Geoscience Reference
In-Depth Information
(1 February, 2005). There was no precipitation with the sunshine duration
of 7.6 h, and wind direction changed from SW to NE with the speed of
3-12 m/s. The relative humidity was as low as 20% to 50%. The relation
with the front is not clear.
7. Summary
In this chapter, we have analyzed the data of the automatically
operated, temporary high resolution (20 s/file) lidar in conjunction with
meteorological data obtained from a nearby weather observatory and
public weather map. Important features can be summarized as follows:
(1) Behavior of lidar data is strongly related to the relative humidity
(RH). Daily average RH, in turn, exhibit noticeable correlation with the
average temperature, although in a day, RH is negatively correlated with
temperature. (2) Average ground temperature of 15
◦
provides a good
criterion separating the summer and winter modes of the atmospheric
profile. The pattern of lidar data is classified into summer-type and winter-
type, in accordance with the daily average temperature. (3) In winter-type
data, RH is typically smaller. It is often observed that raindrops evaporate
even before reaching the ground level. (4) Cloud-capped boundary layers
are frequently observed. The condition for this phenomenon is the high
RH, with a minimum RH value being over 60%. (5) When sunshine and
precipitation coexist on the same day, the rapid, vertical movement of
cloud base height is observed, presumably representing the instability of
the atmosphere. (6) The following cases (for both summer and winter
data) have been analyzed, and the lidar data have been compared with the
meteorological conditions: clear day, precipitation, coexistence of sunshine
and precipitation, cloud-capped boundary layer, frontal passage, and
sudden change (drop) of cloud height. In future extension of this work, more
quantitative treatment of the aerosol profile will give detailed understanding
of the atmospheric processes that may lead to the observed features. The
combination of lidar and concurrent radar data will improve the analysis
of rain clouds.
References
1. J. D. Spinhirne, Micro pulse lidar,
IEEE Trans. Geosci. Remote Sensing
31
(1993) 48-54.
2. http://mplnet.gsfc.nasa.gov/
