Geoscience Reference
In-Depth Information
The received photon number is counted and integrated by a scaler.
The digitized signal is saved and displayed on the screen of a PC that
also controls the total system. The PC, in turn, is remotely monitored and
controlled through the LAN system from Chiba University.
3. Available Data
In this chapter, we use the following data: lidar (PAL) data, hourly
meteorological data, and weather map of each day at 9:00 JST. Since
December 2002, the PAL system has been operated continuously except
for the maintenance time: March to May, 2004 and February to May, 2006.
In this chapter, we focus on the data of 2004 and 2005.
Synoptic features of meteorological conditions can readily be seen from
the weather map provided from the Japan MeteorologicalAgency(JMA).
Hourly meteorological data of 143 observatories in Japan are displayed in
JMA climate statistics: URL http://www.data.jma.go.jp/obd/stats/etrn/
index.php (in Japanese). There, the following parameters are tabulated
for every hour: temperature, precipitation, dew temperature, water vapor
pressure, relative humidity, wind velocity, wind direction, and sunshine
time duration. The descriptions of snowfall, snow amount, weather, cloud
amount, and visibility at 9:00, 15:00, and 21:00 hrs, can also be found. We
use the data from the weather station (Chiba weather station; 35.60N,
140.10E), nearest from the location of PAL (CERC). The weather map of
Japan at 9:00 JST is available from “Every day weather map,” http://www.
data.jma.go.jp/fcd/yoho/hibiten/index.html. The locations of high and low
pressures, fronts, and isobaric lines can be obtained from the map.
4. Data Processing of Lidar Data
PAL provides a vertical profile of aerosol every 20 s. The range-corrected
signal,
X
(
R
), is obtained as
X
2
P
X
(
R
)=
(
R
)
,
(1)
where
) is the observed signal substrated by the
background due to skylight and dark noise. The ratio of the extinction to
the backscattering coecient (lidar ratio) is assumed to be
R
is distance,
P
(
R
S
1
=
α
1
/β
1
for
aerosols, and
S
2
=
α
2
/β
2
=8
.
53 (sr) for air molecules. Then, the extinction
