Department of Climatology and Landscape Ecology University of Szeged, Hungary

1. Department of Climatology and Landscape Ecology University of Szeged, Hungary High resolution model simulation of Urban Heat Island for a medium sized Hungarian city Case studies and verification András Zénó Gyöngyösi, Gergely Molnár, and Tamás Gál zeno@nimbus.elte.hu

2. Motivation • Small area (280 km2), 170k inhabitants, • Surface of (low or high intensity) urban landuse is even much less • Frequent hot, summer nights (tropical nights/“beer-garden” days: 50/80d per annum, respectively). • Heat waves are relatively common • Only few grid cells are involved • High model resolution is required

3. Szeged

4. Szeged

5. Szeged

6. UC monitoring sys • Stations installed • Represent LCZs • Installation: light poles • Electricity + protection

7. UC monitoring sys • 22 (urban) + 2 (rural) stations • Minute average observations at 4 mAGL • T, Rh • From end of March, 2014 w/ gaps

8. Typical diurnal variation • Representative stations • BAR urban • HMS rural • Other stations • Nocturnal UHI • ΔT defined as: • ΔT=TBAR – THMS • Daily variations • ΔTn: 06 – 12Z • ΔTx: 00 – 06Z

9. UC monitoring sys HMS BAR

10. Seasonal variation • Clear summer nights: ΔT=[-2,+6] • (ΔT)x≠Δ(Tx) • Modeling 26 days in 2015 summer – reproduction

11. Test period in 2015 Selection criteria: • ∆T Observed larger than 4.5°C • Clear conditions: Radiation larger than 750Wm-2 • No precip

12. Test period in 2015 Cases (7) • 3rd June • 03rd, 6th and 7th July • 6th, 7th and14th August Periods (26 days) • 31st May – 7th June • 1st – 7th July • 5th – 14th August

13. Model domain ∆x = 10km

14. Model domain

15. Model domain ∆x = 2km

16. Model domain

17. Model domain ∆x = 0.4km

18. Model domain 97 x 97

19. Model domain

20. Model domain

21. Model domain HMS BAR

22. Model setup • Modified URB PARM table • Modified geog database • Landuse USGS → CORINE → LandSat • Soiltype FAO → DKSIS More info: Poster H60 Molnar et al.

23. Modified URB PARM data More info: Poster H60 Molnar et al.

24. Geog database More info: Poster H60 Molnar et al.

25. Modeling strategy • 48-hour runs on GFS .25 3-hourly input • 24-hour overlap for spin-up • Urban heat effects appear in the model results only on the second evening • Output in urban (BAR) and rural (HMS) grid cells at every time steps (60, 12 and 2.4s resp). • 1-minute average 2m Temperature • Comparison to observations

26. Results – 20150603 • Output from different model setups have been compared to observed urban effects • Sensitivities for • geographic database • resolution • parameterizations • urban parameters have been tested.

27. Results – 20150603

28. Results – 20150603 • Temporal and spatial variation patterns have been captured properly • Tx and ΔT values are acceptable • However, both URB and RUR Tn values are too high compared to measurements • Best performance: • 3 domains, geog3 modified database, UCM urban physics and modified urban parameter table • Even for 2 domains results were acceptable • Further tests were performed on two domains with uniform setup

29. More results... • Temporal and spatial variation patterns have been captured properly • Tx and ΔT values are acceptable • However, both URB and RUR Tn values are too high compared to measurements

30. Conclusions • An appropriate modeling system for the representation of urban heat effects for a medium size city in Hungary have been established • Appropriate static data and evaluation method have been constructed • Model results have been verified on extensive and representative measurements • Good agreement is found but further development is necessary • Inclusion of anthropogenic heat • Definition of more urban categories based on LCZs • Testing further parameterization schemes (RAD?) and domain setups

31. Urban Climate Research Group at the University of Szeged, Hungary Thank you very much for your kind attention Hungarian Scientific Research Fund (OTKA K-111768)