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| Titel |
Variability of raindrop size distribution over Sumatra and its effect on the Z-R relationship |
| VerfasserIn |
Marzuki Marzuki, W. L. Randeu, T. Kozu, T. Shimomai, H. Hashiguchi, M. Schoenhuber |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037038
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| Zusammenfassung |
| A systematic and intensive analysis is performed on 2 years (2006-2007) of two-dimensional
video distrometer (2DVD) data to re-investigate the variability of raindrop size
distributions (DSDs) over Sumatra and their impact on the radar reflectivity (Z)
to rainfall rate (R) conversion. Linear regression on log-transformed values both
R over Z (LREG1) and Z over R (LREG2), minimizing the root mean square
difference (RMSD), and probability matching method (PMM) are used to calculate the
coefficient A and exponent b of the Z - R relationship. The sequential intensity
filtering technique (SIFT) and sorting and averaging based on two parameters (SATP)
are used to minimizes the effect of the spurious variability on 2DVD data. From a
whole dataset, the Z - R relationship before (and after) the filtering procedure are
Z = 155R1.54 (153R1.55), Z = 166R1.40 (191R1.40), Z = 158R1.47 (171R1.47),
Z = 204R1.41 (314R1.31), for LREG1, LREG2, PMM, RMSD respectively. It is found that
SATP (SIFT) increase (decrease) the coefficient A, in comparison with the values
estimated from non-filtered data. During 2006-2007, we analyzed 385 rain events. Of
385 Z - R relations, the diurnal variation is observed, consistent with previous
results. A-coefficients during 00-06, 06-12, 12-18 and 18-24 local time (LT) are in
an interval of 98-249 (86 % of the values < 200), 93-220 (99 % of the values <
200), 98-283 (87 % of the values < 200) and 88-301 (89 % of the values < 200),
respectively. Other scales (seasonal, intraseasonal, rain type, time average, rainfall rate
threshold) of the DSD variability and their effect on rainfall intensity R estimation from
radar reflectivity Z are explored in terms of bias and random errors. In addition,
we also discussed the effect of binning procedure of 2DVD data on the Z - R
relation. Physical processes leading to the formation of DSDs are then classified
according to the vertical structure of radar data as measured by a 1.3GHz wind
profiler collocated with the distrometer. Besides Z - R analysis, relationship for
rainfall estimation using polarimetric radar measurements at frequencies 3, 5 and 10
GHz, by using real drop shape from 2DVD measurement, will be also presented. |
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