Dual-parameter radar rainfall measurement from space: a test result from an aircraft experiment

Kozu, Toshiaki; Nakamura, Kenji; Meneghini, R.; Boncyk, W.C.

doi:10.1109/36.83983

Cited by 40 publications

(10 citation statements)

References 20 publications

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“…This supports the pragmatic assumption of N 0 remaining constant with height on a statistical basis, at least for stratiform events. Effectively, this is the main assumption underlying the N 0 adjustment method used for the TRMM retrieval process [ Kozu et al , 1991]. If the N 0 does indeed remain constant, then the decrease in dBZ with decreasing height implies that the mass weighted mean velocity D 0 should also decrease with decreasing height.…”

Section: Drop Size Distribution In Rainmentioning

confidence: 99%

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

et al. 2003

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[1] This paper presents the results and analyses of Doppler radar measurements taken as part of a long-term campaign conducted in Singapore. Eight months of data taken in the zenith-pointing mode have been analyzed, in order to examine the validity of the assumptions underlying the retrieval algorithm proposed for the precipitation radar on board the TRMM satellite. Stratiform and convective events were analyzed separately. The former exhibits a clear melting layer in the 4-5 km height region, defined by an enhancement in the radar reflectivity, an increase in the mean fall velocity from 1-2 m/s in the snow region just above the melting layer to over 8 m/s in the rain region just below it. The corresponding width increases from less than 1 m/s to greater than 1 m/s. The variation in all three parameters can be accurately represented by the NoncoalescenceNonbreakup melting layer model used for the satellite radar retrieval algorithms. Also examined was the monthly variation of the reflectivity-height profiles. In the rain region below the melting layer, a consistent decrease in the radar reflectivity with decreasing height is seen, indicating that the drop size distribution (DSD) cannot be assumed constant over all heights. However, if only the parameter N 0 of the DSD is assumed constant, then good agreement is obtained between the mean velocity estimated from the reflectivity data and the measured velocity throughout the height profile. The agreement is also obtained in the spectrum width profile in the rain region. Convective precipitation on the other hand, does not exhibit a melting layer, and its averaged dBZ and velocity profiles cannot be characterized even under the constant N 0 assumption. Its averaged reflectivity-height profiles show more variability than stratiform precipitation. For such cases, factors such as up and down drafts and nonstandard atmosphere need to be taken into account. The implication for the so-called N 0 adjustment method is that while it can be applied to stratiform precipitation, the convective events need additional information, such as dual-frequency radar measurements, in order to improve the accuracy of the rainfall estimates.

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Section: Drop Size Distribution In Rainmentioning

confidence: 99%

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

et al. 2003

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“…Previous work on algorithm development relied on airborne dual-frequency radar data [15]- [20], ground-based radars [21]- [23], numerical model simulations [24]- [26], and data simulated from the TRMM/PR [27]- [31]. In this paper, we use the last of these approaches.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Precipitation Estimates by at-Launch Codes of GPM/DPR Algorithms Using Synthetic Data from TRMM/PR Observations

Kubota

Yoshida

Urita

et al. 2014

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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The Global Precipitation Measurement (GPM) Core Observatory will carry a Dual-frequency Precipitation Radar (DPR) consisting of a Ku-band precipitation radar (KuPR) and a Ka-band precipitation radar (KaPR). In this study, "at-launch" codes of DPR precipitation algorithms, which will be used in GPM ground systems at launch, were evaluated using synthetic data based upon the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data. Results from the codes (Version 4.20131010) of the KuPR-only, KaPR-only, and DPR algorithms were compared with "true values" calculated based upon drop size distributions assumed in the synthetic data and standard results from the TRMM algorithms at an altitude of 2 km over the ocean.The results indicate that the total precipitation amounts during April 2011 from the KuPR and DPR algorithms are similar to the true values, whereas the estimates from the KaPR data are underestimated. Moreover, the DPR estimates yielded smaller precipitation rates for rates less than about 10 mm/h and greater precipitation rates above 10 mm/h. Underestimation of the KaPR estimates was analyzed in terms of measured radar reflectivity ( ) of the KaPR at an altitude of 2 km. The underestimation of the KaPR data was most pronounced during strong precipitation events of < (high attenuation cases) over heavy precipitation areas in the Tropics, whereas the underestimation was less pronounced when the > 26 (moderate attenuation cases). The results suggest that the underestimation is caused by a problem in the attenuation correction method, which was verified by the improved codes.

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“…In those papers, a melting snow particle is modeled by a spherical or spheroidal particle, which has an average dielectric constant of air, ice and water. Computed results of radar backscattering and attenuation by the melting layer have been available at 100 GHz [4,5]. On the other hand, radar observations of the melting layer have also been reported at millimeter wavelength and at centimeter wavelengths.…”

mentioning

confidence: 95%

A New Melting Particle Model and its Application to Scattering of Radiowaves by a Melting Layer of Precipitation

Sun

Wang

Han

et al. 2007

Int J Infrared Milli Waves

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A melting layer of precipitation is composed of melting snow particles, and we modeled them by three-layered spherical particles, in which the innermost layer is air, the middle ice and the outermost water. Based on this model, the radar reflectivity, together with the specific phase shift and the specific attenuation of a melting layer of precipitation, were computed at 1-100 GHZ by using the Mie theory. The radar bright band is explained by this model. We compared our numerical results with that in the literature Zhang (IEEE Transactions on Antennas and Propagation 42 (3): [347][348][349][350][351][352][353][354][355][356] 1994), Zhang (IEEE Transactions on Antennas and Propagation 42(3): [492][493][494][495][496][497][498][499][500] 1994). It demonstrates that the three-layered snow sphere model is appropriate and practicable, so the computed results are more accurate. This study can be used in radar remote sensing and satellite-earth communications.

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Dual-parameter radar rainfall measurement from space: a test result from an aircraft experiment

Cited by 40 publications

References 20 publications

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

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

Evaluation of Precipitation Estimates by at-Launch Codes of GPM/DPR Algorithms Using Synthetic Data from TRMM/PR Observations

A New Melting Particle Model and its Application to Scattering of Radiowaves by a Melting Layer of Precipitation

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