Radar observations in Singapore and their implications for the TRMM precipitation radar retrieval algorithms

Thurai, Merhala; Iguchi, Toshio; Kozu, Toshiaki; Eastment, J.D.; Wilson, C.L.; Ong, Jin

doi:10.1029/2002rs002855

Cited by 21 publications

(17 citation statements)

References 12 publications

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“…Such steep VPRGs particularly for heavy rain can be due to significant growth of raindrop at Kototabang. However, such strong VPRGs were not obtained by the BLR though the VPRG of BLR is consistent with several previous studies [40,39]. Moreover, the BLR operates in L-band frequency, hence it is almost unaffected by attenuation.…”

Section: Vertical Dsd Profile and Z-r Relationships From Mrrsupporting

confidence: 78%

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Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Marzuki¹,

Hashiguchi²,

Shimomai³

et al. 2016

PIER M

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Abstract-Micro Rain Radar (MRR) is a vertical pointing microwave profiler to measure hydrometeors and related parameters in high resolution. However, it is known that the MRR suffers from certain limitations due to several factors. This paper evaluates the performance of the MRR installed at Kototabang, west Sumatra, Indonesia (0.20 • S, 100.32 • E, 864 m above sea level). The DSD and rainfall rate from the MRR standard processing method had been evaluated by using collocated measurements of MRR, Parsivel disdrometer and Optical Rain Gauge (ORG) during 2014. Furthermore, 1.3 GHz wind profiler (BLR) observation was used to examine the vertical profiles of radar reflectivity and Doppler velocity. It was found that there were noticeable differences between the MRR and Parsivel in the small and large size ends of the DSD. At small sized drop (< 1 mm), the DSD spectra of MRR was higher than that obtained by the Parsivel otherwise it was smaller for large sized drop (> 2 mm). Underestimation of large sized drops in the MRR could be responsible for the underestimation of surface rainfall rate and daily rainfall. The source of differences in the DSD seems the measurement shortcomings such as attenuation correction and vertical wind effects, particularly during heavy rain. The shortcomings were observed from the comparison of mean Doppler velocity profiles between the MRR and the BLR. While the melting layer height of the two instruments was the same, the mean Doppler velocities of MRR shown downward increasing (DI) pattern through all rainfall intensities. On the other hand, for the BLR, the DI was only observed for heavy rain (> 10 mm/h), while downward decreasing was observed for light rain (< 5 mm/h). Similar pattern was also observed for the vertical profile of radar reflectivity. Thus, some corrections are needed for heavy rain, nevertheless, the MRR installed at Kototabang can be utilized for light rain. Comparisons indicated that the mean Doppler velocity and the DSD for the light rain as well as Z-R relation were in reasonable agreement with the reference of BLR, Parsivel and previous studies using the MRR.

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Section: Vertical Dsd Profile and Z-r Relationships From Mrrsupporting

confidence: 78%

“…The heavy rain or convective cases (Figs. 4(e)-(f)) have the highest DI of fall velocities, which are also supported by the observations from other regions [40,23,24]. Such DI values were also observed for the BLR but the gradient is smaller than the MRR.…”

Section: Comparison Of Mrr With Blrsupporting

confidence: 78%

Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Marzuki¹,

Hashiguchi²,

Shimomai³

et al. 2016

PIER M

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“…Conversely, Yuter and Houze (1997) (stratiform). In GD and SG, a boundary layer radar (Reddy et al 2002) and a vertical looking S-band rain radar (Thurai et al 2003) have been operated, respectively. Using Doppler and Z-factor profiles, we have made an approximate convective and stratiform classification.…”

Section: Discussionmentioning

confidence: 99%

“…We have been conducting rainfall observations at (i) Gadanki (GD), South India, (ii) Singapore (SG), and (iii) Kototabang (KT), West Sumatra, including disdrometer and radar measurements, see Reddy et al (2002), Thurai et al (2003) and Fukao (2006) for the GD, SG and KT cases, respectively. These sites, shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Seasonal and Diurnal Variations of Raindrop Size Distribution in Asian Monsoon Region

Kozu

Reddy

Mori

et al. 2006

Journal of the Meteorological Society of Japan

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112

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Diurnal and seasonal variations of raindrop size distribution (DSD) at Gadanki (GD), Singapore (SG) and Kototabang (KT) are studied to elucidate characteristics of DSD in the Asian monsoon region. It is found that DSDs are affected by diurnal convective cycles and seasonal variations in precipitation characteristics. GD has the most significant seasonal variation in DSD. Clear difference in rainfall characteristics between the Southwest and Northeast monsoon seasons is considered to be the main cause of such clear seasonal variation. KT has the most significant diurnal variation of DSD, which is probably caused by the fact that KT is greatly affected by ocean-land contrast and mountain effects to generate local convection in the afternoon. SG has less diurnal and seasonal variations compared with the other two locations, which is related to the fact that SG is affected both by land and oceanic rainfall. Z-R relations apCorresponding author: Toshiaki Kozu, Faculty of Science and Engineering, Shimane University, Matsue, 690-8504, Japan. E-mail: kozu@ecs.shimane-u.ac.jp ( 2006, Meteorological Society of Japan plicable to radar rainfall measurement in these areas are derived. It is shown that the use of the Marshall-Palmer Z-R relation (Z ¼ 200R 1:6 ) gives bias errors of about 1.5 dB or less in rain rate estimation except for the northeast monsoon season in GD, for 12@18 local time during pre-southwest monsoon season in GD, and for 06@12 local time during some monsoon seasons in KT.

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“…Thus, we have successfully obtained fairly long-term statistics for up-and downlink rain attenuation of the Ku-band satellite communications, for the first time, in both temperate and tropical regions. Furthermore, Xband meteorological radar observations which have been also conducted at the EAR site are introduced to reveal the rain distribution of precipitating clouds at the same time in the tropics as was done in Singapore (Thurai et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Maekawa

Fujiwara

Shibagaki

et al. 2006

Journal of the Meteorological Society of Japan

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This study investigates the effects of tropical rainfall on the Ku-band satellite communications links that connect Research Institute for Sustainable Humanosphere (RISH), Kyoto University in Japan to Equatorial Atmosphere Radar Observatory (EAR; 0.2 S, 100.3 E) in Indonesia, using the satellite Superbird C (144 E in orbit). Rain attenuation of the up-and down-link radio wave signals is, for the first time, obtained at the same time in the tropics, monitoring each signal level that has been received at both stations in Japan and Indonesia for the past three years from 2003 to 2005. The up-link attenuation at each station can be estimated from the down-link signal level measured at its opposite station, because SCPC (Single Channel Per Carrier) signals used in this experiment are linearly amplified without saturation of the satellite transponders. At EAR in Indonesia, a slightly larger attenuation ratio between up and down links is statistically presented for the attenuation range of higher that 10 dB, suggesting the effects of smaller raindrop size distributions (DSD) than observed at RISH in Japan. This tendency is more conspicuous in the rainfall events when the observed attenuation shows only one peak in its time series, indicating the effects of simple convective precipitating clouds with one single cell. At RISH in Japan, a larger difference between worst month and yearly average statistics is found, due to a larger variation of the ground temperature that affects the slant-path length during the seasons, although the yearly average time percentages as such are larger at EAR than RISH up to the up-link attenuation of 15 dB. Using time percentages of their local rainfall rates, fairly good agreement is found between the observations and the ITU-R (International Telecommunication Union-Radiocommunication Sector) predictions for both locations. At EAR in Indonesia, however, the time percentages of the attenuation of more than 10 dB become significantly smaller than those predicted by the ITU-R methods for both up and down links. This indicates the remarkable reduction of equivalent path lengths down to about 2 km, caused by a fairly localized structure of convective precipitating clouds. Simultaneous X band radar observations have revealed that intense echo cores of typical rain cells causing severe attenuation are confined to about 2 km along the propagation path. This result, which seems rather small even compared with those obtained in other tropical observation sites, may be attributed to unique features of the EAR site that is located in a highland basin 865 m above the mean sea level and frequently observes simple precipitating clouds with a single cell.

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Radar observations in Singapore and their implications for the TRMM precipitation radar retrieval algorithms

Cited by 21 publications

References 12 publications

Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Seasonal and Diurnal Variations of Raindrop Size Distribution in Asian Monsoon Region

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

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