1. Institute of Environmental Physics
Fiducial Reference Measurements for Ground-Based IR Greenhouse Gas Observation (FRM4GHG)
J. Notholt, M. De Mazière, R. Kivi, H. Chen, T. Blumenstock, D. Griffith, D. Weidmann and co-workers
University of Bremen, Royal Belgian Institute for Space Aeronomy, Finnish Meteorological Institute, University of Groningen, Karlsruhe Institute of Technology, University of Wollongong, Rutherford Appleton Laboratory
University of Bremen
Institute of Environmental Physics

2. Current situation and requirements
Optimum validation for NADIR satellite observations of GHGs
is provided by ground-based solar absorption spectrometry
- TCCON is the reference system
- Complete TCCON observation system (container, Bruker 125 HR, solar tracker)
is expensive k€
- Requires high maintenance and operations costs
- Difficult to transport, limits possibility for campaigns
- Limits the extension of the network
Development of cheaper and easier deployable systems for remote sensing
GHG observations

3. Aim of FRM4GHG
Perform an intercomparison of measured total column concentrations
of a few GHG (CO2, CH4, CO) using several different infrared spectrometric
instruments at a TCCON site.
We plan to perform measurements with five different spectrometers
plus the in-situ Aircore balloon system
The measurement campaign is planned to take place in Sodankyla/Finland
in Project starts in Aug
FMI runs there a TCCON instrument and has experience
with AirCore launches (allowed in Sodankyla !) since September 2013.

4. Instruments for FRM4GHG
TCCON Bruker 125HR (FMI)  XCO2, XCH4, XCO; resol cm-1
Bruker EM27/SUN (KIT)  XCO2, XCH4; resol. 0.5 cm-1
+ dual channel version  XCO
Bruker Vertex 70 (BIRA & IUP)  XCO2, XCH4 , XCO; resol cm-1
IR cube (UoW)  XCO2, XCH4, XCO; very low resol.
Quantum cascade later heterodyne radiometer (RAL)
 CH4, CO, CO2; resol cm-1
In-situ Aircore system (RUG)  CO2, CH4, CO vertical profiles
Calibrated to WMO standards

5. FRM4GHG campaign set-up
South
C: Hole in the wall 5 cm, 1 meter from inside floor
D: Hole in the wall 5 cm, at 2.2 m
E: Hole in the wall 5 cm, at 2.2 m
A: Hole in the roof: 20 cm Tracker;
B: 5 cm cables
F: Internet RACK,
19 inches, inside, on the wall
Tracker
EM27/SUN
IR Cube
QCLHR
Cables inlet: power cable, ethernet cable
Vertex 70
Ilmalämpöpumppu
Window, 0.82*1.1m
Window, 0.82*1.1m
Double door

6. Bruker Vertex 70
EM27/SUN
IR cube

7. Aircore
QCLHR
Plans to miniaturize the QCLHR

8. Work packages within FRM4GHG
WP0: Preparation of container to host the spectrometers
(not financed by ESA)
WP1: Requirements Identification
WP2: Intercomparison Preparation (end of 2016)
WP3: Intercomparison Execution (2017)
- semi-blind comparison
WP4: Data analysis and Corrective Measures
including aircore profiles as a priori
WP5: Project Outreach
- conclusions
- involvement of satellite groups, NDACC & TCCON
WP6: Development of an AirCore Gliding System
(optional, depending on funding)
WP7: Project management

9. Ny-Ǻlesund issue (Christoph Petri) Institute of Environmental Physics
Sometimes we found inconsistencies between forward- and backward-runs
for the upgraded instrument using TCCON splitting software i2s
(forward/backward interferogram)
University of Bremen
Institute of Environmental Physics

10. Institute of Environmental Physics
No bias for OPUS-splitted forward- and backward spectra
 Problem due to splitting into forward/backward in i2s
University of Bremen
Institute of Environmental Physics

11. Institute of Environmental Physics
Biggest differences found in the O2-retrieval
Effect hardly visible in the CO2 retrieval
University of Bremen
Institute of Environmental Physics

12. Institute of Environmental Physics
For those wrong retrievals spectra show wave-like structure
Position of ZPD ? Phase correction in slice-i2s might be the problem ?
University of Bremen
Institute of Environmental Physics

13. A Python module for Opus files and slices
Matthias Buschmann, IUP Bremen
Problem:
- Opus files and slices not server-side accessible
- Access to ifg/spc via conversion to ascii only
- For limited data transfer from remote sites (e.g. Palau):
Check interferograms before transfer
Solution:
- GGG/i2s has all necessary infos to look at spectra/slices/header
- Implemented in Python using standard libraries + NumPy
- Access to slices, spectra and interferograms
- Full header information access

14. Example - First line: how to install the module in Python
- Second line: open a spectrum
- Rest: how to get OPUS Header infos
- Replacement of data blocks and header parameters possible

15. Slices
Interferogram
Spectrum