volume | PIER Journals

Abstract

A Z-R relation is derived using a data set which consists of nine rain events selected from Singapore's drop size distribution. Rain events are separated into convective and stratiform types of rain using two methods: the Gamache-Houze method, a simple threshold technique, and the Atlas-Ulbrich method. In the Atlas-Ulbrich method, the variability of the rain integral parameters R, Z, N_w, D₀ and gamma model parameter $\mu $ are used for the classification of rain into convective, stratiform and transition. Z-R relations are derived for each type of rain after classification. The changes in the coefficients of the Z-R relations for different rain events are plotted and analyzed. The Z-R relations of the different methods using the Singapore data are compared and analyzed. It is concluded that the coefficient A of the Z-R relation is higher for the convective stage followed by the stratiform and transition stages. The coefficient b values are higher for the transition stage followed by the stratiform and convective stages. Reflectivities are extracted from RADAR data above NTU site for rain events and compared with the reflectivities derived from the distrometer data. Rain rates retrieved from RADAR data using the proposed relations from Singapore's data set are compared with the distrometer rain rates. The RADAR extracted rain rates are found to be constantly lower than the distrometer derived rain rates but matches well.

1. Marshall, J. S. and W. M. Palmer, "The distribution of raindrops with size," Journal of Atmos. Sci., Vol. 5, 165-166, 1948. Google Scholar

2. Ulbrich, C. W., "Natural variation in the analytical form of the raindrop size distribution," J. Appl. Meteor., Vol. 22, No. 10, 1764-1775, 1983.
doi:10.1175/1520-0450(1983)022<1764:NVITAF>2.0.CO;2 Google Scholar

3. Battan, L. J., Radar Observations of the Atmosphere, 323, Univ. of Chicago Press, 1973.

4. Feingold, G. and Z. Levin, "The lognormal fit to raindrop spectra from frontal convective clouds in Israel," J. Appl. Meteor., Vol. 25, 1346-1363, 1986.
doi:10.1175/1520-0450(1986)025<1346:TLFTRS>2.0.CO;2 Google Scholar

5. Fujiwara, M., "Raindrop-size distribution from individual storms," J. Atmos. Sci., Vol. 22, 585-591, 1965.
doi:10.1175/1520-0469(1965)022<0585:RSDFIS>2.0.CO;2 Google Scholar

6. Tokay, D. and A. Short, "Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds," J. Appl. Meteor., Vol. 35, No. 3, 355-371, 1996.
doi:10.1175/1520-0450(1996)035<0355:EFTRSO>2.0.CO;2 Google Scholar

7. Atlas, D., C. W. Ulbrich, F. D. Marks, E. Amitai, and C. R. Williams, "Systematic variation of drop size and radar --- Rainfall relations," J. Geophysical Research, Vol. 104, 6155-6169, 1999.
doi:10.1029/1998JD200098 Google Scholar

8. Tokay, A., D. A. Short, C. R. Williams, W. L. Ecklund, and K. S. Gage, "Tropical rainfall associated with convective and stratiform clouds: Intercomparison of disdrometer and profiler measurements," J. Appl. Meteor., Vol. 38, No. 3, 302-320, 1999.
doi:10.1175/1520-0450(1999)038<0302:TRAWCA>2.0.CO;2 Google Scholar

9. Maki, M., T. D. Keenan, Y. Sasaki, and K. Nakamura, "Characteristics of the raindrop size distribution in tropical continental squall lines observed in Darwin, Australia," J. Appl. Meteor., Vol. 40, 1393-1412, 2001.
doi:10.1175/1520-0450(2001)040<1393:COTRSD>2.0.CO;2 Google Scholar

10. Wilson, C. L. and J. Tan, "The characteristics of rainfall and melting layer in Singapore: Experimental results from radar and ground instruments," 11th International Conference on Antennas and Propagation, No. 480, 852-856, Conference Publication, Apr. 17--20, 2001.

11. Bringi, V. N., V. Chandrasekar, J. Hubbert, E. Gorgucci, W. L. Randeu, and M. Schoenhuber, "Raindrop size distribution in different climatic regimes from disdrometer and dual-polarized radar analysis," J. Appl. Meteorol., Vol. 60, No. 2, 354-365, 2003. Google Scholar

12. Ulbrich, C. W. and D. Atlas, "Microphysics of raindrop size spectra: Tropical continental and maritime storms," J. Appl. Meteor. Climatol., Vol. 46, 1777-1791, 2007.
doi:10.1175/2007JAMC1649.1 Google Scholar

13. Ulbrich, C. W. and D. Atlas, "Radar measurement of rainfall with and without polarimetry," J. Appl. Meteor. Climatol., Vol. 47, 1929-1939, 2008.
doi:10.1175/2007JAMC1804.1 Google Scholar

14. Montopoli, M., F. S. Marzano, and G. Vulpiani, "Analysis and synthesis of raindrop size distribution time series from disdrometer data," IEEE Trans. Geosci. Remote Sens., Vol. 46, No. 2, 466-478, 2008.
doi:10.1109/TGRS.2007.909102 Google Scholar

15. Distrome Ltd., Distrometer RD-69 Instruction manual, 1993.

16. Gunn, R. and G. D. Kinzer, "The terminal velocity of fall for water droplets in stagnant air," J. Atmos. Sci., Vol. 6, No. 4, 243-248, 1949. Google Scholar

17. Campos, E. and I. Zawadski, "Instrumental uncertainties in Z-R relations," J. Appl. Meteor., Vol. 39, 1088-1102, 2000.
doi:10.1175/1520-0450(2000)039<1088:IUIZRR>2.0.CO;2 Google Scholar

18. Atlas, D., C. Ulbrich, F. D. Marks, R. A. Black, E. Amitai, P. T. Willis, and C. E. Samsury, "Partitioning tropical oceanic convective and stratiform rains by draft strength," J. Geoph. Res., Vol. 105, No. D2, 2259-2267, 2000.
doi:10.1029/1999JD901009 Google Scholar

19. Zhang, G., J. Sun, and E. Brandes, "Improving parameterization of rain microphysics with disdrometer and radar observations," J. Atmos. Sci., Vol. 63, 1273-1290, 2006.
doi:10.1175/JAS3680.1 Google Scholar

20. Cao, Q. and G. Zhang, "Errors in estimating raindrop size distribution parameters employing disdrometer and simulated raindrop spectra," J. Appl. Meteor. Climatol., Vol. 48, No. 2, 406-425, Feb. 2009.
doi:10.1175/2008JAMC2026.1 Google Scholar

21. Smith, P. L., D. V. Kliche, and R. W. Johnson, "The bias and error in moment estimators for parameters of drop size distribution functions: sampling from gamma distributions," J. Appl. Meteor. Climatol., Vol. 48, No. 10, 2118-2126, 2009.
doi:10.1175/2009JAMC2114.1 Google Scholar

22. Testud, J., S. Oury, R. Black, P. Amayenc, and X. Dou, "The concept of ``normalized" distribution to describe raindrop spectra: A tool for cloud physics and cloud remote sensing," J. Appl. Meteorol., Vol. 40, No. 6, 1118-1140, 2000.
doi:10.1175/1520-0450(2001)040<1118:TCONDT>2.0.CO;2 Google Scholar

23. Gamache, J. F. and A. R. Houze, "Mesoscale air motions associated with a tropical squall line," Monthly Weather Review, Vol. 110, 118-135, 1982.
doi:10.1175/1520-0493(1982)110<0118:MAMAWA>2.0.CO;2 Google Scholar

24. Bringi, V. N., C. R. Williams, M. Thurai, and P. T. May, "Using dual-polarized radar and dual-frequency profiler for DSD characterization: A case study from Darwin, Australia," J. Atmos. Oceanic Technol., Vol. 26, 2107-2122, 2009.
doi:10.1175/2009JTECHA1258.1 Google Scholar

25. Sharma, S., M. Konwar, D. K. Sarma, M. C. R. Kalapureddy, and A. R. Jain, "Characteristics of rain integral parameters during tropical convective, transition, and stratiform rain at Gadanki and its application in rain retrieval," J. Appl. Meteor. Climatol., Vol. 48, 1245-1266, 2009.
doi:10.1175/2008JAMC1948.1 Google Scholar

26. Villarini, G. and W. F. Krajewski, "Review of the different sources of uncertainty in single polarization radar-based estimates of rainfall," Surveys in Geophysics, Vol. 31, 107-129, 2009. Google Scholar

27. Ladd, D. N., C. L. Wilson, and M. Thurai, "Radar measurements from papua new guinea and their implications for TRMM PR retrieval algorithms," Geoscience and Remote Sensing, IGARSS'97, Remote Sensing --- A Scientific Vision for Sustainable Development , Vol. 4, 1648-1650, 1997.
doi:10.1109/IGARSS.1997.609004 Google Scholar

Dr. Lakshmi Sutha Kumar

Dr. Yee Hui Lee

Dr. Jun Xiang Yeo

Dr. Jin Teong Ong