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Sonic boom sag

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We intend to estimate advection by taking the differences between data from the upwind sonic array and data from the downwind, bottom array.  Therefore I have calculated the height difference between the sonic measurement volume and the nominal sonic heights measured at the base of the boom.  The nominal heights were closely matched between the upwind and downwind arrays.  I calculated the height difference as

sonic height above height measured at base of boom = boom-length*sin(pitch-angle) = boom-length*sin(lean*cos(leanaz))

where lean and leanaz were determined with the planar fit technique and recorded in the sonic cal files.  The boom-length is the distance from the base of the boom to the sonic measurement volume = 1.765 cm.

In the following tables, a positive height difference indicates that the sonic is higher than the base of the boom.  The height differences are in cm.  The Date/time in the first column is when the new height difference takes effect.

Upwind array

Date/time (PDT)

Config

boom ht

3u

4u

5u

6u

7u

8u

9u

10u

11u

mean

June 25 00:00

1

3.74 m

1.7

-0.5

-2.4

-2.3

3.0

0.6

0.9

-1.0

-0.6

-0.1

July 1 13:00*

1

3.24

1.0

-0.8

-3.3

-3.4

2.2

0.5

0.3

-2.1

-0.8

-0.7

July 20 16:00

2

3.64

0.4

6.1

0.4

3.0

4.0

3.1

1.5

0.2

-0.2

2.1

July 29 12:30

3

4.83

0.9

1.6

-3.3

1.5

1.8

1.2

2.5

2.2

0.2

1.0

Aug 9 18:00

4

6.98

6.1

7.7

7.3

4.1

4.1

7.7

2.8

4.6

1.1

5.0

* changed upwind array height from 3.74m to 3.24m

Bottom, downwind array

Date/time (PDT)

Config

boom ht

1b

2b

3b

4b

5b

6b

7b

8b

9b

10b

11b

12b

13b

mean

June 25 00:00

1

3.24 m

1.4

-0.2

-1.4

0.4

0.2

-2.7

-0.6

-4.0

2.4

1.0

-1.5

-1.3

0.9

-0.4

July 20 16:00

2

3.64

-1.8

-7.7

-11.4

-7.2

-4.8

2.2

-2.5

-7.9

-9.6

-10.7

-7.6

-1.3

-2.7

-5.6

July 29 12:30

3

4.83

-2.4

-8.7

-12.3

-8.4

-7.0

0.3

-4.2

-10.5

-11.2

-11.3

-7.9

-3.3

-0.5

-6.7

July 31 17:00*

3

4.83

5.9

3.3

0.9

2.1

3.0

1.1

2.4

-1.4

0.3

-1.2

-1.8

-2.0

-0.5

0.9

Aug 9 18:00

4

6.98

5.4

3.5

2.5

2.4

3.0

1.9

2.9

2.4

3.1

-0.7

-0.4

1.0

3.1

2.3

* adjusted height of downwind array sonics to decrease boom sag

Top, downwind array

Date/time (PDT)

Config

Boom ht

3t

4t

5t

6t

7t

8t

9t

10t

11t

mean

June 25 00:00

1

4.24 m

-2.1

-0.9

-0.9

0.6

-0.6

-2.1

0.7

2.1

0.4

-0.3

July 20 16:00

2

4.64

-3.4

-2.9

-0.9

3.2

-3.3

-4.5

-5.4

-5.0

-4.6

-3.0

July 29 12:30

3

5.83

-4.4

-5.1

-3.1

0.6

-4.7

-6.9

-6.8

-5.7

-4.7

-4.5

July 31 17:00*

3

5.83

2.6

0.8

0.3

2.1

2.2

5.8

7.2

4.3

3.5

3.2

Aug 9 18:00

4

7.98

3.8

2.5

3.5

2.6

2.0

2.1

3.6

3.1

4.6

3.1

* adjusted height of downwind array sonics to decrease boom sag

Profile sonics

Date/time (PDT)

Config

1.5m

3m

4m

5.5m

7m

8m

June 25 00:00

1

-1.1

-2.2

-1.0

-1.0

-0.7

1.0

July 20 16:00

2

-0.6

-2.7

-0.2

0.0

-0.8

0.9

July 29 12:30

3

0.2

-3.1

-0.5

-1.3

-1.5

0.6

Aug 3 09:00*

3

0.2

-3.1

-0.5

-1.3

-1.5

-1.0

Aug 3 09:41**

3

0.2

-3.1

-0.5

-1.3

0.2

-1.0

Aug 5 15:25*

3

0.2

-3.1

-0.5

-1.3

1.4

-0.2

Aug 9 18:00

4

-0.8

-3.7

-2.3

-2.5

-1.4

0.3

Aug 11 12:15*

4

-0.8

-3.7

-2.3

-2.5

-1.4

-2.1

* replaced 7m and/or 8m sonics

** moved 7m sonic up

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