Validation of a numerical simulation of the North Atlantic Ocean with ARGO Data

VALIDATION OF A NUMERICAL SIMULATION OF THE NORTH ATLANTIC OCEAN WITH ARGO DATA Deg ee in Ma ine Sciences Lau a Gómez Na a o Tu o : Alonso He nández Gue a Co- u o : Joaquim Ballab e a Poy June 2014 Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. Abs ac The ou pu s o a nume ical simula ion ha e been alida ed wi h A go da a; wi h he idea o being able o use hese ou pu s o assimila e SSS in o ma ion e ie ed by he sa elli e SMOS. In addi ion o A go da a, he model is also compa ed agains he WOA09 clima ology. The e a e a conside able amoun o alid p o iles a ailable du ing yea 2012, and he co e age does no ha e empo al biases, as he amoun o da a is homogeneous h oughou he yea . This demons a es ha choosing A go o alida e he simula ion was a co ec choice. The esul s show ha he e exis s a easonable ag eemen be ween model and A go da a in he open Ocean. Howe e , i has been obse ed ha he simula ion s ill con ains spa ial and empo al e o s p obably due o a bad ep esen a ion o ce ain oceanic p ocesses. Ne e heless, as he e o s a e easily iden i ied and do no co e he open Ocean in he opical and sub opical egions, he simula ion could s ill be conside ed as an app op ia e ool o imp o e he emo e sensing o SSS da a. Lau a Gómez Na a o 4 Table o Con en s 1. In oduc ion ................................................................................................................. 6 2. Da a .............................................................................................................................. 8 2.1. Model and simula ion desc ip ion .......................................................................... 8 2.2. Wo ld Ocean A las ................................................................................................. 9 2.3. A go ..................................................................................................................... 10 3. Me hodology and esul s ............................................................................................ 14 3.1. P elimina y da a explo a ion. ............................................................................... 14 3.2. The 2012 No h A lan ic nume ical simula ion ................................................... 19 3.3. The 2012 No h A lan ic A go da a ..................................................................... 23 3.4. Simula ion-A go di e ences. ............................................................................... 28 4. Conclusions ............................................................................................................... 34 5. Re e ences ................................................................................................................. 37 6. Appendices ................................................................................................................. 39 6.1. Appendix 1 ........................................................................................................... 39 6.2. Appendix 2 .......................................................................................................... 40 6.3. Appendix 3 ........................................................................................................... 41 7. Addi ional in o ma ion abou he de elopmen o his s udy .................................... 42 7.1. De ailed desc ip ion o he ac i i ies ca ied ou . ................................................ 42 7.1.1. S a is ical cha ac e iza ion o he simula ion’s ou pu s. ................................ 42 7.1.2. Reco e y and analysis o he da a measu ed by A go loa s. ................... 43 7.1.3. Global compa ison o he nume ical model and A go da a. ......................... 44 7.2. T aining ecei ed ................................................................................................. 45 7.3. Le el o in eg a ion and in ol emen in he depa men and ela ionship wi h pe sonnel. .................................................................................................................... 45 7.4. Posi i e and nega i e aspec s ela ed o he de elopmen o his s udy. ............. 46 7.5. Pe sonal app aisal o he lea ning achie ed du ing his s udy. ............................ 46 Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 5 Lis o igu es Figu e 1. Schema ic o he su ace ci cula ion o he A lan ic Ocean ......................................................... 6 Figu e 2. Wo ld dis ibu ion o he uppe Oceans’ wa e masses ................................................................ 7 Figu e 3. A go loa s dis ibu ion on 11 h o May 2014 ............................................................................ 10 Figu e 4. Desc ip ion o A go loa s’ cycle ............................................................................................... 11 Figu e 5. Di e en pa s o one o he A go loa s models ....................................................................... 12 Figu e 6. Sea Su ace Heigh (m) in 2008 ................................................................................................. 14 Figu e 7. His og ams o po en ial empe a u e da a a laye 1 ................................................................... 16 Figu e 8. Change o mean and median alues wi h dep h ......................................................................... 16 Figu e 9. Con ou map o salini y (psu) a laye 1 wi h he pe iphe al egions ma ked. ........................... 17 Figu e 10. T-S diag am o all he simula ion da a. .................................................................................... 18 Figu e 11. Loca ion o Sm alues lowe han 30 psu. ............................................................................... 19 Figu e 12. Maximum alues’ dis ibu ion in me es o SSH and MLD ................................................... 20 Figu e 13. SSH’s s a is ical pa ame e s a ia ion wi h ime. ..................................................................... 20 Figu e 14. MLD’s s a is ical pa ame e s a ia ion wi h ime. ................................................................... 21 Figu e 15. Salini y 1D plo a laye 15 o yea 2012. .............................................................................. 22 Figu e 16. Minimum salini y alues’ dis ibu ion o 2012 laye 5 and WOA09 salini y alues. ............. 23 Figu e 17. Minimum salini y alues’ dis ibu ion o 2012 laye 14 and WOA09 salini y alues . .......... 23 Figu e 18. A go p o iles o 2012 .............................................................................................................. 25 Figu e 19. Po en ial empe a u e (ºC) o he A go p o iles o laye 1 and laye 2. .................................. 26 Figu e 20. Salini y (psu) o he A go p o iles o laye 1 and laye 2. ...................................................... 27 Figu e 21. Ta and Sa s a iscal pa ame e s a ia ion wi h ime o laye 3 ................................................. 27 Figu e 22. Sca e map o he ΔT (ºC) o laye 2, laye 14 and laye 29. ................................................. 29 Figu e 23. Sca e map o ΔS (psu) o laye 2 .......................................................................................... 30 Figu e 24. ΔT and ΔS alues o e e y buoy. ............................................................................................ 30 Figu e 25. Loca ion o he A go buoys wi h an absolu e alue o ΔT and ΔS .......................................... 31 Figu e 26. Va ia ion o ΔT and ΔS wi h ime o laye 2. ......................................................................... 31 Figu e 27. Posi ions o he selec ed buoys o he T-S diag ams ............................................................... 32 Figu e 28. T-S diag ams o he A go and simula ion da a ......................................................................... 33 Figu e 29. Salini y alues a he Gul o Sain Law ence, o he 15 h o No embe a 30m.................... 35 Lis o ables Table 1. Ad an ages o he A go da ase in compa ison o o he sou ces o da a ..................................... 12 Table 2. A go quali y con ol lag scale .................................................................................................... 13 Table 3. Desc ip ion o he s a is ical pa ame e s calcula ed. .................................................................... 15 Table 4. S a is ical pa ame e s o SSH and MLD ...................................................................................... 17 Table 5. Da es o he 12 p o iles selec ed o he T-S diag ams. ............................................................... 32 Lau a Gómez Na a o 6 1. In oduc ion The A lan ic Ocean has been ho oughly s udied o mo e han a cen u y, and i is s ill a subjec o g ea ocus o a ious easons. I has a signi ican ole in egula ing he clima e, o he no he n hemisphe e ( o example, he hea anspo ed by he wa e o he Gul S eam con ibu es o wa m he Eu opean Subcon inen ). In addi ion, deep con ec ion occu s in he No h A lan ic Ocean. Finally, i has a human impo ance in ma i ime secu i y, economic, social and mili a y ac i i ies. All o hese oles o he A lan ic Ocean a e due by he wind and hea o cing, bu egula ed by i s wa e masses and ci cula ion which can be seen in Figu e 1. Figu e 1. Schema ic o he su ace ci cula ion o he A lan ic Ocean. Con inuous lines a e wa m and discon inuous cold cu en s (B own e al., 1988). The Ocean ci cula ion is modula ed by local densi y, which is a unc ion o empe a u e and salini y. Acco ding o Eme y and Thomson (2004), in oceanog aphy, wa e masses a e de ined in di e se ways; “ eal, objec i e physical en i ies, building blocks om which he oceanic s a i ica ion ( e ical s uc u e) is cons uc ed”, “mainly desc ip i e wo ds, summa y sho hand o poin ing o p ominen ea u es in p ope y dis ibu ions” o “a single poin on a cha ac e is ic diag am such as a Tempe a u e- Salini y (T-S) cu e”. Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 7 Thus, he analysis o he cha ac e is ics o he wa e masses p esen in a gi en egion is impo an as i p o ides elemen s helping o desc ibe he Oceans’ ci cula ion. In he A lan ic Ocean di e en wa e masses a e ound:  No h A lan ic Cen al Wa e (NACW) o No h A lan ic Eas Cen al Wa e (NAECW) o No h A lan ic Wes Cen al Wa e (NAWCW)  Sou h A lan ic Cen al Wa e (SACW)  An a c ic In e media e Wa e (AIW)  A c ic In e media e Wa e (AAIW)  Medi e anean In e media e Wa e (MIW)  No h A lan ic Deep Wa e (NADW) o No h A lan ic Eas Deep Wa e (NAEDW) o No h A lan ic Wes Deep Wa e (NAWDW)  An a c ic Bo om Wa e (ABW) Each one can be iden i ied by hei pa icula empe a u e, salini y and dep h. Fo example he MIW, is iden i ied easily by i s high salini y and empe a u e. In addi ion, di e en egions ha e di e en p ominen wa e masses (Figu e 2). Figu e 2. Wo ld dis ibu ion o he uppe Oceans’ wa e masses (Chen, 2009). Lau a Gómez Na a o 8 In his s udy, he ou pu s o a nume ical simula ion o he No h A lan ic Ocean a e alida ed. This wo k ep esen s a i s s ep owa ds he goal o p oducing a be e Seas Su ace Salini y (SSS) emo ely-sensed p oduc in he No h A lan ic Ocean. Indeed, since he launch o he Soil Mois u e/Ocean Salini y (SMOS) sa elli e, membe s o he Ins i u de Ciències del Ma (CSIC) a e wo king o p oduce wo ldwide maps o SSS om he in o ma ion ga he ed by he sa elli e. Howe e , he SSS e ie als a e pa icula ly noisy in he A lan ic Ocean as he sa elli e measu es (in he L-band, 1.4GHz) a e con amina ed by many adio equency in e e ences in his egion. The nume ical model used he e is going o be used o help educe he noise o signal a io o he SMOS SSS in he No h A lan ic using a ious da a assimila ion echniques ha will use he model as a dynamical in e pola o . 2. Da a 2.1. Model and simula ion desc ip ion The nume ical model sol es he so called P imi i e Equa ions wi h a ee su ace o mula ion (B odeau e al., 2010). The egional, eddy-pe mi ing con igu a ion co esponds o he No h A lan ic Ocean. The sou he n and no he n open bounda ies a e elaxed owa ds he Wo ld Ocean A las 09 (WOA09) clima ology da a, o ep esen mo e ealis ically he Me idional O e u ning Ci cula ion (Hoa eau e al., 2014). This con igu a ion couples he Nucleus o Eu opean Modelling o he Ocean (NEMO) oceanic model and he Lou ain-la-Neu e Ice Model (LIM2.0), which is inside he ORCA4 ¼º g id global model. The ho izon al domain o his g id includes he A lan ic Ocean’s basin om 80ºN o 20ºS, he No dic Seas, he Denma k S ai and pa o he Medi e anean Sea, up o 23ºE (Min ielle e al., 2011). The spa ial esolu ion is 0.25 deg ees. I s e ical domain is o 45 geopo en ial le els, and he g id spacing is 6 m a he su ace and 250 m a he bo om (Hoa eau e al., 2014). Ri e uno is simula ed by adding a lux o wa e wi h a salini y o 0 psu and wi h he same empe a u e as he one a i s mou h. The solu ions a e ad anced in ime using a Leap-F og me hod, combined wi h a Robe -Asselin il e o ensu e he s abili y o he scheme. The ime s ep o he simula ion is 40 minu es. Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 9 A 2001-2012 simula ion using ealis ic o cing ields has been ca ied ou by Ms. Nina Hoa eau. The simula ion equi es abou 6 hou s o each simula ed yea when 60 Cen al P ocessing Uni s (CPUs) a e used. Each ou pu ile o he simula ion was sa ed in Ne CDF o ma , occupied 106 Mb, and includes he i e-day a e age o he s o ed pa ame e s. 2.2. Wo ld Ocean A las Clima ology is, as de ined by he Na ional Wea he Se ice o he Na ional Oceanic and A mosphe ic Adminis a ion (NOAA), “a quan i a i e desc ip ion o clima e showing he cha ac e is ic alues o clima e a iables o e a egion” (www.nws.noaa.go /clima e/help/glossa y.php). Clima ologies a e s a ic, a e aged alues o a gi en pa ame e , calcula ed du ing a ce ain pe iod o ime. The e o e, i does no p o ide, in gene al, an obse able alue, bu i should gi e an idea o he mos p obable alue o be measu ed. In pa icula , empe a u e and salini y clima ologies in a gi en a ea a e usually es ima ed by he a e age alues o all obse a ions e e measu ed a ha a ea, and hus, hey would de ine he mean s a e o he Ocean i he sampling we e app op ia e. The T and S obse a ions a e collec ed om measu ed su ace da a (as he mosalinog aphe s) and/o p o iles. Howe e , as measu emen s a e nei he cons an in ime no space, hey equi e ime-spa ial a e aging and smoo hing (Higgison e al., 2009). The Wo ld Ocean A las, WOA (An ono e al., 2010; Loca nini e al., 2010) is he mos widely used clima ology o oceanic empe a u e and salini y. This Wo ld Ocean clima ology was i s published by Le i us in 1982, and h oughou he yea s i has been imp o ed by including mo e da a and using new me hods o calcula e clima ology, and he e o e eleasing new a lases e e y ew yea s (Cha e jee e al., 2012). The uses o hese clima ology a lases a e di e se: bounda y and/o ini ial condi ions in Ocean ci cula ion nume ical models and A mosphe e-Ocean models, e i ica ion o nume ical simula ions o he ocean, as a o m o “sea u h” o sa elli e Lau a Gómez Na a o 16 empe a u e, i is in e es ing o no ice he educ ion o he di e ences be ween he mean and he median. The la ge he di e ences be ween he mean and he median, he la ge is he impac o he ails o he dis ibu ion, and he less signi ican a e he alues o he s a is ical pa ame e s lis ed in Table 3. On he o he hand, he esul s shown in Table 4 indica e ha he s a is ical desc ip ion o SSH is li le a ec ed by he la i ude limi s, bu he MLD is. Figu e 7. His og ams o po en ial empe a u e da a a laye 1 (3m). Le : O iginal da a. Righ : Wi h la i ude limi s and land alues changed. Figu e 8. Change o mean ( ed line) and median (blue line) alues wi h dep h o he o iginal da a (le ) and wi h la i ude limi s and land alues changed ( igh ). -5 0 5 10 15 20 25 30 35 0 0.5 1 1.5 2 2.5 3x 104 Po en ial empe a u e (ºC) F equency -5 0 5 10 15 20 25 30 35 0 0.5 1 1.5 2 2.5 3x 104 Po en ial empe a u e (ºC) F equency 010 20 30 0 1000 2000 3000 4000 5000 6000 Po en ial empe a u e (ºC) Dep h (m) 010 20 30 0 1000 2000 3000 4000 5000 6000 Po en ial empe a u e (ºC) Dep h (m) Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 17 Table 4. S a is ical pa ame e s o SSH and MLD o he o iginal da a and columns ma ked wi h* a e o da a be ween 60ºN and -5ºN. Pa ame e s SSH (m) SSH* (m) MLD (m) MLD* (m) Maximum 0,79 0,79 393,84 249,92 Minimum -0,94 -0,94 12,84 12,84 Range 1,74 1,74 381,00 237,08 Pe cen ile 99 0,53 0,55 189,89 139,91 Pe cen ile 1 -0,87 -0,89 12,84 12,84 Robus ange 1,40 1,44 177,05 127,08 Pe cen ile 75 (Uppe qua ile) 0,13 0,17 74,89 77,93 Pe cen ile 25 (Lowe qua ile) -0,38 -0,24 27,09 28,89 In e qua ile ange 0,51 0,41 47,79 49,04 Median -0,12 0,03 45,82 59,89 Mean -0,12 -0,04 56,28 57,62 Va iance 0,11 0,10 1530,65 1010,65 S anda d de ia ion 0,33 0,32 39,12 31,79 E en hough he p esence o ex eme alues has been educed, some his og ams emain bimodal (see Figu e 7). Wi h he help o salini y maps (like he one in Figu e 9), some egions could be iden i ied, whe e he e was s ill anomalous da a. These co esponded o pe iphe al egions, speci ically he Medi e anean Sea, he No h and Bal ic Seas and he Hudson Bay. Figu e 9 shows one o he con ou maps used o es ablish he pe iphe al egions, pa icula ly in his case he Bal ic Sea and Hudson Bay due o hei low salini y. Figu e 9. Con ou map o salini y (psu) a laye 1 (3m) wi h he pe iphe al egions ma ked. Longi ude (ºE) La i ude (ºN) -100 -80 -60 -40 -20 0 20 -10 0 10 20 30 40 50 60 5 10 15 20 25 30 35 Lau a Gómez Na a o 18 Figu e 10 shows a T-S diag am o he whole egion (including pe iphe al egions). Some cha ac e is ic wa e masses s and ou om he es o he sys em. The Medi e anean wa e (12-20ºC S>35), he Bal ic and No h seas’ wa e (T<10, wide ange o S), and he Hudson Bay wa e (T<3ºC, 15<S<33), all appea concen a ed a ound localized egions o he TS plo . Mo eo e , he ci cles ci cled in pu ple co espond o he Chesapeake Bay (15<T<18ºC, 25<S<35) ha also s ands ou om he es o he sys em. Figu e 10. T-S diag am o all he simula ion da a. The T-S diag am also allows o iden i y wa e om pa icula egions: Eas coas o Canada ( om he Gul o Sain Law ence up o Unga a Bay), Mississippi-Alabama Shel and Ma shland Island, Gul o Pa ia (T inidad Island), Amazon Ri e del a, Gul o Guinea, pa icula ly a he Bigh o Bonny and Chesapeake Bay al eady iden i ied as a egion o anomalous salini y (Figu e 11). Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 19 Figu e 11. Loca ion o Sm alues lowe han 30 psu. 3.2. The 2012 No h A lan ic nume ical simula ion A e he i s se o p elimina y expe imen s was done, all he iles co esponding o he yea 2012 we e p ocessed. This co esponds o a o al o 73 iles in Ne CDF o ma . The p ocedu e ca ied ou was he same as he p e ious one wi h he excep ion ha he s a is ical pa ame e s we e calcula ed bo h in space (2D) and ime (1D). Fo example, a each g id-poin , he maximum alue eached du ing he whole 2012 can be es ima ed, and a (2D) map o he maximum alues can be cons uc ed. Al e na i ely, he maximum alue a each snapsho can be calcula ed o e he egion o in e es , and a (1D) ime se ies o egional maximum alues can be c ea ed. Figu e 12 displays he map showing he maximum 2012 alues o he sea le el and he mixed laye dep h. Al hough he g aph does no include in o ma ion abou he ime o occu ence o he maximum alue, i clea ly is a ool o delinea e he di e en dynamical p o inces o he No h A lan ic Ocean. I also helps o illus a e he main mechanisms a wo k in he egion as he 1 m sea le el nea he wes e n bounda y due o he wind d i en oceanic ci cula ion (combined wi h he mal e ec s), as well as he ela i e size o he esul ing me idional and zonal g adien s a he egion. On he o he hand, he la ges alues o he mixed laye dep h a e ound a he wes e n A lan ic Ocean, nea he pa h o he Gul S eam. The lowes alues a e concen a ed a he 100oW 80oW 60oW 40oW 20oW 0o 20oE 40oE 0o 15oN 30oN 45oN 60oN Lau a Gómez Na a o 20 no h-eas e n coas o Canada and a he Gul o Guinea, wo egions s ongly in luenced by he p esence o su ace esh wa e luxes. Figu e 12. Maximum alues’ dis ibu ion in me es o SSH (le ) and MLD ( igh ). Figu e 13. SSH’s s a is ical pa ame e s a ia ion wi h ime. Longi ude (ºE) La i ude (ºN) -100 -80 -60 -40 -20 0 20 -10 0 10 20 30 40 50 60 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 Longi ude (ºE) La i ude (ºN) -100 -80 -60 -40 -20 0 20 -10 0 10 20 30 40 50 60 20 40 60 80 100 120 140 160 180 200 220 240 Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 21 Figu e 14. MLD’s s a is ical pa ame e s a ia ion wi h ime. An example o ime se ies o he s a is ical p ope ies o he sys em is gi en in Figu e 13, whe e he ime e olu ion o he minimal, cen al, and la ges sea le el alues is shown. The mean alue emains nea o ze o as he model uses a olume conse a ion cons ain in he pa ame e iza ion o he open bounda ies. The depa u es o ze o a e due o he non-accoun ed con ibu ion o he pe iphe al seas. The ime e olu ion o he obus maximum ( he 99 pe cen ile) eaches i s la ges alue du ing he mon h o Augus , indica ing he seasonal wa ming o he uppe Ocean. Con a ily, he ime e olu ion o he absolu e maximum has wo maximum alues (a he beginning o he yea and owa ds he end o he mon h o Oc obe ). The mo e easonable e olu ion o he obus maximum illus a es he need o emo ing ex eme alues be o e he s a is ical explo a ion o he da a. Figu e 14 helps o isualize he s ong seasonal a ia ion o he MLD. As i would be expec ed, he maximum alues occu du ing win e due o he combined e ec o low s a i ica ion and s ong wind s i ing, and he lowes alues occu du ing he summe season due o he s abilizing e ec o he su ace seasonal wa ming. Figu e 15 shows he co esponding ime se ies o he salini y a laye 15 (cen ed on 228 m dep h). The mos s iking ea u e is he anomalous beha iou o he minimum salini y owa ds he end o he yea . Fu he analysis ha e shown ha such Lau a Gómez Na a o 22 sudden educ ion o salini y happens in some isola ed g id-poin s, and ha a e no linked o any physical p ocess. The analysis was epea ed o he yea 2011, and i was ound ha some g id-poin s, loca ed a di e en dep hs, had simila e o s. All poin s a ec ed by his beha iou a e loca ed a he ba hyme y, indica ing a p oblem in he pa ame e iza ion o he ace s in he bo om mixed laye . Figu e 15. Salini y 1D plo a laye 15 (228m) o yea 2012. The spa ial dis ibu ion o he minimum salini y du ing he yea 2012 in he Gul o Sain Law ence a e shown in Figu es 16 (32 m dep h) and 17 (191 m dep h). The model alues a e compa ed wi h he WOA09 salini y da a. The model su ace salini y can be much lowe han he clima ological salini y (mo e han 10 psu eshe ). A dep h, he di e ences a e o abou 1 psu. Such a 10 psu su ace salini y di e ences be ween he model and clima ology indica es de iciencies o he model in ob aining ealis ic esh-wa e balances in such egion domina ed by local wa e uno and shallow ba hyme y. Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 23 Figu e 16. Le : Minimum salini y alues’ dis ibu ion o 2012 laye 5 (32m). Righ : WOA09 Salini y alues o Decembe 2012 laye 4 (30m). Figu e 17. Le : Minimum salini y alues’ dis ibu ion o 2012 laye 14 (191m). The pink poin is whe e he lowes alue is loca ed. Righ : WOA09 Salini y alues o Decembe 2012 laye 10 (200m). 3.3. The 2012 No h A lan ic A go da a The A go da a co esponding in ime and space o he simula ion was ob ained om he Ba celona Expe Cen e (BEC) da abase which is a mi o o he Co iolis da abase. Only he p o iles which we e ound in he A lan ic Ocean, be ween 60ºN and 5ºS and o he yea 2012, we e e ie ed om he da abase. Only Delayed mode da a and p o iles ou side he pe iphe al egions ha e been conside ed in his pa o he wo k. The hyd og aphic p o iles whe e hen p ocessed ollowing hese s eps: Longi ude (ºE) La i ude (ºN) -65 -60 -55 -50 -45 -40 42 44 46 48 50 52 54 56 58 60 18 20 22 24 26 28 30 32 34 36 Longi ude (ºE) La i ude (ºN) -65 -60 -55 -50 -45 -40 42 44 46 48 50 52 54 56 58 60 18 20 22 24 26 28 30 32 34 36 Longi ude (ºE) La i ude (ºN) -65 -60 -55 -50 -45 -40 42 44 46 48 50 52 54 56 58 60 33 33.5 34 34.5 35 35.5 36 Longi ude (ºE) La i ude (ºN) -65 -60 -55 -50 -45 -40 42 44 46 48 50 52 54 56 58 60 33 33.5 34 34.5 35 35.5 36 Lau a Gómez Na a o 24 a. Adjus ed p essu e, empe a u e and salini y a iables we e ead. b. I he numbe o measu emen le els is less han 20, he whole p o ile is dismissed c. I Z_QC a a poin was no equal o 1, he co esponding p essu e, empe a u e and salini y alues we e se o 99999 (missing alue). d. I T_QC o a poin was no equal o 1, he co esponding empe a u e and salini y alues we e se o missing. e. I S_QC o a poin was no equal o 1, he co esponding salini y alue was se o missing. This is done as he salini y alues depend on bo h empe a u e and p essu e, while empe a u e alue depends only on p essu e. . Fo each e ained A go p o ile, a p o ile is c ea ed in such a way ha only alid salini y da a a e s o ed. g. The numbe o da a in each p o ile o hese new a iables was coun ed. I he e we e no a leas 20 alues o i mo e han 40% o he da a in he o iginal p o ile was disca ded, he whole p o ile was disca ded. Also, o his da a il e , all he p o iles which hei i s alid salini y measu e was a dep h lowe han 100m we e disca ded oo. h. As he empe a u e measu ed by he buoys is in si u he po en ial empe a u e was calcula ed. See Appendix 1 o see he p og amme used o i s calcula ion. i. The po en ial empe a u e alues we e e ically in e pola ed. j. The da a was in e pola ed using h ee in e pola ion me hods:  Akima splines  Cubic splines  Thi d-o de polynomial i ing k. When he A go da a was in e pola ed o he simula ion’s e ical le els, any le el o he simula ion deepe han he las dep h o he p o ile and shallowe han he i s alid dep h o he p o ile was changed o missing. l. A e he in e pola ion he mean was calcula ed. m. I he absolu e di e ence be ween each indi idual in e pola ion and he mean was g ea e han 5% o he mean, he co esponding po en ial empe a u e alue was changed o missing. n. S eps g) o k) we e epea ed o salini y. Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 25 The inal esul s o po en ial empe a u e and salini y o he A go da a he ea e e e ed o as Ta and Sa espec i ely, we e sa ed in a Ne CDF ile. In his ile, in o ma ion abou each p o ile was sa ed oo: i s longi ude, la i ude, da e and he ID o he p o ile (Did) in he BEC da abase. In addi ion, he addi ional pa ame e s we e calcula ed and included in his ile. The indices ipos and jpos a e he alues o he x and y dimension espec i ely, o he poin in he model’s g id which is closes o he A go p o ile’s posi ion. The pos a iable poin s o he model snapsho ha co esponds o he A go measu emen . In addi ion, he numbe o alid Ta and Sa alues o 3 di e en su ace dep hs; 10 m, 25 m and 50 m, and in di e en poin s o he da a p ocessing (a e ha ing applied di e en il e s). This was done o know how much da a was eally a ailable and alid, as pa icula ly in he su ace, he e a e many A go da a p oblems, bu on he o he hand, i ‘s he su ace da a which is o g ea e in e es o alida e, o i s use o SMOS SSS. F om a o al o 4121 A go p o iles, only 3117 p o iles ha e passed he Quali y Con ol desc ibed abo e (Figu e 18). Some egions, as he No h A lan ic sub opical gy e, show a clea lack o A go da a, due o he ee ad ec i e na u e o he buoys. Figu e 18. A go p o iles o 2012. The alid p o iles a e ma ked in blue and he in alid in ed. The spa ial dis ibu ion o he Ta (Figu e 19) and Sa (Figu e 20) is shown o laye s 1 (3 m) and 2 (9 m). No ice he lack o A go da a o he i s laye o he model. 100oW 80oW 60oW 40oW 20oW 0o 20oE 40oE 0o 15oN 30oN 45oN 60oN Lau a Gómez Na a o 32 These 4 egions a e he ones shown in Figu e 2 (Chen, 2009). The da es o he 12 andomly selec ed p o iles a e shown in Table 5. Table 5. Da es o he 12 p o iles selec ed o he T-S diag ams. Buoy numbe Day Mon h Yea 1 12 10 2012 3 6 1 2012 2 11 10 2012 4 6 2 2012 5 1 2 2012 6 3 7 2012 7 23 11 2012 8 25 3 2012 9 4 4 2012 10 23 7 2012 11 20 2 2012 12 8 10 2012 Figu e 27. Posi ions o he selec ed buoys o he T-S diag ams. The blue ci cles indica e he egion. The T-S diag ams in Figu e 28 show ha , o egion 4 (bo om), bo h T-S diag ams a e simila . Simila ly, in egion 2 (second ow) he model and A go ag ee wi h he excep ion o he su ace laye s. On he o he , o egions 1 ( op) and 3 ( hi d ow) he T-S diag ams o some o he p o iles a e qui e di e en , especially nea he su ace. Again, hese T-S diag ams p o ide u he e idence ha he nume ical simula ion is less accu a e a high la i udes, as he ones wi h he g ea es di e ences a e hose o egions 1 and 3, which a e he egions wi h buoys selec ed a highe la i udes. 100oW 80oW 60oW 40oW 20oW 0o 20oE 40oE 0o 15oN 30oN 45oN 60oN 1 2 3 4 5 6 7 8 9 10 11 12 3 4 2 1 Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 33 Figu e 28. T-S diag ams on he le co espond o he A go da a, and on he igh o he simula ion’s ou pu s. F om bo om o op hey co espond o poin s om egion 4 o 1, and ollowing he colou o de blue, ed, black, hey co espond o he poin s 1 o 12, as labelled on Figu e 27. The g een, dashed lines a e he isopycnals. 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 22 23 24 25 26 27 28 29 Salini y (psu) Tempe a u e (C) 32 34 36 38 0 5 10 15 20 25 30 · . ' '" ... 1// Lau a Gómez Na a o 34 4. Conclusions The analysis o he ou pu s o he nume ical simula ion has indica ed ha no h and sou h egions, close o he open bounda ies o he model, oge he wi h he pe iphe al egions a e iden i ied as p oblema ic. As desc ibed in Sec ion 2.1, he open bounda ies o he simula ion a e elaxed owa ds clima ology da a. The e o e, i s a iabili y is no e lec ed accu a ely. In addi ion, a high la i udes, an impo an p ocess is no ep esen ed a all by he simula ion: he in e annual a ia ion o he cold, eshwa e inpu om he A c ic Ocean. In he pe iphe al egions, he cha ac e is ics o he wa e masses a e e y di e en han he cha ac e is ics o he pelagic Ocean ha is he main objec i e o he simula ion. The cha ac e is ics o he pe iphe al egions a ise om he complex in e ac ion be ween la ge i e uno , semi-closed domain, shallow ba hyme y and a mosphe ic o cing. E o s in any o hese ac o s ( o example, he i e uno ) may s ongly a ec he ealism o he simula ion. As he e a e e y ew, o none, A go p o ile sampling hese egions, hey a e elimina ed om ou analysis. The eas e n Canadian coas could ha e also been conside ed a pe iphe al egion as i clea ly ollows a di e en da a dis ibu ion, han he es o he sys em. The simula ion a he Gul o Sain Law ence has been ound excessi ely esh by espec o he clima ology da a and by espec o published da a om he egion (Pe ie e al., 2006). The minimum salini y obse ed in he A las a a dep h o 30 m du ing he win e is o 29 psu (Figu e 29), whils he co esponding alue o he simula ion is 18 psu. This is a e y impo an di e ence in salini y alues, which could no be de ec ed wi h he A go da a as his is one o he egions which a e poo ly ep esen ed by he A go ne wo k (Figu e 17). Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 35 Figu e 29. Salini y alues a he Gul o Sain Law ence, o he 15 h o No embe a 30m (Pe ie e al., 2010). The egion o he Gul o Sain Law ence is a pa icula case, as eshwa e seems o accumula e he e. This could be due o he combined e ec o he i e uno , he p esence o ice du ing ce ain imes o he yea and due o ba hyme y e o s. As s a ed in Buongio no (2012), empe a u e and salini y alues, especially he su ace ones, a e sensible o ex e nal o ces, like eshwa e inpu s om i e s o p ecipi a ion, and o he Ocean’s in e nal dynamics, like con ec ion, ad ec ion and mixing p ocesses. Consequen ly, i hese in lows o eshwa e and in e nal p ocesses a e no accu a ely ep esen ed by he model, i s e ec can be clea ly obse ed in he su ace laye s. As is he case o igu e 10 whe e low alues o salini y can be de ec ed a he mou h o g ea i e s, as he model a ibu es a salini y o 0 psu o hem, which is qui e an unde es ima e. The anomalous esul s ob ained om he simula ion, as al eady discussed abo e, could ha e a ious easons and explana ions. In Tho pe e al., 2005 i is sugges ed ha possible sou ces o e o a e low e ical esolu ion, poo ep esen a ion o he ba hyme y, and issues wi h he e ical mixing schemes (as desc ibed by Buongio no, 2012), which lead o an un ealis ic oceanic ci cula ion, which can cause ce ain wa e masses o no be de ec ed in simula ions. The impo ance o he ba hyme y used in simula ions, is also highligh ed in Min ielle e al. (2011) and Gi on and San o d (2003). They s a e ha i s impo ance is due o ha i a ec s bo om laye p ocesses which con ol he deep oceanic ci cula ion. Lau a Gómez Na a o 36 The T-S diag ams (Figu e 28) and he di e ence be ween he model and A go da a (Figu es 22, 23 and 24), show how he empe a u e o he model has a posi i e bias and he salini y has a nega i e one. The nega i e salini y endency is much mo e ma ked han he posi i e one seen o he empe a u e alues. This means ha he model is oo ‘ esh’, and could be due o all he easons exposed abo e. They also show ha he simula ion is mo e inaccu a e nea he su ace, bu also i should be kep in mind ha he e is whe e he oceanic pa ame e s show a g ea e a iabili y. The shallowes dep h a which he simula ion could be alida ed was 9 m, due o he lack o alid A go da a nea he su ace, and also he e we e egions like he No h A lan ic Sub opical gy e and he Gul o S . Law ence be ween o he s we e he e was a lack o da a oo. In he la e egion, ano he sou ce o da a had o be used o alida e he ou pu s o he simula ion he e. This lack o alid A go da a a he su ace was expec ed, as in many occasions when he buoys a e nea he su ace he hyd aulic pump is s opped and so he salini y senso s ops measu ing. Mo e A go da a a he su ace da a could ha e been ob ained i no only he p o iles lagged wi h a QC = 1 ha e been conside ed, bu also he ones lagged wi h a QC o 2, 5 o 8 (Table 2). Due o he limi ed amoun o ime o his s udy, only he da a wi h QC=1 we e selec ed. Howe e , i has been no iced ha he A go obse ing sys em is able o ep esen seasonal a iabili y o he Ocean (Figu e 21). The e is a conside able amoun o alid p o iles (3117) o yea 2012, wi h he excep ion o some poin s and buoys he da a hey measu e is e y easonable (Figu e 20) and he e a e no empo al biases as hey p o ide da a h oughou he yea . This demons a es ha choosing A go o alida e he simula ion was a co ec choice. To conclude, in his wo k I ha e con ibu ed o he i s e o s o he Depa men o Physical and Technological Oceanog aphy o he Ins i u de Ciències del Ma (CSIC) o he alida ion o hei No h A lan ic Ocean simula ion. This simula ion couples wo o he s a e-o -a oceanic models: NEMO (oceanic dynamics) and LIM-2 (sea-ice dynamics). By compa ing he ou pu s o he model agains he A go hyd og aphic p o iles, I ha e ound ha he pelagic ci cula ion o he model has some easonable simila i ies wi h he obse a ions. Al hough impo an de ia ions be ween he model and da a exis nea he me idional bo de s and o he Canadian Coas , ou esul s indica e ha he pelagic ci cula ion o he model has some easonable simila i ies Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 37 wi h obse a ions. This is impo an because he abili y o e ie ing SSS om emo e sensing is ex emely low in cold wa e s and nea he coas (due o land sea ab up emissi i y ansi ion). Tha is, he model p o ides he la ges compa ibili y wi h da a igh in he egion whe e i would be mo e use ul o p o ide a cohe en map o salini y in he No h A lan ic Ocean. 5. Re e ences An ono , J. I., Seido , D., Boye , T. P., Loca nini, R. A., Mishono , A. V., Ga cia, H. E., Ba ano a, O. K., Zweng, M. M. and Johnson, D. R. (2010): Wo ld Ocean A las 2009 Volume 2: Salini y. S. Le i us Ed. NOAA A las NESDIS 69, U.S. Go . P in ing O ice, Washing on, D.C., 184 pp. B odeau, L., Ba nie , B., T eguie , A. M., Pendu , T. and Gule , S. (2010): An ERA40-based a mosphe ic o cing o global ocean ci cula ion models. Ocean Modelling 31, 88–104. B own, E., Colling, A., Pa k, D., Phillips, J. and Ro he y, D. (1988): Ocean Ci cula ion. The Open Uni e si y, 287 pp. Buongio no Na delli, B. (2012): A No el App oach o he High-Resolu ion In e pola ion o In Si u Sea Su ace Salini y. J. A mos. Oceanic Technol., 29, 867– 879. Ca al, T., Keeley, B., Taka suki, Y., Yoshida, T., Loch, S., Schmid, C., Goldsmi h, R., Wong, A., McC eadie, R., Th eshe , A. and T an, A. (2012): ARGO USER’S MANUALVe sion 2.4, 85 pp. Cha e jee, A., Shanka 1, D., Shenoi, S. S. C., Reddy, G. V., Michael, G. S., Ra ichand an, M., Gopalk ishna, V. V., Rama Rao, E. P., Udaya Bhaska , T. V. S., and Sanjee an, V. N. (2012): A new a las o empe a u e and salini y o he No h Indian Ocean. J. Ea h Sys . Sci.121, No. 3, 559–593. Chen, C. (2009): Ocean Wa e Masses-T-S Diag ams and Uppe Ocean Wa e s. Gene al Physical Oceanog aphy, MAR 555, School o Ma ine Sciences and Technology, Umass-Da mou h, 18 pp. Eme y, W. J., and Thomson, R. E. (2004): Da a analysis me hods in physical oceanog aphy 2nd edi ion. Else ie Ed., 654 pp. Gi on, J.B. and San o d, T. B. (2003): Descen and modi ica ion o he o e low plume in he Denma k S ai . J. Phys. Oceanog ., 33, 1351–1364. Loca nini, R. A., Mishono , A. V., An ono , J.I., Boye , T. P., Ga cia, H. E., Ba ano a, O. K., Zweng, M. M. and Johnson, D. R. (2010): Wo ld Ocean A las 2009, Volume 1: Tempe a u e. S. Le i us, Ed.,NOAA A las NESDIS 68, U.S. Go e nmen P in ing O ice, Washing on, D.C., 184 pp. Lau a Gómez Na a o 38 Higgison, S., Thompson, K. R. and Liu, Y. (2009): Es ima ing ocean clima ologies o sho pe iods: A simple echnique o emo ing he e ec o eddies om empe a u e and salini y p o iles. GEOPHYSICAL RESEARCH LETTERS, 36, 4 pp. Hoa eau, N., Po abella, M., Ga cia-Ladona, E., Tu iel, A. and Ballab e a-Poy, J. Me idional a iabili y o No h-A lan ic Sea Su ace Salini y: Wa enumbe spec a de i ed om clima ology, ocean model and sa elli e obse a ions. Submi ed o J. Geophys. Res. Me O ice, Uni ed Kingdom: h p://www.me o ice.go .uk/wea he / ma ine/obse a ions/ga he ing_da a/a go.h ml Min ielle, M., Cassou, C., Bou dallé-Badie, R., Te ay, L. and Najac, J. (2011): A s a is ical–dynamical scheme o econs uc ing ocean o cing in he A lan ic. Pa II: me hodology, alida ion and applica ion o high- esolu ion ocean models. J. Clima e Dynamics, 36, 401-417. Na ional Wea he Se ice, NOAA: www.nws.noaa.go /clima e/help/glossa y.php Pe ie, B., D inkwa e , K., Sands öm, A., Pe ipas, R., G ego y, D., Gilbe , D. and Sekhon, P. (1996): Tempe a u e, salini y and sigma- A las o he Gul o S . Law ence. Canadian Technical Repo o Hyd og aphy and Ocean Sciences 178, 263 pp. Tho pe, S. E., S e ens, D. P. and Heywood, K. J. (2005): Compa ison o wo ime- a ian o ced eddy-pe mi ing global ocean ci cula ion models wi h hyd og aphy o he Sco ia Sea. Ocean modeling, 9, 105-132. Uni e si y o Cali o nia, San Diego: h p://www.a go.ucsd.edu/ Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 39 6. Appendices 6.1. Appendix 1 SUBROUTINE sw_p mp(n,S,T,P,PR,TP) IMPLICIT NONE INTEGER, INTENT(in) :: n eal(kind=8), dimension(n), in en (in) :: T,P eal(kind=8), in en (in) :: PR eal(kind=8), dimension(n), in en (in) :: S eal(kind=8), dimension(n), in en (ou ) :: TP ! ... Local a iables eal(kind=8), dimension(n) :: ADGT,del_P,del_ h,q, h,PP ! ... he a1 del_P = PR - P CALL sw_ad g(n,S,T,P,ADGT) del_ h = del_P * ADGT h = T + 0.5D0 * del_ h q = del_ h ! ... he a2 PP = P+0.5D0*del_P CALL sw_ad g(n,S, h,PP,ADGT) del_ h = del_P * ADGT h = h + (1.0D0 -1.0D0/sq (2.0D0))*(del_ h -q) q = (2.0D0-sq (2.0D0)) * del_ h + (-2.0D0+3.0D0/sq (2.0D0))* q ! ... he a3 PP = P+0.5D0*del_P CALL sw_ad g(n,S, h,PP,ADGT) del_ h = del_P * ADGT h = h + (1.0D0 +1.0D0/sq (2.0D0))*(del_ h -q) q = (2.0D0+sq (2.0D0)) * del_ h + (-2.0D0-3.0D0/sq (2.0D0))* q ! ... he a4 PP = P+del_P CALL sw_ad g(n,S, h,PP,ADGT) del_ h = del_P * ADGT TP = h + (del_ h -2.0D0*q)/6.0D0 END SUBROUTINE sw_p mp !%%%%%%%%%%%%%%%%%% ! Adiaba ic empe a u e g adien SUBROUTINE sw_ad g(n,S,T,P,ADGT) IMPLICIT NONE in ege , in en (in) :: n eal(kind=8), dimension(n), in en (in) :: S,T,P eal(kind=8), dimension(n), in en (ou ) :: ADGT ! ... Pa ame e s: eal(kind=8), pa ame e :: a0 = 3.5803D-5 eal(kind=8), pa ame e :: a1 = 8.5258D-6 eal(kind=8), pa ame e :: a2 = -6.836D-8 eal(kind=8), pa ame e :: a3 = 6.6228D-10 eal(kind=8), pa ame e :: b0 = 1.8932D-6 eal(kind=8), pa ame e :: b1 = -4.2393D-8 eal(kind=8), pa ame e :: c0 = 1.8741D-8 eal(kind=8), pa ame e :: c1 = -6.7795D-10 eal(kind=8), pa ame e :: c2 = 8.733D-12 eal(kind=8), pa ame e :: c3 = -5.4481D-14 eal(kind=8), pa ame e :: d0 = -1.1351D-10 eal(kind=8), pa ame e :: d1 = 2.7759D-12 eal(kind=8), pa ame e :: e0 = -4.6206D-13 eal(kind=8), pa ame e :: e1 = 1.8676D-14 Lau a Gómez Na a o 40 eal(kind=8), pa ame e :: e2 = -2.1687D-16 ADGT = a0 + (a1 + (a2 + a3 * T)*T)*T + (b0 + b1 *T) * (S -35.0D0) + ((c0 + (c1 + (c2 + c3 *T) *T)*T) + (d0 + d1 *T)*(S-35.0D0))*P + ( e0 + (e1 + e2 *T)*T) *P *P END SUBROUTINE 6.2. Appendix 2 SUBROUTINE pe cen iles (n,x,np,p,xp) IMPLICIT NONE in ege , in en (in) :: n,np eal(kind=8), dimension(np), in en (in) :: p eal(kind=8), dimension(n), in en (in) :: x eal(kind=8), dimension(np), in en (ou ) :: xp in ege i,kk eal(kind=8) ,dd in ege indx(n) CALL indexx(n,x,indx) DO i=1,np = p(i)*(n-1.0D0)/100.0D0 + 1.0D0 kk = FLOOR( ) dd = - kk IF (kk.EQ.0) THEN xp(i) = x(indx(1)) ELSE IF (kk.EQ.n) THEN xp(i) = x(indx(n)) ELSE xp(i) = x(indx(kk)) + dd*(x(indx(kk+1))-x(indx(kk))) ENDIF ENDDO RETURN END Valida ion o a nume ical simula ion o he No h A lan ic Ocean wi h A go da a. 6.3. Appendix 3 SUBROUTINE a e a (da a,n,a e, a ) IMPLICIT NONE in ege , in en (in) :: n eal(kind=8), dimension(n), in en (in) :: da a eal(kind=8), in en (ou ) :: a e, a ! ... Local a iables: in ege j eal(kind=8) s,ep a e = SUM(da a(1:n))/n a = 0.0d0 ep = 0.0d0 do j=1,n s = da a(j) - a e ep = ep + s a = a + s*s ENDDO a = ( a -ep**2/n)/(n-1) RETURN END ! (C) Cop . 1986-92 Nume ical Recipes So wa e *5sV1. ! ... ! ===================================== ! ... SUBROUTINE a e a 4 (da a,n,a e, a ) IMPLICIT NONE in ege , in en (in) :: n eal(kind=4), dimension(n), in en (in) :: da a eal(kind=4), in en (ou ) :: a e, a ! ... Local a iables: in ege j eal(kind=8) s,ep, 8 a e = SUM(da a(1:n))/n 8 = 0.0d0 ep = 0.0d0 do j=1,n s = DBLE(da a(j) - a e) ep = ep + s 8 = 8 + s*s ENDDO 8 = ( 8-ep**2/n)/(n-1) a = SNGL( 8) RETURN END ! (C) Cop . 1986-92 Nume ical Recipes So wa e *5sV1.