Presented at the 3rd ICOS Science Conference in Prague, Czech Republic, 11-13 Sep 2018.

1. Assessing GHG exchange at landscape
scale
Bart Kruijt, Ronald Hutjes, Cor Jacobs, Merit van den Berg,
Christain Fritz, Torsten Sachs, Andrei Serafimovich, Stefan
Weideveld, Wilma Jans
Wageningen University&Research; Radboud University
Nijmegen; GeoForschungs Centrum Potsdam

2. FACCE ERA-GAS
2

3. ERA-GAS projects
3

4. Can we optimise the GHG budget of
landscapes?
4

5. Measuring at landscape scale
 Effects of management
 GHG exchange of the landscape mosaic
Today:
- Peatland emission measures and monitoring
- Simpler flux measurement on small fields
- Integral landscape and fluxes an inventories: aircraft
fluxes
5

6. Drained peatlands
 Emission Netherlands: 4.2
million ton CO2
 Submerged drains (SMD) a
solution?
Peat
CO2
Peat
Degraded peat
CO2
-60 cm
Ditch
-60 cm
Ditch
Submerged drains
6 m
Winter (wet) Summer (dry)
Business as usual

7. Effect of submerged drains on water
table and Reco
Translucent soil chamber measurements:
Take light response curves to derive
dark flux
PhD research work, Stefan Weideveld

8. Pair of eddy covariance sets on peat
meadows with and without submerged drains
8

9. Routine eddy covariance over multiple
fields...?
9

10. Simplifying flux measurement:
reviving old ideas.
 Eddy covariance: 𝐹𝑙𝑢𝑥 = 𝑤′ 𝑐′
 Variance methods: 𝐹𝑙𝑢𝑥 = 𝑐𝑜𝑛𝑠𝑡 × 𝜎 𝑐
 Budget methods: 𝐹𝑙𝑢𝑥 =
𝜕𝑐
𝜕𝑡
𝑑𝑡 × 𝑣𝑜𝑙/𝑎𝑟𝑒𝑎
 Surface renewal methods, similar to budget but shorter
time scale:
10
McElrone et al, 2013

11. Lots of data around to test
 CO2 in-canopy gradients at Loobos pine forest, August
2018 switchover from drought to rains
11

12. Wall-to-wall landscape fluxes:
Aircraft inventories ...... PH-WUR
12
turbulence probe
Novatel GPS antenna
laser altimeter
infra-red thermometer
net radiation
PAR sensors
LICOR 7500
thermocouple
operator
display
C-Migits
IGPS
antenna
turbulence probe
Novatel GPS antenna
laser altimeter
infra-red thermometer
net radiation
PAR sensors
LICOR 7500
thermocouple
operator
display
C-Migits
IGPS
antenna

13. And Polar 5 at GFZ Potsdam..
13

14. Polar 5 in NE Germany
14
Andrej Serafimovich preliminary results

15. 2008 data PH-WUR
Flight Strategy
• Full seasonal cycle, mar08-feb09, weekly flights
• Three routes, representative landscapes
Unique data set
• ~215 flight hours, 40 days, nobs=6102 (after QA)
Stratification
• Temporal m, bm, s
• Soil regions: 5
• 13 LUC types
turbulence probe
Novatel GPS antenna
laser altimeter
infra-red thermometer
net radiation
PAR sensors
LICOR 7500
thermocouple
operator
display
C-Migits
IGPS
antenna
turbulence probe
Novatel GPS antenna
laser altimeter
infra-red thermometer
net radiation
PAR sensors
LICOR 7500
thermocouple
operator
display
C-Migits
IGPS
antenna

16. Footprint of airborne measurements
Ede
 is footprint model (Kljun, 2004 BLM)
Method Dis-aggregation (DFMR)
 footprint analysis: fractional areas cover class in footprint
of airborne flux observation (right)
 find cover class-specific fluxes FK by multiple regression or
other (constrained) linear solvers (left)
p x 1 vector of airborne
flux observations
p x n matrix of coverclass
fractional areas,
footprint weighted
n x 1 vector of errors
n x 1 vector of coverclass-
specific fluxes

17. Extrapolate and map fluxes
17
𝑭𝒄 𝒍𝒐𝒄𝒂𝒍
𝑷𝑨𝑹 𝒍𝒐𝒄𝒂𝒍
× PAR 𝒂𝒓𝒆𝒂 = 𝑵𝑬𝑬 𝒂𝒓𝒆𝒂, (DAY!)
(Hutjes & Kruijt in prep)

18. Airborne NEE and tower validation
18
Hutjes, Vellinga, Elbers

19. So far: daytime only. How get 24-hour NEE?
 Aircraft can only fly in DAYTIME
 What is lacking is nighttime/ Ecosystem respiration
● Get it from zero-intercept of NEE light response?
● Need to fit non-linear light response on
sparse data – difficult!
● Response is linear on LONGER time scales
● But is that useful?
19

20. Is night-time NEE predictable from day-
time NEE?
Daytime or GPP fluxes are ‘easy’:
- good turbulence for EC
- Aircraft can fly
- Remote sensing works
- Photosynthesis well understood
 Is NEEnight / NEEday
predictable?
20

21. A ‘quick look’ at
(NEEnight / NEEday)/night hr
 Analysed a few EC tower data data sets
21

22. A ‘quick look’ at
abs [(NEEnight / NEEday)/night hr]
 Analysed a few EC tower data data sets
22
(low values)
Vegetated,
MINERAL soil gives
reasonably
consistent ratio.
Peat soil and bare
soil give higher
values

23. Still some work
to do!
- Comparative flux
measurements at small
fields
- Develop satisfactory
routine measurement
methods
- Extend aircraft flux
inventories to include
nighttime/dark flux
23

24. 24

25. Annual light response curves...
25
Fit:
𝑁𝐸𝐸 = 𝑅𝑒 0 × 𝑒 𝑐𝑇 + 𝑎 × 𝑃𝐴𝑅