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 one second dataset contains averages and single point values of many variables measured by the 7 NCAR ISFS stations during PCAPS.
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_1Hz_YYYYMMDD.nc", where YYYY, MM and DD are the numeric year, month and day.
The base_time variable contains one value, the time of the start of the file, as a number of POSIX (non-leap) seconds since 1970 Jan 1, 00:00 UTC.
Values for each time-varying measurement will be found in the NetCDF files, as a variable with a time dimension. There are 288 5 minute periods per day, so the time dimension is 288.
The time variable contains the time to be associated with each sample, in units of seconds since base_time, or 00:00 UTC of the day. Each time value is the middle of the averaging period, and will have values of 0.5 (00:00:00.5 UTC), 1 (00:00:01), etc, up to 86399.5 (23:59:59.5 UTC).
Time-series variables and variables associated with multiple stations have one or both of the following dimensions:
Dimension name
size
description
time
86400
number of seconds in a day
station
7
index for each of the 7 ISFS stations
Variables that were recorded at rates faster than 1 Hz, namely u, v and spd from sonic anemometers, have been averaged to 1 second. Radiation and soil variables that were recorded at approximately 1/5 Hz will have missing values interspersed with measured values.
The missing data value is 1.0 x 10^37, indicating the sensor was not reporting at the corresponding time and station for the given variable, or that the data value did not meet QC criteria during post-project analysis.
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
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
Lambdasoil. Lambdasoil_aux
W/m/degK
time,station
Soil thermal conductivity, computed from measurements of Hukseflux TP01.
asoil, asoil_aux
m^2/s
time,station
Soil diffusivity from TP01
Cvsoil, Cvsoil_aux
J/(m^3 K)
time,station
Soil heat capacity from TP01
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 sonic tilt, 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 >= 59 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, sometimes 59 or 61 samples will be averaged in a second.
Note 3: Auxiliary soil measurements, as indicated with an "_aux" suffix, were sampled at stations 1,5 and 6.
For values of the surface heat flux, derived from the soil heat flux at 5 cm and the heat storage in the soil from 0 to 5 cm, see the 30 minute dataset.
