These data contain surface meteorological measurements of the Integrated Surface Flux System (ISFS) during the Persistant Cold-Air Pool Study (PCAPS) in the Salt Lake basin, during the winter of 2010, 2011.
For general information about the operations of the ISFS during PCAPS click here.
The ISFS five minute dataset contains first moments and some second moments of variables measured by the 7 NCAR ISFS stations during PCAPS.
Each measured variable will have a short_name attribute in the NetCDF header. For second moments, such as variances and co-variances, the short_name will contain single quote marks after a variable to indicate it is an average of a deviation. For example, a short name of w'kh2o', indicates the quantity is an average of (w-mean(w)) * (kh2o-mean(kh2o)), where mean(w) is the 5 minute mean of w. The actual NetCDF variable names will have underscores, '_', in place of the single quotes.
The following second moments are provided:
u | v | w | tc | kh2o | |
---|---|---|---|---|---|
u | u'u' | u'v' | u'w' | u'tc' | u'kh2o' |
v | v'v' | v'w' | v'tc' | v'kh2o' | |
w | w'w' | w'tc' | w'kh2o' | ||
tc | u'tc' | v'tc' | w'tc' | tc'tc' | |
kh2o | u'kh2o' | v'kh2o' | w'khqo' | kh2o'kh2o' |
The missing data value is 1.0 x 10^37, indicating data is not available at the corresponding time for the given variable.
The dataset consists of 93 day-long NetCDF files on the EOL CODIAC site, see PCAPS datasets in CODIAC. The first ISFS measurements were recorded on Nov 10, 2010, the last on Feb 10, 2011.
Each file contains data for one day, from 00:00 UTC to 24:00 UTC. The file names contain the date, formatted as "isfs_YYYYMMDD.nc". The date is also coded in the variable base_time in each file.
Time-series variables and variables associated with multiple stations are defined by one or both of the following dimensions:
Dimension name | size | description |
---|---|---|
time | 288 | number of 5 minute periods in a day |
station | 7 | index for each of the 7 ISFS stations |
The variables in the NetCDF files are:
Variable name | units | dimensions | description |
---|---|---|---|
latitude | degrees-north | station | Latitude of each station |
longitude | degrees-east | station | Longitude of each station |
base_time | seconds | POSIX time, non-leap seconds since 1970-01-01 00:00:00 00:00 UTC | |
time | seconds | time | Middle of each sampling period, in seconds since base_time. |
P_2m | mb | time,station | Barometric pressure at 2 meters |
T_2m | degC | time,station | Ambient air temperature at 2 meters |
RH_2m | % | time,station | Relative humidity at 2 meters |
Rainr | mm/hr | time,station | Liquid water precipitation rate, measured by ETI weighing precipitation gauge, at stations 3,4 and 6 |
u (See Note 1) | m/s | time,station | U component of wind, as measured by Campbell CSAT3 sonic anemometer, averaged from 60Hz samples. |
v (See Note 1) | m/s | time,station | V component of wind, from CSAT3, averaged from 60Hz samples |
w (See Note 1) | m/s | time,station | W component of wind, corrected for sonic tilt from the plane of mean horizontal flow. |
tc | degC | time,station | Virtual temperature from the speed of sound, as measured by a CSAT3 |
u_u_, u_v_, u_w_, etc | varies | time,station | seconds moments of wind components and fast scalar quantities as shown in the table above. |
spd_max | m/s | time,station | Maximum 60Hz wind speed during the five minute period |
ldiag (See Note 2) | time,station | QC indicator for CSAT3 data, the fraction of time in the 5 minutes that a CSAT3 diagnostic bit was set or a sample was missing. | |
counts_sonic (See Note 2) | time,station | Number of CSAT3 samples averaged. The usual value of 18000 indicates that all 60 Hz samples were received during the 5 minute period. | |
sonicHeight | m | station | Approximate measurement height above ground of the CSAT3 anemometer at each station. |
kh2o (See Note 3) | g/m^3 | time,station | Water vapor density from Campbell Krypton hygrometer |
kh2oV | V | time,station | Raw voltage from Campbell Krypton hygrometer |
counts_kh2o | time,station | Number of krypton hygrometer samples that were co-incident with CSAT3 samples in the five minute period. This value is usually around 17150, since the krypton was sampled at approximately 57 samples/sec. | |
U_10m | m/s | time,station | U component of wind speed, as measured by RMYoung prop-vane anemometer at 10 meters at stations 1 and 6. |
V_10m | m/s | time,station | V component of wind speed from RMYoung at 10 meters. |
Rpile_in | W/m^2 | time,station | Thermopile value of up-looking pyrgeometer, converted to W/m^2 |
Tcase_in | degC | time,station | Case temperature of up-looking pyrgeometer |
Tdome_in* | degC | time,station | Dome temperature of up-looking pyrgeometer |
Rpile_out | W/m^2 | time,station | Thermopile value of down-looking pyrgeometer, converted to W/m^2 |
Tcase_out | degC | time,station | Case temperature of down-looking pyrgeometer |
Tdome_out* | degC | time,station | Dome temperature of down-looking pyrgeometer |
Rsw_in | Wm^2 | time,station | Incoming short wave (solar) radiation, as measured by pyranometer |
Rsw_out | W/m^2 | time,station | Outgoing short wave radiation |
Rsw_dfs | W/m^2 | time,station | Incoming, diffuse (indirect) solar radiation, measured by Licor pyranometer with a manually adjustable shadowband |
Rsw_global | W/m^2 | time,station | Incoming global solar radiation, Licor pyranometer without shadowband |
Rsw_dfs_spn1 | Wm^2 | time | Incoming, diffuse solar radiation, as measured by SPN1 sunshine pyranometer at station 7 |
Rsw_global_spn1 | W/m^2 | time | Total incoming solar radiation, as measured by SPN1 at 7 |
Gsoil_5cm, Gsoil_5cm_aux (See Note 4) | W/m^2 | time,station | Soil heat flux at approximately 5 cm below surface. |
Qsoil, Qsoil_aux | vol% | time,station | Soil moisture content, at approximately 2.5 cm below surface |
Tsoil_0_6cm, Tsoil_0_6cm_aux |
degC | time,station | Soil temperature at approximately 0.6 cm below surface |
Tsoil_1_9cm, Tsoil_1_9cm_aux |
degC | time,station | Soil temperature at a depth of approx 1.9 cm |
Tsoil_3_1cm, Tsoil_3_1cm_aux |
degC | time,station | Soil temp at a depth of approx 3.1 cm |
Tsoil_4_4cm, Tsoil_4_4cm_aux |
degC | time,station | Soil temp at a depth of approx 4.4 cm |
dTsoil_dt_* | degC/s | time,station | Average of [ Tsoil(t) - Tsoil(t-dt) ] / dt at each of the above depths. |
Vheat, Vheat_aux | V | time,station | Hukeseflux TP01 heater voltage |
Vpile_off, Vpile_off_aux | uV | time,station | Hukeseflux TP01 thermopile before heating |
Vpile_on, Vpile_on_aux | uV | time,station | Hukesflux TP01 thermopile after heating |
Tau63, Tau63_aux | s | time,station | TP01 time to decay to 37% of Vpile.on-Vpile.of |
Lambdasoil, Lambdasoil_aux | W/m/degK | time,station | TP01 derived thermal conductivity |
- Note 1: u and v wind components from CSAT3 sonic anemometers are in standard meteorological coordinates, where a positive u is wind TO the east, positive v is wind TO the north. The original 3D wind vectors have been corrected for the estimated tilt of the sonic with respect to a plane of mean horizontal flow, as described here.
- Note 2: Signal levels of CSAT3 sonic anemometers are strongly influenced by liquid water. The ldiag and counts_sonic variables provide a quality indicator for the wind measurements, where ldiag=0 and counts_sonic =18000 +- 1 (60Hz * 300 seconds) indicate that no signal problems were detected during the second. Note that due to oscillator clock drift of the sonic relative to the data system, often 17999 or 18001 samples will be averaged in a 5 minute period.
- Note 3: kh2o is the water vapor density, as measured by the Campbell Krypton ultra-violet hygrometer. It has not been corrected for the ultra-violet absorption by O2. kh2oV is the raw voltage output of the detector. If liquid water contaminates the optical path, or if the optics have become scaled with contaminants, the water vapor measurement is compromised. In this case, the raw voltage value will be small, often less than 0.01 V. Until approximately December 1, the krypton optics at all stations were scaled. See the project logbook for details of the krypton cleanings.
- Note 4: Auxiliary soil measurements, as indicated with an "_aux" suffix, were sampled at stations 1,5 and 6.
For derived values of the latent, sensible, and surface heat fluxes, see the 30 minute dataset.