ICOS Science Conference, Session 2

1. Inter-annual variability of Eddy Covariance
CO₂ flux measurements in the city center of
Heraklion, GreeceKonstantinos Politakos1
, Stavros Stagakis2
,
Nektarios Chrysoulakis1
Remote Sensing Lab | IACM | http://rslab.gr
ICOS Conference
15/09/2020
1. Foundation for Research and Technology Hellas, Remote Sensing Lab, Greece
2. University of Basel, Environmental Sciences, Switzerland

2. Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 2
Introduction
Site Description
Tools & Methods
Interannual Patterns
Greek government’s measures
for COVID-19
Conclusions
References
Table of Contents

3. Introduction
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 3
A tower-based Eddy Covariance system is active for a three-year period
over the city center of Heraklion accomplishing some certain goals:
 Monitoring the anthropogenic emissions
 Estimating the major sources of 𝐶𝑂2 emissions
 Analyzing periodic flux patterns
 Contributing to the carbon dioxide fluxes inventory of Heraklion
 Collaborating with the municipality of Heraklion by consulting and
contributing to the action plan for the reduction of 𝐶𝑂2 emissions
(Covenant of Mayors)
The EC tower (Heraklion)
Under this perspective, the RsLab is planning to
install a new EC tower in order to monitor and
analyze the 𝐶𝑂2 emissions in a new area in
Heraklion.

4. Site Description
The center of Heraklion is an interesting study area in the global network of urban EC stations due to the urban morphology, the Mediterranean
climate and the mixture between residential neighborhoods and busy commercial zone.

5. Sonic Anemometer
Gas AnalyzerNet Radiometer
25 m Net Radiation
27 m Eddy Covariance
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 5
Site Description
(Stagakis et al. 2019)

6. Tools & Methods
The carbon dioxide fluxes (𝐹𝑐) were calculated at 30-min time step
and the time-series were quality-controlled and gap-filled (Stagakis
et al. 2019) using a moving look-up table (mLUT) technique (Schmutz
et al. 2016). Gap-filled time-series were then temporally aggregated
to monthly and yearly emission totals (Stagakis et al. 2019):
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 6
IRGASON Integrated CO2/H2O Open-
Path Gas Analyser and 3D Sonic
Anemometer (Campbell Scientific, Inc,
Utah, USA).

7. Annual Diurnal
Patterns
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 7

8. Week Patterns
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 8

9. Annual Diurnal Patterns Per Sector
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 9
Now, it is time for our poll.
We have separated our measurements per
sector.
• 0 𝑜
− 90 𝑜
• 90 𝑜 − 180 𝑜
• 180 𝑜 − 270 𝑜
• 270 𝑜 − 360 𝑜

10. Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 10
Wind Roses (average) Nov/2017-Oct/2018
Wind Roses (average) Nov/2016-Oct/2017

11. 𝐹𝑐 vs Angles
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 11

12. Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 12
𝐹𝑐 per Month

13. Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 13
Diurnal Patterns Per Month

14. Greek government’s measures for
COVID-19
On 23/03/2020 the Greek government announced a
national lockdown which was withdrawn on
04/05/2020. The impact of these measures affected
the carbon dioxide emissions of Heraklion city center
by reducing the 𝐹𝑐 up to 70% comparing to the same
period on 2018.
Heraklion case study was included in the ICOS Media
Release of 14/05/2020:
Clear evidence of reduction in urban 𝐶𝑂2 emissions as
a result of COVID-19 lockdown across Europe (Dario
Papale et als. 2020)
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 14

15. Conclusions
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 15
Similar carbon dioxide fluxes patterns for the first two years
Basic carbon dioxide flow measurement zones: North (Heraklion shopping area, heavy traffic)
& South-Southwest (residential zone)
Sector from 0 𝑜 − 90 𝑜converges better to the daily rush hour pattern
Similar annual wind patterns
Observation of unique 𝐹𝑐 for the winter months due to the burning of fossil fuels for heating in
the residential zone
Observation of new carbon dioxide patterns for the period of mobility restrictions (March 2020
– April 2020)
Reduced fluxes due to changes in traffic regulations applied by the municipality of Heraklion
have been observed in this 3-years period study

16. References
Stagakis, S., Chrysoulakis, N., Spyridakis, N., Feigenwinter, C., Vogt, R., (2019). Eddy Covariance measurements and
source partitioning of CO2 emissions in an urban environment: Application for Heraklion, Greece. Atmospheric
Environment. https://doi.org/10.1016/j.atmosenv.2019.01.009
Papale, D., Antoniella, G., Nicolini, G.,& Gioli, B., Zaldei, A., Vogt, R., Feigenwinter, C., Stagakis, S., Chrysoulakis, N., Järvi,
L., Nemitz, E., Helfter, C., Barlow, J., Meier, F., Velasco, E., Christen, A., Masson, V., (2020). Clear evidence of reduction in
urban CO 2 emissions as a result of COVID-19 lockdown across Europe.
Grimmond, C.S.B., Oke, T.R., 1999. Aerodynamic properties of urban areas derived from analysis of surface form. J.
Appl. Meteorol. 38, 1262–1292. https://doi.org/10.1175/1520-0450(1999)038<1262:APOUAD>2.0.CO;2.
Schmutz, M., Vogt, R., Feigenwinter, C., Parlow, E., 2016. Ten years of eddy covariance measurements in Basel,
Switzerland: seasonal and interannual variabilities of urban CO2 mole fraction and flux. J. Geophys. Res. 121, 8649–
8667. https://doi.org/10.1002/2016JD025063
Konstantinos Politakos | ICOS Science Conference | 15 September 2020 | Slide 16