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Upper Ocean Processes in the Indian Ocean associated with t Upper Ocean Processes in the Indian Ocean associated with t

Upper Ocean Processes in the Indian Ocean associated with t - PowerPoint Presentation

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Upper Ocean Processes in the Indian Ocean associated with t - PPT Presentation

Julian Oscillation Toshiaki Shinoda Texas AampM Univ Corpus Christi Weiqing Han Univ of Colorado Yuanlong Li Univ of Colorado Chunzai Wang NOAAAOML ID: 621124

strong ocean variability weak ocean strong weak variability surface sst shinoda variation year indonesian satellite jet large impact wang

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Slide1

Upper Ocean Processes in the Indian Ocean associated with the Madden-Julian Oscillation

Toshiaki Shinoda (Texas A&M Univ., Corpus Christi), Weiqing Han (Univ. of Colorado), Yuanlong Li (Univ. of Colorado), Chunzai Wang (NOAA/AOML)

1. Large-scale ocean variability: Satellite observations and OGCM experiments

2. Impact on Indonesian

T

hroughflow

3

.

Diurnal cycle

4

.

Variability of the Seychelles-

Chagos

thermocline ridgeSlide2

Large-scale Ocean VariabilitySlide3

CINDY/DYNAMO field campaign September 2011 – March 2012Describe large-scale upper ocean variations surrounding the intensive array based on the analysis of the satellite-derived data and OGCM experiments.Slide4

MJO events during DYNAMO

Strong convection in the Indian Ocean associated with the MJOStrong westerly anomaliesSlide5

Satellite-derived Data

Surface winds: Windsat Daily 3-day average 0.25x0.25 deg. Precipitation: TRMM 3B52 3-hourly 0.25x0.25 deg. Sea Surface Height (SSH): AVISO Daily 1x1 deg. Sea Surface Temperature (SST): Blended Analysis (Reynolds et al. 2007) Daily 0.25x0.25 deg. Surface current: OSCAR 5-day average 1x1 deg. Sea Surface Salinity (SSS): Aquarius weekly 1x1 deg.Slide6

Horizontal resolution: 1/25

º, 1/12º Period: 2003-2012 Surface forcing fields: NOGAPSGlobal Hybrid Coordinate Ocean Model (HYCOM)Slide7

RAMA

WindsatNCEPSurface windsShinoda et al. (2013)Slide8

Large–scale SST variationSlide9

Large-scale surface salinityAquarius

RAMASlide10

Zonal CurrentSSHSlide11

Reflected Rossby waves

SSH (Satellite)SSH (HYCOM)D20 (HYCOM)Slide12

Yoneyama

et al. (2013)Webber et al. (2010)Slide13

Impact on Indonesian ThroughflowSlide14

Seasonal variation of the Indonesian Throughflow

Observation (Gordon et al. 2008) Modeling (Shinoda et al. 2012) PAC Rossby wavesWyrtki JetVelocity component (50 m depth: shading )and SSH(contour) along the line

Wyrtki

JetSlide15

Yoshida Jet

Wyrtki JetGlobal HYCOMHow do strong MJO events during DYNAMO impact the Indonesian Throughflow?Slide16

Large changes in upper ocean currents

Southward current is very weak in Jan.-Feb. in contrast to the seasonal cycle (rapid recovery of southward currents in Jan.-Feb.)Meridional velocity at Makassar StraitSlide17

Yoshida jet

Indonesian ThroughflowAnomalous northward currents in the Indonesian Sea in January can be traced back to the Yoshida Jet generated by the MJOSlide18

Diurnal CycleSlide19

High vertical resolution (1m) in the upper 10m  HYCOM is able to reproduce observed diurnal warming Slide20

Impact of diurnal cycle on intraseasonal variability

TOGA COARE Nov. 1992-Mar. 1993Shinoda (2005), Shinoda and Hendon (1988)SCTR 55°–70°E, 12°–4°SCEIO (65°–95°E, 3°S–3°N)Li et al. (2013)Slide21

Thermocline Ridge VariabilitySlide22

Impact of SCTR interannual variation

Interannual variations of SCTR (e.g., deeper thermocline during IOD)How does ocean interannual variabiliti (OIV) impacts intraseasonal SST in SCTR?Additional HYCOM experiments (NoOIV): No interannual variation of surface forcing fields.---------- 95% significance ----------- 85% significance based on F-testThe OIV effect enhances the intraseasonal SSTs in the eastern TR region by about 0.1 C (20% of the total SST variability) (significant at 95% level) and slightly reduces them in the western TR (not significant).Li et al. (2014)Slide23

Amplitude of the 20-90-day SST

Enhancing effect, strong-TR years,

Shallow Z20

Reducing effect,

weak-TR years,

Deep Z20

Yearly Z20 from

MR

and

NoOIV

MR

NoOIV

A Strong TR

(shallow thermocline) enhances intraseasonal SSTs, while

a weak TR

(deep thermocline) reduces intraseasonal SSTs.

The OIV effect varies from year to year !Slide24

SSTt

HFENTComposite analysis for strong and weak TR yearsWeak-year compositeStrong-year compositeSST variability, HF and ENT are greatly enlarged by a strong TR year

, but only slightly reduced by a weak TR.

An asymmetry between strong and weak yearsSlide25

MLD is an important cause

Weak-year compositeStrong-year composite> 10 m

< 5 m

An important source of the asymmetry:

the

MLD changes

, which is shallower than normal by at least 10m in strong TR years, but is deeper than normal by only less than 5m in weak TR years. This difference leads to the strong/weak asymmetry of ENT and HF and thus the overall enhancing effect of the OIV.Slide26

12S-4S Mean Winter TemperatureStrong TR

Weak TRSlide27

SummaryA variety of upper ocean processes associated with the MJO that influence SST are identified by the analysis of

OGCM experiments and satellite observations. These include:Equatorial jetDiurnal cycleVariation of theromocline ridgeRemote ocean variabilityFurther analyses are needed to understand how SST changes caused by these upper ocean processes feedback on the atmosphere.References:Li, Y., W. Han, T. Shinoda, C. Wang, R.-C. Lien, J.N. Moum, and J.W. Wang, 2013: Effects of Solar Radiation Diurnal Cycle on the Tropical Indian Ocean Mixed Layer Variability during Wintertime Madden-Julian Oscillation Events. J.

Geophys

. Res., DOI:10.1002/jgrc.20395.

Li Y., W. Han, T. Shinoda, C. Wang, M.

Ravichandran

, J.-W. Wang, 2014: Revisiting the Wintertime

Intraseasonal

SST Variability in the Tropical South Indian Ocean: Impact of the Ocean

Interannual

Variation. J. Phys.

Oceanogr

.,

doi

: http://

dx.doi.org

/10.1175/JPO-D-13-0238.1.

Shinoda, T,. Jensen, M.

Flatau

, S. Chen, W. Han, C. Wang 2013: Large-scale oceanic variability during the CINDY/DYNAMO field campaign from satellite observations. Remote Sensing –Special issue on Observing the Ocean’s Interior from Satellite Remote Sensing, 5, 2072-2092

.

Shinoda, T., W. Han, E. J. Metzger, H. E.

Hurlburt

, 2012: Seasonal Variation of the Indonesian

Throughflow

in Makassar Strait. J. Phys.

Oceanogr

., 42, doi:10.1175/JPOD-11-0120.1.