An unstructured-grid, finite-volume model of the Irish Sea and Celtic Sea: Application to tides, surges, and temperature evolution.

Transcription

1 An unstructure-gri, finite-volume moel of the Irish Sea an Celtic Sea: Application to ties, surges, an temperature evolution. Jiuing Xing, Alan avies, Phil Hall an Eric Jones National Oceanography Centre, Liverpool (NOC)

2 Introuction Avantages of unstructure girs; Applications of finite element moels at NOC (e.g., TELEMAC, ACIRC, ICOMS); A moel of Irish Sea an Celtic Sea base on FVCOM (ICS-FVCOM).

3 An introuction to FVCOM evelope at Massachusetts-artmouth (Chen et al, 23); Hyrostatic, terrain-following co-orinate (similar to POM, BOM or POLCOMS); Finite-volume metho on triangle gris; Tracer avection: MPATA (Smolarkiewicz 25); Mellor-Yamaa turbulence closure; Avantages incluing gri fleibility at comple coastal line, better conservation, etc. ; Many moules: seiment, ecosystem, win waves, ice, etc., Long-term integration of the moel has not been teste; Improvements are mae for the moel of the Irish Sea.

4 Application to ties, surges an temperature evolution in the Irish Sea an Celtic Sea 1. Bartropic ties: force at the open bounary Jones + avies (Ocean Moelling, 27) ; 2. Iealize win force of 1 N/m^2 (effects of breaking wases) 3. Realistic meteorological forcing ue to win an heating an ties (temperature evolution); 4. ROFI in Liverpool Bay.

5 Irish sea moel gris (g3a)

6 Refine gris in river Mersey 6

7 M2 tie: TELMAC 2 (k=.3) ICS-FVCOM (k=.3) ICS-FVCOM(k=.25)

8 K1 TELMAC 2 (k=.3) ICS-FVCOM (k=.3) ICS-FVCOM(k=.25

9 Compute M2 tie in the Eastern Irish Sea TELEMAC 2 ICS-FVCOM 2 ICS-FVCOM 3

10 Compute M4 tie in the Eastern Irish Sea TELEMAC 2 ICS-FVCOM 2 ICS-FVCOM 3

11 Compute M6 tie in the Eastern Irish Sea TELEMAC 2 ICS- FVCOM 2 ICS- FVCOM 3

12 Surface an bottom currents (south win stress 1pa) 12

13 Be stress at a location in the Liverpool Bay Be stress at a location in the Liverpool 13

14 Effects of wave breaking parameterization on maimum be stress in the shallow water region 14

15 Temperature on 16 Aug Surface temp (Ts) Nearbe temp (Tb) Ts-Tb

16 Surface temperature on 26 June 1995 OBS Xing+avies JPO 2 ICS-FVCOM 16

17 Time series of temperature at the West Irish sea 17

18 (-z) section of temperature along 53 o 4 N from observations, moels of POM an ICS-FVCOM OBS Horsburgh+Hill JPO 22 ICS-FVCOM 25 Jul 16 Aug 21 Sep 18

19 ROFI: fresh water ischarge in Liverpool Bay Surface salinity bottom salinity

20 Conclusions A robust finite-volume, unstructure-gri moel of the Irish sea base on FVCOM is establishe; Valiation work is in progress (bartropic ties are well reprouce); A shelf wie finite-volume unstructure-gri moel for the purpose of climate stuy is achievable in the near future; Future improvements: turbulence, HPG, efficiency

21 The seamount test case (Haivogel+Beckman, Berntsen+Furnes 25, etc.)

22 Moel setup an parameters FVCOM v2.7 (full non-linear hyrostatic moel), with uniform resolution 3, 6 km No vertical iffusion an bottom friction No horizontal iffusivity Horizontal viscosity (1 3, 1 2 m 2 /s) A Gaussian form of topog. (45-45m) An initial eponential ensity profile (=1.5 kg/m 3 )

23 Internal pressure graient in -coorinate system, [=(z-)/] an finite volume metho (Chen et al) u equation an internal pressure graient term: Green s Theorem: y y g y y g IPG 2 2 y y N M My N ) ( 2 g Vu t u

24 Maimum velocities (Ah=1m^2/s) (isosceles, resolution, left: 6km, right: 3km)

25 Top an bottom layer (u,v) at ay 1 (ci=.5 cm/s, isosceles,res=3km)

26 Maimum velocities (Ah=1m^2/s) (left: isosceles, right: equilaterals)

27 Thank you for your attention!

28 An introuction to FVCOM evelope at Massachusetts- artmouth (Chen et al, 23); Hyrostatic ; terrain-following coorinate (similar to POM); Secon-orer accurate iscrete flu calculation in the integral form ofeample of the continuity eq. equations; u v Trace avection: MPATA y ( ) t y (Smolarkiewicz 25); horizontal iffusion: Smagorinsky; vertical: Vns Mellor Yamaa closure scheme; Avantages inclue gri fleibility at comple coastal line, better conservation, etc. ; Long-term integration of the moel has not been teste yet; Improvements are mae for the moel Irish Sea. Bergen y

29 Internal pressure graient in -coorinate system, [=(z-)/] an finite volume metho (in FVCOM) u equation an internal pressure graient term: Green s Theorem: y y N M My N ) ( 2 2 g g g Vu t u... y y g y y g y y g y m m m m m m m Integration by parts