Background solar irradiance and the climate of the Earth in the end of the 20th century

A mosphe ic and Clima e Sciences, 2012, 2, 191-195 h p://dx.doi.o g/10.4236/acs.2012.22019 Published Online Ap il 2012 (h p://www.SciRP.o g/jou nal/acs) 191 Backg ound Sola I adiance and he Clima e o he Ea h in he End o he 20 h Cen u y Maxim Ogu so 1,2, Ma kus Lindholm3, Ris o Jalkanen3 1Io e Physico-Technical Ins i u e, Russian Academy o Sciences, S . Pe e sbu g, Russia 2Gene al As onomical Obse a o y a Pulko o, S . Pe e sbu g, Russia 3Me la, Ro aniemi, Finland Email: maxim[email p o ec ed] e. u Recei ed Janua y 13, 2012; e ised Feb ua y 26, 2012; accep ed Ma ch 9, 2012 ABSTRACT The possible esponse o global clima e o he changes o backg ound adia ion de i ed om sa elli e measu emen du ing 1983-2001 is analyzed. Es ima ion is made by means o one-dimensional ene gy-balance clima ic model. I is shown ha he inc ease o he global su ace adia ion by 3 W × m–2 h ough 1983-2001 should esul in a co espond- ing ise o empe a u e, which exceeds he ac ual obse ed alues by 0.6˚C - 2.0˚C. Possible causes o such disag ee- men a e discussed. Keywo ds: Clima e; Sola I adiance 1. In oduc ion I is gene ally ag eed ha he global wa ming o ecen decades is caused p ima ily by an h opogenic inc ease o g eenhouse gases concen a ion [1,2]. Howe e , no only human-made a ia ions o a mosphe ic composi ion in- luence global clima e. Changes in he clima e o he Ea h depend e iden ly on he backg ound sola i adi- ance, i.e. on he amoun o sho wa e sola adia ion in- coming in o he a mosphe e and he ac ion o his a- dia ion, which is e lec ed back o he space. Recen e i- dence show ha sola adia ion inciden a he Ea h’s su ace has inc eased app eciably in he end o 20 h cen- u y [3]. The phenomenon is o en called a global b igh- ening. Es ima ions o he adia i e o cing (Figu e 1) global pe u ba ion o he adia ion balance o he e es- ial a mosphe e—a e based on he ollowing da a: 1) Sola adia ion a he Ea h’s su ace, a e aged o e he globe, which was de i ed in he wo k [4] om he da a on cloudiness ob ained in amewo k o he In e na- ional Sa elli e Cloud Clima ology P ojec (ISCCP) du - ing 1983-2001; 2) Globally-a e aged change in sola adia ion a he Ea h’s su ace du ing 1984-2003, de i ed om he da a on he Ea h’s e lec ance ob ained by Palle e al. [5] using ISCCP da a and he da a on dayside ea hligh e- lec ed om he Moon. 3) A e age o he 8 eco ds o anomalies in g ound- based obse a ions o he sola adia ion inciden on he Ea h’s su ace du ing 1993-2001 [6]. Change in backg ound sola adia ion h ough 1983- 2001 causes a posi i e adia i e o cing anging om 3 W × m–2 o 6 - 7 W × m–2 [3] (Figu e 1). I we ake a alue o clima ic sensi i i y adop ed by IPCC (  с = 0.53˚C - 1.23˚C × m2/W) [2], we ob ain ha inc ease o he global empe a u e by 1.5˚C - 3.6°C is a esul o he adia i e o cing o 3 W × m–2. Thus, an inc ease o he amoun o sola adia ion ha eaches Ea h’s su ace in he end o he 20 h cen u y, de e mined in di e en ways, should cause a jump o he global empe a u e, which, howe e , has no been obse ed. O cou se, he o e sim- pli ied es ima ion abo e is no su icien o any decisi e conclusion. A mo e p ecise model assessmen is neces- sa y. In he p esen wo k such an e alua ion is done by means o he ene gy-balance clima e model. 2. Ene gy-Balance Model o Global Clima e In amewo k o he ene gy balance app oach, changes in he clima e sys em a e es ima ed om an analysis o he change in he Ea h’s hea s o age. The basis o hese models was in oduced by Budyko and Selle s [7,8]. In i s simples o m, ene gy-balance model p o ides glob- ally a e aged alues o he compu ed a iables. We use he su ace-ene gy balance clima e model coupled wi h deep ocean wi h ho izon ally uni o m e ical hea di u- sion and a cons an upwelling:      d d sSW LW inc ou oc c T qF F F F  C opy igh © 2012 SciRes. ACS M. OGURTSOV ET AL. 192 Figu e 1. Sho -wa e adia i e o cing assessed by means o : (a) Sa elli e-de i ed su ace adia ion ( he da a we e elec- onically scanned and digi ized om [4]); (b) Su ace a- dia ion es ima ed using he da a on he Ea h’s albedo [5] (solid line wi h squa es), su ace adia ion es ima ed using he da a on g ound-based measu emen (dashed line wi h he emp y ci cles). The da a we e elec onically scanned and digi ized om [3,4].    2 2 ,, OO z Tz Tz k z    , O z Tz w z     T  ,Tz  SW inc (1) whe e: s is he global-mean su ace empe a u e, o is he global-mean empe a u e o he ocean a he dep h z, q is he e ec i e plane a y hea capaci y, F  LW ou is he abso bed sho -wa e sola adia ion, F  is he ou going long-wa e e es ial adia ion, oc F is he hea exchange be ween he su ace and he deep laye s o he ocean,   c F   oc desc ibes he di e en adia i e o cings, kz is he e ical hea di usion coe i- cien , wz is an upwelling eloci y. F is exp essed as:    0 , z O z wTz d, 1 d O oc z Tz F k hz         (2) whe e h is he dep h o he mixed ocean laye .   1 4 S SW inc F    LW ou (3) S( ) is he o al sola i adiance (TSI) o he sola con- s an ,  is he e es ial albedo. F is exp essed as a linea unc ion o TS:   00 LW ou S F abT  0.144 0.096qh (4) E ec i e global hea capaci y is de e mined by o - mula, gene alizing he esul s o [9]:   NET (5) whe e q in W × y × m–2 × K–1, h in me e s. 3. Resul s Clima e o cings used in calcula ions (Figu e 2) we e as ollows. G eenhouse gases o cing and an h opogenic ( oposphe ic) ae osol o cing was aken om [10]. Vol- canic (s a osphe ic) ae osol o cings we e aken om [11]. We used h ee TSI econs uc ions ob ained in he wo ks [12-14]. The o al (ne ) clima e o cing F  calcula ed using TSI econs uc ion [14] is shown in Fig- u e 2( ). The same o cing bu conside ing he amoun o sola adia ion ha eaches he Ea h’s su ace de i ed om sa elli e obse a ions N ET F   0 T   00T  S is shown in Figu e 2(g). The model (1) was sol ed by he me hod o con- secu i e app oxima ion. Ini ially we ob ained he em- pe a u e in a ze o app oxima ion S by solu ion o he i s equa ion o he model (1) wi h he ini ial condi- ion S = 14.6˚C and wi hou he accoun o he hea lux om he ocean, i.e.  oc F     = 0. Then he sec- ond equa ion o (1) is sol ed wi h he ini ial condi ion: 0 ,0 0 exp z OpSp z zw Tz T T T k           0 0, OS T T  (6) and he ollowing bounda y condi ions: (7)   ,, O z Ozpz zH Tz kTz wTw z      (8) The second bounda y condi ion [15] desc ibes balance o he hea luxes—di usion and upwelling nea a bo - om compensa e he powe ul sink o cold wa e o e he a eas o he deep wa e o ma ion (G eenland, No we- gian and Lab ado seas in No he n Hemisphe e, Wed- dell and Ross seas in Sou he n Hemisphe e). The pola sea empe a u e Tp was equal o 1.2˚C [15] and he dep h o he ocean H was conside ed o be 5000 m. The solu- ion o he second equa ion o (1) wi h condi ions (6-8) b ings us   ,Tz   0,Tz   0,Tz   1 T   2   3 T O. A e his we sol e he i s equa ion o (1) de e mining he O wi h o mula (2) by using O. This esul s in he i s app oxima ion o he su ace empe a u e S. Repea ing he p o- cedu e b ings o he app oxima ions S T , S e c., bu he i s app oxima ion usually is enough. Cal- cula ions a e pe o med by using he ollowing pa ame- Copy igh © 2012 SciRes. ACS M. OGURTSOV ET AL. Copy igh © 2012 SciRes. ACS 193 Figu e 2. Clima e o cings (in W × m–2) used in calcula ions. (a) G eenhouse gases o cing [10]; (b) Human-made ae osol o cing [10]; (c) To al sola i adiance econs uc ions a e Hoy and Scha en ([12], hick line), Lean e al. ([13], do ed line), Mo d ino e al. ([14], hin line); (d) Volcanic ae osol o cing [11]; (e) Sa elli e-de i ed backg ound adia ion [4]; ( ) Ne o c- ing wi hou he accoun o a sa elli e-measu ed adia ion; (g)-( ) Ne o cing wi h he accoun o a sa elli e-measu ed adia- ion. Time esolu ion 0.5 yea . e s o he model: kz = 3000 m2 × y –1, wz = 5 m × y –1, h = 150 m, α = 0.3, q = 14.6 W × y × m–2 × K–1, a0 = 204.0 W × m–2, b0 = 2.05 W × m–2 × K–1. The ne o cing N ET F  and TSI econs uc ion [14] a e used in calcula- ions (Figu e 3(a)). S anda d de ia ion be ween he empe a u e calcula ed om he model and ins umen- ally measu ed empe a u e h ough 1880-2009 is 0.15. Da a on he global empe a u e we e aken om he si e p:// p.ncdc.noaa.go /pub/da a/anomalies/mon hly.land _ocean.90S.90N.d _1901-2000mean.da . The use o o he TSI eco ds in calcula ions b ings simila esul s. The model cu e ep oduces se e al impo an ea u es o he global-mean su ace empe a u e (Figu e 3(a)). Howe e , i we use he o al o cing N ET FS, which akes in o ac- coun he global b igh ening, he di e gence be ween he model and ac ual empe a u e eaches 2˚C, i.e. hi een imes mo e han he modeling e o is (Figu e 3(b)). Such disag eemen , in p inciple, could appea i he long- wa e emission   LW ou F du ing he las decades di e s app eciably om he p e ious alues. The e o e i is use- M. OGURTSOV ET AL. 194 Figu e 3. (a) Ins umen al global empe a u e ( p:// p.ncdc.noaa.go /pub/da a/anomalies/, hin line), global empe a u e calcula ed om he model using ne o cing ΔFNET ( hick line); (b) Ins umen al global empe a u e ( hin line), global empe a u e calcula ed om he model using ne o cing ( hick line). Time esolu ion 0.5 yea . NET S F ul o es he model o e he ime in e al 1983-2001. Fi ing o he model pa ame e s o e 1983-2001 showed ha he bes ag eemen be ween he calcula ed and ac ual empe a u e is eached when a0 = 205.0 W × m–2, b0 = 2.2 W × m–2 × K–1 (Figu e 4, mon hly da a we e used). S anda d de ia ion be ween he calcula ed and ins u- men ally measu ed empe a u e o e 1983-1999 is 0.13. Howe e du ing 1999-2001 he wo cu es appa en ly di e ge and he di e ence eaches 0.6˚C (almos 5 imes mo e han he e o o e 1983-1999). As in he p e ious case, calcula ion using he ene gy balance model, which conside s he da a o he su ace adia ion measu emen , g ea ly o e es ima es he ac ual empe a u e. 4. Conclusions An analysis o he possible clima e esponse o he changes in sola adia ion a he Ea h’s su ace based on sa elli e measu emen s [4] du ing 1983-2001, pe o med by means o bo h quali a i e es ima ions and calcula ions o he ene gy-balance model, sugges ha he obse ed inc ease o he backg ound adia ion by 3 W × m–2 should esul in a s ong ise o he global empe a u e, which exceeds he ac ually measu ed alues by 0.6˚C - 2.0˚C. I we use he o he expe imen al es ima ions o global b igh ening, which p o ides 6 - 7 W × m–2 o cing h ough 1983-2001 [3], he disag eemen would be e en la ge . I has been sugges ed ha he global b igh ening s a - ing in 1990s was p eceded by p olonged global dimming subs an ial dec ease in su ace sola adia ion du ing he pe iod 1960-1990 [16-18]. Thus, sola b igh ening o ecen decades only compensa es p e ious dec ease in sola adia ion and does no app eciably change he global empe a u e end, caused by g eenhouse e ec [17,18]. I should be no ed, howe e , ha he spa ial co e age o he su ace adia ion s a ions, which da a we e used in he wo ks [16-18], is a he limi ed—all he s a ion a e si ua ed o e he land and hey a e clus e ed a he domains o high popula ion densi y—see Figu e 1 o he wo k [18]. Mo eo e e idence has been ob ained ha he dimming o 1950-1980 ac ually was no global bu had local o egional na u e and was obse ed mainly o e Figu e 4. Ins umen al global empe a u e ( p:// p.ncdc.noaa.go /pub/da a/anomalies/, hin line), global empe a u e calcu- a ed om he model using ne o cing ( hick line). Time esolu ion 1 mon h. NET S Fl Copy igh © 2012 SciRes. ACS M. OGURTSOV ET AL. 195 a eas o high indus ial ac i i y [19]. The e o e i is di - icul o make a decisi e conclusion abou he global- scale change in he su ace sola adia ion o e 1960-1990. Thus, we conclude ha he expe imen al es ima ions o sola adia ion ha eaches he Ea h’s su ace appa en ly con adic wi h he ac ually measu ed global empe a- u es a leas in he amewo k o he ene gy balance ap- p oach. We belie e ha he disag eemen could be a e- sul o he ollowing causes: 1) The o e simpli ied ene gy-balance app oach is no enough o analysis o he p ocesses in a eal clima e sys em. 2) The ise o empe a u e, caused by a global b igh - ening du ing 1983-2001, has been compensa ed by a cu - en ly unknown, ex a cooling ac o . In any case, he eac ion o a global clima e sys em o changes in backg ound adia ion in he end o he 20 h cen u y needs u he p o ound in es iga ion using he no el global ci cula ion models. 5. Acknowledgemen s M. G. 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