Download - Seasonal variations in SAGE II background aerosols in the upper troposphere and lower stratosphere
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 16-22 km, rapid horizontal transport and mixing
=> How is the role of microphysics and dynamics ? (Also how is the hemispheric difference and tropical varia
tions ?)
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 …
& Reff (2.5S-N) at 24 km (Fig.1)Before Pinatubo:
& Reff are larger than those in 2000-2003
After Pinatubo:
-1998~ for &
-2000~ for & Re
=> use data for 1998-2004 to remove interannual variability
3.1. Time variation
↑El Reventador (Nov 2002)
↑ Pi
↑ Ruiz
↑ Rev
Seasonal Amplitude (Fig.2)
0.452 (%)
Reff (%)
3.2. Seasonal Cycle
Large amplitude > 15%1) at 45S-40N above 26
km2) at 14-21km & 15S-30N3) over high latitudes above
18 km4) Below 14 km in subtropics
to mid-latitudes -> 1), 2) のみ注目
0.452 (%)
Reff (%)
Hemispheric Asymmetry, & a comparison with qw :
- Above 26 km, large in SH for , but in NH for qw
- Below 20 km: larger in NH for (& qw from other study)
qw (ppmv)
Seasonal Amplitude (Fig.2)
Climatological0.452 (Fig. 3) 20-30S 5S-SN 20-30N
30 km: be out-of-phase between NH & SH18 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
0.452 (Fig. 4)
Jan Apr
Jul Oct
32
16
0
km
90S Eq 90N
3. Very small value at 20-30o 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
Reff (m) (Fig. 5)
32
16
0
km
small
largevertical decrease ~26km: steadily exists even in 2000-2003
A isoline gap depelops with the isoline decline from local fall to winter, and is prominent in local winter-spring
Reff value ranges in 0.19-0.20 below 28 km
0.452 & Reff over 10S-N (Fig.6)
32
24
16
km
Jan Jan
0.452: Tape recorder signal up to 24 km (qw~32 km),
0.452, qw : in phase
Dry Wet
Smallvalues
Largevalues
Reff & 0.452: the uplift of isoline in Jan-Mar, anomalies in Jan-Jun & Jun-Jan
0.452: Phase reversal at the peak altitude (28 km)
--
-
Month-altitude sections of 0.452
(Fig.7)km30
20
10
Downward propagation of positive/negative anomalies down to 26 km
Above 26 km, the decline of E0452 peak altitude in local fall-spring (28-23 km in SH, 27-24 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 0.452
(Fig.7)
km30
20
10
negative negative
negative positve
20-30N
Upward phase propagation only in NH
Below 16 km: a negative in local winter
At 16-18 km: a negative in Mar-Jul both in NH & SH with large amplitude in NH
positve negative
Horizontal map of 0.452 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