CEOP/EOP-1 GAPP SGP Hourly Surface Meteorology, Flux, and Radiation Data Set
1.0 Contact Information
1.1 UCAR/JOSS Contact
Steven F Williams
Data Specialist
UCAR/JOSS
P.O. BOX 3000
Boulder, CO, USA, 80307-3000
Telephone: 303-497-8987
Facsimile: 303-497-8158
E-Mail Address: sfw@ucar.edu
1.2 ARM EBBR Contact
David R. Cook
Argonne National Laboratory
9700 South Cass Avenue
Building 203
Argonne, IL 60439.
Phone: (630) 252-5840
FAX: (630) 252-5498
E-mail: drcook@anl.gov
1.3 ARM SMOS Contact
Michael T. Ritsche
Scientific Assistant
Argonne National Laboratory
Bldg. 203
Argonne IL 60439
Phone: (630) 252-1554
Fax: (630) 252-5498
Email: mtritsche@anl.gov
1.4 ARM SIRS Contact
Tom Stoffel
National Renewable Energy Laboratory
1617 Cole Blvd.
Golden, CO 80401-3393
Voice: 303-384-6395
Fax: 303-384-6391
E-mail: Tom_Stoffel@nrel.gov
2.0 General Description
This data set contains the Coordinated Enhanced Observing Period (CEOP)
Enhanced Observing Period 1 (EOP-1) Global Energy and Water Cycle Experiment
(GEWEX) Americas Prediction Project (GAPP) Surface Meteorology, Flux, and
Radiation data. This data set contains hourly data from 24 Department of
Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains
(SGP) stations for the CEOP EOP-1 time period (01 July 2001 to 30 September
2001). The University Corporation for Atmospheric Research/Joint Office for
Science Support (UCAR/JOSS) did not perform quality control processing on this
data set.
3.0 Detailed Data Description
The data comprising this data set are also available on-line in native format at
www.joss.ucar.edu/ghp/ceopdm/archive/eop1_data/index.html
under the heading CEOP EOP-1 "Native Format" Reference Site Data Sets, GAPP.
This composite data set is composed of data from four sources which report
data at different frequencies. It was developed by the merging of radiation
data from the Solar Infrared Radiation Station (SIRS), flux data from the
Energy Balance Bowen Ratio (EBBR), meteorological data from the Surface
Meteorological Observation System (SMOS), and skin temperatures from the
Infrared Temperature (IRT) networks. These stations are located at many of the
ARM SGP Extended Facilities in southern Kansas and northern Oklahoma.
3.1 SGP Algorithms
This hourly data set was formed by extracting the top of the hour observations
from the native format data. The U and V wind components were computed from
wind speed and direction. More information regarding this site can be found
under the CEOP Reference Site Station Characteristics link on the UCAR/JOSS
CEOP Data Management page at www.joss.ucar.edu/ghp/ceopdm/.
3.1.1 Heat Flux
Heat flux sensors consist of a differential temperature sensor which measures
heat flow. Heat flux is a vector quantity of energy flowing through a 1 meter
square surface in one second. Sensible heat flux is the transfer of sensible
heat between the surface and the air, or vice versa. Latent heat flux is the
transfer of latent heat (heat released or absorbed by water) between the
surface and the air, or vice versa. Ground, or soil, heat flux is the transfer
of sensible heat in the soil, either toward the surface or away from the
surface.
3.1.2 Surface Energy Exchange
Energy balance Bowen ratio measure the rates of heat and moisture exchange
between the surface of the Earth and the atmosphere at selected locations.
The Energy Balance Bowen Ratio (EBBR) system is a ground-based system using in
situ sensors to estimate the vertical fluxes of sensible and latent heat at
the local surface. The flux values are representative of the grassy area
within about 50 meters of the EBBR station. Flux estimates are made from
observations of net radiation, soil heat flow, and the vertical gradients of
temperature and relative humidity; these data are used in the Bowen ratio
energy balance technique.
In this composite data set, all energy flux densities have a negative sign
when directed toward the surface and positive when directed away. For example,
a representative value for latent heat flux could be 100-500 watts per meter
squared during the daytime in the summer.
3.1.2.1 ARM EBBR
The components of the energy balance were determined with the
Bowen Ratio Energy Balance (BREB) method. The BREB method is a
combination of the transport and the energy balance equations. The
Bowen ratio, B {a ratio of the gradient equations of sensible
heat, H and latent heat, E} is given by:
B = H / E (1)
where:
H = -rho*c(p)*K(h)*dT/dz
E = -(rho*epsilon / P)*l(v)*K(v)*de/dz
where symbols are defined as:
e = Air vapor pressure
epsilon = Ratio of the molecular weights of water vapor and
dry air
c(p) = Specific heat of air at constant pressure
K(h) = Eddy diffusivity for heat
K(v) = Eddy diffusivity for water vapor
p = Atmospheric pressure
rho = Air density
T = Air temperature
z = Height or depth
l(v) = Latent heat of vaporization
Substituting (1) in the energy balance equation (2) yields the
BREB (3). Q is net radiation and G is soil heat flux density.
Q + G + H + E = 0 (2)
In this system surface-air interface is considered as a closed
system. Any energy flux coming in is considered positive and going
out is negative.
E = -(Q + G) / (1 + B) (3)
(FIFE, 1999)
3.1.3 Radiation
The ARM SIRS provides measurements of upwelling and downwelling hemispherical
solar irradiances, direct-beam solar irradiance, diffuse hemispherical solar
irradiance from the sky and up- and downwelling hemispherical infrared
irradiances via its collection of instruments including the Multifilter
Rotating Shadowband Radiometer (MFRSR), pyranometer, pyrheliometer, and
pyrgeometer at 19 of the ARM extended facilities (including the central
facility).
The ARM Solar Infrared Radiation Station (SIRS) provides continuous
measurements of broadband shortwave (solar) and longwave (atmospheric or
infrared) irradiances for downwelling and upwelling components.
3.2 Station Information
The following is a complete description of the station information provided
with this CEOP GAPP SGP data set. Table 1 details the station list parameters.
GAPP SGP values for each parameter are listed in brackets at the end of each
line. The beginning and ending dates for the period of coverage are in
Universal Time Coordinated (UTC). The Identification Type field is network
dependent and indicates the source of the Identification field. The Occurrence
field is an integer value used to indicate co-located stations. Note that when
a particular parameter is unknown for a station, either a blank, a question
mark, or all 9's will appear in that parameter's position. For a complete list
of Country, State, and County values, refer to the document in the references
(Section 5.0). Possible platform types and frequency values are listed in
Tables 2 and 3, respectively. Note that only those platform types present in
the CEOP EOP-1 data have been listed.
Table 1
Parameter Description
--------- -----------
Identification ID in data. [SGP]
Identification Type Internal ID number type. [32]
Latitude Station Latitude. [48.31000]
Longitude Station Longitude. [-105.10000]
Occurrence Station occurrence. [0]
Lat/Lon Accuracy Number of digits accuracy
in lat/lon values. [2]
Name Expanded station name. [GAPP:SGP]
Commissioned Flag `(C)' indicates commissioned station,
`(N)' indicates station which is NOT
commissioned. [(N)]
Begin Period of Coverage Beginning date of period of coverage
(YYYYMMDD). [20010701]
End Period of Coverage End date of period of coverage
(YYYYMMDD). [20010930]
Country Country in which station is located. [US]
State State code. [30]
County County code. [???]
UTC offset Hour Offset from UTC time. [0.00]
DST switch 'y' indicates station does switch to
Daylight Savings Time (DST). 'n' indicates
station does not switch to DST. [n]
Platform type Collection Platform. See Table 2. [264]
Reporting Frequency Frequency of data collection. [30min]
Elevation Station elevation. [634]
Fixed/Mobile flag Flag indicating if station has fixed
location. 'f' indicates a fixed station.
'm' indicates a mobile station. [f]
Table 2
Platform Type Description
------------- -----------
264 CEOP Reference Site Platform
Table 3
Reporting Frequency
-------------------
varies by site
3.3 Detailed Format Description
The CEOP EOP-1 GAPP SGP Hourly Surface Meteorology, Flux, and Radiation Data
Set contains 10 metadata parameters and 22 data parameters. The metadata
parameters describe the station location and time at which the data were
collected. The time of observation is reported both in Universal Time
Coordinated (UTC) Nominal and UTC actual time. Days begin at UTC 0100 and end
at UTC 0000 the following day. Note that missing parameter values are
indicated by "-999.99". The table below details the data parameters in each
record.
Parameters Units
---------- -----
Date of Observation UTC Nominal
Time of Observation UTC Nominal
Date of Observation UTC Actual
Time of Observation UTC Actual
CSE Identifier Abbreviation of CSE name
Reference Site Identifier Abbreviation of Site name
Station Identifier Reference Site Dependent
Latitude Decimal degrees, South is negative
Longitude Decimal degrees, West is negative
Station Elevation Meters
Station Pressure Hectopascals (mb)
Dry Bulb Temperature Celsius
Dew Point Celsius
Relative Humidity Percent
Specific Humidity g/kg
Wind Speed m/s
Wind Direction Degrees
U Wind Component m/s
V Wind Component m/s
Total Precipitation mm
Snow Depth cm
Sensible Heat Flux W/m2
Latent Heat Flux W/m2
Incoming Shortwave Radiation W/m2
Outgoing Shortwave Radiation W/m2
Incoming Longwave Radiation W/m2
Outgoing Longwave Radiation W/m2
Net Radiation W/m2
Skin Temperature Celsius
CO2 Flux uMoles/m2/s
Incoming PAR uMoles/m2/s
Outgoing PAR uMoles/m2/s
4.0 Data Remarks
This data set contains only the hourly observations for the CEOP EOP-1
time period. This data set is also available on-line in native format at
http://www.joss.ucar.edu/ghp/ceopdm/ under the link "CEOP EOP-1 Reference
Site Data Sets".
4.1 ARM Data Quality Reports
A few problems occurred with instrumentation during CEOP EOP-1 which affected
the quality of the data. Summarized below are the time period within CEOP
EOP-1, as well as the cause and possible resolution. This information was
taken from Data Quality Reports provided by ARM. (ARM, 2003)
4.1.1 SGP/SMOS/E1 - E1 SMOS RH% VALUES SUSPECT
START DATE: 06/21/2001 START TIME: 0 END DATE: 07/17/2001 END TIME: 1901
DESCRIPTION: RH% values approximately 10% high at values of 70% and higher.
Sensor replaced.
4.1.2 SGP/SMOS/E1 - E1 SMOS DATA VALUES OFF SCALE
START DATE: 07/17/2001 START TIME: 1830 END DATE: 07/17/2001 END TIME: 1901
DESCRIPTION: All data values off-scale during replacement of T/RH probe.
4.1.3 SGP/SMOS/E15 - E15 SMOS ALL DATA OFF-SCALE
START DATE: 07/25/2001 START TIME: 1424 END DATE: 07/25/2001 END TIME: 1801
DESCRIPTION: All data values off-scale during routine maintenance.
4.1.4 SGP/SMOS/E11 - E11 ALL DATA VALUES OFF SCALE
START DATE: 07/25/2001 START TIME: 1726 END DATE: 07/25/2001 END TIME: 1803
DESCRIPTION: All data values off-scale during routine maintenance.
4.1.5 SGP/SMOS/E24 - E24 SMOS TEMP AND RH VALUES SUSPECT
START DATE: 08/10/2001 START TIME: 1936 END DATE: 08/23/2001 END TIME: 1701
DESCRIPTION: T/RH probe began reading high values of temperature and RH
intermittently. High RH values noticed above 70% RH compared to neighboring sites.
High temperature values more difficult to determine but very noteceable on 08/10
from 19:36 - 21:07z. Probe replaced.
4.1.6 SGP/SMOS/E21 - E21 SMOS DATA VALUES INCORRECT
START DATE: 09/18/2001 START TIME: 2109 END DATE: 09/18/2001 END TIME: 2111
DESCRIPTION: All data values off-scale during routine maintenance.
4.2 ARM EBBR Data Quality Reports
4.2.1 ARM_DQR_20010401_20010823.html
4.2.2 ARM_DQR_20010401_20011005.html
4.2.3 ARM_DQR_20010401_20010823.html
4.2.4 ARM_DQR_20010401_20010823.html
where
ARM_DQR is the type of file
20010401 is the start date of the earliest quality report
in the file
20010823 is the end date of the latest quality report in
the file
4.3 ARM SIRS Data Quality Reports
None.
4.4 Quality Control Processing
UCAR/JOSS performed limited gross limit and visual checks on this data set. No
data values have been changed.
5.0 References
Bolton, D., 1980: The computation of equivalent potential temperature.,
Mon. Wea. Rev., 108, pp 1046-1053.
Department of Commerce - National Institute of Standards and Technology
(NIST), 1985: Federal Information Processing Standards Publication)
10-3 Countries, Dependencies, & Areas of Special Sovereignty.
Department of Commerce - NIST, Washington, DC.
Energy Balance Bowen Ratio (EBBR),
www.arm.gov/docs/instruments/static/ebbr.html; September 6, 1999
FIFE Bowen Ratio Surface Flux: Smith Data Set Guide Document,
http://www-eosdis.ornl.gov/FIFE/Datasets/Surface_Flux/Bowen_Ratio_Smith.html;
September 8, 1999
Wexler, A., and W. A. Wildhack, 1963: Humidity and Moisture.
Vol. 3: Fundamentals and Standards. Reinhold Publ. Corp., 562 pp.