1

Wind Direction, Intensity, andDominant Wave Period Analysis

Keweenaw North Waterway BuoyBob Shuchman: shuchman@mtu.eduColin Brooks: colin.brooks@mtu.eduNate Jessee: nljessee@mtu.edu

www.michigantechlakesuperior.orgwww.mtri.org

2

Analysis of Wind Direction and Speed

The Keweenaw Waterway North buoy gathered data from 7/9/2010 through 10/11/2010. Data is located at www.michigantechlakesuperior.org

A limited selection of records were removed for pre-deployment recording and sensor errors.

Data presented here represents dates from 7/9/2010 through 10/10/2010.

Two of the parameters collected were wind direction and wind speed.

This data was organized to determine the frequency, duration, and strength of winds moving off shore (from land to water) and on shore (from water to land).

3

General Wind Speed Analysis

For all records spanning from July 9th through October 10th 2010, wind speed measurements were recorded every ten minutes.

During this time span, wind speeds were less than 2 m/s for 11.41% of all records and wind speed was equal to zero for 0.07% of all records.

4

Analysis of Wind Direction and Speed

On shore and off shore winds are characterized based on the buoy location and the direction of the land.

Wind direction is absolute in that it indicates the direction that wind is moving towards.

On shore events are defined by consecutive recordings of winds with a direction between 45 and 225 degrees where 360/0 is north and 180 degrees as south.

45

225On ShoreDirection

5

Analysis of Wind Direction and Speed

Off shore events are consecutive recordings with a direction greater than 225 and less than 45 degrees where 360/0 is north and 180 degrees is south. 45

225

Off ShoreDirection

6

Buoy Location

7

Off Shore and On Shore Wind Direction Frequency

Off Shore On Shore0

1000

2000

3000

4000

5000

6000

7000

8000

9000

8005

5448

Histogram: Count of wind direction frequency

Frequency

Freq

uenc

y

40.5%

59.5%

The frequency of wind direction recordings described as either off shore or on shore,a total of 13453 records were taken from July 9th to October 10th.

Coun

t of R

ecor

ding

s

8

Off Shore Wind Event* Duration Statistics

Hour

s

Minimum Maximum Average Median Standard Deviation0

10

20

30

40

50

60

70

80

90

0.17

77.5

2.68 0.33

8.35

Value (Hours)

Value (Hours)

Min5.31m/s

Ave.8.07m/s

WindSpeedsFor thisevent

Max10.83m/s

Description of off shore wind events, described by duration of events in hours.*Events are defined as time periods greater than 10 minutes where wind is consistently moving in the on or off shore direction.

9

Off Shore Wind Speed Statistics

Minimum Maximum Average Median Standard Deviation0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

0.00

15.07

3.473.05

2.40

Wind Speed Values (m/s)

Values (m/s)

Win

d Sp

eed,

m/s

Summary of all off shore wind speeds for all off shore events.

10

On Shore Wind Event* Duration Statistics

Minimum Maximum Average Median Standard Deviation0.00

1.00

2.00

3.00

4.00

5.00

6.00

0.17

5.17

0.440.17

0.76

Value (Hours)

Values (Hours)Hour

s Max5.92m/s

Min4.32m/s

Ave.4.98m/s

Description of on shore wind events, described by duration of events in hours.*Events are defined as time periods greater than 10 minutes where wind is consistently moving in the on or off shore direction.

11

On Shore Wind Speed Statistics

Minimum Maximum Average Median Standard Deviation0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00

12.56

3.803.38

2.46

Wind Speed Values (m/s)

Values (m/s)

Win

d Sp

eed,

m/s

Summary of all on shore wind speeds for all on shore events

12

Off Shore and On Shore Event Duration Comparison

Event Duration Statistics

Hour

s

Minimum Maximum Average Median Standard Deviation0

10

20

30

40

50

60

70

80

90

0.17

77.5

2.690.33

9.17

0.175.17

0.44 0.17 0.76

Off Shore Values (Hours)On Shore Values (Hours)

13

Off Shore and On Shore Wind Speed Comparison

Minimum Maximum Average Median Standard Deviation0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

0.00

15.07

3.473.05

2.40

0.00

12.56

3.803.38

2.46

Off Shore Values (m/s)On Shore Values (m/s)

Win

d Sp

eed,

m/s

Represents all wind speed records for all events categorized as on or off shore

14

Major Off Shore Wind Event Started on September 11th at 7:30

p.m. and lasted through September 15th at 1:00 a.m. Lasting a total of 77 hours, 30 minutes.

The event had the following characteristics:

Average wind speed: 8.07 m/s Minimum wind speed: 5.31 m/s Maximum wind speed 10.83 m/s The following slide represents the

temporal distribution of wind speed.

15

Major Off Shore Event, Wind Speed Graph

9/11/10 19:30 9/12/10 6:40 9/12/10 18:10 9/13/10 5:30 9/13/10 16:50 9/14/10 4:10 9/14/10 15:300

2

4

6

8

10

12

Wind Speed (m/s)

Wind Speed (m/s)

Win

d Sp

eed,

m/s

16

Major Wind Event Airport and Buoy Data Comparison

9/11/2010 19:309/12/2010 12:50 9/13/2010 6:30 9/14/2010 0:00 9/14/2010 17:300

50

100

150

200

250

300

350

0

50

100

150

200

250

300

350

400

Wind Direction Degrees (Buoy)Wind Direction Degrees (Airport)

*Wind Directions indicate the actual direction that wind is moving

*

Win

d Di

rect

ion

17

Wind Speed for Entire Data Series

7/10/2010 2:00 7/26/2010 5:40 8/11/2010 9:408/27/2010 10:309/11/2010 6:209/27/2010 12:500

2

4

6

8

10

12

14

16

WindSpeed(m/s)

WindSpeed(m/s)

Win

d Sp

eed,

m/s

Represents all records from July 9th through October 10th.

18

Major Off Shore Wind Event Within Entire Time Line

7/9/2010 14:507/21/2010 18:308/2/2010 22:10 8/15/2010 1:50 8/27/2010 3:50 9/7/2010 1:00 9/19/2010 1:40 10/1/2010 9:300

2

4

6

8

10

12

14

16

Wind Speed (m/s)Major offshore wind event

Win

d Sp

eed,

m/s

Represents all records from July 9th through October 10th and highlights the major off shore event

19

Dominant Wave Period Analysis High Frequency (HF) Radar is sensitive to

dominant wave period length. Wave periods of small length, less than 2

seconds for example, may be unnoticed by HF Radar.

An analysis was performed to determine how frequently the dominant wave period dropped below a specific value. Each event was also characterized by the length of time the wave period value was below the threshold.

20

General Dominant Wave Period Analysis

For all records spanning from July 9th to October 10th, dominant wave period measurements were recorded every ten minutes.

The dominant wave period had a value of zero second for 0.01% of all records.

Also, dominant wave period value was less than 2 seconds for 15.98% of all records and greater than 5 seconds for 16.03% of all records between July 9th and October 10th.

21

Frequency and Duration of Wave Periods less than 2 seconds.

less th

an 10

minutes

10 minu

tes1 h

our

2 hou

rs

3 hou

rs

4 hou

rs

5 hou

rs

6 hou

rs

7 hou

rs

8 hou

rs

9 hou

rs

10 ho

urs

11 ho

urs

12 ho

urs

13 ho

urs

14 ho

urs

15 ho

urs

16 ho

urs

17 ho

urs

18 ho

urs

19 ho

urs

20 ho

urs

21 ho

urs

22 ho

urs

23 ho

urs1 day

0

50

100

150

200

250217

6

142

23 18 6 11 3 1 2 1 1 0 1 0 0 0 0 0 0 0 0 0 1 0 0

Count and Duration of Wave Period Events less than 2 Seconds

Frequency

Duration of Wave periods less than 2 seconds

Freq

uenc

y

This graph represents 15.98 % of all records from July 9th through October 10th.

Coun

t of E

vent

s

22

Frequency and Duration of Wave Periods less than 1.5 Seconds

less th

an 10

minutes

10 minu

tes

30 minu

tes1 h

our

2 hou

rs

3 hou

rs

4 hou

rs

5 hou

rs

6 hou

rs

7 hou

rs0

20406080

100120140160 147

6

67

2110

1 0 0 0 0

Count and Duration of Wave Period Events less than 1.5 Seconds

Frequency

Duration of Wave Periods less than 1.5 Seconds

Freq

uenc

y

This graph represents 3.95 % of all records from July 9th through October 10th.

Coun

t of E

vent

s

23

Frequency and Duration of Wave Periods equal to zero seconds

less than ten minutes 10 minutes 20 minutes greater than 20 minutes0

0.5

1

1.5

2

2.5

0

2

0 0

Count and Duration of Wave Period Events less than 1.1 Seconds

Frequency

Duration of Wave Periods of Zero Seconds

Freq

uenc

y

This graph represents 0.01 % of all records from July 9th through October 10th.

Coun

t of E

vent

s