This paper describes the first light and subsequent test observations with the 8.2 m aperture Subaru Telescope constructed at the summit of Mauna Kea. Following the engineering first light, which started 1998 December, the astronomical first light and test observations were carried out in 1999 January with 4 testing instruments under seeing conditions of 0″.2*#x2013;0″.5 for near-infrared and 0″.3–0″.6 for optical wavelengths. The actively supported primary mirror was shown to achieve an overall imaging performance of 0″.1 (FWHM) or better in the absence of any atmospheric disturbance. The pointing accuracy of the telescope is about 1″ rms, and a closed-loop tracking accuracy of ≲ 0″.07 rms has been achieved. Infrared images of the Orion Nebula covering 5′ × 5′, obtained with J, K″, and H2v = 1–0 S(1) filters, have revealed much finer and fainter details of the BN/KL region, the bright bar, and other conspicuous features compared with previous observations. K′ band photometry of 516 point sources yielded a luminosity function with a peak at K′ ∼ 12 mag with a long tail in K′ ∼ 13 mag down to K″ ∼ 17 mag, suggesting a fairly large number of young brown dwarfs existing in the Trapezium cluster. Several new features around the Orion BN/KL region are also reported.

A coherent 2 microm differential absorption and wind lidar (Co2DiaWiL) was developed to measure CO(2) concentration and line-of-sight wind speed. We conductively cooled a pumping laser head to -80 degrees C and diode arrays to approximately 20 degrees C. A Q-switched laser outputs an energy of 80 mJ (pulse width 150 ns (FWHM), pulse repetition frequency up to 30 Hz). CO(2) measurements made over a column range (487-1986 m) for 5 min accumulation time pairs achieved 0.7% precision. Line-of-sight wind speeds for ranges up to approximately 20 km and returns from a mountainside located 24 km away from the Co2DiaWiL were obtained.

We analyzed the time series data of dust vertical profiles, observed using polarization elastic lidar, from April 8 th -21 st , 2002, during the first intensive observation period of the Aeolian Dust Experiment on Climate impact (ADEC), in Shapotou, Ninxia Province in China. We conducted the analysis with consideration to the upper atmospheric soundings and surface weather data. The results are summarized as follows. 1) A well-mixed dust layer dominated in the boundary layer sampled from around 11 a.m. until around 1 or 2 a.m. local time (Beijing time). Under well-mixed conditions, the mixed layers grew well with dry convections in the boundary layer, especially during the day and in the early evening. 2) Dry convections developed deeper during synoptic low-pressure conditions because of the systematic upward motions prevalent in the low-pressure systems. Vertical wind shear affected growth of the mixed layer as well, that is, weak vertical wind shear condition was favorable for the growth of the mixed layer. The deepest mixed layer was observed on April 13 th at a thickness of about 6-km above ground, when the pressure was the lowest, the vertical wind shear was very weak, and the atmosphere was dry. The aspect ratios (horizontal/vertical scale ratios) of the convections decreased under low-pressure and weak-shear conditions. On the other hand, the aspect ratios of the convections increased dramatically under highpressure and strong-shear conditions, because convection growth was suppressed by systematic downdrafts of the high-pressure system and by strong vertical wind shears.

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The Kiyokawa-dashi (strong local wind) was observed with a coherent Doppler lidar at the exit of the Mogami Valley, in Kiyokawa (38.80 N, 140.01 E, 20 m MSL) . When the Kiyokawa-dashi blew, the synoptic patterns tended to be high-pressure in the east and low-pressure in the west. After the Kiyokawa-dashi was extracted, the data measured by the coherent Doppler lidar with a high spatial and temporal resolution were then utilized to investigate it. On the basis of the range height indicator and Plane position indicator scans, the coherent Doppler lidar was able to detect the three-dimensional dynamical structure of the Kiyokawa-dashi up to 8-10 km downstream from the Kiyokawa observation site. The coherent Doppler lidar clearly showed that a low-level critical layer (horizontal wind speed A 0 m s À1 ) existed at altitudes of 0.5-1.2 km, and that a strong easterly/southeasterly wind confined below the critical layer blows away about 10-km downstream of the Mogami Valley. Intensive upward/downward vertical motion under the critical layer was indicated by the velocity-azimuth display scan. The line-of-sight wind speeds obtained by high-frequency plane position indicator scans were high, not only near the exit of the Mogami Valley but also over the entire Shonai plain, and the distributions of the line-of-sight wind speeds were almost steady, indicating the existence of transient disturbances.