Indian Ocean Forecast System (INDOFOS)

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Indian Ocean Forecast System (INDOFOS) National
Report Francis P. A. (Indian National Centre
for Ocean Information Services Ministry of Earth
Sciences, Govt. of India, Hyderabad) 3rd GOVST
meeting ESA, Paris 16th November 2011
Government of India Ministry of Earth Sciences
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Status report 1. Increased horizontal resolution
of the INDOFOS to 1/8 o from 1/4o 2. GODAS
(from NCEP) is setup at INCOIS and several
experiments were done to quantify the impact of
atmospheric forcing and observations chosen for
DA. 3. A major program (Indian coastal forecast
system) is proposed for the next 5-year plan
(2012-2017) 4. International school of
operational oceanograpgy.
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Improvements in the operational setup
Horizontal resolution 0.25 x 0.25 deg 0.125 x 0.125 deg Remarks
Vertical levels 40 sigma levels 40 sigma levels
Vertical Mixing scheme Mellor-Yamada (1982) KPP (Large et al 1994)
Minimum water depth (hmin) 150m 75m grids with water depth less than hmin is deepened to hmin.
Vertical viscosity /horizontal diffusion Second order harmonic Fourth order biharmonic
Air-sea fluxes Bulk aerodynamic formulation Bulk aerodynamic formulation Base on Fairall et al (1996)
Spin up 10 years 10 years QucikSCAT wind climatology and NCEP Reanalysis radiation fluxes
Interannual run 2000-2011 2000-2011 QuickSCAT wind and NCEP Reanalysis radiation fluxes (2000-2009). NCMRWF wind and radiation fluxes (2009 onwards)
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A few temperature profiles from high and low
resolution set ups are compared with ARGO
profiles
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Observation
ADCP
Observation
ROMS (1/8)
ROMS (1/4)
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Dominent Empirical Orthogonal Functions of Sea
Level Anomaly
25.18
26.01
16.11
20.07
Period considered for the study
2000-2008 Frequency of data Monthly
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Dominent Empirical Orthogonal Functions of Sea
Level Anomaly
13.42
12.04
7.81
6.89
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Principal components of the leading modes in the
Sea Level Anomaly
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Experiments with data assimilation

• An optimal interpolation based assimilation
  scheme is used here

• Merged and gridded weekly mean sea level data
  obtained from AVISO is assimilated.
• Experiment started from 1April 2007 and continued
  till 31Dec2008.
• Solutions for the period 1Jan2008 to 31Dec2008 is
  analyzed here to assess the performance of the
  assimilation scheme.

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RMS error of sea level anomaly simulated by ROMS
in the equatorial Indian Ocean (w.r.t AVISO sea
level anomaly)
RMS error of sea level anomaly simulated by ROMS
in the equatorial Indian Ocean
Without assimilation
With assimilation
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RMS error of zonal current component simulated by
ROMS in the equatorial Indian Ocean (w.r.t OSCAR
currents)
Without assimilation
With assimilation
A significant reduction in the RMS error after
assimilation, particularly in the western and
eastern equatorial Indian Ocean where the errors
are relatively large without assimilation.
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Surface currents near equator are compared with
RAMA observation
Zonal current (cm/s)
Meridional current (cm/s)
90oE, EQ 90oE, EQ 90oE, 1.5oN 90oE, 1.5oN
RMS Error NO-ASSIM ASSIM NO-ASSIM ASSIM
Zonal current 39 cm/s 23 cm/s 28 cm/s 19 cm/s
Meridional current 20 cm/s 18 cm/s 22 cm/s 20 cm/s
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Bay of Bengal
There is a phase shift in the simulated
thermocline variation compared to the
observation, particularly during Oct-Nov.
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RMS Error without assimilation with assimilation
Zonal current 18 cm/s 18 cm/s
Meridional current 21 cm/s 17 cm/s
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RMS Error of surface currents after the
assimilation of sea level (RMSE without SLA
assimilation in brackets)
Location Zonal Current (cm/s) Meridional Current (cm/s)
90E, EQ 23(39) 18(20)
90E, 1.5N 19(28) 20(22)
90E, 8N 24(27) 16(20)
90E, 12N 16(20) 23(26)
90E, 15N 18(18) 17(21)

Mean reduction in RMS Error after sea level assimilation 25 14
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Application Oil Spill
22.01.2011 23.00 hrs
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(INDOFOS currents used for oil-spill trajectory
hind-cast)
Oilspill model GNOME Forcing ECMWF
winds INDOFOS surface currents
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MV RAK SINK
LOCATION 18º46.29N,72º29.19E Spill Date and
time 06.08.2011,Saturday 07.00 hrs Type of Oil
Fuel oil (290T) Diesel (50T) Model Run
06.08.2011,07.00 hrs to 10.08.2011, 07.00 hrs
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Work in progress A pilot experiment of the
proposed Indian Coastal Forecast System (INCOFOS)
Set up a very high resolution ROMS (1 km)
off-the Mumbai coast. This setup will take
lateral boundary conditions from the Indian Ocean
analysis/forecast setup Tides and waves(SWAN)
will be included in the model setup. Atmospheric
forcing will be provided from a regional WRF.
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GODAS Configuration at INCOIS (M. Ravichandran)

• MOM4p0
• Resolution
• Zonal 0.5 degrees
• Meridional 0.25 within 10 degree of the
  equator, exponential decrease from 10S (10N) to
  30S (30N), 0.5 from 30.
• Vertical 40 layers (27 layers in the upper 400
  m) from surface to a depth approximately 4.5km.
  Vertical resolution is 10 m from the surface to
  the 240 m depth and gradually increasing to about
  511 m in the bottom layer.
• Vertical Mixing Scheme kpp
• Horizontal Mixing Scheme Gent-McWilliams
• FORCING
• Daily Momentum
• Daily P-E
• Daily Radiation fluxes
• Annual River runoff

• 3D VAR
• Assimilates (Argo, Moorings, XBT/XCTD)
• Temperature
• Salinity
• Assimilation window 10 days
• Relaxed to Reynolds SST
• Assimilates at every 6th hour
• Background variances cycle 5 days
• Assimilates upto 750m depth and within /- 63
  degrees

• Ocean Analysis Products
• Temperature, Salinity
• Currents
• SSH, SST

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INCOIS GODAS-MOM Dissemination system
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• Thank you