Earth s energy imbalance and implications By J. Hansen, M. Sato, P. Kharecha, and K. von Schuckmann

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1 Comments on the Pper rth s energy imblnce nd implictions By J. Hnsen, M. Sto, P. Khrech, nd K. von Schuckmnn Gerhrd Krmm 1 nd Rlph Dlugi 2 1 University of Alsk Firbnks, Geophysicl Institute 903 Koyukuk Drive, P.O. Box , Firbnks, AK , USA 2 Arbeitsgruppe Atmosphärische Prozesse (AGAP), Gernotstrße, D Munich, Germny Abstrct: In our comments we gretly welcome the ttempt of Hnsen et l. to evlute vrious uncertinties inherent in geophysicl dt deduced by using different mesuring concepts nd observtion methods. However, from view of the energetic cycle, this pper rises some questions which we will discuss. We will show tht the energy imblnce of the entire rthtmosphere system is, indeed, bsed on these inherent uncertinties. We will demonstrte tht the ccurcy in the quntifiction of the globl energy flux budget s climed by Hnsen et l. is, by fr, not chievble in cse of the entire rth-tmosphere system. 1. Introdcution With gret interest we red the pper of Hnsen et l. (2011). specilly we gretly welcome the evlution of vrious uncertinties inherent in geophysicl dt deduced by using different mesuring concepts nd observtion methods. But from view on the energetic cycle, this pper rises some questions. They will be discussed in the following. In section 2 we

2 demonstrte the interreltion between the so-clled climte feedbck eqution nd the climte sensitivity. The physicl bckground of the globl energy budget of the rth s tmosphere system is nlyzed in Section 3. The rditive imblnce s climed by Hnsen et l. (2011) is ssessed in section 4. Finlly, we conclude tht the ccurcy in the quntifiction of the globl energy flux budget s climed by Hnsen et l. (2011) is, by fr, not chievble in cse of the entire rth-tmosphere system. 2. The interreltion between the climte feedbck eqution nd the climte sensitivity qution (1) of Hnsen et l. (2011) reds: T eq S =. (1) F Here, S is the so-clled climte sensitivity prmeter, temperture, Teq is the chnge of the globl surfce T s, from the equilibrium of the undisturbed system to tht of the system disturbed by the nthropogenic rditive forcing F. This eqution is bsed on the so-clled climte feedbck eqution which hs its origin in the globl energy blnce model of Schneider nd Mss (1975) for the wter lyer of the thickness ϑ w of n qu plnet given by dts S0 R = ( 1 α) FIR,TOA ( Ts ). (2) dt 4 ( ) Here, ( ) ( ) 1 α S 4 = 1 α Θ, θ, φ S cos Θ is the solr rdition energeticlly relevnt for the system rth - tmosphere, S 0 is the solr constnt, A α is the plnetry lbedo in the solr rnge, R = Cw ϑ w is the plnetry inerti coefficient, where C w is the het cpcity of wter, T is the surfce temperture, nd cos Θ 0 = cos θsin δ+ sin θcos δ cos h is the locl s zenith ngle of the Sun s center, where δ is the solr declintion ngle, nd h is the hour ngle from the locl meridin. Furthermore, θ nd φ re the zenith nd zimuthl ngles in the

3 sphericl coordinte frme, respectively. These ngles chrcterize the given loction. Moreover, the surfce verge of the globe, 2009) A, is defined by (e.g., Riley et l., 1998; Krmm et l., r ΦdΩ 1 Φ = = ΦdΩ dω 4 π 2 Ω A 2 r Ω Ω, (3) where Φ is n rbitrry quntity, r is the rdius of the globe, Ω= 4 π is the solid ngle of sphere, nd dω= sin θdθdφ is the differentil solid ngle. The term on the left-hnd side of q. (2) is not entirely correct. It must red R dtm dt, where Tm = T is the volume-verged temperture for this lyer (see Krmm nd Dlugi, V 2010). To replce T m by T s is generlly invlid. However, if dtm of sttionry stte the different mening of T m nd T s becomes insignificnt. dt tends to zero like in cse Following Schneider nd Mss (1975), q. (2) should describe the chnge of the surfce temperture of n qu-plnet with respect to time s function of the energeticlly relevnt 1 α S4, nd the outgoing infrred (IR) rdition counted for the top of the solr rdition, ( ) tmosphere (TOA), F IR,TOA. The ltter is given by FIR,TOA = FIR, +τ FIR, (4) where FIR, F IR, (, ) A the spce nd reching the TOA, F (, ) F T (, ) = θφ is the IR rdition emitted by the entire tmosphere in the direction of ( ) τ = τ θφ θφ is the IR rdition emitted IR IR s A by the rth s surfce, nd τ is the integrl trnsmissivity of the tmosphere in the IR rnge. Note tht the TOA my be interpreted s height of the intervening tmospheric lyer. Above this height neither solr rdition nor IR rdition is notbly ffected by tmospheric constituents.

4 Schneider nd Mss (1975) expressed F F ( T ) = s function of the surfce IR,TOA IR,TOA s temperture using Budyko s (1969, 1977) empiricl formul, { } ( ) ( ) F = + b T T + b T T n. (5) IR,TOA s r 1 1 s r Here, = W m 2, empiricl coefficients, T r b 2.26 W m K 2 1 =, 1 2 = 48.4 W m, nd = re b 1.61 W m K = K is the reference temperture, nd n is the normlized cloud cover. This mens tht this empiricl formul (5) implies ll rditive effects in the IR rnge, i.e., () the bsorption nd emission of IR rdition by the so-clled greenhouse gses hving either nturl or nthropogenic origin, nd (b) the IR rdition tht is emitted by the rth s surfce nd propgting through the tmosphere (it lso includes the terrestril rdition tht is pssing through the tmospheric window). Inserting formul (5) into q. (2) nd considering cler-sky conditions provides dt dt s R =Q Ts λ, (6) with S0 Q= ( 1 α) + btr (7) 4 nd 1 λ= S = b, i.e., the sensitivity prmeter S is the reciprocl of the so-clled feedbck prmeter λ. qution (6) is customrily clled the climte feedbck eqution. If we interpret T s s generlized coordinte nd dts dt s the corresponding generlized velocity nd ssume tht Q is independent of time, we my trnsfer q. (6) into the phse spce, where it is considered s one-dimensionl model becuse it hs only one degree of freedom (Lnge, 2007). As the feedbck prmeter, λ, is positive, the solution of q. (6) tends to n ttrctor given by dts dt = 0, the condition of the fixed point (e.g., Krmm nd Dlugi, 2010).

5 If we insert F into q. (7) relevnt for cler-sky conditions, we will obtin ( d) S Q = ( 1 α) + b Tr + RF, (8) 4 where the superscript ( d ) chrcterizes the disturbed cse. Now, q. (6) cn be solved using qs. (7) nd (8) lterntively. Thus, we obtin two stedy-stte solutions: one for the undisturbed cse nd one for the system disturbed by F resulting in ( d) ( d) Q Q F Teq = Teq Teq = = = SF λ λ λ. (9) Rerrnging this eqution provides formul (1). Thus, close interreltion between the climte feedbck eqution nd the climte sensitivity exists (e.g., Dickinson, 1985; Berger nd Tricot, 1986; Ntionl Reserch Council, 2005). 3. Bsic reltions for the globl energy budget of the rth-tmosphere system The globl energy blnce eqution for the upper lyer of n qu-plnet reds (see lso q. (A17) of Krmm nd Dlugi, 2010, nd Figure 1) dt S0 = ( α ). (10) dt 4 m R 1 A H Hw FIR A S 4 = A Θ, θφ, S cos Θ is the bsorption of solr rdition by the entire Here, ( ) A A is the plnetry bsorption coefficient in the solr rnge, H= H ( θφ, ) A tmosphere, where nd = ( θφ, ) A re the fluxes of sensible nd ltent het, respectively. Furthermore, the net rdition t the rth s surfce in the infrred rnge, FIR, is given by

6 ( ( )) ( ) ( ) F = F T θφ, ε θφ, F θφ,, (11) IR IR s A IR A ( ) where F T s ( θφ, ) is the emitted infrred rdition, F IR (, ) IR rdition, nd ε ( ) ( ) w w A θφ is the down-welling infrred θφ, 1 is the locl emissivity t the rth s surfce. Moreover, H = H θφ, represents the exchnge of het between the upper lyer of the qu-plnet nd the deeper lyers nd/or the ocen floor, respectively. The ltter is usully ignored so tht q. (10) becomes dt S0 = ( α ). (12) dt 4 m R 1 A H FIR However, in cse of the wter lyer under study H w might be contributing to n energy imblnce. Dlugi, 2010): A similr eqution cn be derived for the tmosphere (see lso q. (A18) of Krmm nd d S0 ϑ C T = V A F IR,TOA + H + + F, (13) IR dt 4 where ϑ is the thickness of intervening tmospheric lyer (i.e., between the rth s surfce nd the TOA), T is the tmospheric temperture, nd might express the term of the left-hnd side of this eqution by C is the het cpcity. Similr to q. (10) we d d d ϑ C T = C V ϑ T = R V T, (14) V dt dt dt but this is crude simplifiction. Such simplifictions my ply role in lecture rooms to describe some effects qulittively, but they hve to be voided in rel scientific studies becuse they re, by fr, not fulfilled. Compring q. (10) with q. (2) yields:

7 S0 FIR,TOA = A + H+ + FIR. (15) 4 This reltion is only vlid if the following condition is fulfilled: d S0 ϑ C T = V 0 = A F IR,TOA + H + + F IR. (16) dt 4 This mens tht the tmosphere must lwys be in sttionry stte. It is unlikely tht this condition is generlly fulfilled. Nevertheless, if this condition is inserted into q. (10), one will obtin (see lso Siegenthler nd Oeschger, 1984; Berger nd Tricot, 1986): dt S0 = ( α ). (17) dt 4 m R 1 FIR,TOA Hw Ignoring H w s mentioned before leds to q. (2). If the plnetry rdition blnce t the TOA is fulfilled s suggested by Trenberth et l. (2009) nd mny others (see Tble 1), i.e., S 1 α FIR,TOA = 0, (18) 4 ( ) 0 then q. (12) will red: S0 0= ( 1 α A ) H FIR. (19) 4 In cse of long-term globl verges this energy flux budget is fulfilled, but lrge sctter exists (see Tble 1). Here, it is indispensbly to cite Fortk (1971). In his textbook on meteorology he stted:

8 »The cycle of the long-wve rdition between tht rth s surfce nd the tmosphere does not contribute to the heting of the system. The outgoing emission of infrred rdition of 64 % only serves to mintin the rditive equilibrium t the top of the tmosphere.«note the vlue of 64 % hs to be updted to 70 % for both the energeticlly relevnt solr rdition nd the outgoing IR rdition. 4. On the rditive imblnce t the TOA If the outgoing infrred rdition is reduced by F due to the nthropogenic effect, q. (15) my be written s (d) S0 FIR,TOA = FIR,TOA F= A + H+ + FIR F, (20) 4 where, gin, the superscript ( d ) chrcterizes the disturbed cse. This would men, for instnce, tht the net rdition t the rth s surfce is reduced by F, suggesting, in principle, higher down-welling infrred rdition, ( ) { } F F= F T ε F + F. (21) IR IR s A IR A However, this does not utomticlly men tht the surfce temperture must increse, s suggested by q. (1), to re-estblish plnetry rdition blnce t the TOA, chrcterized by q. (18), s lredy rgued by Rmnthn et l. (1987) nd now repeted by Hnsen et l. (2011):

9 »The bsic physics underlying this globl wrming, the greenhouse effect, is simple. An increse of gses such s CO 2 mkes the tmosphere more opque t infrred wvelengths. This dded opcity cuses the plnet s het rdition to spce to rise from higher, colder levels in the tmosphere, thus reducing emission of het energy to spce. The temporry imblnce between the energy bsorbed from the Sun nd het emission to spce, cuses the plnet to wrm until plnetry energy blnce is restored.«this rgument is physiclly incorrect becuse none of these flux terms on the right-hnd side of 1 A S 4 q. (12), i.e., ( ) α 0, H,, nd FIR, depends on the globlly verged surfce temperture. Furthermore, there is no constnt rtio between H+ on the one hnd nd FIR on the other hnd (see Tble 1). A reduction of FIR by F my esily be compensted by H nd/or to fulfill the requirement of the energy flux budget (19). The sme is true in cse of ny other of these flux terms. Note tht even the Bowen rtio B = His not constnt (see Tble 1). The uncertinty inherent in the determintion of these fluxes is so lrge tht F my be ssessed s noise in the energy flux budget for the rth s surfce (e.g., Krmm nd Dlugi, 2009). In the cpture of their Figure 17 (repeted here for the purpose of convenience s Figure 2) Hnsen et l. stted:»recent estimtes of men solr irrdince (Kopp nd Len, 2011) re smller, ± 0.5 W m 2, but the uncertinty of the bsolute vlue hs no significnt effect on the solr forcing, which depends on the temporl chnge of irrdince.«this rgument hs to be discussed with respect to the recently mesured nd better qulity controlled vlues of the solr irrdince (see Figure 3). If F IR,TOA is reduced by F generting plnetry rditive imblnce t the TOA, q. (18) must be written s

10 S 1 α FIR,TOA = F. (22) 4 0 (d) ( ) Thus, the mount of F = 0.58 ± 0.15W m 2 (the energy imblnce for the period deduced by Hnsen et l., 2011, see subsection 14.4) is notbly smller thn tht of the quntity ( ) α S S 0.88 W m (23) 0,old 0,new if plnetry lbedo of α = 0.3 is ssumed s suggested by Figure 4. Here, nd S0,new S0,old = 1366 W m 2 = 1361 W m. The ltter completely grees with tht of Lue nd Drummond (1968) which is bsed on direct observtions t n ltitude of 82 km. ven the 30-yer men of the Smithsonin Institution (Aldrich nd Hoover, 1952) ws slightly more ccurte thn. Note tht the vribility illustrted in Figure 17 (here Figure 2) of Hnsen et l. (2011) is only relted to S. This vribility does not chrcterize the difference S0,old S0,new. This difference hs to 0,old be ssessed s procedurl error. Consequently, one my rgue tht in cse of the youngest result for the solr constnt the outgoing IR rdition would slightly be lrger thn the energeticlly relevnt solr rdition. Thus, F would become negtive or vnish, i.e., - ccording to q. (9) - Teq 0. It should be noticed tht lredy Duffy et l. (2009) completely ignored the observtionl evidence provided by SORC/TIM since 2003 (see Figure 3). S 0,old 2 Finlly, it is worthy to tke look on the 240 W m, ccording to Hnsen et l. (2011, see subsection 13.2) the solr energy verged over the plnet's surfce. First of ll, it is the mount of the solr rdition tht ffects the entire erth-tmosphere system, i.e., it is the 1 α S 4. According to Trenberth et l. (2009) nd energeticlly relevnt solr rdition ( ) 0 mny others, the solr rdition reching the rth's surfce is much smller (see Tble 1). If vlue of α = 0.3 is used, the solr constnt tht corresponds to S W m must be 2 = 1371 W m. This is vlue which ws delivered by erly stellite observtions (see Figure 3). Additionlly, slight vrition of the plnetry lbedo by α = ± 0.01 (see Figure 4) leds 2

11 to chnge in the energeticlly relevnt solr rdition by ssumed. ± 3.4 W m 2 if S0 2 = 1361 W m is 5. Finl remrks nd conclusions Kopp nd Len (2011) lredy stted:»instrument inccurcies re significnt source of uncertinty in determining rth s energy blnce from spce bsed mesurements of incoming nd reflected solr rdition nd outgoing terrestril therml rdition. A nonzero verge globl net rdition t the top of the tmosphere is indictive of rth s therml disequilibrium imposed by climte forcing. But wheres the current plnetry imblnce is nominlly 0.85 W m 2 [Hnsen et l., 2005], estimtes of this quntity from spce bsed mesurements rnge from 3 to 7 W m 2. SORC/TIM s lower TSI vlue reduces this discrepncy by 1 W m 2 [Loeb et l., 2009]. We note tht the difference between the new lower TIM vlue with erlier TSI mesurements corresponds to n equivlent climte forcing of 0.8 W m 2, which is comprble to the current energy imblnce.«this mens tht Hnsen et l. (2005, 2011) hve lredy overdone their estimtes of the plnetry energy imblnce. Bsed on our findings we, therefore, conclude tht the ccurcy in the quntifiction of the globl energy flux budget s climed by Hnsen et l. (2011) is, by fr, not chievble in cse of the entire rth-tmosphere system. References: Aldrich R.B., nd Hoover W.H.: The solr constnt, Science, 116, 3, 1952.

12 Berger, A., nd Tricot, C.: Die Modellierung des Spurengseinflusses uf ds Klim, promet 1 86, 1-9, 1986 (in Germn). Budyko M.I.: The effect of solr rdition vritions on the climte of the rth, Tellus, 21, , Budyko M.I.: Climtic chnge, Americn Geophysicl Union, Wshington, D.C., Budyko, M.I.: The rth's climte, pst nd future, Interntionl geophysics series, Acdemic Press, New York, Dickinson, R..: Climte sensitivity, Advnces in Geophysics, 28A, , Duffy, P.B., Snter, B.D., nd Wigley, T.M.L., Solr vribility does not explin lte-20thcentury wrming, Physics Tody, 48-49, Fortk, H., Meteorologie, in: von Brun, W. (ed.), Ds Wissen der Gegenwrt, Deutsche Buch- Gemeinschft, Berlin/Drmstdt/Wien, 1971 (in Germn). Fröhlich, C., nd Len, J.: The Sun s totl irrdince: Cycles nd trends in the pst two decdes nd ssocited climte chnge uncertinties, Geophys. Res. Lett., 25, , Hnsen, J., Nzrenko, L., Ruedy, R., Sto, M., Willis, J., Del Genio, A., Koch, D., Lcis, A., Lo, K., Menon, S., Novkov, T., Perlwitz, J., Russell, G., Schmidt, G. A., nd Tusnev, N.: rth s energy imblnce: Confirmtion nd implictions, Science, 308, , doi: /science , Hnsen, J., Sto, M., Khrech, P. nd von Schuckmnn, K.: rth s energy imblnce nd implictions, Atmos. Chem. Phys., 11, , Hltiner, G.J., nd Mrtin, F.L.: Dynmicl nd physicl Meteorology, McGrw-Hill Book Compny, New York/Toronto/London, Hrtmnn, D.L.: Globl physicl climtology, Interntionl geophysics, Acdemic Press, Sn Diego, Henderson-Sellers, A., nd Robinson, P.J.: Contemporry climtology, Longmn Scientific & Technicl; Wiley, London/New York, 1986.

13 Kiehl, J.T., nd Trenberth, K..: rth's nnul globl men energy budget, Bull. Amer. Met. Soc., 78(2), , Kopp, G., nd Len, J.L.: A new, lower vlue of totl solr irrdince: evidence nd climte significnce, Geophys. Res. Lett., 38, L01706, doi: /2010gl045777, Krmm, G., nd Dlugi, R.: On the Accurcy with which the lower boundry conditions cn be determined in numericl models of the tmosphere ( Krmm, G., Dlugi, R., nd Zelger, M.: Comments on the Proof of the tmospheric greenhouse effect by Arthur P. Smith Krmm, G., nd Dlugi, R.: On the mening of feedbck prmeter, trnsient climte response, nd the greenhouse effect: Bsic considertions nd the discussion of uncertinties, The Open Atmospheric Science Journl, 4, , Krmm, G., Dlugi, R.: Scrutinizing the tmospheric greenhouse effect nd its climtic impct, Nturl Science, 3, , Lnge H.-J.: Wetter und Klim im Phsenrum. Summry of two presenttions to climte in the phse spce ( Lue.G., nd Drummond A.J.: Solr constnt: First direct mesurements, Science; 116, , Liou, K.N.: An Introduction to Atmospheric Rdition - Second dition, Acdemic Press, Sn Diego, CA, McCrcken, M.C.: Crbon dioxide nd climte chnge: Bckground nd overview, in: M.C. McCrcken, M.C., nd Luther, F.M. (eds.), Projecting the climtic effects of incresing crbon dioxide, U.S. Deprtment of nergy, 1985, Ntionl Reserch Council (NRC): Rditive forcing of climte chnge: xpnding the concept nd ddressing uncertinties, Ntl. Acd., Wshington, D.C., Pltridge, G.W., nd Pltt, C.M.R.: Rditive processes in meteorology nd climtology, Developments in tmospheric science, lsevier Scientific Pub. Co., Amsterdm; New York, 1976.

14 Peixoto, J.P., nd Oort, A.H.: Physics of climte, Americn Institute of Physics, New York, Rmnthn, V.: The role of rth rdition budget studies in climte nd generl-circultion reserch, J. Geophys. Res.-Atmos., 1987, 92(D4): Rmnthn, V., Cllis, L., Cess, R., Hnsen, J., Isksen, I., Kuhn, W., Lcis, A., Luther, F., Mhlmn, J., Reck, R., nd Schlesinger, M.: Climte-chemicl interctions nd effects of chnging tmospheric trce gses, Rev. Geophys., 25(7): , Riley, K.F., Hobson, M.P., nd Bence, S.J.: Mthemticl methods for physics nd engineering, Cmbridge University Press, Cmbridge, UK, Rossow, W.B., nd Zhng, Y.C.: Clcultion of surfce nd top of tmosphere rditive fluxes from physicl quntities bsed on ISCCP dt sets 2. Vlidtion nd first results, J. Geophys. Res.-Atmos., 100(D1): , Schneider, S.H.: Climte modeling, Scientific Americn, 256(5): 72-80, Schneider, S.H., nd Mss, C.: Volcnic dust, sunspots, nd temperture trends, Science, 190: , Siegenthler, U., nd Oeschger, H.: Trnsient temperture chnges due to incresing CO 2 using simple models, Ann. Glciology, 5, , Trenberth, K.., Fsullo, J.T., nd Kiehl, J.: rth s globl energy budget, Bull. Amer. Met. Soc., , United Sttes Committee for the Globl Atmospheric Reserch Progrm, Understnding climtic chnge: progrm for ction, Ntionl Acdemy of Sciences, Wshington, Vrdvs, I.M., nd Tylor F.W.: Rdition nd climte, Oxford University Press, Oxford, U.K., 2007.

15 Tble 1: Summry of the rth s energy budget estimtes (with respect to Kiehl nd Trenberth, 1997). The sources [1], [2], nd [15] re inserted, nd source [9] is updted (dopted from Krmm nd Dlugi, 2011). rth s surfce Atmosphere TOA Source ( ) 1 α A S4 R L H A α [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [1] Hltiner nd Mrtin (1957), [2] Fortk (1971), [3] United Sttes Committee for the Globl Atmospheric Reserch Progrm (1975), [4] Budyko (1982), [5] Pltridge nd Pltt (1976), [6] Hrtmnn (1994), [7] Rmnthn (1987), [8] Schneider (1987), [9] Liou (2002), [10] Peixoto nd Oort (1992), [11] McCrcken (1985), [12] Henderson-Sellers nd Robinson (1986), [13] Kiehl nd Trenberth (1997), [14] Rossow nd Zhng (1995),nd [15] Trenberth et l. (2009).

16 Figure 1. Sketch of the globl energy flux budget for the upper lyer of n qu-plnet (dopted from Krmm nd Dlugi, 2010).

17 Figure 2. Solr irrdince from composite of severl stellite-mesured time series. Dt through 2 Februry 2011 is from Fröhlich nd Len (1998 nd Physiklisch Meteorologisches Observtorium Dvos, World Rdition Center). Updte in 2011 (through 24 August) is from University of Colordo Solr Rdition & Climte xperiment normlized to mtch mens over the finl 12 months of the Fröhlich nd Len dt. Recent estimtes of men solr irrdince (Kopp nd Len, 2011) re smller, ± 0.5 W m 2, but the uncertinty of the bsolute vlue hs no significnt effect on the solr forcing, which depends on the temporl chnge of irrdince (dopted from Hnsen et l., 2011).

18 Figure 3: Stellite observtions of totl solr irrdince. It comprises of the observtions of seven independent experiments: () Nimbus7/rth Rdition Budget experiment ( ), (b) Solr Mximum Mission/Active Cvity Rdiometer Irrdince Monitor 1 ( ), (c) rth Rdition Budget Stellite/rth Rdition Budget xperiment ( ), (d) Upper Atmosphere Reserch Stellite/Active cvity Rdiometer Irrdince Monitor 2 ( ), (e) Solr nd Heliospheric Observer/Vribility of solr Irrdince nd Grvity Oscilltions (lunched in 1996), (f) ACRIM Stellite/Active cvity Rdiometer Irrdince Monitor 3 (lunched in 2000), nd (g) Solr Rdition nd Climte xperiment/totl Irrdince Monitor (lunched in 2003). The figure is bsed on Dr. Richrd C. Willson s erth_obs_fig1, updted on June 23, 2011 (see

19 Figure 4. Long-term ( ) time series of monthly verged plnetry lbedo (dopted from Vrdvs nd Tylor, 1987).