Inter-comparison of retrieved CO 2 from TCCON, combining TCCON and TES to the overpass flight data...
If you can't read please download the document
Inter-comparison of retrieved CO 2 from TCCON, combining TCCON and TES to the overpass flight data Le Kuai 1, John Worden 1, Susan Kulawik 1, Edward Olsen
Inter-comparison of retrieved CO 2 from TCCON, combining TCCON
and TES to the overpass flight data Le Kuai 1, John Worden 1, Susan
Kulawik 1, Edward Olsen 1, Debra Wunch 3, Run-Lie Shia 3, Brian
Connor 2, Charles Miller 1, and Yuk Yung 3 1.Jet Propulsion
Laboratory, California Institute of Technology, 4800 Oak Grove
Drive, Mail stop: 233-200, Pasadena, CA 91109 2.BC Consulting Ltd.,
6 Fairway Dr, Alexandra 9320, New Zealand 3.California Institute of
Technology, 1200 E. California Blvd., Pasadena, CA, 91125 The
comparison of CO 2 from TCCON profile retrievals and aircraft
overpass data Comparison of dry mole fraction (DMF) profile: f CO2
(z) Comparison of total column-averaged DMF: X CO2 Comparison of
partial column-averaged DMF in boundary layer: pX CO2 BLD
(combining TCCON and TES) Coincidence criteria Time window
selection : Short enough to measure a same air parcel by flight and
TCCON. Long enough for sufficient number of profiles from TCCON for
a good statistical treatment. Overpass time window Lamont: Lat=36,
Lon=-97 Parkfalls: Lat=46, Lon=-90 TCCON site DateFlight time
window (UTC) Retrieval time window (UTC) Number of retrievals
Parkfalls2004/07/1416:18:17 16:48:1915:00 17:3036
Parkfalls2004/07/1513:11:09 15:49:0013:00 16:0081
Parkfalls2004/08/1419:46:37 22:24:2919:00 23:0044
Parkfalls2008/05/1217:1918 17:55:2916:00 20:0036
Lamont2009/01/3019:43:18 20:46:3019:00 21:0042
Lamont2009/07/3114:37:00 17:31:0014:00 18:00111
Lamont2009/08/0215:05:00 17:57:0015:00 18:0085
Lamont2009/08/0315:14:00 18:00:0015:00 19:0090
Lamont2010/07/1816:15:39 20:27:5416:00 20:3079 Aircraft measured
dry profile TCCON retrieved wet profile Sa for temperature Sa for
CO 2 Convert to dry profile A priori: Retrieved: Parkfalls: Apply
averaging kernel FLT_AK: 2004/07/12 2004/07/15 2004/08/02
2008/05/12 2009/01/30 2009/07/31 2009/08/02 2009/08/03 2010/07/18
Lamont: Abstract: The Total Carbon Column Observing Network (TCCON)
provides measurements of column abundances of CO2, CO, CH4 and
other molecules that absorb in the near infrared with high accuracy
and high precision (e.g.< 0.25% for CO2). Therefore, this
dataset serves as a link between satellite measurements and ground-
based in situ network. In this study, a retrieval algorithm is
developed to retrieve the CO2 profiles in addition to the
column-averaged dry-air mole fractions (DMF) (X CO2 ). The
inter-comparison between the TCCON retrieved CO2 products and
flight measurements are performed mainly at Parkfalls and Lamont
for now. The retrieved profiles agree well with the overpass flight
profile at both sites. TCCON X CO2 have about 1% negative bias to
the integrated aircraft data with TCCON operator applied. The
root-mean-square of the current available data is about 0.12%. The
boundary layer partial column-averaged CO2 fraction can be
determined by subtract the column amount within and above free
troposphere by TES data from the total column amount by TCCON data.
This boundary layer partial column-averaged fraction data also
shows a good agreement with the integration of flight profile
within the boundary layer. This study demonstrates a method to
derive the boundary layer CO2 by combine total column amount
measurement (e.g TCCON or GOSAT)and free tropospheric CO2 data
(e.g. TES or AIRS). The boundary layer CO2 by combining TCCON and
TES allow us to study the temporal and latitudinal variability of
CO2 near surface. Without O 2 Correction: With O 2 Correction Total
column-averaged DMF comparison Determine boundary layer partial
column by combining TCCON and TES data P cuf-off RMS P cut-off 800
hPa600 hPa Total column- averaged DMF TCCON0.42 ppm Partial column-
averaged DMF in boundary layer TCCON TES1.78 ppm0.70 ppm TCCON A
priori7.49 ppm2.61 ppm 800 hPa 600 hPa P cut-off = 600 hPaRMS
TCCON0.46 ppm TCCON & TES1.46 ppm TCCON a priori3.2 ppm To
determine dry X CO2, the normal way is to remove amount of water
from the total amount of air. Our retrieval simultaneously
retrieves H 2 O by shift its a priori profile. The derived dry X
CO2 using retrieved H 2 O profile has small bias but low precision.
Since O 2 can also be retrieved, the method by normalizing the
retrieved O 2 not only provides dry X CO2 but also improves the
precision. It is noticed that about 1% negative bias is induced
because the limited knowledge of the spectroscopy in O 2 band.
Profile comparison: Applying the averaging kernel and a priori
constraint vector to the aircraft data (Flt) ( which is on TCCON
grid) yields Flt_AK, a profile which accounts for the TCCON
sensitivity and vertical resolution. Flt_AK also represents the
profile that would be retrieved from TCCON measurements in the
absence of other errors. The comparison should performed between
the TCCON profile (Ret) and aircraft data have had the TCCON
operator applied (Flt_AK). These profile comparisons give a good
overview of the variability and bias in TCCON profile. Combining
TCCON and TES assimilated data, the boundary layer partial column
CO 2 is determined by subtract the partial column amount within and
above free tropospherefrom the total column amount by TCCON. The
remained partial column amount in boundary layer is weighted by the
partial column amount of dry air in the boundary layer for. The
comparison of to those by integral the flight profile within
boundary layer shows small bias and high precision. The knowledge
of boundary layer CO 2 was greatly improved by combining TCCON and
TES assimilated CO 2 data compared to the climatology a priori.
Inter-comparison of TCCON combining TES to SGP flight measurements
TES SGP FLT There are more flight measurements at Lamont in 2009
but these CO 2 profiles only go up to 5 to 6 Km. However, it still
allow us to compare the boundary layer CO 2 from combining TCCON
and TES to the flight data. For the comparison of total column, a
priori CO 2 is replace above the ceiling of the flight
measurements. Here are sixteen days comparison in 2009 from January
to December when flight measurements are available. The bias and
precision of X CO2 are both consist with previous results. The bias
in boundary layer CO 2 stay small but root mean square is increased
due to two outliers. These two outliers are because flight boundary
layer CO 2 are outside the a priori constrain region.