DETERMINATION X-BAND RADAR REFLECTIVITY THRESHOLD VALUE of HAIL INCIDENCE IN BANDUNG (Case Study April 1th â May 4th 2017)
There is no research on the value of the reflectivity threshold to detect the incidence of hail in Bandung with X-Band radar. Many methods have been developed for the detection of hail using radar and there are different methods that are suitable for different regions. Therefore, to overcome thes...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/42669 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | There is no research on the value of the reflectivity threshold to detect the incidence
of hail in Bandung with X-Band radar. Many methods have been developed for the
detection of hail using radar and there are different methods that are suitable for
different regions. Therefore, to overcome these problems, the determination and
analysis of the appropriate X-Band radar threshold will be carried out in Bandung.
In this study the data used are radar data as primary data in the determination and
analysis, hail report data as a determinant of the time of hail events, satellite data
as a determinant of cloud top temperature, Era-Interim data as a determinant of
altitude when the temperature is 0°C and -20°C, and rainfall data for determining
non-hail events and further analysis. The method used is to calculate and determine
the ability to detect hail in the CAPPI, Auer, Wadvogel, VIL, and POSH methods.
The results of the processing of radar reflectivity data indicate that there is a high
reflectivity value in the event of hail and non-hail at low altitudes. The existence of
high reflectivity values in the event of hail has a span of <30 minutes while nonhail
can last up to> 1 hour. The appearance of this high reflectivity in hail occurs
after clouds grow vertically while high reflective in non-hail starts from low altitude
and seems to grow vertically upwards. The results of the comparative analysis show
that the Waldvogel method can detect the occurrence of hail better than all methods
because it can see how the growth of cloud height is happening. However, the use
of this method needs to review the extent of clouds that occur as a differentiator of
two events, because in the event of non-hail clouds grow wider than hail. Further
evaluation of the threshold values in the CAPPI, VIL, and POSH methods resulted
in different threshold values for Bandung.
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