The file sonic.dat can be downloaded by anonymous ftp: ftp eos.atmos.washington.edu, directory pub/roode (ASCII, 0.2 Mb)
|
NR |
VARIABLE |
DESCRIPTION |
UNITS |
|
1 |
JD |
decimal day |
Julian day 1998 |
|
2 |
Ttc |
Temperature thermocouple |
[Celsius] |
|
3 |
Tsonic |
Temperature sonic |
[Celsius] |
|
4 |
q |
Specific humidity |
[kg/kg] |
|
5 |
wsp |
Wind speed |
[m/s] |
|
6 |
wdir |
Wind direction |
[degree true north] |
|
7 |
nflag |
nr of bad data |
- |
|
8 |
uu |
uu variance |
[m^2/s^2] |
|
9 |
uv |
uv momentum flux |
[m^2/s^2] |
|
10 |
uw |
uw momentum flux |
[m^2/s^2] |
|
11 |
uT |
uT temperature flux |
[mK/s] |
|
12 |
uq |
uq humidity flux |
[m/s] |
|
13 |
vv |
vv variance |
[m^2/s^2] |
|
14 |
vw |
vw momentum flux |
[m^2/s^2] |
|
15 |
vT |
vT temperature flux |
[mK/s] |
|
16 |
vq |
vq humidity flux |
[m/s] |
|
17 |
ww |
ww variance |
[m^2/s^2] |
|
18 |
wT |
wT temperature flux |
[mK/s] |
|
19 |
wq |
wq humidity flux |
[m/s] |
|
20 |
TT |
TT temperature variance |
[K^2] |
|
21 |
|
qq humidity variance |
[kg^2/kg^2] |
|
22 |
H |
Sensible heat flux |
[W/m^2] |
|
23 |
LE |
Latent heat flux |
[W/m^2] |
|
24 |
z/L |
scaled height (*) |
- |
|
25 |
Phim |
Nondimensional windgradient (**) |
- |
|
26 |
ril |
integral length scale |
[m] |
|
27 |
ff |
filter frequency |
[s^-1] |
|
28 |
uu_f |
filtered uu variance |
[m^2/s^2] |
|
29 |
uv_f |
filtered uv momentum flux |
[m^2/s^2] |
|
30 |
uw_f |
filtered uw momentum flux |
[m^2/s^2] |
|
31 |
uT_f |
filtered uT temperature flux |
[mK/s] |
|
32 |
uq_f |
filtered uq humidity flux |
[m/s] |
|
33 |
vv_f |
filtered vv variance |
[m^2/s^2] |
|
34 |
vw_f |
filtered vw momentum flux |
[m^2/s^2] |
|
35 |
vT_f |
filtered vT temperature flux |
[mK/s] |
|
36 |
vq_f |
filtered vq humidity flux |
[m/s] |
|
37 |
ww_f |
filtered ww variance |
[m^2/s^2] |
|
38 |
wT_f |
filtered wT temperature flux |
[mK/s] |
|
39 |
wq_f |
filtered wq humidity flux |
[m/s] |
|
40 |
TT_f |
filtered TT temperature variance |
[K^2] |
|
41 |
qq_f |
filtered qq humidity variance |
[kg^2/kg^2] |
|
42 |
z/L_f |
filtered scaled height |
- |
|
43 |
Phim_f |
filtered Phim |
- |
|
44 |
I(0cm) |
energy flux through surface |
[W/m^2] |
|
45 |
I(35cm) |
energy flux through ice layer |
[W/m^2] |
The wind velocities and absolute temperature (Ttc) were measured by a CSAT-3 sonic anemometer from Campbell Scientific. High-frequency humidity fluctuations were measured with a Lyman-Alphy hygrometer made by Mierij Meteo. To check the absolute temperature as measured by the sonic, we had installed a thermocouple near the sonic. The sonic anemometer and Lyman-Alphy hygrometer both sampled at a frequency of 20 Hz. The sonic temperature is used for the computation of the fluxes and variances.
All the raw data were stored in one-hour files. The observed wind is rotated such that the new wind components (u,v,w) are defined in (x,y,z) direction for which we have Vmean=Wmean=0.
The dataset 'sonic.dat' contains both filtered and unfiltered data. The filtering procedure removes mesoscale fluctuations to the fluxes and variances. The cutoff filter length scale is based on the ogives of the vertical velocity spectra.
* 24) the nondimensional scaled height z/L is scaled by the Monin-Obukhov length L.
** 25) the nondimensional wind gradient is defined as Phim=kappa*z/ustar*(d/dz Umean), with kappa the von Karman constant (kappa = 0.4 is used), z the height above the surface, and ustar the friction velocity.
Duynkerke, P. G., S. R. de Roode, 2000: Surface energy balance and turbulence characterist i cs observed at the SHEBA ice camp during FIRE III. Revised version submitted to the special FIREIII issue of the Journal of Geophysical Research, April 2000. Postscript version