an easy and suitable tool for such a systematic study Regimes of strong terrain-induced winds at HKIA 8/78 Alexander Gohm I Requirement for the SWM: two layer structure I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) I No systematic study that relates upstream conditions to various flow regimes I Shallow water model (SWM) is an easy and suitable tool for such a systematic study I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) Regimes of strong terrain-induced winds at HKIA 9/78 Alexander Gohm I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) I No systematic study that relates upstream conditions to various flow regimes I Shallow water model (SWM) is an easy and suitable tool for such a systematic study I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) I Requirement for the SWM: two layer structure Regimes of strong terrain-induced winds at HKIA 10/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Introduction I Various case studies on severe terrain-induced winds at HKIA (e.g., Clark et al. 1997; Shun et al. 2003; Chan 2009, 2011a, b, 2012) I No systematic study that relates upstream conditions to various flow regimes I Shallow water model (SWM) is an easy and suitable tool for such a systematic study I SWM has been successfully used in the past for other regions (e.g., Grubiˇsi´cet al. 1995; Pan and Smith 1999; Gohm and Mayr 2004; Gohm et al. 2008) I Requirement for the SWM: two layer structure I Example: 08 March 2006 ) Chan and Cheung (2009) observed jets and flow reversal Regimes of strong terrain-induced winds at HKIA 11/78 Alexander Gohm Upstream conditions I Layer height H0 = 520 m −1 I Wind speed U0 = 9 m s 0 ∆θ −2 I Reduced gravity g = g = 0:2 m s θ0 p 0 I Froude number F0 = U0= g H0 = 0:9 Introduction Goals and Methods Results Conclusions Appendix Introduction Radiosonde profile at Kings Park at 00 UTC 08 March 2006 2.5 2 1.5 1 Lantau Peak Altitude (km MSL) 0.5 U H 0 0 0 290 295 300 305 310 N NE E SE S SW W NW N 0 5 10 15 20 Potential Temperature (K) Wind Direction (deg) Wind Speed (m/s) Regimes of strong terrain-induced winds at HKIA 12/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Introduction Radiosonde profile at Kings Park at 00 UTC 08 March 2006 2.5 2 1.5 1 Lantau Peak Altitude (km MSL) 0.5 U H 0 0 0 290 295 300 305 310 N NE E SE S SW W NW N 0 5 10 15 20 Potential Temperature (K) Wind Direction (deg) Wind Speed (m/s) Upstream conditions I Layer height H0 = 520 m −1 I Wind speed U0 = 9 m s 0 ∆θ −2 I Reduced gravity g = g = 0:2 m s θ0 p 0 I Froude number F0 = U0= g H0 = 0:9 Regimes of strong terrain-induced winds at HKIA 13/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Introduction Radiosonde profile at Kings Park at 00 UTC 08 March 2006 2.5 2 1.5 1 Lantau Peak Altitude (km MSL) 0.5 U H 0 0 0 290 295 300 305 310 N NE E SE S SW W NW N 0 5 10 15 20 Potential Temperature (K) Wind Direction (deg) Wind Speed (m/s) Upstream conditions I Layer height H0 = 520 m −1 I Wind speed U0 = 9 m s 0 ∆θ −2 I Reduced gravity g = g = 0:2 m s θ0 p 0 I Froude number F0 = U0= g H0 = 0:9 Regimes of strong terrain-induced winds at HKIA 14/78 Alexander Gohm I Figure shows 21 severe wind cases taken from the literature I Regime boundaries valid for 2D ridge (Houghton & Kashara, 1968) I Problem: boundaries not valid for real terrain! Introduction Goals and Methods Results Conclusions Appendix Introduction Regime diagram based on Kings Park radiosonde data 3.5 3 2.5 (km) 0 H 2 1.5 1 Height of Lantau Peak Layer height 0.5 08 Mar 2006 0 0 0.5 1 1.5 2 2.5 F Froude number 0 Regimes of strong terrain-induced winds at HKIA 15/78 Alexander Gohm I Regime boundaries valid for 2D ridge (Houghton & Kashara, 1968) I Problem: boundaries not valid for real terrain! Introduction Goals and Methods Results Conclusions Appendix Introduction Regime diagram based on Kings Park radiosonde data 3.5 3 21 2 2.5 (km) 0 20 H 2 5 7 1 8 1.5 9 6 10 1 19 Height of Lantau Peak 18 Layer height 16 4 15 3 1314 0.5 17 08 Mar 2006 0 0 0.5 1 1.5 2 2.5 F Froude number 0 I Figure shows 21 severe wind cases taken from the literature Regimes of strong terrain-induced winds at HKIA 16/78 Alexander Gohm I Problem: boundaries not valid for real terrain! Introduction Goals and Methods Results Conclusions Appendix Introduction Regime diagram based on Kings Park radiosonde data 3.5 3 21 subcritical, supercritical, hydraulic jumps no jumps no jumps 2 2.5 (km) 0 20 H 2 5 7 1 8 1.5 9 6 10 1 19 Height of Lantau Peak 18 Layer height 16 4 15 3 1314 0.5 17 08 Mar 2006 complete blocking 0 0 0.5 1 1.5 2 2.5 F Froude number 0 I Figure shows 21 severe wind cases taken from the literature I Regime boundaries valid for 2D ridge (Houghton & Kashara, 1968) Regimes of strong terrain-induced winds at HKIA 17/78 Alexander Gohm Introduction Goals and Methods Results Conclusions Appendix Introduction Regime diagram based on Kings Park radiosonde data 3.5 3 21 subcritical, supercritical, hydraulic jumps no jumps no jumps 2 2.5 (km) 0 20 H 2 5 7 1 8 1.5 9 6 10 1 19 Height of Lantau Peak 18 Layer height 16 4 15 3 1314 0.5 17 08 Mar 2006 complete blocking 0 0 0.5 1 1.5 2 2.5 F Froude number 0 I Figure shows 21 severe wind cases taken from the literature I Regime boundaries valid for 2D ridge (Houghton & Kashara, 1968) I Problem: boundaries not valid for real terrain! Regimes of strong terrain-induced winds at HKIA 18/78 Alexander Gohm Goals I Develop a regime diagram for the flow past Lantau Island I Determine diagnostic measures to separate flow regimes Methods I Use a single-layer shallow water model I Perform a large amount of simulations for various upstream conditions Introduction Goals and Methods Results Conclusions Appendix Goals and Methods Regimes of strong terrain-induced winds at HKIA 19/78 Alexander Gohm I Determine diagnostic measures to separate flow regimes Methods I Use a single-layer shallow water model I Perform a large amount of