Author Contributions
Conceptualization, J.S., K.J., D.C. (David Carruthers), and P.-W.C.; methodology, J.S., K.J., R.J. and S.S.; software, S.S. and D.C. (Daniel Connolly); validation, J.S., K.J. and R.J.; formal analysis, J.S. and K.J.; investigation, K.J.; resources, P.-W.C.; data curation, K.J.; writing—original draft preparation, J.S.; writing—review and editing, J.S. and D.C. (David Carruthers); visualization, R.J. and K.J.; supervision, J.S.; project administration, J.S.; funding acquisition, P.-W.C. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Hong Kong International Airport runways © OpenStreetMap (and) contributors, CC-BY-SA.
Figure 1.
Hong Kong International Airport runways © OpenStreetMap (and) contributors, CC-BY-SA.
Figure 2.
Example assignment of wind-shear event time (upper value, 15:53) to modelling period (lower values, 05, 25, and 45 past the hour), with reported and extended time windows.
Figure 2.
Example assignment of wind-shear event time (upper value, 15:53) to modelling period (lower values, 05, 25, and 45 past the hour), with reported and extended time windows.
Figure 3.
Flow chart showing data: processing and evaluation steps (orange), inputs (blue), intermediate outputs (yellow), and final outputs (green).
Figure 3.
Flow chart showing data: processing and evaluation steps (orange), inputs (blue), intermediate outputs (yellow), and final outputs (green).
Figure 4.
Modelled headwind corresponding to a wind event occurring on 14 March 2018 on the vertical slice coinciding with 07LA (event time 13:36, modelled time 13:25); example maximum horizontal and vertical acceleration calculation locations indicated by black arrows; typical wind-speed conditions.
Figure 4.
Modelled headwind corresponding to a wind event occurring on 14 March 2018 on the vertical slice coinciding with 07LA (event time 13:36, modelled time 13:25); example maximum horizontal and vertical acceleration calculation locations indicated by black arrows; typical wind-speed conditions.
Figure 5.
Example receiver operating characteristic (ROC) curve, with threshold value indicated.
Figure 5.
Example receiver operating characteristic (ROC) curve, with threshold value indicated.
Figure 6.
Derivation of metrics for a wind event occurring on 7 January 2018 coinciding with 07LA (event time 09:25, local time zone, modelled time 09:05, local time zone): (a) modelled minimum and maximum vertical acceleration, (b) modelled headwind on vertical slice, (c) modelled minimum and maximum horizontal acceleration. Selected wind observations at CCH (every 100 m) are displayed as wind barbs (in knots) to the right of the headwind vertical slice.
Figure 6.
Derivation of metrics for a wind event occurring on 7 January 2018 coinciding with 07LA (event time 09:25, local time zone, modelled time 09:05, local time zone): (a) modelled minimum and maximum vertical acceleration, (b) modelled headwind on vertical slice, (c) modelled minimum and maximum horizontal acceleration. Selected wind observations at CCH (every 100 m) are displayed as wind barbs (in knots) to the right of the headwind vertical slice.
Figure 7.
The main figure (
a) shows calculated flowfield for 09:05 7 January 2018 at 100 m, with high-resolution detail corresponding approximately to the vertical output slice shown in
Figure 6b. The inset (
b) shows the observed vertical wind-speed (WS) and -direction (WD) profiles at CCH.
Figure 7.
The main figure (
a) shows calculated flowfield for 09:05 7 January 2018 at 100 m, with high-resolution detail corresponding approximately to the vertical output slice shown in
Figure 6b. The inset (
b) shows the observed vertical wind-speed (WS) and -direction (WD) profiles at CCH.
Figure 8.
Derivation of metrics for a wind event occurring on 2 February 2018 coinciding with 07RD (event time 12:50 local time zone, modelled time 13:05 local time zone): (a) modelled minimum and maximum vertical acceleration, (b) modelled headwind on vertical slice, (c) modelled minimum and maximum horizontal acceleration. Selected wind observations at CCH (every 100 m) are displayed as wind barbs (in knots) to the right of the headwind vertical slice.
Figure 8.
Derivation of metrics for a wind event occurring on 2 February 2018 coinciding with 07RD (event time 12:50 local time zone, modelled time 13:05 local time zone): (a) modelled minimum and maximum vertical acceleration, (b) modelled headwind on vertical slice, (c) modelled minimum and maximum horizontal acceleration. Selected wind observations at CCH (every 100 m) are displayed as wind barbs (in knots) to the right of the headwind vertical slice.
Figure 9.
Calculated flowfield for 13:05 2 February 2018 at (a) 100 m above ground and (b) 200 m above ground. The inset (c) shows the observed vertical wind-speed (WS) and -direction (WD) profiles at CCH.
Figure 9.
Calculated flowfield for 13:05 2 February 2018 at (a) 100 m above ground and (b) 200 m above ground. The inset (c) shows the observed vertical wind-speed (WS) and -direction (WD) profiles at CCH.
Figure 10.
Example receiver operating characteristic curves for all metrics calculated for (a) 07LA maximum wind speed horizontal acceleration and (b) 07RA typical wind speed vertical acceleration.
Figure 10.
Example receiver operating characteristic curves for all metrics calculated for (a) 07LA maximum wind speed horizontal acceleration and (b) 07RA typical wind speed vertical acceleration.
Figure 11.
Example receiver operating characteristic curves for all metrics calculated for 25RA typical wind speed with horizontal acceleration.
Figure 11.
Example receiver operating characteristic curves for all metrics calculated for 25RA typical wind speed with horizontal acceleration.
Figure 12.
Wind roses for wind-shear cases associated with the four runway corridors: (
a) 07LA, (
b) 07RD, (
c) 07RA, and (
d) 25RA; percentage of cases shown radially, and colurs indicate wind-speed band (plots generated using the openair package [
20] within R software [
21]).
Figure 12.
Wind roses for wind-shear cases associated with the four runway corridors: (
a) 07LA, (
b) 07RD, (
c) 07RA, and (
d) 25RA; percentage of cases shown radially, and colurs indicate wind-speed band (plots generated using the openair package [
20] within R software [
21]).
Figure 13.
Modelled minimum, maximum, and average probability-of-detection ranges for each runway, including variations with meteorological inputs and metrics: (a) overall, (b) binned according to typical and maximum wind-speed inputs, (c) binned according to horizontal- or vertical-acceleration metric type, and (d) binned according to headwind-metric type.
Figure 13.
Modelled minimum, maximum, and average probability-of-detection ranges for each runway, including variations with meteorological inputs and metrics: (a) overall, (b) binned according to typical and maximum wind-speed inputs, (c) binned according to horizontal- or vertical-acceleration metric type, and (d) binned according to headwind-metric type.
Figure 14.
Sensitivity testing of receiver operating characteristic curves for the 3 metrics to horizontal extent for the 07RA typical wind-speed horizontal-acceleration case using half the horizontal extent of the runway (−6000 to 0) and the full horizontal extent of the runway (−6000 to +6000): (a) headwind at the maximum horizontal acceleration, (b) headwind at the minimum horizontal acceleration, and (c) maximum of the aforementioned headwinds.
Figure 14.
Sensitivity testing of receiver operating characteristic curves for the 3 metrics to horizontal extent for the 07RA typical wind-speed horizontal-acceleration case using half the horizontal extent of the runway (−6000 to 0) and the full horizontal extent of the runway (−6000 to +6000): (a) headwind at the maximum horizontal acceleration, (b) headwind at the minimum horizontal acceleration, and (c) maximum of the aforementioned headwinds.
Table 1.
Summary of previous HKIA wind-shear modelling studies using FLOWSTAR, listing meteorological measurements used for model input and evaluation, and sensitivity analyses.
Table 1.
Summary of previous HKIA wind-shear modelling studies using FLOWSTAR, listing meteorological measurements used for model input and evaluation, and sensitivity analyses.
Item | Paper |
---|
Reference | [16] | [18] | [17] |
---|
Title | Modelling of Wind Shear Downwind of Mountain Ridges at Hong Kong International Airport | Optimised Use of Real-Time Vertical-Profile Wind Data and Fast Modelling for Prediction of Airflow over Complex Terrain | Modelling Adverse Meteorological Conditions for Aircraft Arising from Airflow over Complex Terrain |
---|
Number of wind-shear cases studied | 1 | 1 | 4 (+ 4 non-wind-shear cases for comparison) |
Meteorological measurements used to as input to FLOWSTAR | | Radiosonde data from King’s Park Ground-anemometer data from Cheung Chau Wind-profiler data from Cheung Chau
| |
Meteorological measurements used to evaluate FLOWSTAR output | | | LIDAR traces Pilot wind-shear reports
|
Model-sensitivity analyses | | | |
Table 2.
Metric summary, including mathematical notation, and summary of justification for inclusion in the study; all metrics are calculated in both horizontal and vertical in relation to the 2D vertical slices aligned with the runways.
Table 2.
Metric summary, including mathematical notation, and summary of justification for inclusion in the study; all metrics are calculated in both horizontal and vertical in relation to the 2D vertical slices aligned with the runways.
Metric Desciption | Mathematical Notation | Justification |
---|
Max. value of acceleration | | The product of the headwind and headwind gradient amplifies the impact of sharp changes in headwind. |
Min. value of acceleration | |
Max. magnitude of both acceleration metrics | | Test sensitivity with regard to minimum and maximum values |
Headwind at the max. value of acceleration | | Following previous work where the severity factor was proportional to the cube of the headwind |
Headwind at the min. value of acceleration | |
Max. magnitude of both headwind metrics | | Test sensitivity with regard to minimum and maximum values |
Table 3.
Definition of event parameters.
Table 3.
Definition of event parameters.
| Event Observed |
Yes | No |
Event Modelled | Yes | a | b |
No | c | d |
Table 4.
Summary of the subset of modelled cases corresponding to pilot wind-shear reports; * the number of cases differs for typical and maximum’ inversion-layer wind-speed cases due to the typical cases requiring more comprehensive meteorological-data input parameters than the ‘maximum cases; runway corridors 07LD, 25LA, 25RA, and 25RD were excluded from the modelling due to insufficient corresponding pilot wind-shear reports.
Table 4.
Summary of the subset of modelled cases corresponding to pilot wind-shear reports; * the number of cases differs for typical and maximum’ inversion-layer wind-speed cases due to the typical cases requiring more comprehensive meteorological-data input parameters than the ‘maximum cases; runway corridors 07LD, 25LA, 25RA, and 25RD were excluded from the modelling due to insufficient corresponding pilot wind-shear reports.
| Count of Modelled Wind-Shear Cases (Total Number of Reports) | Along-Runway Modelling Extent from Southwest to Northeast |
---|
Approaches | Departures |
---|
Runway | North | South | South | −6000 to 0 | 0 to 6000 | −6000 to 6000 |
---|
07LA | 88 t/96 m * (96) | | | ✓ | ✗ | ✓ |
07RA | | 27 (29) | | ✓ | ✗ | ✓ |
07RD | | | 15 (15) | ✗ | ✓ | ✓ |
25RA | 12 (12) | | | ✗ | ✓ | ✓ |
Table 5.
Data summary of meteorological parameters required as input for FLOWSTAR for the period from January to April 2018.
Table 5.
Data summary of meteorological parameters required as input for FLOWSTAR for the period from January to April 2018.
Parameter | Units | Minimum | Average | Maximum |
---|
Wind | Maximum speed in the inversion layer | m/s | 0.2 | 7.1 | 25.1 |
Typical speed in the inversion layer | m/s | 0.0 | 4.0 | 20.6 |
Direction at max speed | degrees | 0 | 82 | 360 |
Direction at typical speed | degrees | 0 | 111 | 360 |
Surface-sensible heat flux | W/m2 | −44 | 7 | 140 |
Boundary-layer height | m | 200 | 211 | 550 |
Inversion-layer temperature jump | K | 0.0 | 2.9 | 17.8 |
Buoyancy frequency (above the inversion layer) | 1/s | 0.005 | 0.015 | 0.020 |
Table 6.
Resultant wind-speed (m/s) thresholds calculated from the ROC-curve analysis. A quantitative indicator of performance is given in brackets for each scenario (with better performance indicated in bold, corresponding to POD × (1 − FAR) × (POD − FAR) > 0.2).
Table 6.
Resultant wind-speed (m/s) thresholds calculated from the ROC-curve analysis. A quantitative indicator of performance is given in brackets for each scenario (with better performance indicated in bold, corresponding to POD × (1 − FAR) × (POD − FAR) > 0.2).
| | Vertical | Horizontal |
---|
Metric | Runway | Typical | Max | Typical | Max |
---|
Magnitude of headwind at maximum acceleration | 07LA | 6.0 (0.16) | 6.5 (0.12) | 6.0 (0.17) | 5.5 (0.10) |
07RA | 7.5 (0.28) | 8.5 (0.25) | 7.0 (0.28) | 6.5 (0.19) |
07RD | 6.5 (0.28) | 6.0 (0.21) | 5.0 (0.22) | 5.0 (0.18) |
Magnitude of headwind at minimum acceleration | 07LA | 6.0 (0.17) | 6.0 (0.10) | 6.0 (0.15) | 5.0 (0.12) |
07RA | 7.0 (0.24) | 7.0 (0.17) | 7.0 (0.15) | 5.0 (0.11) |
07RD | 5.5 (0.24) | 6.0 (0.20) | 6.5 (0.27) | 6.0 (0.23) |
Maximum magnitude of both headwind metrics | 07LA | 6.5 (0.19) | 6.5 (0.13) | 6.5 (0.17) | 5.5 (0.12) |
07RA | 8.5 (0.26) | 8.5 (0.24) | 7.0 (0.25) | 7.5 (0.20) |
07RD | 6.5 (0.26) | 6.0 (0.23) | 6.5 (0.27) | 6.0 (0.23) |
Table 7.
Sensitivity of the quantitative indicator of performance (better performance indicated in bold with +1 indicative of ideal performance) to the horizontal extent of data included in ROC calculations. The full runway length or the half-runway extent is based on direction of approach. 07RA runway corridor, typical met, horizontal acceleration, 40 min wind-shear time window.
Table 7.
Sensitivity of the quantitative indicator of performance (better performance indicated in bold with +1 indicative of ideal performance) to the horizontal extent of data included in ROC calculations. The full runway length or the half-runway extent is based on direction of approach. 07RA runway corridor, typical met, horizontal acceleration, 40 min wind-shear time window.
| Metric Performance |
---|
Runway Extent | Headwind at Max. Acceleration | Headwind at Min. Acceleration | Max. of Magnitudes of Headwind |
---|
Half | 0.275 | 0.148 | 0.246 |
Full | 0.260 | 0.145 | 0.236 |
Table 8.
Sensitivity of the quantitative indicator of performance (better performance indicated in bold with +1 indicative of ideal performance) to the extended wind-shear time window. 07RA runway corridor, typical met, horizontal acceleration, half runway extent.
Table 8.
Sensitivity of the quantitative indicator of performance (better performance indicated in bold with +1 indicative of ideal performance) to the extended wind-shear time window. 07RA runway corridor, typical met, horizontal acceleration, half runway extent.
| Metric Performance |
---|
Extended Time Window (mins) | Headwind at Max. Acceleration | Headwind at Min. Acceleration | Max. of Magnitudes of Headwind |
---|
20 | 0.343 | 0.170 | 0.309 |
40 | 0.275 | 0.148 | 0.246 |
60 | 0.214 | 0.120 | 0.206 |
80 | 0.188 | 0.113 | 0.194 |