The Attenuation Correction for Ka Band Cloud Radar

2019 ◽  
Author(s):  
Shuangyu Yao ◽  
Jianxin He ◽  
Hao Wang ◽  
Shunxian Tang ◽  
Xiaofeng Liang
Keyword(s):  
Attenuation Correction ◽  
Ka Band ◽  
Cloud Radar

scholarly journals Attenuation Correction for Ka-band Cloud Radar Using X-band Weather Radar Data

2016 ◽  
Author(s):  
Peng Zhang ◽  
Yunjie Chen
Keyword(s):  
Attenuation Correction ◽  
Weather Radar ◽  
Radar Data ◽  
Contributory Factor ◽  
Ka Band ◽  
Millimeter Wavelength ◽  
Cloud Radar ◽  
X Band ◽  
Bin Method ◽  
Variation Trends

In order to correct attenuated millimeter-wavelength (Ka-band) radar data and address the problem of instability, an attenuation correction methodology (attenuation correction with variation trend constraint; VTC) was developed. Using synchronous observation conditions and multi-band radars, the VTC method adopts the variation trends of reflectivity in X-band radar data captured with wavelet transform as a constraint to adjust reflectivity factors of millimeter-wavelength radar. The correction was evaluated by comparing reflectivities obtained by millimeter-wavelength cloud radar and X-band weather radar. Experiments showed that attenuation was a major contributory factor in the different reflectivities of the two radars when relatively intense echoes exist, and the attenuation correction developed in this study significantly improved data quality for millimeter-wavelength radar. Reflectivity differences between the two radars were reduced and reflectivity correlations were enhanced. Errors caused by attenuation were eliminated, while variation details in the reflectivity factors were retained. The VTC method is superior to the bin-by-bin method in terms of correction amplitude and can be used for attenuation correction of shorter wavelength radar assisted by longer wavelength radar data.

scholarly journals An adaptive echo attenuation correction method for airborne Ka-band precipitation cloud radar based on melting layer

2021 ◽  
Author(s):  
Dongfei Zuo ◽  
Deping Ding ◽  
Yichen Chen ◽  
Ling Yang ◽  
Delong Zhao ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Attenuation Correction ◽  
Relative Error ◽  
Water Film ◽  
Liquid Water Content ◽  
Correction Method ◽  
Ka Band ◽  
Melting Layer ◽  
Mean Relative Error ◽  
Cloud Radar

Abstract. In this study, an airborne Ka-band Precipitation Cloud Radar (KPR) is used to carry out a cloud observation experiment.By analyzing the attenuation of the snow echo, it is found that during the snowfall, due to the low liquid water content, the KPR attenuation is small on the detection path, and after preliminary comparative analysis, the maximum attenuation correction value is 0.5 dBZ. According to the echo attenuation analysis of mixed precipitation, the melting layer is found to be the key factor affecting the attenuation correction. This study hereby proposes an adaptive echo attenuation correction method based on the melting layer (AEC), and uses the ground-based S-band radar to extract the echo on the aircraft trajectory to verify the correction results. The results show that the echo attenuation correction value above the melting layer is related to the flight position. The aircraft above the melting layer is dominated by ice particles, with small attenuation correction value, the maximum correction amount of 0.13 dBZ; when the aircraft is at and just below the melting layer, a water film is prone to be on the antenna, which leads to serious attenuation of the KPR detection path, with the attenuation correction value 1~2 dBZ. For the precipitation echo below the melting layer, due to the abundant rain and water vapor content, the KPR attenuation is significant with maximum correction value of about 5 dBZ. Compared with the S-band radar, before attenuation correction, the total mean relative error is 15 %, and the correlation coefficient is 0.82; after correction, the total mean relative error is 6 %, and the correlation coefficient is 0.90, indicating the significant improvement of the KPR data quality.

Monsoon cloud observations using a low power vertical looking Ka Band Cloud radar

2016 ◽  
Author(s):  
A. Agarwal ◽  
J. S. Pillai ◽  
K. Aurobindo ◽  
J. D. Abhyankar ◽  
G. Isola ◽  
...  
Keyword(s):  
Low Power ◽  
Ka Band ◽  
Cloud Radar

scholarly journals Classification of Hydrometeors Using Measurements of the Ka-Band Cloud Radar Installed at the Milešovka Mountain (Central Europe)

2018 ◽  
Vol 10 (11) ◽  
pp. 1674 ◽  
Author(s):  
Zbyněk Sokol ◽  
Jana Minářová ◽  
Petr Novák
Keyword(s):  
Central Europe ◽  
Terminal Velocity ◽  
Small Particles ◽  
Cloud Droplets ◽  
Vertical Temperature Profile ◽  
Ka Band ◽  
Cloud Radar ◽  
Weather Radars ◽  
Cloud Particles ◽  
Linear Depolarization Ratio

In radar meteorology, greater interest is dedicated to weather radars and precipitation analyses. However, cloud radars provide us with detailed information on cloud particles from which the precipitation consists of. Motivated by research on the cloud particles, a vertical Ka-band cloud radar (35 GHz) was installed at the Milešovka observatory in Central Europe and was operationally measuring since June 2018. This study presents algorithms that we use to retrieve vertical air velocity (Vair) and hydrometeors. The algorithm calculating Vair is based on small-particle tracers, which considers the terminal velocity of small particles negligible and, thereby, Vair corresponds to the velocity of the small particles. The algorithm classifying hydrometeors consists of calculating the terminal velocity of hydrometeors and the vertical temperature profile. It identifies six hydrometeor types (cloud droplets, ice, and four precipitating particles: rain, graupel, snow, and hail) based on the calculated terminal velocity of hydrometeors, temperature, Vair, and Linear Depolarization Ratio. The results of both the Vair and the distribution of hydrometeors were found to be realistic for a thunderstorm associated with significant lightning activity on 1 June 2018.

scholarly journals Low-Cost Ka-Band Cloud Radar System for Distributed Measurements within the Atmospheric Boundary Layer

2020 ◽  
Vol 12 (23) ◽  
pp. 3965
Author(s):  
Roberto Aguirre ◽  
Felipe Toledo ◽  
Rafael Rodríguez ◽  
Roberto Rondanelli ◽  
Nicolas Reyes ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Medium Size ◽  
Physical Parameters ◽  
Mountain Range ◽  
Ka Band ◽  
Range Resolution ◽  
Cloud Radar ◽  
Marine Stratus ◽  
Application Fields

Radars are used to retrieve physical parameters related to clouds and fog. With these measurements, models can be developed for several application fields such as climate, agriculture, aviation, energy, and astronomy. In Chile, coastal fog and low marine stratus intersect the coastal topography, forming a thick fog essential to sustain coastal ecosystems. This phenomenon motivates the development of cloud radars to boost scientific research. In this article, we present the design of a Ka-band cloud radar and the experiments that prove its operation. The radar uses a frequency-modulated continuous-wave with a carrier frequency of 38 GHz. By using a drone and a commercial Lidar, we were able to verify that the radar can measure reflectivities in the order of −60 dBZ at 500 m of distance, with a range resolution of 20 m. The lower needed range coverage imposed by our case of study enabled a significant reduction of the instrument cost compared to existent alternatives. The portability and low-cost of the designed instrument enable its implementation in a distributed manner along the coastal mountain range, as well as its use in medium-size aerial vehicles or balloons to study higher layers. The main features, limitations, and possible improvements to the current instrument are discussed.

scholarly journals Rain‐rate estimation algorithm using signal attenuation of Ka‐band cloud radar

2019 ◽  
Vol 27 (1) ◽  
Author(s):  
Su‐Bin Oh ◽  
Pavlos Kollias ◽  
Jeong‐Soon Lee ◽  
Seung‐Woo Lee ◽  
Yong Hee Lee ◽  
...  
Keyword(s):  
Rain Rate ◽  
Estimation Algorithm ◽  
Signal Attenuation ◽  
Ka Band ◽  
Rate Estimation ◽  
Cloud Radar

Verification and correction of cloud base and top height retrievals from Ka-band cloud radar in Boseong, Korea

2015 ◽  
Vol 33 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Su-Bin Oh ◽  
Yeon-Hee Kim ◽  
Ki-Hoon Kim ◽  
Chun-Ho Cho ◽  
Eunha Lim
Keyword(s):  
Cloud Base ◽  
Ka Band ◽  
Cloud Radar

Attenuation Correction over Ocean for the HIWRAP Dual-Frequency Airborne Scatterometer

2019 ◽  
Vol 36 (10) ◽  
pp. 2015-2030
Author(s):  
R. Meneghini ◽  
L. Liao ◽  
G. M. Heymsfield
Keyword(s):  
Wind Speed ◽  
Attenuation Correction ◽  
Cross Section ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Calibration Error ◽  
Dual Frequency ◽  
Near Surface ◽  
Ka Band ◽  
The Difference

AbstractAn important objective in scatterometry is the estimation of near-surface wind speed and direction in the presence of rain. We investigate an attenuation correction method using data from the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) dual-frequency scatterometer, which operates at Ku and Ka band with dual conical scans at incidence angles of 30° and 40°. The method relies on the fact that the differential normalized surface cross section, δσ0 = σ0(Ka) − σ0(Ku), is relatively insensitive to wind speed and direction and that this quantity is closely related to the magnitude of the differential path attenuation, δA = A(Ka) − A(Ku), arising from precipitation, cloud, and atmospheric gases. As the method relies only on the difference between quantities measured in the presence and absence of rain, the estimates are independent of radar calibration error. As a test of the method’s accuracy, we make use of the fact that the radar rain reflectivities just above the surface, as seen along different incidence angles, are approximately the same. This yields constraint equations in the form of differences between pairs of path attenuations along different lines of sight to the surface. A second validation method uses the dual-frequency radar returns from the rain just above the surface where it can be shown that the difference between the Ku- and Ka-band-measured radar reflectivity factors provide an estimate of differential path attenuation. Comparisons between the path attenuations derived from the normalized surface cross section and those from these surface-independent methods generally show good agreement.

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