The Relative Influence of Salinity and Temperature on Surface Density Gradient in the Tropical Pacific Ocean. Audrey Hasson, Tony Lee

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1 The Relative Influence f Salinity and Temperature n Surface Density Gradient in the Trpical Pacific Ocean Audrey Hassn, Tny Lee Ocean Salinity Science and Salinity Remte Sensing rkshp Met Office, Exeter, UK, 6-8 Nvember 14

2 INTRODUCTION Surface Salinity (SSS) and Temperature (SST) influence surface Density thrugh the Equatin f State : ρ-ρ =ρ ref {-α(t-t )+β(s-s )} Density gradients in the trpical Pacific are mainly meridinal and are assciated with barclinic instabilities Salinity fluctuatins can regulate the barclinic energy transfer (McPhaden et al. 1984, Grdsky et al. 5, Lee et al., 14) The new spacebrn SSS datasets give a new capability t enhance ur knwledge f the density field and its variability as well as the cntributin f SSS and SST Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp

3 DATA SSS : Aquarius/SAC-D level-3 gridded dataset (V3. by the Aquarius Prject via PO.DAAC) 1º spatial reslutin frm cmbined passes averaged ver 7 day fr August 11-July 14 SMOS level-3 gridded dataset (v13 CEC-LOCEAN) ¼º grid every 1 days fr January 1-July 14 ISAS in situ based ptimal interplatin, 1º spatial reslutin, mnthly fr 1-July 14 (Ifremer) SST : OSTIA level-4 prduct (V1. by the UK Met Office),.54º grid at daily interval frm 6 t present Reynlds level-4 prduct (V. by NCDC/NOAA) ¼º daily frm 1981 till present ISAS as fr SSS Currents: OSCAR level-4 prduct (by ESR),.33º grid, every 5 days, 199 t present All averaged n a 1º grid every 7 days ver the Aquarius perid Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 3

4 DATA SSS : Aquarius/SAC-D level-3 gridded dataset (V3. by the Aquarius Prject via PO.DAAC) 1º spatial reslutin frm cmbined passes averaged ver 7 day fr August 11-July 14 SMOS level-3 gridded dataset (v13 CEC-LOCEAN) ¼º grid every 1 days fr January 1-July 14 ISAS in situ based ptimal interplatin, 1º spatial reslutin, mnthly fr 1-July 14 (Ifremer) SST : OSTIA level-4 prduct (V1. by the UK Met Office),.54º grid at daily interval frm 6 t present Reynlds level-4 prduct (V. by NCDC/NOAA) ¼º daily frm 1981 till present ISAS as fr SSS Currents: OSCAR level-4 prduct (by ESR),.33º grid, every 5 days, 199 t present All averaged n a 1º grid every 7 days ver the Aquarius perid Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 4

5 3 1 1S 17E E (b) Density Standard Deviatin Aqua Ostia 1N Pacific Ocean Meridinal gradient f surface ρ Cntributins f SSS (Aquarius v3) and SST (OSTIA) 1S 17 E E (c) Density Mean Meridinal Gradient Aqua Ostia (d) Alpha SST Meridinal Gradient Ostia 1N N S 1 S 17 E 17 E (d) Beta SSS Meridinal Gradient Aqua 6.8 (e) Alpha SST Meridinal Gradient Rey 1E 1 EE 1 1 N N 1S 1 S E E 3 1E 17E E (d) Alpha SST SST Meridinal Gradient Ostia (f) Alpha Meridinal Gradient Isas 3.8 (e) Beta SSS Meridinal Gradient Sms N 1 N N S 7.8 1S 1E 1S 17E E E E E 11 7 Gradient (e)15 Alpha SST Meridinal Rey 1 E N 1 N 1S (f) Beta SSS Meridinal Gradient Isas 1 N.8 x hen lking in the density space, SSS and SST meridinal gradients are f the same magnitude 1..4 x S 17E 17 E x 1 x (f) Alpha SST Meridinal Gradient Isas Nvember 7th, 14 1E 1 E Ocean Salinity Science and Salinity Remte Sensing rkshp

6 3 1 1S 17E E (b) Density Standard Deviatin Aqua Ostia 1N Pacific Ocean Meridinal gradient f surface ρ Cntributins f SSS (Aquarius v3) and SST (OSTIA) 1S 17 E E (c) Density Mean Meridinal Gradient Aqua Ostia (d) Alpha SST Meridinal Gradient Ostia 1N N S 1 S 17 E 17 E (d) Beta SSS Meridinal Gradient Aqua 6.8 (e) Alpha SST Meridinal Gradient Rey 1E 1 EE 1 1 N N 1S 1 S E E 3 1E 17E E (d) Alpha SST SST Meridinal Gradient Ostia (f) Alpha Meridinal Gradient Isas 3.8 (e) Beta SSS Meridinal Gradient Sms N 1 N N S 7.8 1S 1E 1S 17E E E E E 11 7 Gradient (e)15 Alpha SST Meridinal Rey 1 E N 1 N 1S 1 S 17E 17 E 1 N x 1 x x hen lking in the density space, SSS and SST meridinal gradients are f the same magnitude 1..4 x SSS and SST bth cntribute arund the equatr.4.8.8strng reginal gradients : SSS dminates density where we bserve (f) Beta SSS Meridinal Gradient Isas.4 1. in the upwelling znes 1.6 near the ITCZ and SPCZ E (f)15 Alpha arund the Cng, Niger) 11 great 7 estuaries 3 (Amazn, 1 E.8 SST Meridinal Gradient Isas Nvember 7th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp

7 3 1ºN 1ºN 1ºN 17E E 1ºS 17 E (c) ddensity/dy x 1 1 E (f) STD Density (c) ddensity/dy 1ºS (a) Beta.* dsss/dy (a) Beta.* dsss/dy 1 N 1ºS N ºN x 1 1ºN 1S 1 S E E E 17 E E Gradient Ostia (d) Alpha SST SST Meridinal (f) Alpha Meridinal Gradient Isas 3.8 (e) Beta SSS Meridinal Gradient Sms N 1 N N ºS 1S 7.8 1S 1 1 1E 1S 17E 15 3 dsst/dy (b) Alpha.* E x 1 1ºS 17E E E 11 7 Gradient 3 x 1E 6.8 (b) Alpha dsst/dy 1 (e)15 Alpha SST Meridinal.* Rey -α*dt/dy Gradient (f)β*ds/dy Beta SSS Meridinal Isas β S/ y is much 1ºN 17 E larger than α T/ y at the 7equatr 3 1E E 1ºN (c) ddensity/dy 1 (f) STD Density ºN (c) ddensity/dy 1 x 1 (a) Beta.* dsss/dy ºS ver.3 61ºE.4.5 x 1.8 x Aqua 1ºN Aqua Sms Isas 1.6 Isas 1ºS (e) Alpha.* SST (b)std Alpha.* dsst/dy ºS.1 x 1.5 1ºN Ostia 1. Rey Rey Isas.8 1ºS 1.6 (e) STD Alpha.* SST Ostia 1ºN.3 1ºN 1ºS. (e) STD Alpha.* SST 1ºN 1ºN (d) STD Beta.* SSS 1ºS 1ºS.6 Sms 1. Isas Isas ºN 1ºN x 1 Sms Rey (d) STD Beta.* SSS 1ºS.3 11 (f)15 Alpha SST Meridinal Gradient Isas 1ºS 1ºS -6 Nvember 7, 14 Ocean Salinity 1 Science and Salinity Remte 1Sensing rkshp.1 *1 1. 1ºS.3 Prfiles (d) STD Beta.* SSS 4.4 th 1 N. 1ºN Aqua Ostia 1 N S 1 S 17 E 17 E Prfiles 1 EEver x 1 61ºE (d) Beta SSS Meridinal Gradient Aqua 6.8 Prfiles ver 61ºE (e) Alpha SST Meridinal Gradient Rey 1N 1 N 1ºN Equatr 1S 1 S 17E 1ºS x 1 x 1 1ºS x1ºn 1 1ºN (d) Alpha SST Meridinal Gradient Ostia 1ºN 1N Isas (c) Density Mean Meridinal Gradient Aqua Ostia.8 Cntributins f SSS (Aquarius v3) and SST (OSTIA) ºS.55 1ºS.35 Pacific Ocean Meridinal gradient f surface ρ 1S ºN Rey (b) Density Standard Deviatin Aqua Ostia 1N Ostia(e) STD Alpha.* SST 1 1S 1E (b) Alpha.* dsst/dy x (c). ddensity/dy.3 (f) STD Density.4.5 Isas (f) STD Density x 1.5 (f) STD Density. 1ºS 1ºN

8 Pacific Ocean Meridinal gradient f surface ρ Cmparisn f SSS and SST prducts All SSS and SST prducts shw cnsistent meridinal prfiles 1ºN (a) Beta.* dsss/dy Aqua SSS All SSS prducts shw relative maxima at the same latitudes ISAS SSS frnts are weaker SMOS frnts are strnger 1ºS 1 1 (b) Alpha.* dsst/dy x 1 Sms Isas SST All SST prduct shw similar amplitude in the maxima ISAS SST maxima are shifted pleward and less narrw 1ºN Ostia Rey Isas 1ºS 1 1 Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 8

9 1 N Variability f ρ in the 14-5d band Cntributins f SSS (Aquarius v3) and SST (OSTIA) (a) STD Density (14 5d filtered) Aqua Ostia 1 S 17 E 1ºN ºN 3 1 E (b) STD SSS (14 5d filtered) Aqua 1 N (a) STD (< 365d) Density 1 S 17 E E (c) STD SST (14 5d filtered) Ostia (b) STD (5 8d) Density ºN (c) STD TI (14 5d) Density Pacific Atlantic 1 N.3 1 S 1ºS 1ºS 17 E E.8.1 1ºS In the Pacific Ocean, strngest variability fund with 3ºN ff the equatr and arund 7. Cntributin f SSS in the znes Cntributin f SST nly near equatr Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 9

10 1 N Variability f ρ in the 14-5d band Cntributins f SSS (Aquarius v3) and SST (OSTIA) (a) STD Density (14 5d filtered) Aqua Ostia 1 S 17 E 1ºN ºN 3 1 E (b) STD SSS (14 5d filtered) Aqua 1 N (a) STD (< 365d) Density 1 S 17 E E (c) STD SST (14 5d filtered) Ostia (b) STD (5 8d) Density ºN (c) STD TI (14 5d) Density Pacific Atlantic 1 N.3 1 S 1ºS 1ºS 17 E E.8.1 1ºS In the Pacific Ocean, strngest variability fund with 3ºN ff the equatr and arund 7. Cntributin f SSS in the znes Cntributin f SST nly near equatr Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 1

11 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) Trpical Instability aves (TIs) which extract energy thrugh: Barclinic cnversin between the backgrund available ptential energy and the perturbatin ptential energy (PPE) Bartrpic cnversin between the backgrund kinetic energy and the perturbatin kinetic energy e neglect the Kelvin-Helmhltz cnversin (daily and shrter fluctuatins) Freshwater fluxes mainly in the ITCZ and SPCZ Barclinic instabilities via the 5d lw passed (LF) meridinal density gradient (a) Bartrpic instabilities via the LF meridinal gradient f znal current (b) Freshwater fluxes via Precipitatin standard deviatin (c) Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 11

12 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) (a) Mean LF Density Gradient (b) Mean LF dy/du (c) P std deviatin Pacific Atlantic 1ºN 1ºN 1ºN 1ºS 4 x 1 Barclinic prxy Bartrpic prxy Freshwater f. prxy 1ºS x 1 1ºS T give an idea n where surces f variability are imprtant: 3 prxies Barclinic instabilities via the 5d lw passed (LF) meridinal density gradient (a) Bartrpic instabilities via the LF meridinal gradient f znal current (b) Freshwater fluxes via Precipitatin standard deviatin (c) Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 1

13 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) (a) Mean LF Density Gradient (b) Mean LF dy/du (c) P std deviatin Pacific Atlantic 1ºN 1ºN 1ºN ºS 4 x 1 Barclinic prxy Bartrpic prxy Freshwater f. prxy 1ºS T give an idea n where surces f variability are imprtant: 3 prxies Barclinic instabilities via the 5d lw passed (LF) meridinal density gradient (a) Bartrpic instabilities via the LF meridinal gradient f znal current (b) Freshwater fluxes via Precipitatin standard deviatin (c) x 1 1ºS Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 13

14 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) (a) Mean LF Density Gradient (b) Mean LF dy/du (c) P std deviatin Pacific Atlantic 1ºN 1ºN 1ºN ºS 4 x 1 Barclinic prxy Bartrpic prxy Freshwater f. prxy 1ºS x 1 1ºS T give an idea n where surces f variability are imprtant: 3 prxies Barclinic instabilities via the 5d lw passed (LF) meridinal density gradient (a) Bartrpic instabilities via the LF meridinal gradient f znal current (b) Freshwater fluxes via Precipitatin standard deviatin (c) Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 14

15 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) (a) Mean LF Density Gradient (b) Mean LF dy/du (c) P std deviatin Pacific Atlantic 1ºN 1ºN 1ºN ºS 4 x 1 Barclinic prxy Bartrpic prxy Freshwater f. prxy 1ºS x 1 1ºS T give an idea n where surces f variability are imprtant: 3 prxies Barclinic instabilities via the 5d lw passed (LF) meridinal density gradient (a) Bartrpic instabilities via the LF meridinal gradient f znal current (b) Freshwater fluxes via Precipitatin standard deviatin (c) Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 15

16 Surces f variability in the 14-5d band Frm SSS (Aquarius v3) and SST (OSTIA) (a) Mean LF Density Gradient 1 1ºN Barclinic prxy 1ºS 4 x 1 1 The recent SSS datasets give a new insight t the Barclinic Energy cnversin between the backgrund available ptential energy and the TI induced Perturbatin Ptential Energy (PPE) Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 16

17 Indicatin f Barclinic cnversin f energy Cntributins f SSS (Aquarius v3) and SST (OSTIA) Between. and 1. Pacific Atlantic 14-5d SST std SST 14-5d SSS std SSS R =.75 R =.71 LP Mean SST gradient LP Mean SSS gradient High crrelatin in SST as fund by Sheltn et al. () ver High crrelatin in SSS as well Shws the relatin between the 14-5d variability and the lw frequency meridinal gradient, reflecting barclinic energy transfer between the TI and backgrund field Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 17

18 Cntributin f S and T t density variance ρ as a prxy fr the PPE and barclinic cnversin rate 1 N (a) Mean Rh ^.46 Perturbatin Ptential Energy (PPE) : 1 S 17 E E (b) Mean Rh(SSS) ^ 1 N 1 S 17 E E (c) Mean Rh(T) ^ 1 N 1 S 17 E E (d) Mean *Beta*SSS *Alpha*SST 1 N 1 S 17 E E (e) Mean Mean Rh(SSS) ^ *Beta*SSS *Alpha*SST 1 N 1 S 17 E E PPE is linked t Barclinic cnversin if n transfer frm Kinetic t Ptential Energy Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 18

19 Cntributin f S and T t density variance ρ as a prxy fr the PPE and barclinic cnversin rate (a) Mean Rh ^ 1 N 1 S 17 E E (b) Mean Rh(SSS) ^ 1 N 1 S 17 E E (c) Mean Rh(T) ^ 1 N 1 S 17 E E (d) Mean *Beta*SSS *Alpha*SST 1 N 1 S 17 E E (e) Mean Mean Rh(SSS) ^ *Beta*SSS *Alpha*SST 1 N 1 S 17 E E Perturbatin Ptential Energy (PPE) Is prprtinal t :!! =!!!"! +!"!!"#!! Direct cntributin f SSS Direct cntributin f SST Cntributin f the SSS and SST cvariance Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 19

20 Cntributin f S and T t density variance ρ as a prxy fr the PPE and barclinic cnversin rate (a) Mean Rh ^ 1 N 1 S 17 E E (b) Mean Rh(SSS) ^ 1 N 1 S 17 E E (c) Mean Rh(T) ^ 1 N 1 S 17 E E (d) Mean *Beta*SSS *Alpha*SST 1 N 1 S 17 E E (e) Mean Mean Rh(SSS) ^ *Beta*SSS *Alpha*SST 1 N 1 S 17 E E Perturbatin Ptential Energy (PPE) Is prprtinal t :!! =!!!"! +!"!!"#!! Direct cntributin f SST Direct and indirect cntributin f SSS Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp

21 Cntributin f S and T t density variance ρ as a prxy fr the PPE and barclinic cnversin rate (a) Mean Rh ^ 1 N 1 S 17 E E (b) Mean Rh(SSS) ^ 1 N 1 S 17 E E (c) Mean Rh(T) ^ 1 N 1 S 17 E E (d) Mean *Beta*SSS *Alpha*SST 1 N 1 S 17 E E (e) Mean Mean Rh(SSS) ^ *Beta*SSS *Alpha*SST 1 N 1 S 17 E E Perturbatin Ptential Energy (PPE) Is prprtinal t :!! =!!!"! +!"!!"#!! Omitting SSS t the PPE cmputatin lead t an underestimatin f 7% in the entire dmain 66% in the nrthern edge f the CT 84% in the ITCZ cnsistent with Grdsky et al. (5) and Lee et al. (14) findings in the Atlantic Ocean. Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 1

22 CONCLUSIONS Satellite measurements f SSS has enabled the studies f the relative cntributin f SST and SSS n the mean meridinal density gradient as well as the TIrelated density variability n basin scale. Salinity has a substantial effect n meridinal gradient and thus TI-related barclinic energy cnversin, bth in the Pacific and the Atlantic. All SSS and SST prducts are cnsistent. Spacebrn data captures sharp gradients and variability nt seen in gridded bservatins. Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp

24 N 1 N (d) Beta SSS Meridinal Gradient Aqua 1 S 17 E E 1 S 1ºS 17 E (b) Density Standard Deviatin Aqua Ostia 1 1 x 1 E 1 N 1 1 N N 1 S (d) Alpha SST Meridinal Gradient Ostia (e) Beta SSS Meridinal Gradient Sms 1 1 S 17 E E 17 S 17 E 15 E ºS (c) Density Mean Meridinal Gradient Aqua 1Ostia 1 E 1 x 1 E 1 N 1 1 N N 1 S (e) Alpha SST Meridinal Gradient (c) ddensity/dy Rey (f) Beta SSS Meridinal Gradient Isas 1 1 S 17 E E S E 15 E ºS E x 1 E 1 N 1 S (a) Density Mean Aqua Ostia (f) Alpha SST Meridinal Gradient Isas x 1 4 x Date Ges Here Name f presentatin r ther inf ges here 4 17 E E 1ºN 1ºN 1ºN (a) Beta.* dsss/dy (b) Alpha.* dsst/dy Prfiles ver ºE 1ºN ºS x 1 1ºN (e) (b) STD Alpha Alpha.* dsst/dy.* (d) (a) STD Beta Beta.* dsss/dy.* 1ºS x x 1 (f) (c) STD ddensity/dy 1ºN 1ºS x 1 Prfiles ver ºE 1ºN (d) STD Beta.* 1ºS ºN (e) STD Alpha.* 1ºS.1..3 Aqua Sms Isas Ostia Rey Isas 1ºN Aqua Ostia Sms Rey Isas Isas (f) STD Densi 1ºS..4

Barclinic cnversin f energy Cntributins f SSS (Aquarius v3) and SST (OSTIA) Pacific Atlantic Pacific (blue) and Atlantic Oceans (red) between 5.5 11..5 (a).5 (b) 1.

25 Barclinic cnversin f energy Cntributins f SSS (Aquarius v3) and SST (OSTIA) Pacific Atlantic Pacific (blue) and Atlantic Oceans (red) between (a).5 (b) std TI SSS.15.1 std TI SST mean LF SSS gradient x 1 mean LF SST gradient x 1 4. Date Ges Here Name f presentatin r ther inf ges here 5

26 Seasnality f the barclinic cnversin rate Cntributin f SSS and SST (Rh ) (Beta*SSS ) ( Alpha*SST ) *Beta*SSS *Alpha*SST º Oct11 Jan1 Apr1 Jul1 Oct1 Jan13 Apr13 Jul13 Oct13 Jan14 Apr º Oct11 Jan1 Apr1 Jul1 Oct1 Jan13 Apr13 Jul13 Oct13 Jan14 Apr14 Date Ges Here Name f presentatin r ther inf ges here 6

27 Seasnality f the barclinic cnversin rate Cntributin f SSS and SST (Rh ) (Beta*SSS ) ( Alpha*SST ) *Beta*SSS *Alpha*SST º Oct11 Jan1 Apr1 Jul1 Oct1 Jan13 Apr13 Jul13 Oct13 Jan14 Apr14 Seasnal cycle in the prxy fr PPE Maximum frm July t January cnsistent with TI activity cycle Cntributin frm SST fllwing the cycle Cntributin frm SSS has a strng interannual variability Nvember 7 th, 14 Ocean Salinity Science and Salinity Remte Sensing rkshp 7

Aquarius Brings New Understanding to Tropical Instability Waves (TIWs)

Aquarius Brings New Understanding to Tropical Instability Waves (TIWs) Tong Lee1*, Gary Lagerloef2, Michelle M. Gierach1, Hsun-Ying Kao2, Simon Yueh1, Kathleen Dohan2 1NASA Jet Propulsion Laboratory, CalTech,