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Update on in-situ tower-based measurements

Update on in-situ tower-based measurements. INFLUX workshop Purdue University 8 August 2011. Outline. CO2/CH4/CO instrument calibration at PSU Drift tests Instrument calibration and testing at NIST Multi-species data examples Data availability to date Comparison of co-located Picarros

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Update on in-situ tower-based measurements

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  1. Update on in-situ tower-based measurements INFLUX workshop Purdue University 8 August 2011

  2. Outline • CO2/CH4/CO instrument calibration at PSU • Drift tests • Instrument calibration and testing at NIST • Multi-species data examples • Data availability to date • Comparison of co-located Picarros • Deployment readiness update

  3. For CO2, used 4 NOAA tanks for which only CO2 is known for calibration • For CH4 and CO, we had four tanks, but two sets of two • NOAA_co2=[378.22 416.55 378.61 417.06] ; % ppm • NOAA_ch4=[1798.4 2465.6 1790 2461.2] % ppb • NOAA_co=[153.3 239.5 145.3 233.7]; % ppb CO2/CH4/CO instrument calibration

  4. Repeat of CO2 only calibration28 February 2011 Results are very similar to calibration on 26 January 2011 400 ppm tank: suspect? Instr 2005 Instr 2006

  5. CO2/CH4/CO calibration (26 Jan 2011) WMO recommendations CO2: 0.1 ppm CH4: 2 ppb CO: 2 ppb

  6. Drift tests Jan-Feb 2011 • Tested two tanks, alternating between • 5, 10, 5, 10 min, etc • 11 days of data

  7. CO2 • (ppm) CH4 (ppb) CO (ppb)

  8. Time series for 10-min tank 10-sec data 10-min averages 60-min averages • CO2 • (ppm) • Noticeable drift over the 10+ day test, significant for CO2 compared to target accuracy, but drift for CH4 and CO is small compared to target accuracy • How long (and how often) do we need to sample for zero drift of CO CH4 (ppb) CO (ppb) DOY

  9. CO2 • Calculated means over various periods (5, 10, 30, and 60 min) • Calculated range of those means during each day • For CO2 there is slight improvement as period increases; however, for all the range is roughly half of the target (0.1 ppm) Daily range of mean (ppm) DOY

  10. CH4 Daily range of mean (ppb) • For CH4 all the ranges are half of less of the target (2 ppb) DOY

  11. CO Daily range of mean (ppb) • For CO there is marked improvement as the averaging period increases • For 10-min averaging period, the range is roughly 2.5 ppb (target: 2 ppb for clean air) DOY

  12. Allan Variance: CO2σy2(t)=½ <(yn+1 – yn)2>y(n) is the normalized measure departure, measured over sample period n, and t is time per sample period • Minimum: 5 – 40 min • Plan to a better test by sampling tank for several hours (CO2 system)

  13. Allan Variance: CH4 Minimum: 8 - 56 min

  14. Allan Variance: CO

  15. Instrument Calibration and Testing at NIST5 – 7 July 2011 • Using three PSU NOAA-calibrated (CO2/CH4/CO) tanks, we performed calibration of 6 NIST Picarros and testing of 2 PSU Picarros • CC339519: 365.34 ppm CO2, 1714.86 ppb CH4, 141.1 ppb CO • CC342919: 395.08 ppm CO2, 1859.23 CH4, 146.4 ppb CO • CC336629: 451.17 ppm CO2, 2117.14 ppb CH4, 254.5 ppb CO Note that while the calibration tanks for CO2 and CH4 span a good range, two of the tanks measure nearly the same value for CO • Also tested • CC336482 396.04 ppm CO2, 142.0 ppb CO • NIST tank from NOAA Niwot Ridge

  16. Inter-test differences are < 0.04 ppm for CO2, < 1.1 ppb for CH4, and < 1.3 ppb for CO. • Residuals from applying a linear fit are <0.02 ppm for CO2, < 0.12 ppb for CH4 and < 2 ppb for CO. • Both the CO2 and CH4 residuals are well below the WMO recommendations for those species. The maximum CO residual is approximately equal to the WMO recommendation for clean air.

  17. NIST tank from NOAA uncalibratedNiwot Ridge air Results (using calibrated NIST systems) • CO2: 388.26 +- 0.02 ppm (5 instruments) • CH4: 1840.30 +- 0.17 ppb (3 instruments) • CO: 129.1 +- 0.2 ppb (2 instruments) • PSU CADS instruments measured 388.3 ppm and 388.4 ppm (note: CADS07 has failing pump)

  18. NOAA-calibrated tankCO2: 396.04 ppm CH4: not cal’ed CO: 142.0 ppb Results (using calibrated NIST systems) • CO2: 396.03 +- 0.02 ppm (5 instruments) • CH4: 1865.17 +- 0.12 ppb (3 instruments) • CO: 142.1 +- 2.2 ppb (2 instruments) • PSU CADS instruments measured 396.0 ppm and 396.1 ppm (note: CADS07 has failing pump) • Peak-to-peak noise of NIST CFADS and CKADS instruments: 0.05 – 0.15 ppm CO2 • Peak-to-peak noise of PSU CADS instruments: 0.4 – 0.7 ppm CO2

  19. Multi-species data July 2011 / 19-20 April 2011

  20. Multi-species data: July 2011 Green = Rural site Red = Urban site CO2 (ppm) CH4 (ppb) CO (ppb)

  21. 19 April 2011 • Green = Rural site • Red = Urban site • Two instruments measuring CO2 at both sites, but not seen on this scale (it’s a good thing!) • Top level only is plotted • Valve sequencer had “issues” Drive around 2100-2300 UTC 5-7pm local

  22. 20 April 2011 • Green = Rural site • Red = Urban site • Two instruments measuring CO2 at both sites, but not seen on this scale (it’s a good thing!) • Top level only is plotted • Valve sequencer had “issues” • 300-730 UTC = 11pm-3:30am local Drive around 1300-1500 UTC 9-11am local 8:00 UTC = 4am local = 0.3

  23. 20 April 2011 • Green = Rural site • Red = Urban site • Two instruments measuring CO2 at both sites, but not seen on this scale (it’s a good thing!) • Top level only is plotted • Valve sequencer had “issues” • 300-730 UTC = 11pm-3:30am local Green = multi-species instrument at rural site Pink = CO2-only instrument co-located at rural site Drive around 1300-1500 UTC 9-11am local

  24. IND Airport Wind Data (19-20 April 2011)

  25. IND Airport Pressure/Temp (19-20 April 2011)

  26. Data Availability (CO2 only instruments) Site01 (CO2 only) Beginning October 2010 Site02 (CO2 only)

  27. Data Availability (CO2/CH4/CO instruments) Beginning in March 2011 SITE01 (CO2/CH4/CO) SITE02 (CO2/CH4/CO)

  28. Comparison of co-located CRDS instruments

  29. Tower locations (current and planned) 09 • Site 01: CO2/CH4/CO Flasks, PROFILE, “Rural” • Site 02: CO2/CH4/CO Flasks, PROFILE, “Urban” • Site 03: CO2/CH4/CO (2 instruments) Flasks, PROFILE • Site 04: CO2/CO, Flasks • Site 05: CO2/CO, Flasks • Site 06: CO2/CH4 • Site 07: CO2/CH4 PROFILE • Site 08: CO2 • Site 09: CO2 • Site 10: CO2 • Site 11: CO2 06 05 11 02 07 03 10 04 08 01

  30. Additional towers: progress towards deployment readiness • 2 sites in addition to Sites 01 and 02 will be profile sites (4 levels), other 6 sites will measure at top level (100+ m AGL) • In the process of building the 2 profile sampling systems • Note that the CO2-only instruments will be re-located to the SouthEast in 2012

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