De c a da l Wa ve Va ria b ility in the e a ste rn No rth Atla - PowerPoint PPT Presentation

De c a da l Wa ve Va ria b ility in the e a ste rn No rth Atla ntic a sso c ia te d with the NAO Ha rrif Sa nto Pa ul T a ylo r Ric ha rd Gib so n

Mo tiva tio n Pub lishe d o b se rva tio ns sho w No rth Atla ntic wa s g e tting ro ug he r o ve r 1960s – 1990s. - due to c lima te c ha ng e ? ? ? ? ? 2 Ref: Carter, D., and L. Draper (1988), Has the north-east Atlantic become rougher?, Nature, 332, 494.

Que stio ns • I s the re a n a ve ra g e wa ve c lima te a t a pa rtic ula r lo c a tio n? • Are the wa ve s o ve r the la st 25 – 50 ye a rs a re lia b le g uide to the ne xt 25 o r 100 ye a rs? • T he a va ila b le wa ve re c o rds a re to o sho rt, is the re a wa y to infe r a lo ng e r time histo ry fo r wa ve c lima te b a c k to the pa st (o ve r 400 ye a rs)? 3

NAO a nd o the r two mo de s Re f: Mo o re , G., I . Re nfre w, a nd R. S. Pic ka rt (2013), Multide c a da l mo b ility o f the No rth Atla ntic Osc illa tio n, 4 Jo urna l o f Clima te , 26(8), 2453–2466.

Ma p o f the lo c a tio ns  Hindc a st da ta : NORA10 fo r a ll fro m 1958 – 2011 (54 ye a rs)  All da ta c o nta in � � , � � , a nd � � sa mple d e ve ry 3 ho urs.  Da ta a lso c o nta in wa ve dire c tio n, wind spe e d a nd wind dire c tio n, a nd a split o f to ta l wa ve s into swe lls a nd wind wa ve s.  Ana lysis is pre se nte d o n to ta l wa ve s. 5

6 Mo de l/ b uo y c o mpa riso ns • Sho wn he re fo r Ha lte nb a nke n

Wa ve po we r e stima te �� � � � • � � ��� � � � • No te the use o f � � ra the r tha n � � ( � � ~1.2� � ). • Winte r we a the r is wo rst, summe r ra the r b e nig n. • We lo o k a t to ta l a ve ra g e po we r ye a r b y ye a r (with ye a r running fro m summe r to summe r, a vo id splitting winte rs). • I n the ne a r future , se a so na l va ria tio n c a n b e inc lude d fo r mo nthly wa ve po we r va ria b ility. 7

Co rre la tio n with NAO a nd o the r mo de s • Pre dic to r mo de l b a se d o n line a r re g re ssio n using c lima te indic e s. • I ndic e s o b ta ine d fro m Clima te Pre dic tio n Ce nte r (NOAA, a va ila b le fro m 1950 o nwa rds). • Mo de l is tra ine d o ve r the pe rio d o f hindc a st da ta b y minimising the va ria nc e . 8

9 Co rre la tio n with NAO a nd o the r mo de s

10 Co rre la tio n with NAO a nd o the r mo de s

11 Co rre la tio n with NAO a nd o the r mo de s

Ang ula r pa rtitio ning a t F o rtie s 205°-5° No nline a r pre dic to r mo de l fo r b e tte r c o rre la tio n fo r lo c a tio ns in No rth Se a . 12

Pro xy inde x b a se d o n pre ssure fie lds fo r re c o nstruc tio n prio r to 1950 • Using re c o nstruc te d winte r pre ssure fie lds fro m L ute rb a c he r (2002). Re f: L ute rb a c he r, J., E . Xo pla ki, D. Die tric h, R. Ric kli, J. Ja c o b e it, C. Be c k, D. Gya listra s, C. Sc hmutz, a nd H. Wa nne r (2002), Re c o nstruc tio n o f se a le ve l pre ssure fie lds o ve r the E a ste rn No rth Atla ntic a nd E uro pe b a c k to 1500, Clima te 13 Dyna mic s, 18 (7), 545–561.

Re c o nstruc te d o c e a n wa ve po we r a t Orkne y 25% va ria tio n 14

T he M4 wa ve po we r ma c hine – Pro f. Pe te r Sta nsb y • T hre e -flo a t syste m se pa ra te d b y ha lf a wa ve le ng th. • Bro a db a nd fre q ue nc y re spo nse in irre g ula r wa ve s. http:/ / www.ma c e .ma nc he ste r.a c .uk/ 15

Re c o nstruc te d pra c tic a l wa ve po we r e xtra c te d b y the M4 ma c hine a t Orkne y 10% va ria tio n 16

E stima ting 100-ye a r sto rm se ve rity • Via the mo st pro b a b ly ma ximum individua l wa ve he ig ht in a sto rm, � �� (se e T ro ma ns a nd Va nde rsc hure n 1995). • Pe a ks-o ve r-thre sho ld, thre sho ld va lue = 1000 la rg e st sto rms fo r 54 ye a rs o f da ta , whic h c o rre spo nds to a b o ut 20 sto rms pe r winte r, ro ug hly 1-2 pe r we e k. • Ma ximum like liho o d me tho d a s e stima to r fo r e xpo ne ntia l-type ta il. • F ive -ye a r sliding windo w a na lysis to o b ta in te mpo ra l va ria b ility o f � �� . Re f: T ro ma ns a nd Va nde rsc hure n (1995), Re spo nse b a se d de sig n me tho d in the No rth Se a : Applic a tio n 17 o f a ne w me tho d, in Offsho re T e c hno lo g y Co nfe re nc e , OT C 7683, Ho usto n.

Co rre la tio n with the te le c o nne c tio ns • Sa me pre dic to r mo de l a s the me a n wa ve c lima te c o rre la tio n, e xc e pt a ll NAO, E A a nd SCA indic e s a re lo w pa ss filte re d (mo ving a ve ra g e ) o f 5 ye a rs. F ive -ye a r sliding windo w: 18

Re c o nstruc tio n o f e xtre me a nd me a n wa ve c lima te F o r o pe n No rth-Atla ntic lo c a tio ns: va ria tio ns o f me a n a nd e xtre me wa ve c lima te a re c o mpa ra b le . 19

Re c o nstruc tio n o f e xtre me a nd me a n wa ve c lima te F o r No rth Se a lo c a tio ns: va ria tio ns o f me a n a nd e xtre me wa ve c lima te a re diffe re nt. 20

I n c o nc lusio n: • I s the re a n a ve ra g e wa ve c lima te a t a pa rtic ula r lo c a tio n? Yes, but the aver age has to be oversever al decades as ther e is a lot of decadal var iability (in gener al). • Are the wa ve s o ve r the la st 25 – 50 ye a rs a re lia b le g uide to the ne xt 25 o r 100 ye a rs? Maybe? Depending on what the NAO is doing. • T he a va ila b le wa ve re c o rds a re to o sho rt, is the re a wa y to infe r a lo ng e r time histo ry fo r wa ve c lima te b a c k to the pa st (o ve r 400 ye a rs)? Yes, by establishing a str ong link with the NAO. 21

Ac kno wle dg e me nt We tha nk BP Sunb ury fo r pro viding the wa ve da ta a nd a c kno wle dg e suppo rt fro m UKE PSRC thro ug h pro je c t SMART Y. F o r mo re info rma tio n: • Sa nto , H., T a ylo r, P. H., Wo o lling s, T ., & Po ulso n, S. (2015). De c a da l wa ve po we r va ria b ility in the No rth ‐ E a st Atla ntic a nd No rth Se a . Ge o physic alRe se arc h L e tte rs , 42 (12), 4956-4963. • Sa nto , H., T a ylo r, P. H., Wo o lling s, T ., & Gib so n, R. (2015). De c a da l va ria b ility o f e xtre me wa ve he ig ht a s a me a sure o f sto rm se ve rity in the No rth ‐ E a st Atla ntic a nd No rth Se a . Ge o physic alRe se arc h L e tte rs (submitte d) . • Sa nto , H., T a ylo r, P. H., E a to c k T a ylo r, R. a nd Sta nsb y, P. (2015). De c a da l Va ria b ility o f Wa ve Po we r Pro duc tio n in the No rth-E a st Atla ntic a nd No rth Se a fo r the M4 Ma c hine . Re ne wable E ne rgy (submitte d) . 22