AiR a2R

In the present analysis, we assume S2 = 30sr for aerosols and 17 sr for clouds. In Sec. 6, the PAL data are depicted using the time-height indication (THI): the abscissa shows time, the ordinate shows the height, and the signal intensity is shown in the brightness (color or gray) scale. Because of the elevation angle (38°), the height resolution is improved by a factor of sin 38° = 0.62.

5. Features of Meteorological Data

Before comparing PAL lidar data and meteorological conditions, the aspects of average meteorological conditions in 2004 and 2005 are overviewed. Monthly average of weather parameters of Chiba observatory is shown in Figs. 2(a) and 2(b).

From Figs. 2(a) and 2(b), it is found that in 2004, the precipitation amount of October was exceptionally large, while in July it was quite small. Usually in Chiba, precipitation is small from November to May, and large from August to October (except September, 2005). From the graph,

Fig. 2. Meteorological parameters at Chiba Observatory in 2004 and 2005. (a) Monthly precipitation (mm), sunshine hour (h), and relative humidity (%), (b) temperature (°C), relative humidity (%), wind speed (m/s), and temperature difference in a day (°C).

relative humidity exhibits some correlation (but not very significant) with precipitation and with temperature. Wind speed does not change so much annually, and the average speed is about 5 m/s. The average temperature in April and November is about 15° C: as mentioned later, the lidar data show different behaviors above and below 15°C, though the temperature difference (maximum temperature - minimum temperature) in a day stays between 15° and 25° throughout the year.

0 0

Post a comment