TITLE: CEOP EOP-3 and EOP-4 ARM NSA Meteorological Tower Data Set CONTACT: Raymond McCord Building 1507 PO Box 2008, MS 6407 Oak Ridge, TN 37831-6407 Telephone: (865) 574-7827 Fax: (865) 574-4665 E-Mail: mccordra@ornl.gov 1.0 DATA SET OVERVIEW This data set contains 30-minute resolution meteorological tower data from the Coordinated Enhanced Observing Period (CEOP) Reference Site operated by the Atmospheric Radiation Measurement (ARM) Program at its North Slope of Alaska (NSA) facility in Alaska. This data set includes observations from two locations. This data set covers the time period 1 October 2002 through 31 December 2004. Further information about the ARM NSA site is available at the following URL: http://www.arm.gov 1.1 Station Locations Site Elev (m) Latitude Longitude ------------------------------------------------- C1_Barrow AK 8.0 71.32300 -156.60900 C2_Atqasuk AK 20.0 70.47180 -157.40660 1.2 Time Period Covered by Data All stations cover the complete EOP-3 and EOP-4 period (1 October 2002 to 31 December 2004). 1.3 Temporal Resolution All data are 30-minute resolution. See the instrumentation section for further information. The C1_Barrow station has the following observations at the specified heights: # At the 2.00 m height: station pressure, temperature, dew point, relative humidity, specific humidity, wind speed, wind direction, U wind component, V wind component. # At the 10.00 m height: temperature, dew point, relative humidity, wind speed, wind direction, U wind component, V wind component. # At the 20.00 m height: temperature, dew point, relative humidity, wind speed, wind direction, U wind component, V wind component. # At the 40.00 m height: temperature, dew point, relative humidity, wind speed, wind direction, U wind component, V wind component. The C2_Atqasuk station has the following observations at the specified heights: # At the 2.00 m height: station pressure, temperature, dew point, relative humidity, specific humidity. # At the 5.00 m height: temperature, dew point, relative humidity. # At the 6.00 m height: temperature, dew point, relative humidity. As detailed below, the instrumentation changed at the C2_Atqasuk site on 6 November 2003 and the parameters that were measured at the 6.00 m height prior to that date were measured at the 5.00 m height from that date forward. 2.0 INSTRUMENTATION DESCRIPTION The ARM NSA meteorological tower measurements at the Barrow site are from their Barrow Meteorology (BMET) tower. At the Atqasuk site the meteorological tower measurements are from their Atqasuk Meteorology (AMET) tower. Starting on 6 November 2003 C2_Atqasuk changed instrumentation to the METTWR2H and on 31 October 2003 C1_Barrow changed instrumentation to the METTWR4H. The radiation data come from the GNDRAD and SKYRAD instrumentation at both sites. 2.1 BMET Sensors (Barrow site) Full descriptions of the instruments used at the Barrow site prior to 31 October 2003 are available in the pdf file Other_NSA_BMET.pdf included with your order. ARM NSA BMET Handbook. 2.2 AMET (Atqasuk) Sensors Full descriptions of the instruments used at the Atqasuk site prior to 6 November 2003 are available in the pdf file Other_NSA_BMET.pdf included with your order. ARM NSA AMET Handbook. 2.3 METTWR2H (Atqasuk) Sensors Full descriptions of the instruments used at the Atqasuk site starting to 6 November 2003 are available in the pdf file Other_NSA_METTWR2H.pdf included with your order. ARM NSA METTWR2H Handbook. 2.4 METTWR4H (Barrow) Sensors Full descriptions of the instruments used at the Barrow site starting to 31 October 2003 are available in the pdf file Other_NSA_METTWR4H.pdf included with your order. ARM NSA METTWR4H Handbook. 2.4 GNDRAD and SKYRAD Sensors Full descriptions of the radiation instruments used at both sites are available in the pdf file Other_GNDRAD.pdf and Other_SKYRAD.pdf included with your order. ARM NSA GNDRAD Handbook and ARM NSA SKYRAD Handbook. 3.0 DATA COLLECTION AND PROCESSING 3.1 ARM Data Collection and Processing For complete information on the SKYRAD instrumentation see the ARM SKYRAD Handbook. For complete information on the GNDRAD instrumentation see the ARM GNDRAD Handbook. For complete information on the METTWR4H instrumentation see the ARM METTWR4H Handbook. For complete information on the METTWR2H instrumentation see the ARM METTWR2H Handbook. For complete information on the AMET instrumentation see the ARM AMET Handbook. For complete information on the BMET instrumentation see the ARM BMET Handbook. 3.2 UCAR/JOSS Data Processing The University Corporation for Atmospheric Research/Joint Offfice for Science Support (UCAR/JOSS) converted the data from the raw format provided by ARM into the CEOP EOP-3 data format agreed to by the CEOP Scientific Steering Committee. This format is described in detail as part of the CEOP Reference Site Data Set Procedures Report which is available at the following URL: http://www.joss.ucar.edu/ghp/ceopdm/refdata_report/ceop_met_tower_format.html The METTWR4H, METTWR2H, AMET, BMET , GNDRAD and SKYRAD provide 1 minute measurements, the observations at the 00 and 30 minute marks of every hour are included in the final data set. 4.0 QUALITY CONTROL PROCEDURES 4.1 ARM Quality Control Procedures For futher information on ARM QC Procudures see the instrument handbooks mentioned above and in the references below. 4.2 UCAR/JOSS Quality Control Procedures UCAR/JOSS converted the ARM QC flags into the CEOP QC flags in the following manner. If a parameter failed one of the ARM QC checks it was flagged as Questionable/Dubious ("D") and if it failed two or more ARM QC checks it was flagged as Bad ("B"). Additionally, UCAR/JOSS conducted two primary quality assurrance/control procedures on the reference site data. First the data has been evaluated by a detailed QA algorithm that verifies the format is correct, examines any QC flags, and conducts basic checks on data values. Second, JOSS conducts a manual inspection of time series plots of each parameter. 5.0 GAP FILLING PROCEDURES No gap filling procedures were applied to these data by either ARM or UCAR/JOSS. 6.0 DATA REMARKS 6.1 ARM Data Quality Report for station C2 (Atqasuk) All Parameters Missing data from 0029 UTC on 22 September 2002 to 1935 UTC on 21 November 2002: Due to unknown wiring differences and pin changes by Vaisala to their Wind Speed and Direction sensors, a power feedback into the QLI data collector occurred. This caused an overload which shut the QLI data collector down. Once trouble shooting pinpointed the power feedback, wiring diagrams were created and the differences were found. Wiring was changed to prevent and remove the power feedback. 6.2 ARM Data Quality Report for station C2 (Atqasuk) All parameters From 1430 UTC on 25 November 2002 to 2229 UTC on 26 March 2003: Missing met, present weather, and snow depth data due to comm error An error in the communication sub-routine of the Bridgeview collection software occurred resulting in data loss from the Snow Depth sensor, Present Weather Sensor and the Barometer. 7.0 REFERENCE REQUIREMENTS To support the continuation of this program, please include the following 'credit line' in the acknowledgments of your publication: "Data were obtained from the Atmospheric Radiation Measurement (ARM) Program sponsored by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Environmental Sciences Division." 8.0 REFERENCES For complete information on the SKYRAD instrumentation see the ARM SKYRAD Handbook. For complete information on the GNDRAD instrumentation see the ARM GNDRAD Handbook. For complete information on the METTWR4H instrumentation see the ARM METTWR4H Handbook. For complete information on the METTWR2H instrumentation see the ARM METTWR2H Handbook. For complete information on the AMET instrumentation see the ARM AMET Handbook. For complete information on the BMET instrumentation see the ARM BMET Handbook.