1. Jon A. Arrillaga (UCM, SP)
Sea-breeze occurrences in cabauw: implications for the scalar-transport and dynamics of the boundary layer
Jon A. Arrillaga (UCM, SP)
Jordi Vilà-Guerau de Arellano (WUR, NL)
Fred Bosveld (KNMI, NL)
Henk Klein Baltink (KNMI, NL)
Carlos Yagüe (UCM, SP)
Arjan Hensen (ECN, NL)
Danielle van Dinther (ECN, NL)
Arnoud Frumau (ECN, NL)
Mariano Sastre (UCM, SP)
Carlos Román-Cascón (CNRS, FR)
BBOS Barcelona - 14 October 2016

2. De Haij et al., 2007
Sunrise
Sunset
BBOS Barcelona - 14 October 2016

3. De Haij et al., 2007
BBOS Barcelona - 14 October 2016

4. Sudden breakdown of the convective boundary layer:
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
Sudden breakdown of the convective boundary layer:
Interaction between the mesoscale (SB) and microscale?
How does it affect the afternoon-evening transition of the ABL?
BBOS Barcelona - 14 October 2016

5. Time period: 01/01/2001 - 31/12/2010. (10 YEARS)
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
Observational site
AREA OF STUDY
Ideal site: CESAR (Cabauw).
Time period: 01/01/ /12/2010. (10 YEARS)
≈ 50 km from the sea.
Two main SB directions.
EUMETSAT/OSI SAF, full resolution METOP data (SST 28/06/09-02/07/09).
BBOS Barcelona - 14 October 2016

6. Cabauw Experimental Site for Atmospheric Research (CESAR)
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
Cabauw Experimental Site for Atmospheric Research (CESAR)
Validated data:
Temperature
Specific humidity
Wind speed and direction
Surface turbulent fluxes
Turbulent fluxes at different levels ( )
CO2 concentration (several gaps)
222Rn concentration ( ).
* Mixing layer height from LD40 AND CT75 ceilometers and LAP3000 wind profiler
200 m
140 m
80 m
40 m
20 m
10 m
2 m
BBOS Barcelona - 14 October 2016

7. 1) We select only the warm period from the 10 years: MJJA
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
1) We select only the warm period from the 10 years: MJJA
2) SB filtering SB algorithm (Arrillaga et al., 2016)
Weak synoptic forcing and fair-weather conditions
Clear SBF (sea-breeze front) passage
Steele et al., 2013
45º
ONSHORE 𝜶
OFFSHORE
225º
BBOS Barcelona - 14 October 2016

8. SB ALGORITHM 18 UTC – FILTER 3 (21.8 %) 18 UTC – FILTER 4 (17.1%)
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
SB ALGORITHM
Wind speed (m s-1)
18 UTC – FILTER 3
(21.8 %)
18 UTC – FILTER 4
(17.1%)
18 UTC – FILTER 1
(31.2 %)
18 UTC – FILTER 2
(26.6 %)
18 UTC – FILTER 5
(8.4 %).
18 UTC – NO FILTER
BBOS Barcelona - 14 October 2016

9. 102/1220 (8.4%) well-defined Sea-Breeze (SB) days
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
102/1220 (8.4%) well-defined Sea-Breeze (SB) days
NW [290º-350º]: 44%
N-NE [350º-45º]: 47%
Rest [225º-290º]: 9%
July: 26%
June: 35%
August: 16%
May: 23%
BBOS Barcelona - 14 October 2016

10. Impact of the SBF on the ABL?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
Impact of the SBF on the ABL?
ARRIVAL
-2h
+2h
t = 0
RQ1: Impact of different SB directions, scalar transport?
RQ2: Interaction with turbulence under different ABL regimes?
3 different ABL regimes:
Convective: S 𝐻 𝑎𝑟𝑟𝑖𝑣𝑎𝑙 ≥0.5 𝑆𝐻 𝑚𝑎𝑥 (14 events)
Transition: 0.5 𝑆𝐻 𝑚𝑎𝑥 > 𝑆𝐻 𝑎𝑟𝑟𝑖𝑣𝑎𝑙 ≥0 (66 events)
Stable: 𝑆𝐻 𝑎𝑟𝑟𝑖𝑣𝑎𝑙 <0 (22 events)
BBOS Barcelona - 14 October 2016

11. RQ1: Impact of different SB directions?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ1: Impact of different SB directions?
∆𝜑= 𝜑( 𝑡 𝑎𝑟𝑟𝑖𝑣𝑎𝑙 )−𝜑( 𝑡 𝑎𝑟𝑟𝑖𝑣𝑎𝑙 −1)
Specific humidity (10’)
Δq (g·kg-1)
CO2 (30’)
ΔCO2 (ppm)
Cabauw
Main cities in the area of Cabauw.
SB events from the N-NE trigger the largest q jumps.
Sharp CO2 increment in some W-NW events.
BBOS Barcelona - 14 October 2016

12. RQ2: Interaction with turbulence under different ABL regimes?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ2: Interaction with turbulence under different ABL regimes?
Surface heat fluxes (W m-2)
Time from SB onset
The local surface fluxes remain virtually unchanged by the SBF.
BBOS Barcelona - 14 October 2016

13. RQ2: Interaction with turbulence under different ABL regimes?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ2: Interaction with turbulence under different ABL regimes?
Wind speed (m s-1)
Time from SB arrival
Clear SB frontal passage
Transition and stable regimes: significant increase of wind shear!
BBOS Barcelona - 14 October 2016

14. RQ2: Interaction with turbulence under different ABL regimes?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ2: Interaction with turbulence under different ABL regimes?
Potential temperature (K)
Substantial differences between the regimes.
Abrupt transition in the transition regime.
Time from SB onset
BBOS Barcelona - 14 October 2016

15. RQ2: Interaction with turbulence under different ABL regimes?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ2: Interaction with turbulence under different ABL regimes?
ABLH from wind profiler (m)
The arrival of the SB accelerates the afternoon transition of the ABL.
We explore how the shear (S) and buoyancy (B) are affected by the SB.
Time from SB onset
BBOS Barcelona - 14 October 2016

16. RQ2: Interaction with turbulence under different ABL regimes?
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
RQ2: Interaction with turbulence under different ABL regimes?
𝑑𝑆 𝑑𝑡 = 𝑑 𝑑𝑡 𝜕𝑢 𝜕𝑧 𝜕𝑣 𝜕𝑧 2
𝑑𝐵 𝑑𝑡 = 𝑑 𝑑𝑡 𝑔 𝜃 𝑣 𝜕 𝜃 𝑣 𝜕𝑧
𝑑 2 𝐵 𝑑𝑡 2 <0
𝑑 2 𝐵 𝑑𝑡 2 >0
Both dB/dt and dS/dt indicate an acceleration of the afternoon ABL transition (SH>0).
𝑑 2 S 𝑑𝑡 2 (30)>0
𝑑 2 S 𝑑𝑡 2 (30)=0
Time from SB onset
BBOS Barcelona - 14 October 2016

17. CHALLENGING INTERACTION WITH LOCAL TURBULENCE (30 m, 110 m, 170 m)
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
CHALLENGING INTERACTION WITH LOCAL TURBULENCE (30 m, 110 m, 170 m)
Acceleration of the afternoon ABL transition
TRANSITION REGIME
dB/dt and dS/dt increase at all levels
Thermally-buoyant conditions are maintained
CONVECTIVE REGIME
σw/w* constant
w*/u* very slight decrease
Tendency towards a weakly-stable state in the evening transition
STABLE REGIME
SC increases
BBOS Barcelona - 14 October 2016

18. take-home ideas future work
MOTIVATION
DATA
METHODOLOGY
SB EVENTS IN CABAUW
DYNAMICS
TRANSPORT
FINAL REMARKS
take-home ideas
The transport of scalars is occasionally affected by the SB direction.
The impact of the SB on the ABL is different depending on the ABL regime.
Surface fluxes remain unaltered by the SBF: the observed features are only due to the mesoscale.
The arrival of the SB accelerates the ABL afternoon transition but shifts the NBL towards a weakly stable/continuously turbulent state during the evening transition.
future work
Theoretical studies for the different ABL regimes (CLASS).
10-year WRF simulations.
BBOS Barcelona - 14 October 2016

19. THANK YOU FOR YOUR ATTENTION!
ACKNOWLEDGEMENTS: Basque Government (PRE_2016_2_0160, EP_2016_1_0048), Spanish Government (CGL C3-3-R), Royal Netherlands Meteorological Institute (KNMI), OSI SAF.
BBOS Barcelona - 14 October 2016