Seasonal variations in SAGE II background aerosols in the upper troposphere and lower stratosphere SAGE II 論文の要点まとめ 庭野 将徳 2 Sep, 2007

Stratospheric Background Aerosol (SBA) - Mean Vertical profiles of SBA: Vertical decrease in the number of particles at larger mode in the lower stratosphere [Thomason & Peter, 2006] Vertical decrease of the amount of carbonaceous aerosols in the lower stratosphere [Murphy et al., 2007] => How is the vertical profile of SAGE II Reff ? - Seasonal cycle in SBA: [Hitchman et al., 1994] Above 26 km, the enhanced uplift of aerosols in summer with the suppressed uplift or horizontal mixing in winter (contrast of winter vs summer) At km, rapid horizontal transport and mixing => How is the role of microphysics and dynamics ? (Also how is the hemispheric difference and tropical variations ?)

Aerosol formation in tropical upper troposphere (TUT) - In UTU, cold temperature, much water in the cloud region => Aerosol formation: the production of OH, and consequently of gaseous H2SO4 Aerosol loss: the uptake of gaseous H2SO4 & SO2, and the homogeneous freezing of aerosol particles to form cirrus clouds However, the horizontal distribution of aerosols on the whole global in UTU is still unclear …

b l,  & R eff (2.5S-N) at 24 km (Fig.1) Before Pinatubo:  & Reff are larger than those in After Pinatubo: -1998~ for b & b ~ for b 1.02, a & Re => use data for to remove interannual variability 3.1. Time variation ↑ El Reventador (Nov 2002) ↑ Pi ↑ Ruiz ↑ Rev

Seasonal Amplitude (Fig.2) b (%) R eff (%) 3.2. Seasonal Cycle Large amplitude > 15% 1) at 45S-40N above 26 km 2) at 14-21km & 15S-30N 3) over high latitudes above 18 km 4) Below 14 km in subtropics to mid- latitudes -> 1), 2) のみ注目

b (%) R eff (%) Hemispheric Asymmetry, & a comparison with q w : - Above 26 km, large in SH for , but in NH for q w - Below 20 km: larger in NH for  (& q w from other study) q w (ppmv) Seasonal Amplitude (Fig.2)

Climatological b (Fig. 3) 20-30S 5S-SN 20-30N 30 km: be out-of-phase between NH & SH 18 km: be in-phase between NH, Eq, and SH 30 km 18 km Min In late spring Max In early winter Min In late winter Max In early winter Min In Apr-Aug Min In Apr-Aug Min In Apr-Aug

E (Fig. 4) JanApr JulOct km 90S Eq 90N 3. Very small value at o below 16 km in winter-spring 2.Decline of isolines from winter to spring (most robust in spring-summer) 1. Peak value and altitude over tropics decrease toward higher latitudes

R eff ( mm ) (Fig. 5) km small large vertical decrease ~26km: steadily exists even in A isoline gap depelops with the isoline decline from local fall to winter, and is prominent in local winter-spring Reff value ranges in below 28 km

E & R eff over 10S-N (Fig.6) km Jan Jan E : Tape recorder signal up to 24 km ( q w ~32 km), E 0.452, q w : in phase DryWet Small values Large values R eff & E : the uplift of isoline in Jan-Mar, anomalies in Jan-Jun & Jun-Jan E : Phase reversal at the peak altitude (28 km)

Month-altitude sections of E (Fig.7) km Downward propagation of positive/negative anomalies down to 26 km Above 26 km, the decline of E 0452 peak altitude in local fall-spring (28-23 km in SH, km in NH) => larger decline in SH ! => larger amplitude of E in SH Negative in local winter-summer & positive in local summer-winter at 30 km

20-30S Month-altitude sections of E (Fig.7) km negative positve 20-30N Upward phase propagation only in NH Below 16 km: a negative in local winter At km: a negative in Mar-Jul both in NH & SH with large amplitude in NH positve negative

Horizontal map of b at 14 km (Fig. 8) Feb Aug H H H H Very small value of  in the winter subtropics at 14km Corresponding to anti-cyclonic outflow from convective area Summer value: larger value than winter value