-------------------------------------------------------------------------- Daily Average of Carbon Dioxide Dry Column-Averaged Mixing Ratios from Park Falls Wisconsin, 2004 - 2006 Version: 2006-11-29.0001 -------------------------------------------------------------------------- CONTENTS 1. Data source and contacts 2. Use of data 3. Reciprocity 4. Warnings 5. Update notes 6. Introduction 7. General Comments on data 8. File Format 9. References -------------------------------------------------------------------------- 1. DATA SOURCE AND CONTACTS California Institute of Technology Correspondence concerning these data should be directed to: Paul Wennberg, Rebecca Washenfelder, Gretchen Aleks, and Geoffrey Toon Email: wennberg@gps.caltech.edu, rebecca.washenfelder@noaa.gov, gka@gps.caltech.edu, geoffrey.c.toon@jpl.nasa.gov Paul Wennberg and Gretchen Aleks Division of Engineering and Applied Science California Institute of Technology MC 150-21 1200 E. California Blvd. Pasadena, CA 91125 Funded by NASA grants NAG5-12247 and NNG05-GD07G. -------------------------------------------------------------------------- 2. USE OF DATA These data are made freely available to the public and the scientific community in the belief that their wide dissemination will lead to greater understanding and new scientific insights. The availability of these data does not constitute publication of the data. We expect all users to assure that the authors receive fair credit for their work. If the data are obtained for potential use in a publication or presentation, the authors should be informed at the outset of the nature of this work. If the data are essential to the work, or if an important result or conclusion depends on the data, co-authorship may be appropriate. This should be discussed at an early stage in the work. Manuscripts using the data should be sent to the authors for review before they are submitted for publication, so we can insure that the quality and limitations of the data are accurately represented. -------------------------------------------------------------------------- 3. RECIPROCITY Use of these data implies an agreement to reciprocate. Individuals making similar measurements agree to make their own data available to the general public and to the scientific community in an equally complete and easily accessible form. Modelers are encouraged to make available to the community, upon request, their own tools used in the interpretation of this data, namely well-documented model code, transport fields, and additional information necessary for other scientists to repeat the work and to run modified versions. Model availability includes collaborative support for new users of the models. -------------------------------------------------------------------- 4. WARNINGS Every effort is made to produce the most accurate and precise measurements possible. However, we reserve the right to make corrections to the data. We are not responsible for results and conclusions based on use of these data without regard to this warning. -------------------------------------------------------------------- 5. UPDATE NOTES None. -------------------------------------------------------------------- 6. INTRODUCTION Dry column-average CO2 volume-mixing ratios (VMR) reported in this file were acquired using a Fourier Transform Spectrometer (FTS) located at the Wisconsin Tall Tower site (45.945 deg N, 90.273 deg W, 442 m above sea level). Direct solar spectra were acquired in the near-infrared spectral region. These spectra were used to retrieve column abundances of CO2 and O2. A full description of the observatory, location, spectral retrievals, and calibration procedure are given in Washenfelder, R.A., G.C. Toon, J-F. Blavier, Z. Yang, N.T. Allen, P.O. Wennberg, S.A. Vay, D.M. Matross, and B.C. Daube, 2006, Carbon dioxide column abundances at the Wisconsin Tall Tower site, Journal of Geophysical Research, 2006, 111, doi:10.1029/2006JD007154. ------------------------------------------------------------------- 7. GENERAL COMMENTS ON THE DATA Dry column-average CO2 VMR has been calculated according to CO2 VMR = 0.2095 x column CO2 / column O2. Column CO2 is retrieved for two CO2 bands centered at 6228 cm-1 and 6348 cm-1. Column O2 is retrieved from the electronic band centered at 7882 cm-1. The average of the two calculated CO2 VMRs is presented here. This file reports daily average dry column-average CO2 VMR. This value is calculated by averaging CO2 VMRs between airmass 2 - 4 (SZA 60 - 75 deg) each day. Please note that the average represents different daytime periods during different seasons. The dry column-average CO2 VMR (0.2095 × column CO2 / column O2) used to calculate the daytime averages is affected by three main sources of error: 1. Measurement precision The standard deviation of column CO2 / column O2 during a one hour period is better than 0.1% under clear sky conditions and ~0.2% under partly cloudy conditions. Repeatability of the measurement is not a significant source of error. 2. Spectroscopic errors The retrieved O2 columns were reduced by 2.27% to bring them into agreement with the dry surface pressure, as described in Washenfelder et al. (2006). The absolute accuracy of the CO2 retrievals was calibrated by comparison to integrated aircraft profiles, resulting in a correction of 1.0216 and 1.0240 for the CO2 6228 cm-1 and 6348 cm-1 bands. The standard deviation of the fitting residuals is 0.39 ppmv and 0.42 ppmv, or approximately 0.1%. The aircraft profiles were performed with the sun at airmass 1.1 – 2.0 (SZA 25 – 60 deg), and the column-average CO2 VMR is now well-calibrated for these values. However, additional systematic errors may be present at higher airmass due to errors in the spectroscopy of CO2 and or O2. For example, a 1% change in the air-broadened widths results in a CO2 VMR change of ~0.2% (±0.8 ppmv) at airmass 3 and ~0.6% (±2.3 ppmv) at airmass 12. These parameters are not sufficiently constrained by current spectroscopic linelists, leaving this as a significant source of systematic error correlated with airmass (and thus time of day) and, to a lesser extent, temperature. 3. Systematic instrumental changes over time Retrieved O2 VMR increased by ~0.3% during the observation period reported here. We expect that this error affects both the CO2 and O2 retrievals similarly, but for now assume that the column CO2 / column O2 ratio may also have a systematic error of 0.3% over the observation period. In summary, the measurement precision of ~0.1% under clear sky and ~0.2% under partly cloudy conditions does not affect the accuracy of the measurements. However, spectroscopic errors introduce a systematic bias which depends on airmass. We have calibrated the FTS column retrievals at airmass 1.1 – 2.0 during Jul – Aug 2004, and expect that the absolute accuracy at these airmasses has been maintained within 0.3% throughout the subsequent data record. ------------------------------------------------------------------- 8. FILE FORMAT The data fields for this file are defined as follows: Field 1: [YEAR] Field 2: [MONTH] Field 3: [DAY] Field 4: [HOUR] The average collection time in Universal Time. Field 5: [MIN] The average collection time in Universal Time. Field 6: [SEC] The average collection time in Universal Time. Field 7: [DRY_COLUMN_AVG_CO2_VMR_FOR_AIRMASS_2-4_(PPMV)] Daily-average between airmass 2 - 4 of dry column-average CO2 VMR reported in ppmv. Field 8: [STDEV_DRY_COLUMN_AVG_CO2_VMR_FOR_AIRMASS_2-4_(PPMV)] Standard deviation of the daily-average between airmass 2 - 4 of dry column-average CO2 VMR reported in ppmv. Field 9: [ESTIMATED_ERROR_DRY_COLUMN_AVG_CO2_VMR_FOR_AIRMASS_2-4_(PPMV)] Field 10: [AIRMASS] The average airmass. Field 11: [NUMBER_PNTS_IN_AVG] Number of points included in average and standard deviation. ------------------------------------------------------------------- 9. REFERENCES Washenfelder, R.A., G.C. Toon, J-F. Blavier, Z. Yang, N.T. Allen, P.O. Wennberg, S.A. Vay, D.M. Matross, and B.C. Daube, 2006. Carbon dioxide column abundances at the Wisconsin Tall Tower site, Journal of Geophysical Research, 2006, 111, doi:10.1029/2006JD007154. ------------------------------------------------------------------- Year Month Day Hour Min Sec Dry_column_avg_CO2_VMR_for_airmass_2-4_(ppmv) Stdev_dry_column_avg_CO2_VMR_for_airmass_2-4_(ppmv) Estimated_error_dry_column_avg_CO2_VMR_for_airmass_2-4_(ppmv) Airmass Number_Pnts_in_avg 2004 6 2 23 18 13 377.7 0.14 0.14 2.63 47 2004 7 9 23 40 27 370.8 0.16 0.33 2.91 10 2004 7 12 23 26 3 372.7 0.17 0.30 2.64 10 2004 7 14 16 33 24 372.3 0.19 0.17 2.64 28 2004 7 15 13 4 52 371.8 0.24 0.16 2.38 28 2004 7 16 23 14 33 371.3 0.06 0.37 2.46 6 2004 7 19 12 51 46 371.6 0.23 0.17 2.69 31 2004 7 21 23 25 23 371.9 0.22 0.24 2.81 16 2004 7 22 22 2 39 371.6 0.75 0.33 3.51 13 2004 7 23 19 56 47 369.8 0.38 0.18 2.62 27 2004 7 24 23 19 37 367.8 0.44 0.30 2.76 10 2004 7 25 21 33 17 367.2 1.23 0.19 2.69 22 2004 8 12 23 1 24 367.7 0.19 0.16 2.81 38 2004 8 13 18 33 33 367.9 0.63 0.18 2.63 25 2004 8 14 19 19 37 367.7 0.65 0.14 2.49 41 2004 8 17 22 39 22 369.3 0.54 0.22 2.51 16 2004 8 20 13 35 3 369.8 0.16 0.17 2.46 26 2004 8 21 13 30 22 368.1 0.18 0.20 2.52 20 2004 8 23 22 32 52 369.6 0.55 0.37 2.51 6 2004 8 29 17 42 1 368.7 0.70 0.27 2.21 9 2004 9 1 22 50 21 371.9 0.11 0.37 3.37 9 2004 9 3 16 40 9 371.8 0.50 0.21 2.63 20 2004 9 6 22 19 30 372.2 0.29 0.23 2.85 18 2004 9 8 21 41 43 370.7 0.19 0.23 2.20 12 2004 9 9 19 56 20 370.4 0.33 0.14 2.74 49 2004 9 10 13 50 30 372.3 0.18 0.18 2.74 27 2004 9 13 19 2 8 372.8 0.33 0.26 2.57 12 2004 9 16 16 0 42 372.0 0.59 0.22 2.55 17 2004 9 18 18 43 44 372.5 0.49 0.12 2.46 57 2004 9 19 21 5 49 373.6 0.39 0.18 2.76 27 2004 9 20 16 36 37 372.7 0.60 0.31 2.60 8 2004 9 21 14 41 19 373.2 0.15 0.17 2.34 25 2004 9 30 14 17 7 373.6 0.22 0.14 2.79 46 2004 10 2 21 9 22 373.0 0.29 0.15 2.62 39 2004 10 4 21 11 7 373.0 0.19 0.14 2.72 49 2004 10 5 18 20 29 373.5 0.34 0.16 2.81 33 2004 10 6 21 9 23 374.0 0.16 0.16 2.78 37 2004 10 9 17 26 0 374.3 0.44 0.10 2.68 88 2004 10 12 14 38 16 374.9 0.22 0.27 2.74 14 2004 10 20 20 6 12 376.0 0.16 0.14 2.43 37 2004 10 21 19 48 47 375.2 0.53 0.26 2.26 10 2004 10 25 19 5 26 376.3 0.26 0.10 2.48 84 2004 11 3 19 9 22 375.6 0.19 0.09 2.53 98 2004 11 4 19 45 1 377.3 0.37 0.24 2.83 18 2004 11 6 18 31 57 376.0 0.34 0.18 2.23 22 2004 11 7 16 0 41 376.8 0.25 0.13 2.74 59 2004 11 8 17 44 0 376.6 0.24 0.08 2.62 145 2004 11 9 15 59 24 376.3 0.20 0.11 2.74 77 2004 11 11 17 52 13 377.0 0.23 0.08 2.67 158 2004 11 12 17 55 49 377.3 0.19 0.08 2.68 133 2004 11 13 17 43 54 376.1 0.26 0.08 2.73 150 2004 11 14 16 25 57 376.2 0.27 0.11 2.75 76 2004 11 15 19 48 21 377.8 0.22 0.16 3.05 49 2004 11 22 15 19 3 377.4 0.16 0.47 3.64 7 2004 11 23 19 36 42 378.8 0.17 0.23 3.08 24 2004 11 24 18 37 42 378.4 0.54 0.29 2.68 12 2004 11 28 19 40 53 379.1 0.23 0.29 3.34 16 2004 11 29 19 55 10 378.1 0.19 0.34 3.46 13 2004 11 30 18 4 29 377.5 0.20 0.11 2.97 99 2004 12 14 18 8 5 377.2 0.31 0.12 3.09 89 2004 12 15 19 8 50 378.0 0.24 0.21 3.18 29 2004 12 19 17 12 25 378.0 0.14 0.19 3.05 34 2004 12 22 17 36 53 379.1 0.29 0.28 3.35 18 2004 12 24 19 1 55 378.4 0.20 0.14 3.13 63 2004 12 26 16 59 8 378.5 0.26 0.30 3.47 16 2005 1 2 20 1 31 379.5 0.20 0.34 3.54 13 2005 1 14 17 8 18 379.3 0.24 0.14 3.04 62 2005 1 15 18 0 25 379.4 0.21 0.11 2.92 100 2005 1 16 18 54 21 379.1 0.20 0.14 2.67 54 2005 1 17 19 47 4 378.5 0.22 0.18 3.02 36 2005 1 27 18 33 40 379.0 0.27 0.09 2.64 116 2005 1 28 16 56 30 378.5 0.30 0.31 2.54 9 2005 2 2 19 51 33 379.9 0.26 0.26 2.54 14 2005 2 3 18 41 52 379.7 0.26 0.09 2.33 94 2005 2 4 19 10 14 379.8 0.27 0.11 2.36 70 2005 2 5 18 14 18 379.1 0.24 0.09 2.56 113 2005 2 11 17 28 40 379.4 0.39 0.22 2.04 12 2005 2 12 19 2 38 379.0 0.21 0.09 2.51 109 2005 2 15 19 14 41 379.2 0.21 0.26 3.49 22 2005 2 16 15 44 0 379.9 0.22 0.20 2.65 24 2005 2 17 19 58 29 379.9 0.19 0.19 3.13 35 2005 2 18 15 33 36 379.5 0.35 0.38 3.24 8 2005 2 19 18 18 1 379.9 0.28 0.11 2.54 70 2005 2 21 20 54 24 380.1 0.17 0.14 2.62 48 2005 2 23 16 56 7 380.3 0.15 0.15 2.65 46 2005 2 26 16 54 1 379.7 0.29 0.15 2.15 31 2005 3 2 19 49 39 379.3 0.16 0.11 2.48 64 2005 3 3 21 29 12 379.2 0.16 0.14 2.80 48 2005 3 5 21 21 40 379.8 0.21 0.18 2.56 27 2005 3 6 18 27 44 379.8 0.21 0.15 2.35 35 2005 3 7 21 43 17 380.4 0.38 0.18 2.89 33 2005 3 8 17 57 15 379.0 0.40 0.11 2.73 82 2005 3 9 17 24 21 379.5 0.23 0.11 2.42 71 2005 3 17 18 47 35 380.5 0.22 0.15 2.72 42 2005 3 20 17 43 42 380.2 0.17 0.14 2.42 39 2005 3 22 14 15 4 380.9 0.33 0.18 2.74 29 2005 3 23 20 50 32 380.3 0.30 0.19 2.49 22 2005 3 25 22 3 10 380.2 0.18 0.14 2.71 49 2005 3 26 19 8 14 380.6 0.22 0.12 2.73 66 2005 3 27 13 38 25 381.1 0.26 0.28 3.27 17 2005 3 31 22 29 37 381.4 0.27 0.23 3.02 22 2005 4 2 14 0 49 380.9 0.17 0.16 2.56 35 2005 4 3 18 38 32 381.5 0.21 0.11 2.70 83 2005 4 7 22 27 17 380.6 0.19 0.15 2.81 42 2005 4 8 13 40 13 381.1 0.19 0.19 2.71 26 2005 4 12 21 5 13 381.2 0.30 0.20 2.83 26 2005 4 13 17 45 33 380.6 0.17 0.12 2.77 65 2005 4 14 17 42 3 381.0 0.25 0.11 2.70 75 2005 4 15 19 1 21 381.2 0.31 0.15 2.31 31 2005 4 21 15 2 44 380.8 0.28 0.15 2.63 40 2005 4 24 22 50 40 379.6 0.19 0.18 2.88 31 2005 4 28 13 11 44 381.0 0.21 0.16 2.63 38 2005 5 3 15 5 28 380.9 0.21 0.16 2.95 42 2005 5 4 13 45 18 381.7 0.34 0.19 2.42 22 2005 7 13 23 28 41 376.8 0.23 0.15 2.77 43 2005 7 14 22 16 26 375.6 0.38 0.14 2.66 44 2005 7 15 16 29 49 375.5 1.43 0.21 2.37 17 2005 7 16 23 24 52 370.3 0.24 0.21 2.70 21 2005 7 18 13 17 36 373.7 0.20 0.31 2.20 7 2005 7 19 21 8 6 371.2 0.58 0.13 2.76 56 2005 7 20 23 21 8 374.2 0.36 0.16 2.69 34 2005 7 21 22 28 29 372.9 0.63 0.14 2.85 47 2005 7 22 23 20 44 373.0 0.24 0.15 2.74 42 2005 7 27 14 17 33 370.4 0.27 0.27 2.34 10 2005 7 29 18 11 26 370.9 0.69 0.25 2.83 15 2005 7 30 23 1 44 370.5 0.23 0.25 2.50 12 2005 8 1 22 54 23 372.2 0.30 0.18 2.74 29 2005 8 5 21 0 15 371.8 0.60 0.13 2.70 56 2005 8 6 21 43 44 370.6 0.61 0.13 2.69 49 2005 8 7 20 21 45 369.6 0.79 0.14 2.67 44 2005 8 8 21 34 32 373.8 0.44 0.15 2.54 34 2005 8 10 23 3 43 373.6 0.18 0.15 2.80 39 2005 8 13 23 1 22 371.3 0.24 0.31 2.80 10 2005 8 14 18 36 6 370.8 1.55 0.28 2.90 12 2005 8 15 21 10 50 369.7 0.41 0.15 2.57 36 2005 8 20 18 33 43 372.9 0.87 0.16 2.69 34 2005 8 21 12 59 27 372.5 0.24 0.36 3.19 10 2005 8 22 22 35 48 371.7 0.25 0.20 3.01 27 2005 8 23 18 24 11 372.4 0.93 0.21 2.77 20 2005 8 27 21 42 20 373.5 0.27 0.21 2.31 16 2005 8 29 14 10 47 373.6 0.26 0.29 2.07 7 2005 8 30 15 51 16 374.4 0.57 0.32 2.71 9 2005 8 31 17 53 4 374.4 0.71 0.17 2.23 23 2005 9 1 13 46 1 373.5 0.21 0.22 2.46 17 2005 9 2 22 30 30 373.0 0.19 0.31 3.00 10 2005 9 6 22 1 10 375.3 0.19 0.24 2.46 13 2005 9 7 22 48 10 373.1 0.23 0.38 3.51 10 2005 9 8 22 45 19 373.2 0.15 0.45 3.53 7 2005 9 14 14 22 26 374.6 0.25 0.20 2.21 17 2005 9 15 17 13 53 373.5 0.62 0.19 2.62 23 2005 9 16 21 32 59 373.3 0.21 0.14 2.66 47 2005 9 18 15 19 19 374.9 0.18 0.25 2.14 10 2005 9 19 21 48 22 374.6 0.15 0.34 2.68 8 2005 9 20 21 25 56 374.3 0.41 0.17 2.78 34 2005 9 21 14 32 26 375.5 0.25 0.23 2.23 13 2005 9 22 21 2 31 374.7 0.16 0.26 2.11 9 2005 9 23 19 10 38 373.7 0.51 0.13 2.60 44 2005 9 26 20 46 8 374.4 0.26 0.14 2.60 45 2005 9 27 21 18 18 374.8 0.22 0.25 2.68 12 2005 9 30 21 27 1 374.5 0.20 0.17 2.83 35 2005 10 1 21 29 20 375.5 0.19 0.25 2.89 16 2005 10 2 14 44 6 377.0 0.14 0.26 2.32 11 2005 10 8 18 58 41 374.8 0.28 0.10 2.61 80 2005 10 9 21 2 30 374.9 0.25 0.22 2.92 19 2005 10 10 19 8 55 375.3 0.22 0.12 2.35 50 2005 10 11 19 23 59 375.3 0.29 0.12 2.53 58 2005 10 14 20 39 8 377.4 0.43 0.16 2.62 34 2005 10 15 18 5 27 376.2 0.15 0.46 3.49 7 2005 10 16 17 33 18 375.5 0.26 0.13 2.41 45 2005 10 19 20 4 2 376.2 0.29 0.28 3.04 14 2005 10 20 20 50 28 376.1 0.18 0.21 2.95 26 2005 10 27 18 2 56 376.7 0.29 0.11 2.12 50 2005 10 28 17 55 18 376.3 0.28 0.11 2.71 69 2005 10 29 15 30 51 376.9 0.16 0.34 2.53 8 2005 11 11 19 50 53 376.4 0.36 0.23 3.24 23 2005 11 17 18 22 24 377.5 0.22 0.33 2.49 8 2005 11 26 17 42 41 377.4 0.33 0.22 2.65 21 2005 12 8 16 46 16 380.5 0.14 0.31 3.01 13 2005 12 9 17 36 27 378.3 0.24 0.21 2.81 26 2005 12 19 19 20 47 378.3 0.39 0.48 3.18 6 2005 12 20 17 20 21 379.6 0.18 0.39 2.90 8 2006 1 9 19 40 34 380.1 0.20 0.20 3.19 32 2006 1 10 18 20 5 379.3 0.19 0.16 2.83 44 2006 1 11 18 56 17 379.7 0.29 0.18 2.84 34 2006 1 15 19 29 31 379.4 0.26 0.32 2.83 11 2006 1 18 20 35 2 380.1 0.21 0.30 3.59 17 2006 1 21 17 49 11 380.4 0.25 0.18 2.59 30 2006 1 23 16 44 25 380.0 0.26 0.31 2.98 12 2006 1 25 19 37 7 379.6 0.35 0.14 2.77 50 2006 1 26 18 0 27 379.6 0.27 0.10 2.60 100 2006 1 27 16 41 14 380.4 0.20 0.17 2.91 41 2006 2 2 18 34 34 380.7 0.47 0.20 2.19 17 2006 2 5 20 17 44 380.0 0.18 0.20 2.66 24 2006 2 6 19 28 55 380.0 0.31 0.10 2.44 74 2006 2 7 19 24 7 380.3 0.24 0.34 2.20 6 2006 2 8 20 32 5 380.2 0.22 0.17 2.92 34 2006 2 13 20 45 46 380.6 0.22 0.16 2.78 38 2006 2 15 16 15 20 380.7 0.26 0.23 2.38 15 2006 2 19 17 51 34 380.6 0.25 0.12 2.29 54 2006 2 20 16 9 28 381.0 0.13 0.20 2.24 18 2006 2 25 21 8 0 381.7 0.32 0.13 2.70 56 2006 2 28 20 51 4 380.7 0.13 0.26 2.29 11 2006 3 4 19 3 38 380.8 0.26 0.14 2.36 39 2006 3 22 14 41 37 381.7 0.15 0.35 2.26 6 2006 3 25 22 33 50 380.8 0.28 0.32 3.33 14 2006 3 26 20 7 35 381.3 0.23 0.12 2.62 58