1.2.2. BRW Programs

A more detailed analysis of all data collected at BRW can be found in the section detailing each of the major programs

Aerosols

The single biggest change in the measurement curriculum was in the aerosol program.  During September 1997 the entire aerosol system was upgraded with new equipment that fits into one 483 mm (19-in.) rack.  A Thermal Systems Inc. (TSI) 3-channel integrating nephelometer replaced the 25-year old Meteorology Research Inc. 4-channel nephelometer that was the station instrument.  The TSI condensation nucleus counter (CNC) was replaced with another unit of the same design and soon developed problems.  A spare will be installed as soon as one becomes available.  The Magee Scientific aethalometer was replaced by a Radiance Research particle soot absorption photometer for measurement of optical absorption coefficient, and a system of size-resolved impactor and filter samples were collected for gravimetric and chemical analysis at NOAA’s Pacific Marine Environmental Laboratory in Seattle.  A selectable time base was used as well as sector-selected sampling to allow for differing lengths of sample exposure depending on time of year and external conditions such as out-of-sector wind.  Both programs will run concurrently for 1 year to allow for instrument comparisons.  See CMDL No. 23 Summary Report 1994-1995, chapter 3, for a more detailed description of regional aspects of the program.  Routine maintenance and calibrations were performed as scheduled.

Funding of the new equipment was provided by a grant from the Atmospheric Radiation Measurement Program (ARM) of the Department of Energy.  For a description of the ARM program, see the section listed in the Barrow Cooperative programs. 

Solar Radiation

Two new instruments were added to the suite of solar radiation measurements at BRW.  The new instruments are used to monitor ultraviolet (UV) radiation.  In addition to the global and direct irradiance, albedo, and IR radiation, BRW will now monitor biologically-active UV using a Yankee Environmental Systems (YES) UVB-1.  The UVB-1 measures the erythemal spectra between 280 and 320 nm.  The second instrument is a Biospherical Instruments Inc. (BSI) GUV-511C ground-based UV radiometer.  The BSI instrument measures five discreet wavelength intervals at 305, 320, 340, and 380 nm and PAR from 400 to 700 nm at a rate of 2 Hz.  PAR is the portion of the spectrum associated with plant growth.

Because no useful data can be collected in the visible spectrum between sunset in mid-November to sunrise in mid-January, solar radiation instruments were sent to Boulder for calibration and cleaning in November.  The terrestrial infrared (IR) radiation program, both up- and downwelling, continued throughout the winter using Eppley pyrgeometers. 

Carbon Cycle

Carbon Dioxide Nondispersive Infrared Analyzer.  The Siemens Ultramat 5-E continued to be the station instrument and ran well the entire period.  The data continue to show normal seasonal variations. Highs of up to 370 ppm and lows to 340 ppm were observed.  System calibrations were performed as scheduled. 

An HP-Unix workstation replaced the CAMS unit as the control and data acquisition system for recording data for the CMDL Carbon Cycle Group.  Realtime data can be monitored at the station both in digital format and graphically, providing useful information on system performance.  The data can now be transferred daily over the Internet and updated regularly on the CMDL homepage.  Control and modification of the data acquisition program and operating parameters are available to Boulder personnel in a manner never before possible at BRW.

Methane.  A major upgrade to the equipment was made when the Hach-Carle gas chromatograph (GC) was replaced with an HP-6890 GC.  The instrument is connected to the data acquisition system described previously.  Once again, realtime data plots assist in troubleshooting the system and ensuring that the GC is maintained in an optimal running configuration.  All data are stored on a 3.5 in. rewritable optical disk that is mailed to Boulder once a month.

Carbon Monoxide.  A Trace Analytical GC has been in continuous operation since 1991.  No major problems were noted.  The CO analyzer is connected to the carbon cycle data acquisition system described previously.  As with the other carbon cycle data, CO data are transmitted to Boulder daily using the Internet.  Data are also stored on the 3.5 in. optical disk described previously.  Realtime data are displayed graphically on the computer monitor and aid in quality control and troubleshooting the system.

Flask Samples.  Flask samples were collected as scheduled.  The data concerning flask samples can be found in sections 2 and 5 of this report.  No major problems were encountered.

¹³C.  Isotopic carbon analysis was performed on samples collected at the CMDL global network of which BRW is a part.  Data are available since 1990.  See section 2 of this report. 

Meteorology

There were no major changes in the meteorology program during 1996-1997.  The system continued to run with minimal problems.  The data are updated daily on the Observatory Operations page of the CMDL homepage.  Calibrations were performed twice each year, once in the spring and once in the fall, to ensure correct operation of all sensors.  Temperature probes were checked and corrected, if needed, to 0.2°C.  Alignment of the wind sensor was checked and the speed accuracy was traceable to National Institute of Standards and Technology standards. 

The winters of 1996-1997 and 1997-1998 were among the warmest on record with several new record high temperatures being recorded.  During the summer of 1997 there were 25 straight days of rain with a total of 63.5 mm (2.5 in.) falling during this time.

CAMS

With the replacement of the final CAMS unit during the summer of 1997 there are no longer any CAMS units in BRW.  They had an operational life of over 10 years and performed well the entire time.  Newer PC-based data acquisition systems (DAS) have become the standard and allow for unprecedented data quality control and transfer to Boulder.

Ozone

Surface Ozone.  Surface ozone, as measured by the Dasibi ultraviolet absorption photometer, continues to be one of the long-term staples of the BRW measurement complement.  During July of 1997 the CAM unit used for the Dasibi was replaced by a PC-based system.  It was connected to the BRW Local Area Network (LAN) and data are now transferred to Boulder via the Internet.  Calibrations and maintenance were performed as scheduled and no major problems have arisen.

Total Column Ozone.  BRW continued to operate Dobson no. 91 for total column ozone measurements.  Seasonal variation of total ozone continued as in past years with highs in the spring and lows occurring in the fall.  Values in April were as high as 440 Dobson Units (DU) and lows in September were as low as 290 DU.  The Dobson was not operated during the winter months due to lack of sunlight, but calibration continued to ensure proper functioning when the sun rises the next year.  Observations are usually made from February until October.

On March 17, 1997, station personnel recorded a reading of 300 DU which was a record low for March.  The March average from 1974 until 1982 was 430 DU.  The low values in March 1997 coincided with record low ozone in the arctic polar vortex region as recorded by the NASA TOMS satellite instrument. 

Nitrous Oxide and Halocarbons

Gas Chromatographs.  Both the Shimadzu GC-8A and the HP-5890 gas chromatographs ran well during the 1996-1997 season.  Data continued to show decreased growth rates noted in past years related to the decreased use of CFC’s attributed to the Montreal Protocol, which phased out production of certain CFC’s. 

Data were stored on 3.5 in. floppy disks and mailed to Boulder once per week.  The primary data transfer scheme continued via the Internet.

Flask Samples.  Flask samples were collected as scheduled.  Data showed a very distinct reduction in the CFC-12 growth rate attributed to the Montreal Protocol.  A more detailed list of the chemicals analyzed can be found in Table 1.2. 

Cooperative Projects

A comprehensive list of all BRW cooperative projects and affiliations can be found in Table 1.2.

DOE/ARM.  On July 1, 1997, the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program dedicated the North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) Cloud and Radiation Testbed (CART) site.  The site is located downwind of BRW on NOAA property and consists of a modular unit to house instrumentation and three instrument platforms.  ARM’s data acquisition system and offices are located in the Ukpeagvik Inupiat Corporation-NARL (UIC-NARL) facility about 2 km from the sensors.  A 40-m tower was erected during the summer of 1997 and will have three levels of meteorology sensors as well as several solar radiation sensors mounted by the spring of 1998.

TABLE 1.2.   Summary of Measurement Programs at BRW in 1996-1997 

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