Son3D_s

Sonic Anemometer at Met Mast on South Beach

Wind speed is calculated from a 3-axis sonic anemometer (Solent Model R3) located atop the meteorological mast at South Beach, 41° 20.996' N, 70° 31.606' W. The height of the anemometer is 12.5 meters above mean sea level. This type of anemometer measures the wind speed with no moving parts. Instead, it measures how long it takes two pulses of sound, moving in opposite directions, to travel a known distance. The pulses are created and detected using pairs of transducers and are inaudible to humans. The time of flight is shorter for the pulse moving with the wind, so the difference in time is a measure of the wind speed between the transducers. Three pairs of transducers are used to measure the wind speed and wind direction.

Most of the data parameters include valus for the mean and median value as well as the standard deviation of the variable. The table below shows the field name suffix used to differentiate amoung the different values:

Approximate Sensor Heights

Sonic - windspeed - 12.5 m above MSL
Vaisala - air temp/rel humidity - 11 m above MSL
pressure sensor - air pressure - 3 m above MSL

Field name Description

_mean The mean value of the variable over the averaging period

_m50 The median value of the variable over the averaging period

_std The standard deviation of the variable over the averaging period

_length The number of valid data points collected over the averaging period

Field name	Description
_mean	The mean value of the variable over the averaging period
_m50	The median value of the variable over the averaging period
_std	The standard deviation of the variable over the averaging period
_length	The number of valid data points collected over the averaging period

Here is the list of field names:

Field name Description Units

Year The year the data were collected n/a

Yday Decimal year day UTC, January 1 at 00:00 is 1.0

MO The month the data was collected UTC

DA The day the data were collected UTC

HH The hour the data were collected UTC

MM The minute the data were collected UTC

SS The second the data were collected UTC

lrec_son3d Total number of records collected during averaging period n/a

wspd_son3d_mean mean wind speed

wdir_son3d mean wind directions 180=winds from south
90= winds from east

w_son3d vertical velocity m/s

tson_son3d_mean air temp from speed of sound Deg C

winst_son3d ??Instantaneous Wind Speed m/s

wspd_son3d_m50 median wind speed m/s

tson_son3d_m50 median air temp from speed of sound Deg C

wspd_son3d_std std along-wind windspeed m/s

v_son3d_std std cross-wind component m/s

w_son3d_std std vertical wind component m/s

uv_son3d_var covariance m^2/s^2

uw_son3d_var along-wind covariance m^2/s^2

vw_son3d_var cross-wind covariance m^2/s^2

wT_son3d_var covariance vertical wind speed with air temp ??

wspd_son3d_length # recs between 0 100 and < 4*std from mean n/a

tson_son3d_length # recs between -25 and 35 and < 4*std from mean n/a

Field name	Description	Units
Year	The year the data were collected	n/a
Yday	Decimal year day	UTC, January 1 at 00:00 is 1.0
MO	The month the data was collected	UTC
DA	The day the data were collected	UTC
HH	The hour the data were collected	UTC
MM	The minute the data were collected	UTC
SS	The second the data were collected	UTC
lrec_son3d	Total number of records collected during averaging period	n/a
wspd_son3d_mean	mean wind speed
wdir_son3d	mean wind directions	180=winds from south 90= winds from east
w_son3d	vertical velocity	m/s
tson_son3d_mean	air temp from speed of sound	Deg C
winst_son3d	??Instantaneous Wind Speed	m/s
wspd_son3d_m50	median wind speed	m/s
tson_son3d_m50	median air temp from speed of sound	Deg C
wspd_son3d_std	std along-wind windspeed	m/s
v_son3d_std	std cross-wind component	m/s
w_son3d_std	std vertical wind component	m/s
uv_son3d_var	covariance	m^2/s^2
uw_son3d_var	along-wind covariance	m^2/s^2
vw_son3d_var	cross-wind covariance	m^2/s^2
wT_son3d_var	covariance vertical wind speed with air temp	??
wspd_son3d_length	# recs between 0 100 and < 4*std from mean	n/a
tson_son3d_length	# recs between -25 and 35 and < 4*std from mean	n/a

Aug 4, 2005
removed SN#145 (calibrated 7/04)
Installed SN#6
Swapped out the wand (not working) on the Vaisala No obvious damage noted.

Sept 7, 2006
removed SN#6 and installed R3 SN#145 (calibrated 9/22/05)
Removed Vaisala wand Z3350003 (corroded/broken pins on cable) Installed Vaisala wand A301001 and cable HMP45a-0 (ht 26' 4")
Cleaned camera lens.

Trouble with sensor in 2007 missing Feb, Apr-Sep
??
Get offshore winds from Vane at shore lab (Campmt_s) or offshore (3D1_s)

Aug 23, 2007
Removed SN#145 and installed SN#6 ... replaced cable

June 16, 2009
Installed R3 SN#145 (calibrated 2/28/2008)

Last updated 6/1/2011 - jf