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- Table of Variables
- Processing Notes
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- 5-minute averages of first and second-order moments of calibrated data. We recommend combining these to obtain more statistically-significant averages over longer time periods. These are available in NetCDF data files.

A complete list of variables is available. This list shows the NetCDF variable name, dimensions, descriptive variable name, units, and additional comments, if available. Each file contains all the statistics for one day, beginning at 00:00:00 UTC. Most variables are dimensioned (time, station), where time is in 5 minute increments (288 per day), station is 1 or 2 for variables common to NCAR (station=1) and Oklahoma (station=2). Variables without a station dimension were measured by either NCAR or OK, but not both. See the Sensors description below for guidance as to where the variables were measured.

Most descriptive variable names hopefully are self-explanatory. Those beginning with Capital letters came from slow response sensors and those with lower cases letters from fast response sensors. Higher order statistics are indicated by products of variables. For example, w'tc' is the covariance between vertical velocity and sonic virtual temperature and h2o'h2o'h2o'h2o' is the fourth order moment of water vapor mixing density. For some variables, the sensor name is appended, e.g. "v.nuw1" is the lateral velocity component from the one of the new sonic anemometers we built with a University of Washington-style array, to distinguish it from "v" which is the same variable measured by other sonic anemometers.

A series of views forming a panorama from the 9m level of the sonic tower is available here:

The data files contain data from NCAR and the University of Oklahoma Mesonet. The NCAR sensors are mostly described in the ASTER Facility Description. A color-coded diagram of the variables from these sensors was created to help sort out the variables.

Variable Name | Description | Units | Dimension | Sensor | Notes |
---|---|---|---|---|---|

base_time | Seconds since 1970 Jan 1 00:00 GMT | seconds | |||

time | Seconds since base_time | seconds | time | ||

Gsoil.5cm.1 | Soil Heat Flux | W/m^2 | time x station | ||

Gsoil.5cm.2 | Soil Heat Flux | W/m^2 | time x station | ||

Gsoil.5cm.3 | Soil Heat Flux | W/m^2 | time | ||

Mp.5cm.1 | msec | time | |||

Mp.5cm.2 | msec | time | |||

Mp.5cm.3 | msec | time | |||

Msoil.5cm.1 | Soil Moisture | V frctn | time x station | ||

Msoil.5cm.2 | Soil Moisture | V frctn | time | ||

Msoil.5cm.3 | Soil Moisture | V frctn | time | ||

P | Barometric Pressure | mb | time x station | ||

RH.0.5m | Rel. Humidity | % | time | ||

RH.1.5m.2 | Rel. Humidity | % | time | ||

RH.1.5m.3 | Rel. Humidity | % | time | ||

RH.1.5m | Rel. Humidity | % | time x station | ||

RH.4.5m | Rel. Humidity | % | time | ||

RH.6.5m | Rel. Humidity | % | time | ||

RH.9m | Rel. Humidity | % | time x station | ||

Rlw.in.CNR1a | Incoming Longwave | W/m^2 | time | ||

Rlw.out.CNR1a | Outgoing Longwave | W/m^2 | time | ||

Rnet.CNR1a | Net Radiation | W/m^2 | time | ||

Rnet.NRLite.3 | Net Radiation | W/m^2 | time | ||

Rnet | Net Radiation | W/m^2 | time x station | ||

Rpile.in.CNR1a | Up-looking Thermopile | W/m^2 | time | ||

Rpile.in | Up-looking Thermopile | W/m^2 | time x station | ||

Rpile.out.CNR1a | Down-looking Thermopile | W/m^2 | time | ||

Rpile.out | Down-looking Thermopile | W/m^2 | time x station | ||

Rsw.in.CNR1a | Incoming Shortwave | W/m^2 | time | ||

Rsw.in | Incoming Shortwave | W/m^2 | time x station | ||

Rsw.out.CNR1a | Outgoing Shortwave | W/m^2 | time | ||

Rsw.out | Outgoing Shortwave | W/m^2 | time x station | ||

Spd.2m | Wind Speed | m/s | time x station | ||

Spd.9m | Wind Speed | m/s | time x station | ||

T.0.5m | Air Temp | degC | time | ||

T.1.5m.2 | Air Temp | degC | time | ||

T.1.5m.3 | Air Temp | degC | time | ||

T.1.5m | Air Temp | degC | time x station | ||

T.4.5m | Air Temp | degC | time | ||

T.6.5m | Air Temp | degC | time | ||

T.9m | Air Temp | degC | time x station | ||

Tadam.marigold | Electronics Temp | degC | time | ||

Tadam.ragwort | Electronics Temp | degC | time | ||

Tcase.CNR1a | W/m^2 | time | |||

Tcase.in | Up-looking Case Temp | degC | time x station | ||

Tcase.out | Down-looking Case Temp | degC | time x station | ||

Tdome.in | Up-looking Dome Temp | degC | time x station | ||

Tdome.out | Down-looking Dome Temp | degC | time x station | ||

Tsfc | Surface Temp | C | time | ||

Tsoil.5cm.1 | Soil Temperature | degC | time x station | ||

Tsoil.5cm.2 | Soil Temperature | degC | time x station | ||

Tsoil.5cm.3 | Soil Temperature | degC | time | ||

U.10m | Eastward Wind | m/s | time | ||

U.1m | Eastward Wind | m/s | time | ||

U.2m | Eastward Wind | m/s | time | ||

U.4.5m | Eastward Wind | m/s | time | ||

U.6.5m | Eastward Wind | m/s | time | ||

U.9m | Eastward Wind | m/s | time | ||

V.10m | Northward Wind | m/s | time | ||

V.1m | Northward Wind | m/s | time | ||

V.2m | Northward Wind | m/s | time | ||

V.4.5m | Northward Wind | m/s | time | ||

V.6.5m | Northward Wind | m/s | time | ||

V.9m | Northward Wind | m/s | time | ||

cflag.nuw1 | time | ||||

cflag.nuw2 | time | ||||

diag.csat | time | ||||

h2o'h2o'.4.5m | h2o variance | (g/m^3)^2 | time x station | ||

h2o'h2o'.9m | h2o variance | (g/m^3)^2 | time | ||

h2o.4.5m | Water Vapor Density | g/m^3 | time x station | ||

h2o.9m | Water Vapor Density | g/m^3 | time | ||

lev.rad.x | deg | time | |||

lev.rad.y | deg | time | |||

lev.u.4.5m | deg | time | |||

lev.u.9m | deg | time | |||

lev.v.4.5m | deg | time | |||

lev.v.9m | deg | time | |||

mr'mr'.bph.4.5m | (gm/kg)^2 | time | |||

mr.bph.4.5m | gm/kg | time | |||

raina | Rain Accumulation | mm | time x station | ||

rainr | Rain Rate | mm/hr | time x station | ||

rh.bph.4.5m | % | time | |||

t't'.4.5m | t variance | (degC)^2 | time x station | ||

t't'.bph.4.5m | t variance | (degC)^2 | time | ||

t.4.5m | Air Temperature | degC | time x station | ||

t.bph.4.5m | Air Temperature | degC | time | ||

tc'tc'.4.5m | tc variance | (degC)^2 | time x station | ||

tc'tc'.9m | tc variance | (degC)^2 | time | ||

tc'tc'.csat | tc variance | (degC)^2 | time | ||

tc'tc'.nuw1 | tc variance | (degC)^2 | time | ||

tc'tc'.nuw2 | tc variance | (degC)^2 | time | ||

tc.4.5m | Virtual Temperature | degC | time x station | ||

tc.9m | Virtual Temperature | degC | time | ||

tc.csat | Virtual Temperature | degC | time | ||

tc.nuw1 | Virtual Temperature | degC | time | ||

tc.nuw2 | Virtual Temperature | degC | time | ||

tcflag.4.5m | Spike fract for tc | time | |||

tcflag.9m | Spike fract for tc | time | |||

tcflag.csat | Spike fract for tc | time | |||

u'h2o'.4.5m | u h2o covariance | m/s g/m^3 | time x station | ||

u'h2o'.9m | u h2o covariance | m/s g/m^3 | time | ||

u'mr'.(,bph).4.5m | m/s gm/kg | time | |||

u't'.(,bph).4.5m | u t covariance | m/s degC | time | ||

u't'.4.5m | u t covariance | m/s degC | time x station | ||

u'tc'.4.5m | u tc covariance | m/s degC | time x station | ||

u'tc'.9m | u tc covariance | m/s degC | time | ||

u'tc'.csat | u tc covariance | m/s degC | time | ||

u'tc'.nuw1 | u tc covariance | m/s degC | time | ||

u'tc'.nuw2 | u tc covariance | m/s degC | time | ||

u'u'.4.5m | u variance | (m/s)^2 | time x station | ||

u'u'.9m | u variance | (m/s)^2 | time | ||

u'u'.csat | u variance | (m/s)^2 | time | ||

u'u'.nuw1 | u variance | (m/s)^2 | time | ||

u'u'.nuw2 | u variance | (m/s)^2 | time | ||

u'v'.4.5m | u v covariance | (m/s)^2 | time x station | ||

u'v'.9m | u v covariance | (m/s)^2 | time | ||

u'v'.csat | u v covariance | (m/s)^2 | time | ||

u'v'.nuw1 | u v covariance | (m/s)^2 | time | ||

u'v'.nuw2 | u v covariance | (m/s)^2 | time | ||

u'w'.4.5m | u w covariance | (m/s)^2 | time x station | ||

u'w'.9m | u w covariance | (m/s)^2 | time | ||

u'w'.csat | u w covariance | (m/s)^2 | time | ||

u'w'.nuw1 | u w covariance | (m/s)^2 | time | ||

u'w'.nuw2 | u w covariance | (m/s)^2 | time | ||

u.4.5m | Sonic U Wind Comp | m/s | time x station | ||

u.9m | Sonic U Wind Comp | m/s | time | ||

u.csat | Sonic U Wind Comp | m/s | time | ||

u.nuw1 | Sonic U Wind Comp | m/s | time | ||

u.nuw2 | Sonic U Wind Comp | m/s | time | ||

uaflag.nuw1 | G | time | |||

uaflag.nuw2 | G | time | |||

uasamples.nuw1 | time | ||||

uasamples.nuw2 | time | ||||

ubflag.nuw1 | time | ||||

ubflag.nuw2 | time | ||||

ubsamples.nuw1 | G | time | |||

ubsamples.nuw2 | G | time | |||

ucflag.nuw1 | time | ||||

ucflag.nuw2 | time | ||||

ucsamples.nuw1 | G | time | |||

ucsamples.nuw2 | G | time | |||

uflag.4.5m | Spike fract for u | G | time | ||

uflag.9m | Spike fract for u | G | time | ||

uflag.csat | Spike fract for u | time | |||

usamples.4.5m | # of samples averaged | G | time | ||

usamples.9m | # of samples averaged | G | time | ||

v'h2o'.4.5m | v h2o covariance | m/s g/m^3 | time x station | ||

v'h2o'.9m | v h2o covariance | m/s g/m^3 | time | ||

v'mr'.(,bph).4.5m | m/s gm/kg | time | |||

v't'.(,bph).4.5m | v t covariance | m/s degC | time | ||

v't'.4.5m | v t covariance | m/s degC | time x station | ||

v'tc'.4.5m | v tc covariance | m/s degC | time x station | ||

v'tc'.9m | v tc covariance | m/s degC | time | ||

v'tc'.csat | v tc covariance | m/s degC | time | ||

v'tc'.nuw1 | v tc covariance | m/s degC | time | ||

v'tc'.nuw2 | v tc covariance | m/s degC | time | ||

v'v'.4.5m | v variance | (m/s)^2 | time x station | ||

v'v'.9m | v variance | (m/s)^2 | time | ||

v'v'.csat | v variance | (m/s)^2 | time | ||

v'v'.nuw1 | v variance | (m/s)^2 | time | ||

v'v'.nuw2 | v variance | (m/s)^2 | time | ||

v'w'.4.5m | v w covariance | (m/s)^2 | time x station | ||

v'w'.9m | v w covariance | (m/s)^2 | time | ||

v'w'.csat | v w covariance | (m/s)^2 | time | ||

v'w'.nuw1 | v w covariance | (m/s)^2 | time | ||

v'w'.nuw2 | v w covariance | (m/s)^2 | time | ||

v.4.5m | Sonic V Wind Comp | m/s | time x station | ||

v.9m | Sonic V Wind Comp | m/s | time | ||

v.csat | Sonic V Wind Comp | m/s | time | ||

v.nuw1 | Sonic V Wind Comp | m/s | time | ||

v.nuw2 | Sonic V Wind Comp | m/s | time | ||

vflag.4.5m | Spike fract for v | time | |||

vflag.9m | Spike fract for v | time | |||

vflag.csat | Spike fract for v | time | |||

vsamples.4.5m | # of samples averaged | G | time | ||

vsamples.9m | # of samples averaged | G | time | ||

w'h2o'.4.5m | w h2o covariance | m/s g/m^3 | time x station | ||

w'h2o'.9m | w h2o covariance | m/s g/m^3 | time | ||

w'mr'.(,bph).4.5m | m/s gm/kg | time | |||

w't'.(,bph).4.5m | w t covariance | m/s degC | time | ||

w't'.4.5m | w t covariance | m/s degC | time x station | ||

w'tc'.4.5m | w tc covariance | m/s degC | time x station | ||

w'tc'.9m | w tc covariance | m/s degC | time | ||

w'tc'.csat | w tc covariance | m/s degC | time | ||

w'tc'.nuw1 | w tc covariance | m/s degC | time | ||

w'tc'.nuw2 | w tc covariance | m/s degC | time | ||

w'w'.4.5m | w variance | (m/s)^2 | time x station | ||

w'w'.9m | w variance | (m/s)^2 | time | ||

w'w'.csat | w variance | (m/s)^2 | time | ||

w'w'.nuw1 | w variance | (m/s)^2 | time | ||

w'w'.nuw2 | w variance | (m/s)^2 | time | ||

w.4.5m | Sonic W Wind Comp | m/s | time x station | ||

w.9m | Sonic W Wind Comp | m/s | time | ||

w.csat | Sonic W Wind Comp | m/s | time | ||

w.nuw1 | Sonic W Wind Comp | m/s | time | ||

w.nuw2 | Sonic W Wind Comp | m/s | time | ||

wflag.4.5m | Spike fract for w | time | |||

wflag.9m | Spike fract for w | time | |||

wflag.csat | Spike fract for w | time | |||

wsamples.4.5m | # of samples averaged | G | time | ||

wsamples.9m | # of samples averaged | G | time |

Note that small wind direction differences were observed during the field program which were tracked down to the vanes being slightly bent. Once this problem was identified, some of the vanes were flipped (upside-down) to make the directions more consistent. Again, no attempt to correct the data was made (since it would be very difficult to model this effect and the error is smaller than the accuracy needed for wind directions for this program). See the logbook for details of this problem.

The new UW sonic anemometers spiked much worse (5-10%; probably due to the longer pathlength). Furthermore, nuw1 developed a transducer problem on 7/26, and nuw2 stopped reporting data on 8/5. These problems are being investigated. The geometry for both arrays was measured on 10/6/98 and found to be within 1 degree of specifications. The new angles have been used in post-processing of the data.

Tilt corrections have been calculated for all of the sonic anemometers using our standard algorithm. These corrections have been applied to all of the statistics in the data files (including those from the Oklahoma Mesonet CSAT sonic anemometer). The maximum "lean" angle found was 1.9 degrees, and most were less than 1 degree, which is typical for a nearly flat site. The values used are:

# yr mon day hh:mm(GMT) lean leanaz woffset 4.5m.OKMN: 98 6 23 00:00 0.642 176.3 0.018 4.5m.NCAR: 98 6 17 00:00 1.239 25.3 0.006 # Releveled using bubble level 98 6 29 14:30 0.316 -146.9 -0.022 9m.NCAR: 98 6 17 00:00 0.693 27.4 -0.017 # After v transducer replacement 98 7 10 00:00 1.908 20.5 -0.023 nuw1: 98 7 15 00:00 0.771 -26.6 # After rotating 98 7 24 15:00 0.882 -74.0 # Sensor goes bad (path a transducer?) 98 7 26 12:00 0 0 0 nuw2: 98 7 1 00:00 0.300 27.6 # after flipping and rotating # (179.3 = 180.0-0.6 and -177 = 2.7 - 180, to compensate for flip) 98 7 24 15:00 179.341 -177.3The corresponding plots are:

4.5m.OKMN

4.5m.NCAR; first part

4.5m.NCAR; second part

9m.NCAR; first part

9m.NCAR; second part

nuw1; before flip & rotate

nuw1; after flip & rotate

nuw2; before flip & rotate

nuw2; after flip & rotate

18 | 19 | 20 | ||||

21 | 22 | 23 | 24 | 25 | 26 | 27 |

28 | 29 | 30 | . | . | . | . |

1 | 2 | 3 | 4 | |||

5 | 6 | 7 | 8 | 9 | 10 | 11 |

12 | 13 | 14 | 15 | 16 | 17 | 18 |

19 | 20 | 21 | 22 | 23 | 24 | 25 |

26 | 27 | 28 | 29 | 30 | 31 | . |

1 | ||||||

2 | 3 | 4 | 5 | 6 | 7 | 8 |

If anything, the flipped and rotated comparision looks better than for the parallel configuration. This may be due to the arrangement of the supporting booms. The sonic arrays were closer together (and thus would have affected each other over a wider range of wind directions) for the parallel configuration than for flipped and rotated. However, in both cases directions from about 110 to 250 through 180 should have been okay. This still doesn't explain the apparent variation of the parallel data - perhaps the tilt correction was confused by the distortion from the sides and should be recomputed.

Also, the flipped and rotated data show a consistent speed difference (nuw2 higher by 2%). During this period, the Tc values also are higher from nuw2 by 4C (1.3%). Since u~Tc(t1-t2)/2d, about half of the error is explained by how the sensors were zeroed. I'm not sure why this 4C error occurred.

In any case, I would conclude that these arrays do not appear to have flow distortion (no flow distortion correction has been applied to these data) which is evident from this test.

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This page was prepared by
Steven Oncley,
NCAR Research Technology Facility