Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-08.14, Japan. H. Gernandt, R. Neuber. Alfred Wegener Institute for Polar and Marine ...
Journal of the Meteorological Society of Japan, Vol. 76, No. 4, pp. 549-560, 1998
Size and Number
Concentration
of Liquid
at Ny-Alesund,
By M. Hayashi,
Norway
PSCs:
Balloon-Borne
in Winter
549
Measurements
of 199495
Y. Iwasaka,1 M. Watanabe,
T. Shibata
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-0814, Japan M. Fujiwara Laboratory of Applied Physics, Fukuoka University, Fukuoka 814-0180, Japan H. Adachi, T. Sakai, M. Nagatani Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-08.14,Japan H. Gernandt,
R. Neuber
Alfred Wegener Institute for Polar and Marine Research, Potsdam D-14401 and M. Tsuchiya Shonan Institute of Technology,Tsujido-Nishikaigan,Fujisawa p51-8511, Japan (Manuscript received 28 January 1998, in revisedform 80 April 1998) Abstract Size (radius: 0.15-1.8 um) and number concentration of polar stratospheric clouds (PSCs) were observed with a balloon-borne particle counter at Ny-Alesund, Norway (79N, 12E) in winter of 1994/95 (December 18, 1994and January 17, 1995). The measurements suggested that PSCs actively formed in the cold winter stratosphere. During the balloon-borne measurements, the depolarization ratio of PSCs was monitored with a lidar near the balloon observational site to see the phase (liquid or solid) of PSCs. Both measurements suggested that many sub-layers were contained in the PSCs. Particle size distribution of the early PSCs event (December 18, 1994) was different from that observed on January 17, 1995, after active PSCs events. This difference possibly suggests that particle formation processes were largely disturbed by redistribution of chemical constituents relating with PSCs formation and growth in the polar winter stratosphere. Lidar measurements suggested active formation of liquid phase PSCs in addition to solid phase PSCs. The number-size distribution pattern showed enhancement of the number of particles with their radius larger than 1.8,am in the solid state sub-layer of PSCs. On the other hand, not only large particles (r > 1.8 um) but also smaller particles (r=0.25-0.6um) were enhanced in the liquid state PSCs.
1. Introduction Polar stratospheric clouds (PSCs) have been believedto play an important role in large ozonedeple1
Corresponding author: Yasunobu Iwasaka, Solar-Terrestrial Environment Laboratory, Nagoya Univ., Nagoya 464-0814, Japan 1998, Meteorological Society of Japan
tion in the polar stratosphere through heterogeneous reaction including PSCs. The nature of PSCs is a large concern because PSCs convert inert chlorine to active chlorine. Extensive research in the past 10 years has produced a outline of PSCs structure and composition (McCormick et al., 1985;Iwasaka et al., 1985, 1986; Hanson et al., 1988; Browell et al., 1990;
550
Journal
of the
Meteorological
Society
of Japan
Vol. 76, No. 4
Pool et al., 1990; Toon et al., 1990; Wofsy et al., nically difficult. Fortunately, simultaneous mea1990; Hamill and Toon, 1991; Dye et al., 1992; surements of PSCs with a lidar and balloon-borne Middlebrook et al., 1993; Molina et al., 1993;Beyer particle counter were made at Ny-Alesund, Noret al., 1994; Carslaw et al., 1994; Larsen, 1994; way (79N, 12E) in winter of 1994/1995 as part Luo et al., 1994; Tabazadeh et al., 1994; Anthony of cooperative measurements between Japan (Solaret al., 1995; Toon and Tolbert, 1995). According Terrestrial Environment Laboratory, Nagoya Unito those studies the particles have been classified versity and Laboratory of Applied Physics, Fukuoka into type I and II, according to their size and forUniversity) and Germany (Alfred WegenerInstitute mation temperature. It is widely recognized that for Polar and Marine Research) . Here, we showed type II PSCs consist of ice particles. On the other the size and number concentrations of various types hand, composition and phase of type I PSCs rePSCs on the basis of the measurements. mains uncertain. Type I PSCs are a particularly 2. Observation and results interesting form of stratospheric aerosol, because the condensed volume of type I PSCs cannot be 1 Balloon-borne measurements on particle size explained by the formation of ice particle and/or and number concentration by growth of liquid H2SO4-1120droplets with water The main specification of the balloon-borne optivapor uptake (Carslaw et al., 1997). The particles cal particle counter used here is summarizedin Table containing lots of HNO3 could account for the ob1, and the optical system of the particle counter is servation of type I PSCs (e.g., Crutzen and Arnold, schematically shown in Fig. 1. The details of the 1986; Toon et al., 1986). Amounts of nitric acid vacounter were described in a paper by Tsuchiya et al. por in the Arctic stratosphere were consistent with (1996). Particle size discrimination is made at 0.15, the particle sizes estimated from the lidar observa- 0.25, 0.4, 0.6, and 1.8 um (in radius) on the basis tions. They were soon corroborated in laboratory of a laboratory experiment for the refractive index experiments (e.g., Hanson and Mauersberger,1988), of particulate matter, n=1.4+Oi (for sulfuric acid which showedthat particles of nitric acid trihydrate droplet of about 70 wt. %, which is referred from the calculated values of Steele and Hamill (1981), and (NAT; HNO3.3H2O) would be stable under the polar stratospheric conditions. Someinvestigators sugthe observational values of Baumardner et al. (1996) gested that background H2SO4-H20 droplets froze in the stratosphere). The sizingrange of the counter in the polar winter stratosphere and subsequently will be easily modified when we treat other aerosol served as sites for NAT nucleation and growth (e.g., materials that have different refractive indices. Poole and McCormick,1988; Fahey et al., 1989). Atmospheric particle size and number concentraDespite the widespread acceptance of solid PSCs tion were observed with a balloon-borne particle particles (NAT and ice) in the decade since discov- counter at Ny-Alesund,Norway (79N, 12E) on Deery of the ozone hole, the freezing mechanism of cember 18, 1994and January 17, 1995 (Fig. 2). The the background H2504-H20 droplets remains unstatistical uncertaintyin countingis about 3, 10, certain. 32, and 100% for particle concentrationsof 1, 0.1, Some observations contradicted the particle for0.01, and 0.001cm-3, respectively.Therefore,the mation model for type I PSCs by solid NAT (Dye relativeerror range of number concentrationof the et al., 1992;Toon and Tolbert, 1995;Carslaw et al., particleswith radius>0.25m can be estimated, 1997). Then, type I PSCs were classified into two forexample,as about 4 %at 18km wherenoticeable sub-types, called type Ia of solid particles and type peakof numberconcentrationwasfoundin the meaIb liquid particles (Dye et al., 1992). Most recently surementsof December18, 1994.However,the error Shibata et al. (1997) suggested, on the basis of the rangebecomeslargerthan about 56 % aboveabout lidar measurements made at Ny-Alesund, Norway 21km, sincethe numberconcentrationbecomesvery low. The mass mixingratio of particulatematter, (79N, 12E), that a relatively large size droplet PSCs layer (called type X in the paper) appeared calculatedusingEq. (1), is also shownin Fig. 2. frequently and the layer was accompaniedby a solidMR=((Nl-N2) x4/3xrrxri2 state PSCs layer in the Arctic winter stratosphere. However,lidar observations cannot obtain the exact +(N2-N3)x4/3xrrxr23 size distribution and concentration of PSCs parti+(N3-N4) x4/3xrrxr34 cles, even though they are very important to under+(N4-N5) x4/3xrrxr45 stand the role of PSCs on the ozone depletion and -FNsx4/3xrrxr5)xdx109/p, the mechanism of PSCs development. (1) There are, although a great deal of observational work continues in the Arctic region, few reports describing PSCs particle size distribution measured where MR: mass mixing ratio of particulate with a particle counter, since performing balloonmatter ranging from 0.15 am to borne measurements in the Arctic winter was tech1.8 um in radius (ng/g),
August
1998
M. Hayashi, Table
Fig.
1.
Optical
810 nm particulate
of the
for source
balloon-borne
light
M. Watanabe
of Balloon-Borne
particle
and photo-diode
Optical
counter.
is used
and
et al.
Particle
A laser
as a detector
551 Counter.
diode
with
a wave
of forward-scattering
length light
of from
matter.
Nn:
integrated particle number concentration for channel n (cm-3), and discrimination radii for channel 1, 2, 3, 4, and 5 are 0.15, 0.25, 0.4, 0.6, and 1.8 um, respectively,
mm:
mean radius for channel n and m (cm),
rn:
and
system
is used
1. Specification
Y. Iwasaka,
radius for channel n (cm),
d:
specific density of particulate matter, assumed as 1.5 (g/cm3),
p:
air density (g/cm3),
it:
the circular constant; 3.1416.
The observations indicate the existenceof particle sub-layers in which mass mixing ratio was enhanced; peak height of layers were 22 km (A) and 18 km
(B) in the measurements of December 18, 1994. Below the enhanced sub-layers, the broad particle layer (possibly the background sulfate layer) was found from about 12.5 to 16 km in altitude. In the measurements of January 17, 1995, aerosol sub-layers (A, B, and C) were identified because of following reasons. Sub-layer B (around 18 km) is characterized by enhancement of particle concentration whose radius is larger than 0.4 um. Sub-layerA (around 20 km) and sub-layer C (around 15.5 km) are characterized by enhancement of mass mixing ratio and/or particle concentration whose radius is larger than 1.8 im. Temperature distributions of December 18, 1994 and January 17, 1995 are compared with the frost point of nitric acid trihydrate (NAT: Type I PSCs) in Fig. 3. The frost point temperatures of nitric acid vapor on the surface of NAT and water vapor on the surface of ice are estimated, under the assumed
552
Journal
(a)
(b)
1994.12.18
of the
Meteorological
Society
of Japan
Vol. 76, No. 4
13:17UT
1995.01.17 11:24UT
Fig. 2. Vertical profiles of particle concentration of particle radius larger than 0.15, 0.25, 0.4, 0.6, and 1.8 am measured with a balloon-borne particle counter at Ny-Alesund, Norway (79N, 12E). Profiles of mass mixing ratio of particulate matter, calculated by Eq. (1) (see text), are also shown in right panels. (a) profiles observed on December 18, 1994. Polar stratospheric clouds contained sub-layers A and B showing enhancement of number concentration and/or mass mixing ratio. (b) profiles observed on January 17, 1995. Polar stratospheric clouds contained sub-layer A, B, and C.
August
1998
M. Hayashi,
Y. Iwasaka,
M. Watanabe
and
et al.
553
18-Dec-94 17-Jan-95 ---
NAT(N10W5)
--t-- NAT(N5W5) -+-
NAT(N1W5)
--*--NAT(N10W3) -0-
Ice(W5)
--0- Ice(W3)
Fig. 3. Vertical profiles of stratospheric temperature measured at Ny-Alesund, Norway (79N, 12E) during the measurements of aerosol concentration (December 18, 1994 and January 17, 1995). "NAT" and "ICE" mean the frost point temperatures of nitric acid trihydrate particles and ice crystal particles, respectively. Assumed mixing ratios of HN03 and water vapor are indicated by (NxWy), which means HN03 mixing ratio of x ppbv and water vapor of y ppmv.
atmospheric condition that mixing ratio of HNO3 and 1120 are 10, 5, 1 ppbv and 5, 3 ppmv respectively,on the basis of the laboratory experiments by Hanson and Mauersberger (1988), Jaecker-Voirolet al. (1990), and Luo et al. (1995). These values are referred from observational values of stratospheric water vapor (e.g., Kelly et al., 1990; Pruvost et al., 1993; Overlez and Overlez, 1994), and of nitric acid vapor (e.g., Clarmann et al., 1993; Oelhaf et al., 1994; Murcray et al., 1994; Hofner et al., 1996). From the temperature distributions, it is suggested that stratospheric temperature decreased the expected threshold temperature of PSCs (Type I) formation in those days. Comparing the stratospheric temperature of December 18, 1994 and January 17, 1995, the stratosphere of January 17 was apparently colder (Fig. 3). Assumingthe equilibriumcondition, larger mass content of particulate matter were expected during the lower temperature (January 17) rather than the higher one (December 18). However,sub-layer B of December 18 had the largest mass content of 5.7 ng/g in the measurements (Fig. 2), which suggested that PSCs growth was affected by not only cold temperature, but also some other factors.
2.2 Lidar
measurements
The scattering ratio (definedby Eq. (2)), depolarization ratio (defined by Eq. (3)), and Angstrom exponent (defined by Eq. (4)) are obtained by the lidar to know temporal and spacial changes in concentration, phase, and size distribution of PSCs, respectively. Detailed description of specification of the lidar used here was given by Shibata et al. (1997). The scattering ratio and depolarization ratio are defined here by the followingrelations; (2) R Scattering Ratio=3/t1=(i31+/32)/32 and (3) 6= Depolarization Ratio=321/(82+321), where j1 and 32are backscattering coefficientof atmospheric moleculesand atmospheric aerosolparticles, respectively. Total backscattering coefficient 3 contains both components of molecules and aerosols, and suffixes and 1 mean parallel and perpendicular components, respectively, of backscattering light to the optical plane of emitted laser light. Therefore, the value of (R-1)=32 31 can be recognized as the mixing ratio of particulate matter measured by a lidar. The depolarized component in backscattering light from Rayleigh scattering of atmospheric molecules is extremely low (S=about 0.4%),
554
Journal
of the
Meteorological
Society
of Japan
Vol. 76, No. 4
and the depolarized component of backscattering tion of PSCs in the Arctic stratosphere (Figs. 4 and light from non-spherical particles becomes notice- 5). Enhancement of depolarization ratio larger than ably high. Therefore it is easy to detect nonabout 1.0 % was also observed frequently, however spherical particles such as crystalized PSCs (e.g., it did not correspondto the enhancement of scatterShibata et al., 1997) or tropospheric soil particles ing ratio. Enhancement of the scattering ratio with a low depolarization ratio was sometimes observed, (Iwasaka et al., 1988) from the measurements of defor example around 18 km in altitude on January polarized ratio of particulate matter. Angstrom exponent c is defined here by follow- 10, 1995. A similar feature was suggested on the ing relation: (4) a=-ln(3MI/l3M2)/ln(1064/532), analysis of lidar measurements in 1989 AASE (Airwhere 13M1 and 3M2 are aerosol backscattering coef- borne Arctic Stratospheric Expedition) (Browell et ficients at 1064 and 532 nm, respectively. The larger al., 1990). They revealed two sub-classes of Type I value of c shows more rich for smaller particle in PSCs (crystals of Type Ia and droplets of Ib), both the size distribution of aerosols,and values of a for appearing at temperature at, or below, the equilibbackground stratospheric aerosols is about 1.4. rium threshold point of NAT, but higher than ice Temporal changes in scattering ratio and depofrost point. Shibata et al., (1997) suggested that larization ratio are shown in Fig. 4. It is clear that liquid phase PSCs containing large size particles freaerosol scattering ratio and depolarization ratio bequently formed, on the basis of the lidar measurecome frequently larger than the background value ments of developed PSCs with high scattering ratio in mid-January, 1995, at Ny-Alesund. They suggest (S=1.3 and S=0.4%), which was extremely enhanced during December 1994 and January 1995 that there are distinct types of liquid PSCs (called type Ib and type X in their paper) with different (Fig. 4). size distributions. Therefore, at least, three types 3. Discussion of nitric acid PSCs were observed during the PSCs Recently great interest has been focused on the event, from mid-December 1994 to the end of Janvariety of types of PSCs in the Arctic winter stratouary 1995over Ny-Alesund. The most active PSCs sphere on the basis of lidar measurements (Browell with a high scattering ratio (larger than 5.0) was obet al., 1990; Toon et al., 1990;Carslaw et al., 1997; servedin mid-January. Therefore, the balloon-borne Shibata et al., 1997), since the variety is caused observation of December 18, 1994was carried out at by differencesof particle size, phase, and materials, an early step of PSCs events, and that of January which affect ozone destruction processes and devel17, 1995was carried out at the end of a stable polar opment of PSCs. Nevertheless, information on the vortex condition after active PSCs events. size of PSCs has been extremely limited, since few In Fig. 6 we show the vertical distribution of the measurements have been simultaneously made with scattering ratio, depolarization ratio, and Angstrom a lidar and a particle counter. We successfullymade exponent measured on December 18, 1994and Jansimultaneous measurements of PSCs with a lidar uary 17, 1995 when balloon-borne particle counters and a balloon-borne particle counter at Ny-Alesund, were sounded. Two sub-layers are identified for DeNorwayon December 18, 1994and January 17, 1995. cember 18. The upper one is characterized by high Atmospheric temperature distribution in winter depolarization ratio (larger than 1.0%), and another of 1994/1995 was monitored on the basis of rouone is characterized by high scattering ratio (larger tine measurements of meteorologicalsonde at Nythan 2.0) and low depolarization ratio. On January Alesund (Fig. 5). Stratospheric temperature rapidly 17, three sub-layers are identified. The middle one decreased in mid December of 1994 corresponding has a high scattering ratio (larger than 2.0), and to the polar vortex formation in the Arctic stratothe upper and lower ones have a high depolarization sphere. Then, the cold region where the temperratio (larger than 1.0 %). ature was lower than the expected threshold of Two sub-layers PSCs, found in size-number conNAT formation was frequently observed from midcentration and/or mixing ratio of December 18, 1994 December to the end of January. Variation of tem(Fig. 2), show good correspondence to the peaks of scattering ratio measured simultaneously, but not perature in the stratosphere was not so large from mid-December1994to the end of January 1995,and completely to peaks of depolarization ratio (Fig. become large after the end of January 1995. This 6). From the profiles of the depolarization ratio of showsthat the polar vortex had been stable and cov- December 18, it is suggested that sub-layer B was ering over Ny-Alesund from mid-December1994 to mainly composed of liquid phase particles, since valthe end of January 1995. ues of S showed a noticeable minimum and/or low Enhancement of scattering ratios (larger than 1.4 (0.4-0.8%) near the peak height of sub-layer B. around 18 km and 1.1 above 20 km in altitude) On the other hand, it is suggested that sub-layer was frequently observedfrom mid-December1994to A contains non-sphericalparticles, by high values of the end of January 1995,according to decreases in S (larger than 1.0 %). stratospheric temperature, suggesting active formaIn the sub-layers found in size-number concentra-
August
1998
M. Hayashi,
Y. Iwasaka,
M. Watanabe
and
et al.
(a)
(b)
Fig. 4. Scattering ratio (a) and depolarization ratio (b) measured with the lidar at Ny-Alesund, Norway (79N, 12E) in winter of 1994/95. Enhancement of scattering ratio and depolarization ratio occurred in the middle of December and continued until the end of January. In early and mid-January 1995, the scattering ratio was extremely enhanced at about 20 km height.
555
556
Journal
of the
Meteorological
Society
of Japan
Vol. 76, No. 4
Fig. 5. Changes in atmospheric temperature over Ny-Alesund, Norway (79N, 12E) in winter of 199495. Launchings of balloon-borne particle counter are shown with arrows. (a)
1994.12.18
13:0415:05
UT
(b)
1995.01.17 10:4913:06
Fig. 6. Vertical profiles of scattering ratio (R; solid line), depolarization ratio (S; broken line), and Angstrom exponent (a; dotted line) observed with a lidar, simultaneously observed with a balloon-borne particle counter. Sub-layers of PSCs are shown by arrows (see text). a: 13:04-14:03 UT (thick line) and 14:06-15:05UT (thin line) on December 18, 1994. b: 10:49-11:36 UT (thick line) and 11:14-13:06UT (thin line) on January 17, 1995.
UT
August
1998
M. Hayashi,
Y. Iwasaka,
M. Watanabe
and
et al.
557
Fig. 7. Size distribution patterns of sub-layers of PSCs estimated on the basis of number-size of PSCs measurements shown in Fig. 2. Size distribution patterns of background sulfate aerosols, referred from Hofmann et al. (1990), are also shown by broken line and open symbols. Types of the symbols is corresponding to the types of size distributions of PSCs, respectively. Left: size distributions corresponding to sub-layers of high depolarization ratio observed with a lidar. Right: size distributions corresponding to sub-layers of low depolarization and high-scattering ratio observed with a lidar. Accumulate levels are shown in the legend.
tion and/or mixing ratio of January 17, 1995 (Fig. 2), we identified the layer showing good correspondence to peaks of scattering ratio or depolarization ratio (Fig. 6). The sub-layer B shown in Fig. 2a has high scattering ratio (about 2.0) and low depolarization ratio (less than 0.4 %), suggesting that this layer also is composed of liquid PSCs particles like the sub-layer B of December 18, 1994. On the other hand, the sub-layers of A and C of January 17 showed existence of particles with r > 1.8 um, even though such large particles are not normally found in the stratosphere. Corresponded sub-layers observed with the lidar (Fig. 6b) show a very small value in scattering ratio (1.2-1.3), and the value of 6 showed noticeable peak (larger than 1.0 %), suggesting that those sub-layers were composed of solid state particles. In Fig. 7 the size-number concentration pattern and integrated particle concentrations of the sublayers of PSCs are compared. A noticeable difference was found between particle size-number distributions of December 18, 1994 and those of January 17, 1995. For example, concentration of super micron particles larger than 1.8 um of the sublayers of December 18, 1994were a little larger than that of January 17, 1995. As described previously,
the mixing ratio of aerosols observed on 18 December, 1994 was also larger than that observed on 17 January, 1995. One possible interpretation for depletion of large particle concentration and mixing ratio is the descending motion of the particles with large size. As shown in Fig. 7, all of the sublayers included super micron particles larger than 1.8 pm in radius. The descending speed of the particles with radius of about 2 tm is expected to be about 1.0 mm/sec at about 20 km (about 1 km descent in half month), and they are expected to contain lots of HN03 and/or 1120. Then, the particles formed early in PSCs events may descend from the main PSCs layer during the PSCs events, transporting HN03 and/or H2O. Therefore, it is reasonable to consider that the densities of HN03, H2O, and others can be largely disturbed through descent of particulate matter from (or on) which those vapors evaporate (or condense) during the particle descending motion. In the patterns of particle size distribution of sub-layers (Fig. 7), liquid phase sub-layers of PSCs (curves of 12/18 B and 1/17 B) show an interesting feature. In those ticle concentrations ground
sulfate
two liquid phase sub-layers, parwere larger than those of back-
aerosol
not
only in sub-micron
size,
558
but
Journal
also
in super
micron
size.
of the
In addition,
Meteorological
the dis-
tribution pattern of 12/18 B shows a larger concentration of size range from 0.3 to 1.8 um in radius, comparing to that of 1/17 B. Shibata et al. (1997) suggest that PSCs sometimes contained large-size droplets (type X PSCs), although the exact size of particles cannot be deduced from lidar measurements. Sub-layers observed with a lidar (Fig. 6) corresponding to sub-layers 12/18 B and 1/17 B observed with balloon-borne measurements are classified into type X (a: less than 0.5) and type Ib (a: larger than 0.5), respectively. Then, it is suggested that curve 12/18 B shows one example of size distribution of type X PSCs and curve 1/17 B that of type Ib. In all of solid state sub-layers,sub-layers A of December 18 and A and C of January 17, had the size distribution showing a high concentration of particles larger than 0.4 um in radius. In addition, they show typical bimodal patterns, running parallel to the horizontal axis at radii larger than 0.4 um. This shows an existence of large particles of 1.8 um in radius, and lack of sub-micron particles ranging from 0.4 to 1.0 um in radius. On the other hand, the concentration of supermicron particles (r>1.8 Cm)in sub-layers observed on January 17, 1995 was less than that on December 18, 1994 (Fig. 7), eventhough the temperature on January 17 was lower than that on December 17 (Fig. 3). The present measurements of size distribution of solid state PSCs sub-layers suggestthat supermicron particles composing early step PSCs had already fallen by January 17, by descending motion of NAT or ice particles, as described above. In the present study, we measured particle concentration only at a size range from 0.15 am to 1.8 1Cm. It is necessary to know the density distributions of the particles with radius smaller than those in order to better understand PSCs formation. In addition, it is necessary to know larger particle concentration in order to understand transport of constituents by PSCs descending motion. Information of temporal variation of PSCs size distribution also is necessary, and therefore balloon sounding should occur quite frequently. 4. Summary Balloon-borne measurements of stratospheric aerosol size, made in winter of 1994/95 at NyAlesund, showed the followingfeatures of PSCs; i) In mid-December, 1994 polar stratospheric clouds appeared corresponding to a decrease in stratospheric temperature. ii) From the measurements of vertical profiles of size-number concentration, the enhanced aerosol layer under the cold atmospheric temperature showed multi-layer structure, and
Society
of Japan
Vol. 76, No. 4
those layers corresponded well to the peaks of scattering ratio and/or depolarization ratio of particulate matter observed simultaneously with a lidar. iii) The number-size distribution patterns of PSCs measured in December 18, 1994 noticeably differed from those of January 17, 1995, and suggested that PSCs particle growth rate and/or production rate were largely disturbed during the PSCs event, possibly due to decrease (or increase) of gases relating with PSCs. iv) The number-size distribution pattern of liquid sub-layer of PSCs showed enhancement of concentration of particles with in sub-micron range. Concerning super-micron range particles, large enhancement was found in December 18, 1994and small enhancement in January 17, 1995. Those enhancement in super-micron particles basically agreed with the suggestion that large size droplets were detected with a lidar (Shibata et al., 1997). v) The number-size distribution pattern of solid state PSCs showed enhancement in supermicron particles and therefore showed good agreement with the suggestion that crystalized type I PSCs had relatively large size (Browell et al., 1990). However, at the end of January, redistribution of nitric acid seemed to occur through the descending motion of NAT or ice particles during PSCs events. Acknowledgments This research was supported by the Japan Ministry of Education, Science, Sports and Culture (Grant-in-aid for Creative Fundamental Research, Studies of Global Environmental Change with Special Reference to Asia and Pacific Region, Leader Prof. S. Tamura, University of Tokyo). Staff members of National Institute of Polar Research, Japan, and Kings Bay Kull Co., Norway, kindly helped us during the balloon-borne observations at NyAlesund. References Anthony, SE., R.T. Tisdale, R.S. Disselkamp,M.A. Tolbert and J.C. Wilson,1995:FTIR studies of low temperature sulfuric acid aerosols. Geophys.Res. Lett., 22, 1105-1108. Baumardner,D., J.E. Dye, B. Gandrud, K. Barr, K. Kerry and KR. Chan, 1996: Refractiveindices of aerosolsin the upper troposphereand lowerstratosphere. Geophys. Res. Lett., 23, 749-752. Beyer, K.D., SW. Seago, BY. Chang and M.J. Molina, 1994: Composition and freezing of aqueous H2SO4/HN03solutions under polar stratospheric conditions. Geophys. Res. Lett., 21, 871-874.
August
1998
M. Hayashi,
Y. Iwasaka,
Browell, E.V., C.F. Butler, S. Ismail, P.A. Robinette, A.F. Carter, N.S. Higdon, O.B. Toon, MR. Schoeberl and A.F. Tuck, 1990: Air-borne lidar observations in the wintertime arctic stratosphere: polar stratospheric clouds. Geophys. Res. Lett., 17, 385-388. Carslaw, KS., B.P. Luo, S.L. Clegg, T. Peter, P. Brimblecombe and P.J. Crutzen, 1994: Stratospheric aerosol growth and HN03 gas phase depletion from coupled HN03 and water uptake by liquid particles. Geophys.Res. Lett., 21, 2479-2482. Carslaw, KS., T. Peter and S.L. Clegg,1997: Modeling the composition of liquid stratospheric aerosols. Rev. Geophys.,35, 125-154. Clarmann, TV., H. Fischer, F. Friedl-Vallon,A. Linden, H. Oelhaf, C. Piesch, M. Seefeldnerand W. Volker, 1993: Retrieval of stratospheric 03, HN03, and C10N02 profiles from 1992 MIPAS-B limb emission spectra: Method, results, and error analysis. J. Geophys. Res., 98, 20495-20506. Crutzen, P.J. and F. Arnold, 1986: Nitric acid cloud formation in the Antarctic stratosphere: A major cause for the spring time "ozone hole." Nature, 324, 651-655. Dye, J.E., D. Baumgardner, B.W. Gandrud, SR. Kawa, K.K. Kelly, M. Loewenstein, G.V. Ferry, KR. Chan and B.L. Gary, 1992: Particle size distributions in arctic polar stratospheric clouds, growth and freezing of sulfuric acid droplets, and implication for cloud formation. J. Geophys.Res., 97, 8015-8034. Fahey, D.W., K.K. Kelly, G.U. Ferry, L.R. Poole, J.C. Wilson, D.M. Murphy, M. Lowenstein and KR. Chan, 1989: In situ measurements of total reactive nitrogen, total water, and aerosol in polar stratospheric cloud in the Antarctic. J. Geophys.Res., 94, 11299-11316. Hamill, P. and O.B. Toon, 1991: Polar stratospheric clouds and ozone hole. Phys. Today,44, 34-42. Hanson, D. and K. Mauersberger, 1988: Vapor pressures of HN03/H20 solutions at low temperatures. J. Chem. Phys., 92, 6167-6170. Hofmann, D.J., T. Deshler, F. Arnold and H. Schlager, 1990: Balloon observations of nitric acid aerosol formation in the Arctic stratosphere: II. Aerosol. Geophys. Res. Lett., 17, 1279-1282. Hofner, M., CE. Blom, T. Blumenstock, H. Fischer and T. Gulde, 1996: Evidence for the removal of gaseous HN03 inside the Arctic polar vortex in January 1992. Geophys.Res. Lett., 23, 149-152. Iwasaka, Y., 1986: Non-sphericalparticles in the Antarctic polar stratosphere -increase in particulate content and stratospheric water vapor budget-. Tellus, 38B, 214-222. Iwasaka, Y., T. Hirasawa and H. Fukunishi, 1985: Lidar measurement on the Antarctic stratospheric aerosol layer I Winter enhancement. J. Geomag. Geoelectr., 37, 1087-1095. Iwasaka, Y., M. Yamato, R. Imasu and A. Ono, 1988: Transport of Asian dust (KOSA) particles; importance of weak KOSA events on the geochemicalcycle of soil particles. Tellus, 40B, 494-503. Jaecker-Voirol, A., J.L. Ponche and P. Mirabel, 1990: Vapor pressure in the ternary system water-nitric
M. Watanabe
and
et al.
559
acid-sulfuric acid at low temperature. J. Geophys. Res., 95, 11857-11863. Kelly, K.K., A.F. Tuck, L.E. Heidt, M. Lowenstein, JR. Podolske, SE. Strahan and J.F. Vedder, 1990: A comparison of ER-2 measurements of stratospheric water vapor between the 1987 Antarctic and 1989 Arctic airborne missions. Geophys. Res. Lett., 17, 465-468. Larsen, N., 1994: The impact of freezing of sulfate aerosols of the formation of polar stratospheric clouds. Geophys. Res. Lett., 21, 425-428. Luo, B., KS. Carslaw, T. Peter and S.L. Clegg, 1995: Vapor pressure of H2S04/HN03/HC1/HBr/H20 solution to low stratospheric temperature. Geophys. Res. Lett., 22, 247-250. Luo, B., Th. Peter and P.J. Crutzen, 1994: Freezing of stratospheric aerosol droplets. Geophys. Res. Lett., 21, 1447-1450. McCormick, M.P., P. Hamill and U.O. Farrukh, 1985: Characteristics of polar stratospheric clouds as observed by SAMII, SAGE, and lidar. J. Meteorol. Soc. Japan, 63, 267-276. Molina, M.J., R. Zhang, P.J. Wooldridge, JR. McMahon, J.E. Kim, H.Y. Chang and K.D. Beyer, 1993: Physical chemistry of the H2S04/HN03/H20 system: Implications for polar stratospheric clouds. Science, 261, 1418-1423. Middlebrook, A.M., L.T. Iraci, L.S. McNeill, B.G. Koehler, OW. Saatah, M.A. Tolbert and DR. Hanson, 1993: FTIR studies of thin H2S04/H20 film: forming water uptake, and solid-liquid phase changes. J. Geophys. Res., 98, 20473-20481. Murcray, F.J., JR. Starkey, W.J. Williams, WA. Matthews, U. Schmidt, P. Aimedieu and C. Camy-Peyret, 1994: HN03 profiles obtained during the EASOE campaign. Geophys. Res. Lett., 21, 1223-1226. Oelhaf, H., T.V. Clarmann, H. Fischer, F. Friedl-Vallon, Ch. Fritzsche, A. Linden, Ch. Piesch, M. Seefeldner and W. Volker, 1994: Stratospheric C10N02 and HN03 profiles inside the Arctic vortex from MIPASB limb emission spectra obtained during EASOE. Geophys. Res. Lett., 21, 1263-1266. Overlez, J. and H. Overlez, 1994: Stratospheric water vapor content evolution during EASOE. Geophys. Res. Lett., 21, 1235-1238. Poole, L.R. and M.P. McCormick, 1988: Polar stratospheric clouds and the Antarctic ozone hole. J. Geophys. Res., 93, 8423-8430. Poole, L.R., S. Solomon, B.W. Grandrud, K.A. Powell, J.E. Dye, R.L. Jones and D.S. McKenna, 1990: The polar stratospheric cloud event of January 24, 1989, 1, Microphysics. Geophys.Res. Lett., 17, 537-540. Pruvost, P., J. Overlez, J. Lenoble and W.P. Chug 1993: Comparison of Stratospheric Aerosol and Gas Experiment II and balloon-borne stratospheric water vapor measurements. J. Geophys.Res., 98, 4889-4896. Steel, H.M. and P. Hamill, 1981: Effects of temperature and humidity on the growth and optical properties of sulfuric acid-water droplets in the stratosphere. J. Aerosol Sci., 12, 517-528. Shibata, T., Y. Iwasaka, M. Fujiwara, M. Hayashi, M. Nagatani, K. Shiraishi, H. Adachi, T. Sakai, K.
560
Journal
of the
Meteorological
Society
of Japan
Vol. 76, No. 4
An analysis of lidar observation of polar stratospheric clouds. Geophys. Res. Lett., 17, 393-396. Toon, O.B. and MA. Tolbert, 1995: Spectroscopic evidence against nitric acid trihydrate in polar stratospheric clouds. Nature, 375, 218-221. Tsuchiya, M., T. Kasai, M. Hayashi, Y. Iwasaka and K. Takami, 1996: Development of aerosol sonde for observation balloon. Keisoku Jidouseigyo Gakkai Ronbunsyu, 32, 290-296 (in Japanese). Wofsy, SR., G.P. Gobbi, R.J. Salawitch and MB. McElroy, 1990: Nucleation and Growth of HNO3 3H2O particles in the polar stratosphere. J. Atmos. Sci., 47, 2004-2012.
Susumu and Y. Nakura, 1997: Polar stratospheric clouds observed by lidar over Spitsbergen in the winter of 1994/1995: Liquid particles and vertical "sandwich" structure. J. Geophys. Res., 102, 1082910840. Tabazadeh, A., R.P. Turco, K. Drdia, M.Z. Jacobson and O.B. Toon, 1994: A study of type I polar stratospheric clouds formation. Geophys. Res. Lett., 21, 1619-1622. Toon, O.B., P. Hamill, R.P. Turco and J. Pinto, 1986: Condensation of HNO3 and HCl in the winter polar stratospheric clouds. Geophys. Res. Lett., 13, 12841287. Toon, O.B., E.V. Browell, S. Kinne and J. Jordan, 1990:
液滴極 成 層 圏雲粒 子 の粒径 と数濃 度=ノ ル ウ ェー領 ニ ーオ ー レス ンに おけ る 1994/95冬 季 の気球 観測 林
政 彦 ・岩坂 泰信 ・渡 辺征春 ・柴 田 (名古屋大学太陽地球環境研究所) 藤原玄 夫
隆
(福岡大学理学部) 足 立 宏 ・酒井 哲 ・長谷 正博 (名古屋大学太陽地球環境研究所) H. Gernandt. R. Neuber (Alfred Wegener Institute for Polar and Marine Research, Potsdam D-14401) 土屋正 義 (湘 南 工 科 大 学)
気球 搭載 型 の パ ー 一テ ィ ク ル カ ウ ン タ ー を用 い て、1994年 の ニ ー オ ー ル ス ン(北 緯79度、
東 経12度)に
か ら1995年
に かけ ての冬 の期 間、 ノルウ ェー
お い て、 極 成 層 圏 雲 の サ イズ(半 径0.15∼1.8μm)と
数濃 度
を 観 測 し た。 観 測 結 果 は、 寒 冷 な 冬 の 期 間PSCsが
活 発 に 生 成 され て い る こ と を示 し て い た。 気 球 観 測 期
間 中、 放 球 場 所 の 近 くで ラ イダ ー に よ っ てPSCsの
相(液 相 か 固 相 か)を 観 測 した。 双 方 の 観 測 か らPSCs
が い くつ か の 層(サ ブ レ イヤ ー)か ら成 っ て い る こ とが 示 さ れ た 。 1994年12月18日(PSCs形 1995年1月17日
成 の 初 期)に 観 測 さ れ た 数 一 サ イ ズ 分 布 は、 活 発 なPSCs活
の もの とは 異 な っ て お り、PSCsの
活 動 が 極 成 層 圏 雲 の 化 学 組 成 、 特 にPSCsに
あ る組 成、 の 分 布 を乱 して い る 可 能 性 を示 して い る。 ラ イダ ー 観 測 か ら は、 固 相 のPSCsに PSCsが
発 生 して い る こ とが 考 え られ る。 固 相 のPSCsの
度 の 増 大 が み られ た。 一 方 で、 液 相 のPSCsの サ イ ズ(0.25∼0.6μm)に
も増 大 が 見 られ た 。
動 を経 た 後 の
数 一 サ イズ 分 布 は、1.8μm以
数 一 サ イズ 分 布 は、1.8μm以
関係 の
加 えて 液相 の
上 の 粒 径 に粒 子 濃
上 の 粒 径 に加 え、 よ り小 さい
