modern problems modern problems in the artic ocean modeling nikolay [y\i]akovlev inm ras, moscow,...

$: Modern problems Modern problems in the Artic Ocean modeling Nikolay [Y\I]akovlev INM RAS, Moscow, Russia Joint INM – Hamburg University seminar on modern$
Modern problems Modern problems in in the the Artic Artic OOcean cean

modelingmodeling

NNikolayikolay [[YY\I]\I]akovlevakovlev INM RAS, Moscow, RussiaINM RAS, Moscow, Russia

Joint INM – Hamburg University seminar on modern problems in atmosphere-ocean modeling

Moscow, 18 June 2010.

1.1. INM RAS efforts in Arctic Ocean modeling.INM RAS efforts in Arctic Ocean modeling.

2.2. Some problems with the ice and ocean Some problems with the ice and ocean numerical model formulations.numerical model formulations.

3.3. Some considerations on the explicit treatment of Some considerations on the explicit treatment of tides in AO models.tides in AO models.

N. Yakovlev, INM RAS, Moscow

INM RAS eddy-INM RAS eddy-permitting ocean permitting ocean

circulation circulation σσ-model-modelThe global version of the model is used as the

oceanic component of the IPCC climate model INMCM3 which is presented in the IPCC Fourth Assessment Report (2007).

The present version of the model is realized for coupled North Atlantic (open boundary at 20°S) - Arctic Ocean – Bering Sea region including Mediterranean and Black Seas.

A rotation of the model grid is employed in order to avoid the problem of converging meridians over the Arctic ocean. The model North Pole is located at geographical equator, 120°W.

1/4° horizontal eddy-permitting resolution is used (620x440 grid points) and 27 unevenly spaced vertical levels.

Biharmonic operator is used for lateral viscosity and Monin-Obuhov-Kochergin parameterization is used for vertical diffusion and viscosity.

The EVP (elastic- viscous- plastic) dynamic - thermodynamic sea ice model (Hunke, 2001; Iakovlev, 2005) is embedded.

Model domain

The design of the experimentThe design of the experiment

The numerical experiment was carried out using the realistic global The numerical experiment was carried out using the realistic global atmosphere forcing for years from 1958 to 2006 provided by GFDL for CLIVAR atmosphere forcing for years from 1958 to 2006 provided by GFDL for CLIVAR Common Ocean-ice Reference Experiments (CORE).Common Ocean-ice Reference Experiments (CORE).http://data1.gfdl.noaa.gov/nomads/forms/mom4/CORE.html

The heat, salt and momentum fluxes at the sea surface are calculated using The heat, salt and momentum fluxes at the sea surface are calculated using 6hr wind, pressure, temperature and humidity; daily shortwave and longwave 6hr wind, pressure, temperature and humidity; daily shortwave and longwave radiation; monthly precipitation and year mean river runoff. radiation; monthly precipitation and year mean river runoff.

Sensible and latent heat fluxes employ bulk formulas using CORE data and Sensible and latent heat fluxes employ bulk formulas using CORE data and model SST. model SST.

Restoring to observed sea surface salinity with coefficient of 1/(30 days) is Restoring to observed sea surface salinity with coefficient of 1/(30 days) is used for salt flux.used for salt flux.

Time step: 1 hour.Time step: 1 hour.

Initial conditions: Levitus data for temperature and salinity and no motion for Initial conditions: Levitus data for temperature and salinity and no motion for velocity.velocity.

Duration: 20 year spin-up, then realistic circulation for years 1958 - 2006.Duration: 20 year spin-up, then realistic circulation for years 1958 - 2006.

Model ice concentration vs. observational datahttp://nsidc.org/data/seaice_index/archives/image_select.html

for High NAO index

Model ice concentration vs. observational datahttp://nsidc.org/data/seaice_index/archives/image_select.html

for Low NAO index

Velocity Velocity ((top panelstop panels)) and and temperaturetemperature ( (bottom panelsbottom panels)) sections sections for West Spitsbergen for West Spitsbergen ((leftleft) ) and and Nord Cape Nord Cape ((rightright) ) currentscurrents (mean for 1998(mean for 1998--20062006 yrsyrs). ).

(latitude and longitude in model coordinates(latitude and longitude in model coordinates).).Section 1 Section 2

INM RAS Model FEMAO-1

1. 3D primitive ocean dynamics equations with free upper surface

2. EVP sea ice rheology

3. Ice thickness redistribution according to Hibler, 1980, Flato & Hibler, 1995

4. Forcing according to AOMIP protocol (ocean, rivers, atmosphere, salinity restoring time scale 180 days)

5. Low spatial resolution to develop local physics parameterizations (100 km)

6. Tide М2, specified as boundary conditions (Norwegian Sea, Denmark Strait, Bering Strait, Canadian Archipelago passages) Flather, 1976.


I c e C o m p a c t n e s s . S e p t e m b e r 1 9 9 0 .

8 0

7 0

I c e C o m p a c t n e s s . S e p t e m b e r 1 9 9 0 . T i d e s .

8 0

7 0


I c e C o m p a c t n e s s . S e p t e m b e r 1 9 9 6 .

8 0

7 0

I c e C o m p a c t n e s s . S e p t e m b e r 1 9 9 6 . T i d e s .

8 0

7 0


Fram StraitFram Strait

0 100 200 300 400 500 600-2000

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0

0 100 200 300 400 500 600-2000

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0

temperature salinity velocity


0

2

4

6

8

1 0

1 2

1 4

1 6

1 8

2 0

2 2

2 4

2 6

2 8

3 0

F r e s h w a t e r C o n t e n t N o T i d e

8 0

7 0

7 5 °

8 0 °

8 5 °

0

2

4

6

8

1 0

1 2

1 4

1 6

1 8

2 0

7 5 °

8 0 °

8 5 °

0

2

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6

8

1 0

1 2

1 4

1 6

1 8

2 0

1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990

0

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8

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

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1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980

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8

Mean Ice drift velocity, cm/s

?

1993.5 1994 1994.5 19950

2

4

6

8D

J

M


8 0

7 0

Model, December 1993

7.22 см/s

Satellite Data, December 1993

~ 8см/s

Satellite Data From: ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-drift/data/arctic/)


Satellite Data, February 1994

~ 3см/s

Model, February 1994

3.25 см/s

8 0

7 0

Satellite Data From: ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-drift/data/arctic/)


Sea IceSea Ice

Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM)

OceanOcean

Model Design

)/()( Hz * ( ) /( )z H z H

1. Various vertical coordinates

free surface z-model

Partial step topography•Trivial pressure gradient errors•Decades of experience•Well known limitations•Irregular and variable computational domain(i.e., land/sea masks and vanishing surface layer)

•Terrain following σ-model•Smooth topography•Regular computational domain (no land/sea masks)•Time independent computational domain (-1 < sigma < 0)•Pressure gradient errors: requires topography filters•Difficult neutral physics implementation: not commonly done in sigma-models

•Irregular computational domain(i.e., land/sea masks needed)•Time independent computationaldomain (-H < z* < 0): no vanishing layers. •Negligible pressure gradient errors since isosurfaces are quasi-horizontal. Correspondingly, can use the same neutral physics technology as in z-models.


HIMPoseidonHyCOM

ρ

ROMS POM

σ

MOMMIT POP

z/z*/p/p*

POSUM

z/z*/p/p*/σ


Not in the climate models!

2. Bottom topography approximation (partial cells and «shaved» cells) – errors in the pressure gradient approximation in the lowermost layer


0

35

-30 0 30

60N

Quasi-Physical parameterizations:

Cascading and Cross-Ridge Exchanges


Tidal mixingTidal mixing

Tides provide about half of the energy for mixing in the open ocean.

At topography tidal energy is converted to waves (baroclinic tides) and/or mixing.

Waves eventually lead to mixing remote from generation site.

Effects of tides need to be included in climate simulations.


Holloway, G., and A. Proshutinsky (2007), Role of tides in Arctic ocean/ice climate, J. Geophys. Res., 112, C04S06, doi:10.1029/2006JC003643.

Periodic changes and strong ice shear were observed by early northern travelers in the Barents and White Seas (Litke, 1844). Nansen (1898, 1902) reported the spring neap cycle of "ice pressure" affecting the Fram as it drifted with ice, and suggested that this was a result of ice interaction with the M2 tidal wave propagating from the North Atlantic. The importance of tides in ice covered seas was corroborated by Sverdrup (1926), Zubov (1945), Murty (1985), Prinsenberg (1988), Bourke and Parsons (1993), Pease et al. (1994, 1995), and many others.

The main conclusions:

1. Results clearly show enhanced loss of heat from Atlantic waters.

2. The impact of tides on sea ice is more subtle as thinning due to enhanced ocean heat flux competes with net ice growth during rapid openings and closings of tidal leads.


Tide Intensifies Vertical Mixing

(the illustration to the conclusion above)

Data by Kowalik & Proshutinsky, 1994Kowalik, Z., and A. Yu. Proshutinsky, 1994. The Arctic Ocean Tides, In: The Polar Oceans and Their Role in Shaping the Global Environment: Nansen Centennial Volume, Geoph. Monograph 85, AGU, 137--158.


The role of tides in the Arctic Ocean thermohaline structure formation

Polyakov, I., E. Dmitriev, and A. Proshutinsky, 1995. Modeling of a three-dimensional structure of the Arctic Ocean M_2 tide with a high spatial resolution. Cray Channels, 17(2), p. 36.

Kowalik, Z., and A. Yu. Proshutinsky, 1995. Topographic enhancement oftidal motion in the western Barents Sea. J. Geophys. Res., 100(C2), 2613-2637.

Прошутинский А. Ю. Колебания уровня Северного Ледовитого океана. Санкт-Петербург. Гидрометеоиздат. 1993. 216 с.


0

2 0

4 0

6 0

8 0

1 0 0

0

2 0

4 0

6 0

8 0

1 0 0

Kowalik & Proshutinsky 1994Kowalik, Z., and A. Yu. Proshutinsky, 1994. The Arctic Ocean Tides, In: The Polar Oceans and Their Role in Shaping the Global Environment: Nansen Centennial Volume, Geoph. Monograph 85, AGU, 137--158.

INM RAS FEMAO-1

M2 Sea Level Amplitude (cm)


0

4

8

1 2

1 6

2 0

2 4

2 8

3 2

3 6

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4 4

4 8

INM RAS FEMAO-1

0

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8

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1 6

2 0

2 4

2 8

3 2

3 6

4 0

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4 8

M2 maximum velocity (cm/s)

Kowalik & Proshutinsky 1994


It is wrong approach just to «embed» tide into a

general circulation model – the results may be any but

the right ones.


-300

-250

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-50

0

50

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M ean S ep tem b er Ice T h ick n ess (cm ) re la tiv e to N T ca se

20 cm /s

10 cm /s

80

70-300

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-100

-50

0

50

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M ean S ep tem b er Ice T h ick n ess (cm ) re la tiv e to N T ca se . 1 0* C d .

20 cm /s

10 cm /s

80

70


The parameterizations of the ice-The parameterizations of the ice-ocean dragocean drag

Non-stratified ocean:

M. STEELE, J. H. MORISON, AND N. UNTERSTE1NER. The Partition of Air-Ice-Ocean Momentum Exchange as a Function of Ice Concentration, Floe Size, and Draft. JGR, V. 94, NO. C9, P. 12,739-12,750, 1989.

Stratified ocean, Ice cover with regular spatial strucuture:

M. G. MCPHEE, L. H. KANTHA . Generation of Internal Waves by Sea Ice. JGR, V. 94, NO. C3, P. 3287-3302, 1989.

«Levitating» ice (ice as a flat rigid plate)

Parameterization with «hummocking» of ice (Standard Russian textbook: Доронин Ю.П. Динамика океана, 1980)

20 2 2 2 2, 10 , 0.08F c c N u u c c

30 , 5.5 10D DF c u u c


Solid line – Stratified Ocean, dashed line – homogeneous ocean

Pite, D.H., D.R. Topham and B.J.van Hardenberg., 1995: Laboratory measurements of the drag force on a family of two-dimensional ice keel models in a two-layer flow, J. Phys. Oceanogr., v. 25, 3008-3031.

Lab Experimental Data


New ParameterizationThe main goal is to take into account seasonal variations of ice and ocean

GWD:

Miles, J.W., 1969: Waves and wave drag in stratified flows. Proc. 12th Inst. Congress of Applied mechanics, M. Hatenyi and W.G. Vincenti, Eds., Springer-Verlag, 52-76.Phillips, D., 1984: Analytic surface pressure and drag for linear hydrostatic flow over three-dimensional elliptic mountains. J. Atmos. Sci., v. 41, 1073-1084.Smith, R.B., 1989: Hydrostatic airflow over mountains. Advances in Geophysics, v. 31, Academic Press, 1-41. M. G. MCPHEE, L. H. KANTHA . Generation of Internal Waves by Sea Ice. JGR, V. 94, NO. C3, P. 3287-3302, 1989.

Blocked Flow:

Lott, F. and Miller, M.J. A new subgrid-scale orographic drag parameterization: Its formulation and testing. Q.J.R. Meteorol. Soc. V. 123, p. 101-127, 1997.

Wake effect:

M. STEELE, J. H. MORISON, AND N. UNTERSTE1NER. The Partition of Air-Ice-Ocean Momentum Exchange as a Function of Ice Concentration, Floe Size, and Draft. JGR, V. 94, NO. C9, P. 12,739-12,750, 1989.


2

4W mm

m

m

F Nd

AUh

22 m

mB D m

m

UFd

C AZ

,,

,

max(0, ), ,m n nc mm m m n

m n

H H NhZ h H

H U

1 7, 0.4 0.75.D ncC H

GWD

Blocked Flow

[ ]2 20, .

1,5w ice

Tskin T m

F h m UF

F F Nh

0 10 20 30U , cm/s

0

4

8

12 Strress per unit area of ice Cd=5.e-3,N=1.e-2,H=10m

Cd=5e-3

R=0.005*X*X+0.1*MIN(20,X)+0.15*X*X*MAX( 0,1-0.05*X)


1. Modern models of the Arctic Ocean are quite skilled to reproduce many of the observed features of ice and ocean.

2. There are both numerical and physical problems in more detailed simulation of the AO. New numerical technologies should be accompanied by the new physical formulations.

3. The explicit simulation of tides should be accompanied by the revision of the parameterizations used in the model. It is necessary to take into account mechanisms, associated with the internal tides generation and with the singularities at the critical latitude 75N.

SUMMARY

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