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
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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?
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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
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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.
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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.
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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
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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:
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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.
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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
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Using the time dependant CO2 variation with latitude
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