ICOS Science Conference, Session 5

1. NEIL HUMPAGE – UNIVERSITY OF LEICESTER
GREENHOUSE GAS COLUMN
OBSERVATIONS FROM A
PORTABLE SPECTROMETER IN
TROPICAL AFRICA
HARTMUT BOESCH* – UNIVERSITY OF LEICESTER
WILLIAM OKELLO – NATIONAL FISHERIES RESOURCES RESEARCH INSTITUTE, JINJA, UGANDA
FLORIAN DIETRICH, JIA CHEN – TU MUNICH
MARK LUNT, LIANG FENG*, PAUL PALMER* – UNIVERSITY OF EDINBURGH
* ALSO NATIONAL CENTRE FOR EARTH OBSERVATION, UK

2. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
MOTIVATION: UNDERSTANDING
GREENHOUSE GAS EMISSIONS IN
TROPICAL AFRICA
• Palmer et al (2019): ‘tropical terrestrial ecosystems store large amounts
of carbon in plants and soil, but are particularly vulnerable to changes in
climate’
• Unexpectedly large net emissions from tropical Africa in 2015 and 2016
• Estimated from satellite data sets (OCO-2, GOSAT) in conjunction with
atmospheric chemistry models (e.g. GEOS-Chem)
• Lunt et al (2019): focus on methane, found robust positive linear trend in
tropical African methane emissions over the period 2011 to 2016
• Increased emissions consistent with increased wetland extend in the
Sudd region, South Sudan
• Findings based on satellite and model datasets – how well do these
represent what’s happening in the atmosphere over the tropical African
region?

3. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
GROUND-BASED REMOTE
SENSING
• Ground based Fourier Transform Spectrometers (FTS) provide
accurate CO2 and CH4 columns
• Same measurement principal as satellites
• Total Carbon Column Observing Network (TCCON) data is essential
to identify and correct for biases
• Gaps in network coverage: South America, Africa, Central and
South Asia
• TCCON sites expensive and logistically challenging to set up…
cheaper, portable solution which still provides similar data quality?

4. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
THE BRUKER EM27/SUN SPECTROMETER
• Automatic solar tracker uses camera-based
feedback system
• Fourier Transform spectrometer: standard operation
takes average of 10 interferograms  1 minute per
observation
• Two detectors at 0.5 cm-1 spectral resolution:
• COCCON (Collaborative Carbon Column Observing
Network, Frey et al. 2019 AMT):
• Calibrated against Karlsruhe Institute of Technology
(KIT) reference instrument  traceability
• Retrieval software (PROFFAST) developed by KIT and
used by all EM27/SUN operators  consistency of
interferogram processing approach

5. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
AUTONOMOUS OPERATION IN ALL WEATHER
• Automated enclosure developed by TU
Munich (Florian Dietrich, Jia Chen) – see
Dietrich et al (2020) in AMTD
• Enables continuous remote operation via
internet connection
• Provides environmental protection and
stability:
• Active cooling and heating
• Automatic retractable dome triggered by rain
sensor
• Webcam for remote visual inspection

6. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
DEPLOYMENT IN JINJA, UGANDA
• Part of NERC Global Methane project
MOYA
• EM27/SUN and enclosure hosted by
NaFIRRI (William Okello)
• Setup in January 2020 for 12 month
deployment
• Ideal location for methane emissions from
wetlands, GHGs from biomass burning as
well as filling gap in validation networks

7. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
DEPLOYMENT IN JINJA, UGANDA

8. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
DEPLOYMENT IN JINJA, UGANDA
• Enclosure operated with a north-south tilt to allow for high solar elevation angles in the middle of the day (tilt currently at 31.6°)

9. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
FIRST THREE MONTHS OF EM27/SUN DATA
FROM JINJA
• Interferogram processing and optimal estimation retrieval (profile scaling) using PREPROCESS and PROFFAST (KIT, see https://www.imk-
asf.kit.edu/english/3225.php)

10. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
FIRST THREE MONTHS OF EM27/SUN DATA
FROM JINJA: NUMBER OF OBSERVATIONS
• Automated enclosure allows good temporal
coverage, even on days when weather is
changeable
• Fewer successful retrievals in 2.3 micron window

11. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
FIRST THREE MONTHS OF
EM27/SUN DATA FROM JINJA:
SENTINEL 5P COMPARISON
• S5P methane quality flagging very sensitive to clouds  lack of spatial coverage
• Data available from s5phub.copernicus.eu

12. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
FIRST THREE MONTHS OF
EM27/SUN DATA FROM JINJA: OCO-2
COMPARISON
• OCO-2 v10 Lite data now available from https://ocov2.jpl.nasa.gov/oco-2-data-center/

13. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
FIRST THREE MONTHS OF
EM27/SUN DATA FROM JINJA: OCO-2
AND OCO-3 COMPARISON
• OCO-3 vEarly Lite data now available from https://ocov2.jpl.nasa.gov/oco-2-data-center/
17th Feb
27th Mar

14. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
OPPORTUNITY FOR VALIDATION: OCO-3
SNAPSHOT AREA MAP (SAM) DATA
• OCO-3 – on board
the International
Space Station – is
point-able, and can
provide mapping of
ground targets
• Jinja is on the list
of OCO-3 targets
 more
opportunities for
validation
• https://ocov3.jpl.na
sa.gov/sams/

15. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
EVALUATING ATMOSPHERIC
CHEMISTRY MODELS:
GEOS-CHEM
• High spatial resolution model output for
methane by Mark Lunt (University of
Edinburgh)
• Based on climatology of emissions averaged
over 2010-2016  emissions probably
underestimated relative to 2020, different
seasonal timing
• Calculations using 2020 emissions data to
follow soon (also for carbon dioxide – Liang
Feng, U. Edinburgh)
• GEOSChem used to infer surface fluxes from
satellite data  essential to check that model
captures observed variability and trends

16. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
SUMMARY AND FUTURE PLANS
• Bruker EM27/SUN spectrometer operating* in Jinja, Uganda
• * some technical problems at the moment which we are trying to resolve
• Validation of Sentinel 5P (SRON), OCO-2/3 (NASA JPL), GOSAT-2
• High resolution GEOS-Chem model runs underway (Mark Lunt, Liang Feng –
University of Edinburgh) – demonstrate validity of models used in other studies
• Break down dataset by local wind direction and speed to investigate East African
GHG sources, in conjunction with Lagrangian transport model
• Lots of collaboration to make this work! Would not be possible without
efforts of colleagues at NaFIRRI and TU Munich, in particular
• For further info or discussion:
• nh58@le.ac.uk
• @DrNeilHumpage

17. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage

18. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
• S5P carbon monoxide (from
s5phub.copernicus.eu) follows our EM27/SUN
observations well
• Emitted through biomass burning, incomplete
combustion – useful proxy for these processes
FIRST THREE MONTHS OF
EM27/SUN DATA FROM JINJA:
SENTINEL 5P COMPARISON

19. ICOS Science Conference, 15th September 2020nh58@le.ac.uk / @DrNeilHumpage
THE LONDON CARBON EMISSIONS
EXPERIMENT CONCEPT
• Establish ground-based remote
sensing network (CO2, CH4, CO,
NO2, aerosol)
• Combine with city-focused
satellites (OCO-3, MicroCarb)
• City-scale modelling to link to
emission inventories
• London as testbed for studies on
CO2 emissions
Satellites: Microcarb, OCO-3
Ground: EM27/SUN, MAX-DOAS
+ emissions inventories, e.g. UKNAEI
GHGs
Air quality