Parameterization of Radar Reflectivity-Rain Rate Relation during Tropical Convective, Transition and Stratiform Rain Types

2019 ◽  
Author(s):  
Adewumi. O. Ayo ◽  
Pius. A. Owolawi ◽  
Joseph. S. Ojo
Keyword(s):  
Rain Rate ◽  
Radar Reflectivity ◽  
Stratiform Rain ◽  
Rate Relation

scholarly journals Estimating Rain Rates from Tipping-Bucket Rain Gauge Measurements

2008 ◽  
Vol 25 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Jianxin Wang ◽  
Brad L. Fisher ◽  
David B. Wolff
Keyword(s):  
Rain Rate ◽  
Tropical Rainfall Measuring Mission ◽  
Rain Gauge ◽  
Radar Reflectivity ◽  
Time Shift ◽  
Estimation Errors ◽  
Rate Estimation ◽  
Reflectivity Data ◽  
Rain Rates ◽  
Event Definition

Abstract This paper describes the cubic spline–based operational system for the generation of the Tropical Rainfall Measuring Mission (TRMM) 1-min rain-rate product 2A-56 from tipping-bucket (TB) gauge measurements. A simulated TB gauge from a Joss–Waldvogel disdrometer is employed to evaluate the errors of the TB rain-rate estimation. These errors are very sensitive to the time scale of rain rates. One-minute rain rates suffer substantial errors, especially at low rain rates. When 1-min rain rates are averaged over 4–7-min intervals or longer, the errors dramatically reduce. Estimated lower rain rates are sensitive to the event definition whereas the higher rates are not. The median relative absolute errors are about 22% and 32% for 1-min rain rates higher and lower than 3 mm h−1, respectively. These errors decrease to 5% and 14% when rain rates are used at the 7-min scale. The radar reflectivity–rain-rate distributions drawn from the large amount of 7-min rain rates and radar reflectivity data are mostly insensitive to the event definition. The time shift due to inaccurate clocks can also cause rain-rate estimation errors, which increase with the shifted time length. Finally, some recommendations are proposed for possible improvements of rainfall measurements and rain-rate estimations.

Characterization of Maximum Radar Reflectivity Height During Stratiform Rain Events

2012 ◽  
Vol 60 (10) ◽  
pp. 4884-4891 ◽  
Author(s):  
J. A. Romo ◽  
M. Maruri ◽  
F. Perez-Fontan ◽  
I. Fernandez
Keyword(s):  
Radar Reflectivity ◽  
Stratiform Rain ◽  
Rain Events

scholarly journals Analysis of Measured Drop Size Spectra over Land and Sea

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Karl Bumke ◽  
Jörg Seltmann
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Exponential Model ◽  
Coastal Areas ◽  
Data Sets ◽  
Size Spectra ◽  
Stratiform Rain ◽  
Open Sea ◽  
Rain Rates

Drop size spectra were measured by using an optical disdrometer of type ODM 470 at different locations. They were subdivided in to four data sets: measurements over land, in coastal areas, over semienclosed seas, and over the open sea. Based on 1-minute measurement intervals, no differences were found in drop size spectra between continental and maritime areas. An exponential model with a rain rate depending on interception number and prefactor in the exponent fits well the spectra, and maximum drop sizes depend strongly on estimated rain rates. In contrast to other investigations, there are no significant differences between spectra of convective and stratiform rain based on 1-minute measurement intervals. However, spectra integrated over 10 minutes show the expected differences.

scholarly journals Estimasi Curah Hujan Radar Cuaca Dengan Hubungan Z-R Berbeda Pada Tipe Awan Hujan Konvektif Dan Stratiform Di Lampung

2019 ◽  
Vol 4 ◽  
pp. 51
Author(s):  
Lilik Ardiyanto ◽  
Anggi M. Hanif ◽  
Muhammad Alfaridzi ◽  
Sony Ariwibowo ◽  
Eko Wardoyo ◽  
...  
Keyword(s):  
Rain Rate ◽  
Convective Cloud ◽  
Weather Radar ◽  
Cloud Type ◽  
Stratiform Rain ◽  
Convective Clouds ◽  
Rain Events ◽  
Reflectivity Data ◽  
Relationship Of ◽  
Rain Cloud

<p class="AbstractEnglish"><strong>Abstract: </strong>Weather radar is used to cover the lack of measurement due to the precision of the amount of rainfall gauges. Products on the weather radar produce reflectivity data (Z), so to get rainfall estimation data processing is required with the reflectivity (Z) and rain rate (R) or Z-R relationships. The Z-R relationship can be different in every condition. One of the influences is the type of rain clouds, namely convective and stratiform. This study aims to determine the relationship of Z-R and radar products that are more suitable for use in Lampung. The study was conducted by classifying the type of rain cloud based on rain rate, then produced CMAX, CAPPI, SRI and RIH radar products at the time of the rain. Next, a comparison of rainfall events from convective and stratiform rain cloud types from actual rain events to radar estimation results using the Z-R relationship from Marshall-Palmer, Rosenfeld Tropical and WSR-88D Convective. The results show that SRI products are most suitable for the case of rain from convective clouds, while CMAX products are more suitable for stratiform rain cloud types. Then it can be seen that there are different uses of Z-R relationships in different types of rain clouds. Convective cloud type is more suitable to use the Z-R WSR-88D Convective (W-C) and Marshall Palmer (M-P) relationship is more suitable for stratiform cloud type.</p><p class="AbstractEnglish"><strong>Abstrak: </strong>Radar cuaca digunakan untuk menutupi kekurangan pengukuran karena ketebatasan jumlah alat pengukur curah hujan. Produk pada radar cuaca menghasilkan data reflektivitas (Z), sehingga untuk mendapatkan data estimasi curah hujan diperlukan pengolahan dengan hubungan reflektivitas (Z) dan rain rate (R) atau hubungan Z-R yang dapat berbeda pada setiap kondisi. Salah satu yang mempengaruhi adalah tipe awan hujan yaitu konvektif dan stratiform. Penelitian ini bertujuan untuk mengetahui hubungan Z-R dan produk radar yang lebih cocok digunakan pada daerah Lampung. Penelitian dilakukan dengan mengklasifikasikan tipe awan hujan berdasarkan rain rate, kemudian dihasilkan produk-produk radar CMAX, CAPPI, SRI dan RIH. Selanjutnya dilakukan perbandingan kejadian hujan sebenarnya dari tipe awan konvektif dan stratiform dengan hasil estimasi radar dengan menggunakan hubungan Z-R dari Marshall-Palmer, Rosenfeld Tropical dan WSR-88D Convective. Hasil penelitian menunjukkan produk SRI paling cocok digunakan untuk kasus hujan dari awan konvektif, sedangkan produk CMAX lebih cocok untuk tipe awan stratiform. Diketahui bahwa terdapat penggunaan hubungan Z-R berbeda pada tipe awan hujan yang berbeda. Untuk tipe awan konvektif lebih cocok menggunakan hubungan Z-R WSR-88D Convective (W-C) dan Marshall Palmer (M-P) lebih cocok untuk tipe awan stratiform.</p>

scholarly journals Raindrop size distributions and radar reflectivity–rain rate relationships for radar hydrology

2001 ◽  
Vol 5 (4) ◽  
pp. 615-628 ◽  
Author(s):  
R. Uijlenhoet
Keyword(s):  
Size Distribution ◽  
Power Law ◽  
Rain Rate ◽  
Radar Reflectivity ◽  
Size Distributions ◽  
Raindrop Size Distribution ◽  
Special Cases ◽  
Fundamental Reason ◽  
Radar Measurements ◽  
Raindrop Size

Abstract. The conversion of the radar reflectivity factor Z(mm6m-3) to rain rate R(mm h-1 ) is a crucial step in the hydrological application of weather radar measurements. It has been common practice for over 50 years now to take for this conversion a simple power law relationship between Z and R. It is the purpose of this paper to explain that the fundamental reason for the existence of such power law relationships is the fact that Z and R are related to each other via the raindrop size distribution. To this end, the concept of the raindrop size distribution is first explained. Then, it is demonstrated that there exist two fundamentally different forms of the raindrop size distribution, one corresponding to raindrops present in a volume of air and another corresponding to those arriving at a surface. It is explained how Z and R are defined in terms of both these forms. Using the classical exponential raindrop size distribution as an example, it is demonstrated (1) that the definitions of Z and R naturally lead to power law Z–R relationships, and (2) how the coefficients of such relationships are related to the parameters of the raindrop size distribution. Numerous empirical Z–R relationships are analysed to demonstrate that there exist systematic differences in the coefficients of these relationships and the corresponding parameters of the (exponential) raindrop size distribution between different types of rainfall. Finally, six consistent Z–R relationships are derived, based upon different assumptions regarding the rain rate dependence of the parameters of the (exponential) raindrop size distribution. An appendix shows that these relationships are in fact special cases of a general Z–R relationship that follows from a recently proposed scaling framework for describing raindrop size distributions and their properties. Keywords: radar hydrology, raindrop size distribution, radar reflectivity–rain rate relationship

scholarly journals Combination of Radar and Rain Gauge Information to Map the Snowy Region in Jeju Island, Korea: A Case Study

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Jung Mo Ku ◽  
Chulsang Yoo
Keyword(s):  
Rain Rate ◽  
Rain Gauge ◽  
Coastal Areas ◽  
Radar Reflectivity ◽  
Jeju Island ◽  
Rain Gauges ◽  
Rate Information ◽  
Fixed Threshold ◽  
Reflectivity Data

Hallasan Mountain is located at the center of Jeju Island, Korea. Even though Hallasan Mountain has a height of just 1,950 m, the temperature during the winter decreases below −20 degrees Celsius. On the contrary, the temperature on the coastal areas remains just above freezing. Therefore, large snowfalls in the mountain and rainfall in the coastal areas are very common in Jeju Island. Most of the rain gauges are available around highly populated coastal areas, and snow measurements are available at just four locations on the coastal areas. Therefore, it is practically impossible to distinguish the rainfall and snowfall in Jeju Island. Fortunately, two radars (Seongsan and Gosan radars) operate on Jeju Island, which fully covers Hallasan Mountain. This study proposes a method of using both the radar and rain gauge information to map the snowy region in Jeju Island, including Hallasan Mountain. As a first step, this study analyzed the Z-R and Z-S relationships to derive a fixed threshold of radar reflectivity to separate snowfall from rainfall, and, in the second step, this study additionally considered the observed rain rate information to implement the problem of using the fixed threshold. This proposed method was applied to radar reflectivity data collected during November 1, 2014, to April 30, 2015, and the results indicate that the method considering both the radar and rain gauge information was satisfactory. This method also showed good performance, especially when the rain rate was very low.

Investigation of precipitation characteristics under the action of acoustic waves in the source region of the Yellow River

2021 ◽  
Author(s):  
Yang Shi ◽  
Jiahua Wei ◽  
Yan Ren ◽  
Zhen Qiao ◽  
Qiong Li ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Rain Rate ◽  
Field Experiments ◽  
Yellow River ◽  
Source Region ◽  
Radar Reflectivity ◽  
The Yellow River ◽  
Weather Modification ◽  
Operation Center ◽  
Reflectivity Factor

AbstractAcoustic agglomerations have increasingly attracted widespread attention as a cost-effective and environmentally friendly approach for fog removal and weather modification. In this study, research on precipitation interference and the agglomeration performance of droplet aerosols under large-scale acoustic waves was presented. In total, 49 field experiments in the source region of the Yellow River (SRYR) in the summer of 2019 were performed to reveal the influences of acoustic waves on precipitation, such as the radar reflectivity factor (Z), rain rate (R), and raindrop size distribution (DSD). A monitoring system that consisted of rain gauges and raindrop spectrometers was employed to monitor near-ground rainfall within a 5 km radius of the field site. The ground-based observations showed that acoustic waves could significantly affect the rainfall distribution and microstructure of precipitation particles. The average values of rainfall increased by 18.98%, 10.61%, and 8.74% within 2 km, 3 km and 5 km of the operation center with acoustic application. The changing trend of microphysical parameters of precipitation was roughly in line with variation of acoustic waves for stratiform cloud. Moreover, there was a good quadratic relationship between the spectral parameters λ and μ. Raindrop kinetic energy (eK) and the radar reflectivity factor (Z) both exhibited a power function relationship with the rain rate (R).

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