Julian Oscillation Toshiaki Shinoda Texas AampM Univ Corpus Christi Weiqing Han Univ of Colorado Yuanlong Li Univ of Colorado Chunzai Wang NOAAAOML ID: 621124
Download Presentation The PPT/PDF document "Upper Ocean Processes in the Indian Ocea..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
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.