Dear Francis, You are certainly not lazy. Many thanks for considering an alternative air inlet for a limited period. Two weeks will be very helpful for evaluations purposes and hopefully it will not affect your normal “data production”. About the paper below I greatfully accept being a coauthor. My major opinions are: (AFTER GOING THROUGH THIS PAPER THE MAJOR PROBLEMS SEEM TO BE: A. TO ESTABLISH A VALUABLE CORRECTION FOR SEASONAL AND SPATIAL VARIATIONS OF CO2 VALUES TO LAND AREAS (FORRESTED OR NOT) B. TO INFORM THAT HISTORICAL CO2 (LAND) VALUES ARE COMPATIBAL WITH MODERN LCD VALUES. EXAMPLES. C. TO EXPLAIN WHY CO2 LAND VALUES DIFFER SO MUCH FROM ACCEPTED OCEAN CO2 VALUES IN AN ABREVIATED FORM D. TO ANALYSE ALL PHYSICAL PROCESSES INVOLVED IN CO2 SINKS AND SOURCES AT A LARGE SCALE BASED ON LCD DATA AND NOAA DATA COMPARISONS. 1. There is a need to establish the existence of the CO2 gradient as the paper will do and especially it big seasonal variation. There are signs that this gradient is played down by propaganda information. 2. This task is urgent for several reasons. One is to meet comments concerning the Beck paper. 3. This paper should be possible to use as an approximate calibration of world wide CO2 data. It means that it has to be clearly defined which physical situation the data is valid (ocean measurements). Physical processes should not be discussed. 4. The level of approximation should be fair. In this part I will suggest a change despite what I claimed in 3. 5. Relating to my comments 1-4 I would recommend a change of title more in line with what the abstract says: “A corrective formula is proposed which will be of use when comparing contemporary CO2 data from land and ocean influenced stations and for validation of historical CO2 mesurements.” 6. The task of the title is gigantic and cannot be treated in a short paper. CO2 varies on time scales from hours, days, months, years and decades and is also dependant on regional factors both on land and at sea. (Consider a step wise expanding in coming papers) 7. The change I would like to do in your calculations (highly recommendable) is to consider the CO2 mixing ration as constant in the SH for a certain year south of -40 lat. You can see that this will get a better fit to your data. The reason is that the southern oceans are the major CO2 sinks in the world and the high winds around Antarctica is one reason for this to happen. This would mean the approximated linear _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 1 gradient will be numerically greater for both seasons. I approve of only treating two seasonal gradients at this stage. Francis Massen francis.massen@education.lu http://meteo.lcd.lu OBSERVED TEMPORAL AND SPATIAL OCEANIC CO2 VARIATIONS USEFUL FOR EVALUATION OF REGIONALLY OBSERVED CO2 DATA. Using the time dependant CO2 variation with latitude to compare historic chemical and modern NDIR CO2 measurements Authors: Francis Massen, Ernst .Beck, Hans Jelbring, Antoine Kies History: version 1.0: original version 23Mar07 version 1.1: changed title added decadal dependancy to calculations page 5, corrected error in latitude difference between Orleans and Mauno Loa (should be 28) added table for clearness (p.6) added remark on possible decadal oscillation in time dependancy (p.5) corrected references (still uncomplete) added a conclusion added legends to figures do be done: add explanation on Massen et al CO2/windspeed method? use more data to compute CO2 gradient? _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 2 Abstract: A short investigation on the dependance of winter and summer CO2 mixing ratios with latitude shows that CO2 increases linearly with latitude, from South-Pole to North-Pole. The slope of this linear function increases with time. A corrective formula is proposed, and used to validate historical CO2 measurements. OBSERVED OCEAN CO2 DATA SHOW BOTH SEASONAL AND SPATIAL VARIATIONS WHERE LATITUDE IS OF MOST IMPORTANCE IN ADDITION TO THE WELL KNOWN INCREASE IN TIME. “AN APPROXIMATE corrective formula is proposed which will be of use when comparing contemporary CO2 data from land and ocean influenced stations and for validation of historical CO2 mesurements.” 1. The source ofthe CO2 data. All data in this study come from the NOAA Globalview ftp site at ftp://ftp.cmdl.noaa.gov/ccg/co2/GLOBALVIEW/gv/ [1] The data files hold 4 columns like: Creation Date: Thu Aug 31 09:28:42 2006 # of rows after column header: 1297 UTC 1979.000000 1979.020833 S(t) 335.4340 335.7970 REF(t) 336.7548 337.1502 diff -1.3208 -1.3532 The CO2 mixing ratio is the sum of REF(t) + diff. 2. Stations and time-span used 10 stations from South-Pole to Spitzbergen are used in this study, having the following latitudes: Station South Pole Mawson Station Barring Head, NZ Amsterdam Island Samoa Island Mauna Loa La Jolla Pier Gozo (Malta) Orleans (F) Barrow Station Spitzbergen NOAA code spo_01D0 maa_02D0 bhd_15C0 ams_11C0 smo_04D0 mlo_01D0 ljo_04D0 goz_01D0 orl005_11D2 brw_01D0 zep_01D0 Latitude -90 -68 -41 -37 -14 20 33 36 48 71 79 _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 3 The data used are from 1985, 1990, 1995, 2000 and 2005; winter data correspond to yyyy.0000 , summer to yyyy.5000 UTC. Table 1 gives the measurements used, yyyyW denotes winter and yyyyS summer. table 1: data used 3. Variation with latitude (THE LINES SOUTH OF -40 SHOULD BE HORISONTAL IN BOTH FIGURES.) The plot of CO2 versus latitude gives the following results for both seasons: fig.1. Variation in CO2 mixing ratios with latitude, first month of the year (i.e. NH winter), computed from 11 stations. _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 4 fig.2. Variation in CO2 mixing ratios with latitude, first month of the year (i.e. NH winter), computed from 11 stations. The conclusions to draw are obvious from inspection: 1. the gradient increases more or less linearly with latitude 2. the winter gradient is 4 to 5 times higher than the summer gradient 3. the relative variability from year to year is lower in winter (maximum factor 1.25) than in summer (maximum factor 5.54) The mean winter gradient is 0.05824 +/- 0.00585, the mean summer gradient 0.01384 +/- 0.00693 (about 1/4th of the winter gradient) An example: if the January CO2 concentration at the South-Pole is 370ppm, one should expect 370 + 0.05824*(90+48) = 370 + 8 = 378 ppm for Orleans; at mid-year the difference would be +1.9 ppm. Over the whole year an average gradient of 0.03604 could be used as a first approximation. _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 5 4. Latitudinal gradient variation with time. (YOU SHOULD ONLY USE THE CORRECTION SEASONALLY AND SPATIALLY. THERE IS NO REASON TO EXPECT CO2 TO KEEP ON RAISING IN A LINEAR WAY. METHANE HAS ALREADY LEVELLED OUT. CONSIDER TO JUST SHOW OBSERVED AVERAGED OCEANIC LATITUDINAL VALUES) Plotting the different gradients versus a decadal time increment (taking year1985 as 0) shows a linear increase with time (with a possible superposed decadal oscillation): fig.3.Decadal time dependancy of the latitudinal gradient The winter gradient increases by 0.055 per decade, the summer by 0.0121, about 4 times less . Latitudinal and time dependencies can be summarized by the following relationship CO2(t,L), with t being the time in decades from 1985 on, and L the latitude: Season Winter Summer avg_year Latitude and time correction (0.055 + 0.0032*t)*L (0.012 + 0.0018*t)*L (0.034 + 0.0025*t)*L Example: 2005 Orleans versus South Pole + 8.5 + 2.2 + 5.4 Measured CO2 difference 9.4 -3.9 2.8 The difference between the gradient computed using the formula and the real measured data is not negligeable, especially in summer. Nevertheless, the formula can _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 6 help to make a raw check for instance on the validity of historic data, as will be shown in the next paragraph . 5. Applying the correction to a historical data series (CONSIDER THE MAJOR ISSUE TO LIMIT THIS PAPER TO INFORMATION OF A SUITABLE CORRECTION FOR SPATIAL AND SEASONAL CO2 VARIATIONS FOR SIMPLICITY AND CLARITY. YOUR FIGURE WILL BE OF MORE VALUE WHEN DISCUSSING IT IN RELATION TO PHYSICAL PROCESSES AT HAND As an example, we will use the measurements done by Steinhauser in Wien during the 8 months Mai-August 1957 and Nov-Feb 1957/58 [2] . This is one of the few well documented chemical measurement series overlapping with the first NDIR measurements by Keeling. From the digitized Steinhauser plots of CO2 versus wind speed one gets a mean rounded value of 327 ppm, the asymptotic CO2-windspeed rule explained in [4] suggests a baseline of 324ppm. To compare with the first Keeling measurements, we will use the results from fig.5. Keeling made early measurements at Mauna Loa, lat. 20°, in 1958; the yearly mean is about 313 ppm.. The latitude of Wien is the same as Orleans (48°); applying the gradient to the Keeling data gives the following results Keeling Mauna Loa, 1958 NDIR 313 ppm Steinhauser, Wien, 1957-1958, chemical Average Base-level over from 8 months windspeed 327 ppm 324 ppm Latitude/time 1958 Wien gradient to add to data Keeling data according to Mauna Loa 0.034+ 314 ppm 0.0025*(-2.7)*28 = 0.76 ~1 ppm Difference between Steinhauser and adjusted NDIR 13 ppm 10 ppm If we use the winter ice floe data (assuming a latitude of -70° which gives a difference of 118° with Wien) and the Steinhauser Nov57-Feb58 series, the results are: Keeling, ice floe Feb., 1958 NDIR 316 ppm Steinhauser, Wien, 1957-1958, chemical Average Base-level over from 4 winter windspeed[ months 336 ppm 329 ppm Latitude/time 1958 Wien gradient to add to data Keeling data according to ice floe Difference between Steinhauser and adjusted NDIR 0.055+ 0.0032*(2.7)*118 = 5.5 ~6 ppm 14 ppm 7 ppm 322 ppm 6. Conclusion Two conclusions can be made from this comparison: _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 7 1. To evaluate historic chemical measurements, the base-level computed using the asymptotic windspeed adjustement [4] and applying a latitude/time gradient reduces the difference between the NDIR and the original chemical measurements. .2. The rather small difference of ~7 -10 ppm found in this study shows that at least some of the historical chemical CO2 measurements can be considered as valid, and could be used to complement (or correct) the traditional ice core data which are exclusively used today to represent the CO2 mixing ratios preceeding the NDIR measurements. ([5]). fig.4. _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 8 fig.5 The early Keeling curve (from Scripps Institution of Oceanography) References: 1. GLOBALVIEW-CO2: Cooperative Atmospheric Data Integration Project - Carbon Dioxide. CD-ROM, NOAA/CMDL, Boulder, Colorado. [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/co2/GLOBALVIEW], 2006. 2. Steinhauser F., Der Kohlendioxyd-Gehalt der Luft. DK 551.510.41 3. The early Keeling Curve. http://scrippsco2.ucsd.edu/program_history/early_keeling_curve_2.html 4. Massen F. et al: Seasonal and Diurnal CO2 Patterns at Diekirch, LU. http://meteo.lcd.lu/papers/co2_patterns/co2_patterns.html 5. Beck E., 180 Years of Atmospheric CO2 Gas Analysis by Chemical Methods. Energy & Environment _____________________________________________________________________ Using the time dependant CO2 variation with latitude page 9