The characteristics of snow crystal growth by vapor diffusion at water saturation and in free fall were quantitatively investigated in a vertical supercooled cloud tunnel for periods up to 30 min at temperatures from -3 to -23*.The results obtained are as follows: 1) the basic growth habits were plates (>-4.0*), columns (-4.0--8.1*), plates (-8.1--22.4*) and columns (<-22.4*), respectively. At about -5.5, -12, -14 .5, -16.5 and -18*, crystal shapes were enhanced with time; 2) for an isometric crystal, the slope of a log-log plot between the crystal mass and the growth time showed the Maxwellian value of 1.5. The mass growth rate of a shape-enhanced crystal was larger than that of the isometric crystal, indicating more effective vapor transfer on the former; 3) in the case of shape-enhanced planar crystals grown at around -12, -14.5 and -16.5*, ventilation effects became recognizable, whereas the effect was not evident for needle crystals grown at about -5.5*. This suggests that the characteristic length of the flow field even around a needle crystal is along the a-axis. The ventilation effect became significant when the Reynolds number exceeded about 2 (sector) and 5 (dendrite); 4) linear relationships between the drag coefficient and the Reynolds number were found in log-log plots.

Dust and anthropogenic aerosol plumes from the Asian continent were observed in the Northwest Pacific (32.0° to 38.0°N, 146.5°E) with a two‐wavelength polarization lidar on board the research vessel Mirai during the MR01‐K02 cruise (May 14 to 28, 2001). Dust aerosols were identified from the aerosol depolarization ratio at 532 nm and the ratio of the backscattering coefficient at 1064 nm and 532 nm. High aerosol density air masses with a low depolarization ratio and a small wavelength ratio (indicating small particle size) were also detected in the plume. The distribution patterns of the dust and the spherical aerosols were conceptionally explained by the model prediction for dust and sulfate with the Chemical Weather Forecast System (CFORS). Aerosols with large particle size but with low depolarization ratio were also observed in between the layers of dust and sulfate. This indicates that the aerosols were possibly an internal mixture of dust and sulfate.

Figure 1). After the small meander passes Cape Shiono-misaki, it slows down and rapidly amplifies in -1 month so that the Kuroshio loops back west of the Izu-Ogasawara Ridge. Then the sharpness of the meander trough gradually relaxes and the LM path is attained. The small meander generated off the southeastern coast of Kyushu is therefore often called the "trigger meander" [Solomon, 1978]. Although the generation of a small meander off the southeastern coast of Kyushu is observed in winter or early spring almost every year, the rapid amplification of the trigger meander leading to the formation of the LM path was observed only five times (1959, 1975, 1981, 1986, and 1989) since the monitoring of the Kuroshio path variation became possible based on observational data -50 years ago.By analyzing the time series of sea level difference between Naze and Nishino-omote (see Figure 1) from 1965 to 1992, Kawabe [1995] showed that the Kuroshio current velocity through the Tokara Strait once increased before the trigger meander was formed and, except for 1975, the trigger meander was generated in -1 month, during which period the increased Kuroshio current velocity was relaxing. Although a number of numerical studies have been carried out to reproduce the bimodal features of the Kuroshio by using inflow-outflow re-

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