This data set contains atmospheric mixing ratios of nitric oxide, ozone, hydrogen peroxide, methylhydroperoxide, and concentrations in surface snow and in snow pits of nitrate, nitrite, and hydrogen peroxide at the WAIS Divide deep ice-coring site.
Get Data
DOWNLOADING DATA VIA FTP
Data can be downloaded through a Web browser or command line via FTP. When using a Web browser, the FTP link first directs you to an Optional Registration Form that if filled out, will allow you to receive notifications about updates or processing changes related to that specific data set. After completing the Optional Registration Form, the FTP directory becomes available. For additional help downloading data through an FTP client, go to the How to access data using an FTP client support page.
Measurements of Air and Snow Photochemical Species at WAIS Divide, Antarctica, Version 1
Geographic Coverage
Spatial Coverage: |
|
---|---|
Spatial Resolution: | Not Specified |
Temporal Coverage: |
|
Temporal Resolution: | Not specified |
Parameter(s): |
|
Platform(s) | Not specified |
Sensor(s): | CHEMILUMINESCENCE |
Data Format(s): |
|
Version: | V1 |
Data Contributor(s): | Roger Bales |
Metadata XML: | View Metadata Record |
Data Citation
As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.
Bales, R. and S. Masclin. 2014. Measurements of Air and Snow Photochemical Species at WAIS Divide, Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5GX48HW. [Date Accessed].Literature Citation
As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.
Masclin, S., M. Frey, W. Rogge, and R. Bales. 2013. Atmospheric Nitric Oxide and Ozone at the WAIS Divide Deep Coring Site: A Discussion of Local Sources and Transport in West Antarctica, Atmospheric Chemistry and Physics. 13. 8857-8877. http://dx.doi.org/10.5194/acp-13-8857-2013
Detailed Data Description
Atmospheric measurements were made 1 m above the snow, 10 m upwind (prevailing winds from NE) from the tent, with ambient air continuously drawn through an insulated and heated PFA (1/4 I.D.) intake line (typically 1.4 STP-Lmin-1) of 12 m for peroxides (ROOH), and of 20 m for nitric oxide (NO) and ozone (O3). All surface snow and snow pits were sampled in a 7200 m2 clean area upwind from the Polarhaven tent. The top 1 cm of the non-cohesive surface snow was collected daily while snow pits were sampled on a weekly basis at 2 cm resolution to a depth of 30 cm. Concentrations of snowflakes from the only snow precipitation observed are reported.
Data are provided in Tab-delimited ASCII Text (.txt
) format.
Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0585_bales/
directory. Within this directory, there are five text files:
WAISchemistry_atm_NO-O3-ROOH.txt
WAISchemistry_snowpit_20081218.txt
WAISchemistry_snowpit_20081228.txt
WAISchemistry_snowpit_20090104.txt
WAISchemistry_surfacesnow.txt
R
efer to Table 1 for an explanation of the content for each text file.
File Name | Description of Content |
---|---|
WAISchemistry_atm_NO-O3-ROOH.txt |
Atmospheric mixing ratios in pptv of nitric oxide (NO), surface ozone (O3), hydrogen peroxide (H2O2), and methyl hydroperoxide (MHP) plus the Standard Deviation (stdev) of the last two variables. Date and Time in UTC. |
WAISchemistry_snowpit_20081218.txt |
Snow concentrations in ppbw of H2O2, formaldehyde (HCHO), nitrate (NO3–), nitrite (NO2–), and their corresponding Standard Deviations (stdev), measured in a 30 cm depth snowpit on 12/18/2008. Depth in cm. |
WAISchemistry_snowpit_20081228.txt |
Snow concentrations in ppbw of H2O2, HCHO, NO3–, NO2–, and their corresponding Standard Deviations (stdev), measured in a 30 cm depth snowpit on 12/28/2008. Depth in cm. |
WAISchemistry_snowpit_20090104.txt |
Snow concentrations in ppbw of H2O2, HCHO, NO3–, NO2–, and their corresponding Standard Deviations (stdev), measured in a 30 cm depth snowpit on 01/04/2009. Depth in cm. |
WAISchemistry_surfacesnow.txt |
Snow concentrations in ppbw of H2O2, HCHO, NO3–, NO2–, and their corresponding Standard Deviations (stdev), measured daily in the top 1 cm of surface snow. Date and Time in UTC. |
The files range in size from 2 KB to 1.1 MB
79.467° S, 112.085° W
Sample location was 5km NW of the WAIS Divide drilling camp.
Spatial Resolution
1766 m above mean sea level (a.m.s.l.)
Data were collected from 10 December 2008 to 11 January 2009.
Temporal Resolution
Antarctic summer only.
Hydrogen Peroxides Mixing Ratios and Concentrations (H2O2)
Nitric Oxide Mixing Ratio (NO)
Ozone Mixing Ratio (O3)
Nitrate Concentrations (NO3–)
Nitrite Concentrations (NO2–)
Formaldehyde Concentrations (CH2O)
Methyl Hydroperoxide Mixing Ratios and Concetrations (CH3OOH)
Sample Data Record
Software and Tools
Data Acquisition and Processing
From 10 December 2008 to 11 January 2009, atmospheric concentrations of NO and O3 were continuously measured at WAIS Divide (local time: LT = UTC-07:30). Mixing ratios of ROOH (H2O2 and MHP) were recorded between 31 December 2008 to 7 January 2009. Snow samples were collected daily from the surface and weekly from 30 cm snow pits for chemical analysis of NO3–, NO2– and H2O2 (Masclin et al 2013).
Atmospheric sampling took place 5 km NW of the WAIS Divide drilling camp (79.467° S, 112.085° W, 1766 m a.m.s.l.). All instruments were run out of a Polarhaven tent heated by a preway heater. Atmospheric measurements were made 1 m above the snow, 10 m upwind (prevailing winds from NE) from the tent, with ambient air drawn through an insulated and heated PFA (1/4 I.D.) intake line (typically 1.4 STP–L min–1) of 12 m for ROOH, and of 20 m for NO and O3. In an attempt to minimize artifacts in the atmospheric records, the two generators (3.5 and 5 KW) that provided electricity to the lab were located about 30 m downwind from the sampling lines, and all activities around the site were restricted. However, the heater exhaust was located on the top of the Polarhaven tent (Masclin et al 2013).
Atmospheric Sampling
Atmospheric Nitric Oxide (NO) measurements were taken using a modified chemiluminescence instrument. NO mixing ratios recorded at 1 Hz were aggregated to 1 min averages. The Limit of Detection (LOD), defined as 2-σ of the background count rate, was 5 pptv (Masclin et al 2013).
A two-minute background signal was monitored every 20 minutes and an automatic four minute calibration was performed every two hours by addition of a 2 ppmv NO standard. Due to late delivery of this NO gas standard to the site, calibration was only run during the last three days of the campaign. The instrument sensitivity remained fairly constant over the three days, with an average over 16 calibrations of 7.10 ± 0.18 Hzpptv –1, similar to the preseason value of 7.00 Hzpptv –1 determined in the lab. We therefore used the three-day average value of these calibrations to process the overall data set. NO spikes related to pollution from generators and heater exhaust were removed using a moving standard deviation filter with a maximum standard deviation of 30 (1.5 times the interquartile range of the data set). This led to the removal of 25 percent from the raw NO record (Masclin et al 2013).
Tropospheric ozone (O3) was monitored at 1 min resolution using a 2B Technologies (Golden, Colorado) O3 Monitor, Model 205, with a 1 ppbv LOD. (Masclin et al 2013).
Atmospheric Hydroperoxides (ROOH) were measured at 10 minute resolutions based on continuous scrubbing of sample air followed by separation in an HPLC column and fluorescence detection, described in detail by Frey et al (2005) and Frey et al (2009a). The detector was calibrated 1–2 times per day with H2O2 solution and MHP standards synthesized in our lab following the protocol described by Frey et al (2009a). The LOD, 2-σ of the baseline, were 87 pptv for H2O2 and 167pptv for MHP. Unexpected variations of the coil-scrubber temperatures may have caused higher LOD than those reported by Frey et al (2005) and Frey et al (2009a).
Snow Sampling
All surface snow and snow pits were sampled in a 7200 m2 clean area upwind from the Polarhaven tent. The top 1 cm of the non-cohesive surface snow, referred to as the skin layer (Frey et al (2009b) and (Erbland et al (2013), was collected daily with a 10 mL glass test tube to assess temporal changes in snow chemistry. Twice during the campaign, the skin layer was sampled simultaneously at five different spots inside the clean area to assess possible local spatial variability of NO3–, NO–2, and H2O2(Masclin et al 2013).
Weekly snow pits were sampled at 2 cm resolution to a depth of 30 cm, covering the snowpack zone where 85 percent of NO3– photolysis is expected to occur (France 2011). Snowflakes were collected on aluminum foil during the only snow precipitation event observed during the campaign, on 12 December 2008 (Masclin et al 2013).
All snow samples were collected in 100 mL SCHOTT bottles and kept frozen during storage and transport until analysis 14 months later. The analysis involved melting the snow one hour before injecting the sample into a self-built Continuous Flow Analysis (CFA) system as described by Frey et al (2006). The LOD, defined as 3σ of the baseline, was 0.4 ppbw for NO3–, NO2–, and H2O2. Only values above LOD were used for further calculations. Some loss of NO2– in the samples may have occurred between the time of collection and analysis, as Takenaka and Bandow (2007) and O'Driscoll et al.(2012) showed that NO2– may be oxidized during freezing and storage(Masclin et al 2013).
More details on database development (experimental method, data processing) and discussion of the results are published in Masclin et al 2013.
Atmospheric Concentration
The average ± 1 σ (median) of NO over the campaign was 19 ± 31 (10) pptv. Refer to Table 2. Some noise remained in the NO data set after filtering; however, the 4 h running median shows very little change in the overall trend of the data due to filtering, with the median value after filtering similar to that of the raw dataset (6 pptv). Refer to Figure 1a. One-minute data did not exhibit any clear diel cycle (Figure 1), but 1 h binned data centered on each hour for the measurement period revealed a diel cycle that can be interpreted with the variations of the average solar elevation angle. Refer to Figure 2b. NO mixing ratios increased at 07:00–08:00 LT with a maximum rise of 36 percent from the daily median of 10 pptv. A decrease was observed afterwards and followed by a second increase of 20 percent above the median value at 19:00 LT. These peaks in NO occurred as solar elevation angle increased and decreased, with lower values of NO at the maxima and minima of solar elevation angle (Masclin et al 2013).


Average ± 1σ (median) mixing ratios of O3 at WAIS Divide were 14 ± 4 (13) ppbv. Refer to Table 2. The mean is two thirds of the 20 ± 2 ppbv average mixing ratio observed at Byrd Station in summer 2002, but is in the range of values from previous measurements between 79.06° S and 85.00° S above the WAIS (Frey et al. 2005 ). Refer to Figure 3. Two events of elevated O3 levels were recorded between 24 and 25 December, and between 27 and 29 December, with concentrations in the range of 20 to 30 ppbv. Refer to Figure 1. Concentrations above 25 ppbv were only observed for winds blowing from ENE to SWS. This 135° sector represents 67 percent of all the wind directions observed during the field campaign. Refer to Figure 4. The hourly binned O3 data (Figure 2b) show a small diel cycle in phase with solar elevation angle and wind speed. The mixing ratios rose by 5 percent of the median value (13 ppbv) in the morning, reaching a maximum at 14:00 LT and dropping thereafter in the afternoon (Masclin et al 2013).


Concentrations of H2O2 and MHP were measured between 31 December 2008 and 5 January 2009. Refer to Figure 1. Averages ± 1 σ (medians) were 743 ± 362 (695) and 519 ± 238 (464) pptv for H2O2 and MHP, respectively. Our records are closer to values observed at West Antarctic sites below 1500 m a.m.s.l. and higher than measurements made in the surrounding area. Refer to Fig. 3. With mixing ratios of H2O2 that were twice those observed at Byrd station in late November 2002 (Frey et al. 2005 ). Refer to Table 2. Average ± 1 σ (range) of the MHP : (H2O2 ± MHP) ratios were 0.42 ± 0.10 (0.12–0.76). These values are in the range of those previously recorded over WAIS (Frey et al. 2005 ). Binned values suggest, for both H2O2 and MHP, a diel cycle with respective maximum 44 and 37 percent above their medians (695 and 464 pptv) observed in the morning. Refer to Figure 2c. (Masclin et al 2013).
Snow Concentration
Average ± 1 σ (median) concentrations of NO2–, NO3–, and H2O2 in the skin layer at WAIS Divide were 0.6 ± 0.4 (0.5), 137 ± 37 (142) and 238 ± 37 (238) ppbw, respectively.Refer to Table 2. Daily concentrations of NO2– in the skin layer showed a decrease of 30 pptw per day ( R 2 = 0.36) over the campaign. Refer to Figure 5. This decrease represents a rate of 5 percent per day of the average concentration of NO2– measured in all of the snow surface samples. Unlike NO2–, NO3–, and H2O2 exhibited some variation but no trend was observed for these species (Masclin et al 2013).
The coefficients of variation of concentrations of NO2–, NO3–, and H2O2 in the skin layer are 49 percent, 26 percent and 17 percent, respectively. The coefficients of variation for samples collected simultaneously on 1 and 8 January 2009 (Figure 5 ) are 17 percent, 31 percent and 7 percent for NO2–, NO3–,, and H2O2 respectively. The similar coefficients of variation for NO3– concentrations in snow imply that spatial variability contributes significantly to the overall variability and thus a temporal trend may be difficult to detect. For NO2– and H2O2, the coefficients of temporal variability (49 percent and 17 percent, respectively) are more than double those calculated from spatial variability (17 percent and 7 percent, respectively). The variations of daily concentrations of NO2– and H2O2 in near-surface snow may then be interpreted as temporal trends. Concentrations of H2O2 in the top 5–15 cm of the profile (Figure 6 ) may also indicate a temporal trend; seasonal increase in concentrations measured over this period was apparent not only in the top 5 cm of snow, but also down to at least 15 cm. Although there was no new snow accumulation during this period, there was wind redistribution and atmosphere–snow exchange of H2O2 and other atmospheric gas species, or nighttime deposition of fog (Masclin et al 2013).


The 30 cm deep profiles of NO2–, NO3–, and H2O2 illustrated in Figure 6 represent concentration changes of these species in snow over the last six months of 2008, based on local mean annual snow accumulation rate of 0.20 m weq yr -1 (Banta et al. 2008) and an average snow density of 0.37. Total concentrations of NO3– in the snow column dropped by about 19 percent between the first and last snow-pit samplings. NO3– concentrations decrease by 94-188 ppbw over the top 5 cm of snow, reaching approximately 30 ppbw below. Total NO2– stored in the 30 cm column decreased by about 65 percent across the three snow-pit samplings. Unlike NO2– and NO3–, total concentrations of H2O2 in the top 30 cm of snowpack doubled over the 18 days of sampling. A 233-298 ppbw decrease of H2O2 concentrations in the first 10 cm of each snow pit was generally observed.
References and Related Publications
Contacts and Acknowledgments
Roger Bales
University of California, Merced
Sierra Nevada Research Institute
5200 North Lake Road
Merced, California 59343
Sylvain Masclin
University of California, Merced
Sierra Nevada Research Institute
5200 North Lake Road
Merced, California 59343
This research was supported by NSF OPP Grant Number 0636929.
Document Information
DOCUMENT CREATION DATE
March 2014
Access complete Knowledge Base
Questions? Please contact:NSIDC User Services
Phone: 1 303 492-6199
Email: nsidc@nsidc.org