Outline. 1 Background Introduction. 3 SST Amphidrome 4 Niño Pipe 5. SST in China Seas. Seasonality Spiral. Eddy Tracking. Concluding Remarks

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Andrea Hood
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1 GHRSST XVIII

2 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe 5 Seasonality Spiral 5 stories in S(S)T oceanography 6 7 Eddy Tracking Concluding Remarks 2

3 Welcome to a Fans-Idols Gathering My professional career started with remote sensing of SST in I grew up with radiometer, but got married with altimeter. In the past 30 years, we produce over 100 babies (papers) with SST and SSH. Many of us, particularly myself, have become loyal fans of SST, of this group, of all of you, so it is a truly fans-idols gathering, that s why you are so welcome! Coincidently, 2017 is the 30-year anniversary of the first graduate with a MS degree on SST in China, I consider you are here to celebrate it with us, that s why you are more than welcome! 3

4 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 4

5 Dynamic Features in China Seas Front Eddy Upwelling Schematic showing the bathymetry and circulation system of the eastern China Seas (winter pattern). 5

6 Fronts 2 Thermohaline front Tidal front 4 2 Thermohaline front Estuarine front 3 Upwelling front 5 1 Shelf-break front SST image of February 18, 1984 derived from AVHRR data showing different types of frontal zones in the eastern China Seas. 6

shear waves created around the east tip of Shandong peninsula.

7 Fronts and Shear Waves Shear Waves Land Shadow SST image of February 18, 1984 derived from AVHRR data showing a sharp frontal zone with a group of shear waves created around the east tip of Shandong peninsula. The land-sea interaction is also clearly evident with the land shadow around the peninsula. 7

8 Mesoscale Eddy SST (in C ) image of 17 November 1987 derived from AVHRR data showing a cyclonic cold eddy in the northern Yellow Sea created by convection due to autumn cooling. 8

9 Mesoscale Eddy SST (in C) image of 29 August 1986 derived from AVHRR data showing a front-eddy coupling structure in the East China Sea caused by shear effect of local currents. 9

Coastal Upwelling These are SST images obtained on 22 and 25 July 1986. There are 3 days between the 2 images He, M., G.

Sugimori, Investigation of mesoscale fronts, eddies and which clearly shows the off-shore spreading of the Zhejiang coastal

10 Coastal Upwelling These are SST images obtained on 22 and 25 July There are 3 days between the 2 images He, M., G. Chen, and Y. Sugimori, Investigation of mesoscale fronts, eddies and which clearly shows the off-shore spreading of the Zhejiang coastal upwelling; upwelling in the China Seas with satellite data, The Global Atmosphere and Ocean System, 3(4): , A cyclonic warm eddy with very short life time is also evident in the Taiwan Strait which disappears after 3 days. 10

11 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 11

12 Global Chart of M2 Tide Zero amplitude Phase undetermined About a dozen well-defined amphidromic points associated with diurnal and semidiurnal tides exist in the world ocean, forming a fundamental feature of the global tidal system. 12

13 Calendar Month in Which Annual SST Peaks T to 2 2 to 3 3 to 4 4 to 5 5 to 6 6 to 7 7 to 8 8 to 9 9 to to to to 13 T1 and T2: Annual amphidromes of SST, serve as ideal sites for monitoring of global warming. T2 Month Amphidrome is not a tide only feature, it may also exist with other geophysical variables with Chen, periodic G., and variation G. D. such Quartly, as SST. Annual Two annual amphidrome: SST amphidromes A common identified feature in the in CP theand ocean? CA; IEEE Geoscience and Remote Sensing Letters, 2(4): , The temperatures around these amphidromes are nearly constant throughout the year, and are likely to be of significant importance to some of the biological processes and fishing grounds migration in the tropical Pacific and Atlantic. 13

The AACST in the Atlantic Ocean 30 30 (b) Depth = 10m (a) Depth = 5m 15 15 A1 A1 SA1 0 0-15 -15-30 -30 300 330 360 300 330 30 30 (d) Depth = 30m (c) Depth = 20m 15 15 A1 A1 0 0-15 -15-30 -30 300 360

14 The AACST in the Atlantic Ocean (b) Depth = 10m (a) Depth = 5m A1 A1 SA (d) Depth = 30m (c) Depth = 20m A1 A to to to to to to to to to to to to Amphidrome is not a surface-only phenomenon. Using the 3-D Argo measurements, 4 annual amphidromic columns of sea temperature have been precisely identified in the global ocean, which range from a depth of 30 m in the Atlantic to 120 m in the Indian Ocean. 14

15 The AACST in the Pacific Ocean (a) Depth = 5m Penetration depth: 70 m (b) Depth = 30m 0 P1 SP1 0 P (c) Depth = 50m P (d) Depth = 70m P1 1 to to to to to to to to to to to to Chen, The G., open H. Zhang, ocean and amphidromic X. Wang, Annual points amphidomic could be thecolumns ideal sites of sea fortemperature long term monitoring in global oceans of from global Argowarming, data, Geophysical since theyresearch are, in theory, Letters, free 41(6): from , interference doi: /2014gl059430, of energetic seasonal signals

16 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 16

17 Niño Regions Global Distribution of ENSO Modes Nino 4Nino3.4Nino3 1/2 A very important role that SST plays is to define the ENSO index. For this purpose, a number of Niño regions have been proposed. They are believed to be the heart of El Niños/La Niñas. 17

18 Period (month) Sub-ENSO Modes in the Niño Region c H C B cd G F E D Longitude (degree) The fine pattern of rich and stable sub-enso modes derived from SST in the Niño region, very useful inenso prediction. 18

Depth (m) From Niño Regions to Niño Pipe 3-D structure of the Niño Pipe in the upper mixed layer of the Pacific Ocean. 0 T( C) 1.5-50 -100-150 -200-250 120 150 180 210 240 270 Longitude ( E) 0 0 1.

19 Depth (m) From Niño Regions to Niño Pipe 3-D structure of the Niño Pipe in the upper mixed layer of the Pacific Ocean. 0 T( C) Longitude ( E) (a) (b) These Chen, NiñoG., regions and H. areli, in fact, Fineapattern surface projection of naturalofmodes what we in call seaniño surface Pipe in temperature the interior of thevariability: equatorial , Pacific which Journal is much of Physical more sensitive Oceanography, to ENSO38(2): occurrences , But why the Niño Pipe Chen, is not G., commonly and H. Chen, used to Interannual define themodality ENSO index? of upper Because ocean it istemperature: out of the reach 4-D of satellite structure measurement, revealed byand Argo therefore data, Journal lack of ofdaily Climate, availability. 28(9): ,

20 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 20

21 Ekman Spiral The Ekman Spiral is a structure of currents near a horizontal boundary in which the flow direction rotates as one moves away from the boundary. 21

22 SST Derived Sea Surface Seasonality Mid-latitude dominance globally, west preference in the NH. Peak in China and Japan Seas. The SST derived surface seasonality over the global oceans. Those of us who live in the mid-latitude NW Pacific and NW Atlantic are very lucky to enjoy the most distinct four seasons in the world! 22

23 Seasonality Spiral Month of sea temperature peaks as a function of depth derived from merged satellite/argo data.(left: NH; Right: SH) 0m 0m 340m 340m Using SST along with Argo data, it is identified that the seasonality of the subsurface ocean also follows an Ekman Spiral. The annual peak of SST occurs in Aug in most areas of the NH, Chen, G., X. Wang, and C. Qian, Vertical structure of upper ocean seasonality: Extratropical but in 30 m depth it becomes Sep, and in 340 m depth, it becomes Dec. The seasonality spiral versus tropical phase lock, Journal of Climate, 29(11): , spiral implies that in the NH when people enjoy their summer vacation on the leisure boat in Aug, the fish family is celebrating their X mas 340 m below! The opposite is true for the SH. 23

24 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 24

25 3-D Eddy Tracking and Observation Satellite Radiometer 3-D eddy structure (POL of OUC) Satellite Altimeter With the continuous improvement of SSH and SST data quality, we are now able to track the evolution of a mesoscale eddy for as long as a few years. It was found that SSH is most effective in doing this job, while SST is also a very good helper. 25

3-D Eddy Tracking and Observation OSTIA AVHRRbetter better 2014.1.27-2014.

using satellite derived SSH and Liu, Y., G. Chen, M. Sun, S.

Tian, A parallel SLA-based algorithm for global mesoscale SST from

We found that AVHRR is effective for 105 eddy identification, Journal

26 3-D Eddy Tracking and Observation OSTIA AVHRRbetter better An energetic warm eddy in the Kuroshio extension area was tracked using satellite derived SSH and Liu, Y., G. Chen, M. Sun, S. Liu, and F. Tian, A parallel SLA-based algorithm for global mesoscale SST from late January to early September inand We found that AVHRR is effective for 105 eddy identification, Journal of Atmospheric Oceanic Technology, 33(12): , 2016.days, while OSTIA is effective for 70 days. There are some 85 days in which both datasets lost tracking. 26

27 Outline 1 Background Introduction 2 SST in China Seas 3 SST Amphidrome 4 Niño Pipe Seasonality Spiral Eddy Tracking Concluding Remarks 27

28 Concluding Remarks As initiated by TIROS over half a century ago, SST was no doubt a pioneer in satellite oceanography. SST set many milestones in modern oceanography, such as ENSO Index which plays a key role in the research of global climate change. The 21 st century is certainly a century of big data, and SST will be a key player of big data oceanography for many years to come! 28

Lecture 13 El Niño/La Niña Ocean-Atmosphere Interaction. Idealized 3-Cell Model of Wind Patterns on a Rotating Earth. Previous Lecture!

Lecture 13 El Niño/La Niña Ocean-Atmosphere Interaction Previous Lecture! Global Winds General Circulation of winds at the surface and aloft Polar Jet Stream Subtropical Jet Stream Monsoons 1 2 Radiation