scholarly journals Performance of the DBS Satellite Receiver under the Impact of Rainfall and Terrestrial Interference

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zaid Ahmed Shamsan ◽  
Ahmed Al-Saman
Keyword(s):  
Rain Rate ◽  
Measured Data ◽  
Semiarid Region ◽  
Receiver Performance ◽  
Mitigation Techniques ◽  
Rain Rates ◽  
The Impact ◽  
Satellite Receiver ◽  
K Band

This article presents a new study on the feasibility of operating a direct broadcasting satellite (DBS) system under the effect of both precipitation and interference from a fixed service (FS) at K-band in a semiarid region. The carrier-to-noise plus interference ratio (CNIR) as a protection criterion has been adopted to make sure that the receiver of the DBS system operates with an acceptable performance under rainfall and interference from FS. Various measured data for rainfall in different areas have been utilized to investigate different rain rate exceedance percentages. Results have been shown that areas with high rain rates have a small CNIR at the DBS receiver and require large protection distances compared to low-rain rate areas and vice versa. Some mitigation techniques have been suggested to alleviate the effect of rain and terrestrial interference on the DBS receiver performance.

scholarly journals Microphysics Regime Impacts on the Relationship between Orographic Rain and Orographic Forcing in the Coastal Mountains of Northern California

2016 ◽  
Vol 17 (11) ◽  
pp. 2905-2922 ◽  
Author(s):  
David E. Kingsmill ◽  
Paul J. Neiman ◽  
Allen B. White
Keyword(s):  
Rain Rate ◽  
Correlation Coefficients ◽  
Northern California ◽  
Orographic Enhancement ◽  
Orographic Forcing ◽  
Warm Rain Process ◽  
Bodega Bay ◽  
Rain Rates ◽  
The Impact ◽  
The Relationship

Abstract This study examines the impact of microphysics regime on the relationship between orographic forcing and orographic rain in the coastal mountains of Northern California using >4000 h of data from profiling Doppler radars, rain gauges, and a GPS receiver collected over 10 cool seasons. Orographic forcing is documented by hourly upslope flow, integrated water vapor (IWV), and IWV flux observed along the coast at Bodega Bay (BBY; 15 m MSL). Microphysics regime is inferred in the coastal mountains at Cazadero (CZC; 478 m MSL), where hourly periods of brightband (BB) and nonbrightband (NBB) rain are designated. BB rain is associated with a microphysics regime dominated by the seeder–feeder process while NBB rain is associated with a microphysics regime dominated by the warm-rain process. Mean BBY upslope flow, IWV, and IWV flux are ~16%, ~5%, and ~19% larger, respectively, for NBB rain compared to BB rain, while mean CZC rain rate is ~33% larger for BB rain compared to NBB rain. The orographic enhancement ratio of CZC to BBY rain rate is 3.7 during NBB rain and 2.7 during BB rain. Rain rate at CZC increases as orographic forcing at BBY increases. For a given amount of BBY orographic forcing, mean CZC rain rates are larger for BB rain compared to NBB rain. Correlation coefficients associated with the relationship between CZC rain rate and BBY orographic forcing are smaller for NBB rain relative to BB rain, but these differences are not statistically significant.

scholarly journals Automated rain rate estimates using the Ka-band ARM Zenith Radar (KAZR)

2014 ◽  
Vol 7 (2) ◽  
pp. 1807-1833
Author(s):  
A. Chandra ◽  
C. Zhang ◽  
P. Kollias ◽  
S. Matrosov ◽  
W. Szyrmer
Keyword(s):  
Rain Rate ◽  
Robust Statistics ◽  
Tropical Indian Ocean ◽  
Ka Band ◽  
Weather Radars ◽  
Automated Algorithm ◽  
Microphysical Processes ◽  
The Tropics ◽  
Rain Rates ◽  
The Impact

Abstract. The use of millimeter wavelength radars for probing precipitation has recently gained interest. However, estimation of precipitation variables is not straightforward due to strong attenuation, radar receiver saturation, antenna wet radome effects and natural microphysical variability. Here, an automated algorithm is developed for routinely retrieving rain rates from profiling Ka-band (35-GHz) ARM zenith radars (KAZR). A 1-D simple, steady state microphysical model is used to estimate the impact of microphysical processes and attenuation on the profiles of the radar observables at 35-GHz and thus provide criteria for identifying when attenuation or microphysical processes dominate KAZR observations. KAZR observations are also screened for saturation and wet radome effects. The proposed algorithm is implemented in two steps: high rain rates are retrieved by using the amount of attenuation in rain layers, while lower rain rates by the Ze–R (reflectivity-rain rate) relation is implemented. Observations collected by the KAZR, disdrometer and scanning weather radars during the DYNAMO/AMIE field campaign at Gan Island of the tropical Indian Ocean are used to validate the proposed approach. The results indicate that the proposed algorithm can be used to derive robust statistics of rain rates in the tropics from KAZR observations.

scholarly journals Measuring Hydrometeors Using a Precipitation Microphysical Characteristics Sensor: Sampling Effect of Different Bin Sizes on Drop Size Distribution Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Monte Carlo Model ◽  
Rain Gauge ◽  
Sampling Schemes ◽  
Distribution Parameters ◽  
Optimum Sampling ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.

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.

scholarly journals Evaluation of Gamma Raindrop Size Distribution Assumption through Comparison of Rain Rates of Measured and Radar-Equivalent Gamma DSD

2014 ◽  
Vol 53 (6) ◽  
pp. 1618-1635 ◽  
Author(s):  
Elisa Adirosi ◽  
Eugenio Gorgucci ◽  
Luca Baldini ◽  
Ali Tokay
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Rain Rate ◽  
Hydrological Cycle ◽  
Drop Size Distribution ◽  
Dual Polarization ◽  
Raindrop Size Distribution ◽  
Radar Measurements ◽  
Raindrop Size ◽  
Rain Rates

AbstractTo date, one of the most widely used parametric forms for modeling raindrop size distribution (DSD) is the three-parameter gamma. The aim of this paper is to analyze the error of assuming such parametric form to model the natural DSDs. To achieve this goal, a methodology is set up to compare the rain rate obtained from a disdrometer-measured drop size distribution with the rain rate of a gamma drop size distribution that produces the same triplets of dual-polarization radar measurements, namely reflectivity factor, differential reflectivity, and specific differential phase shift. In such a way, any differences between the values of the two rain rates will provide information about how well the gamma distribution fits the measured precipitation. The difference between rain rates is analyzed in terms of normalized standard error and normalized bias using different radar frequencies, drop shape–size relations, and disdrometer integration time. The study is performed using four datasets of DSDs collected by two-dimensional video disdrometers deployed in Huntsville (Alabama) and in three different prelaunch campaigns of the NASA–Japan Aerospace Exploration Agency (JAXA) Global Precipitation Measurement (GPM) ground validation program including the Hydrological Cycle in Mediterranean Experiment (HyMeX) special observation period (SOP) 1 field campaign in Rome. The results show that differences in rain rates of the disdrometer DSD and the gamma DSD determining the same dual-polarization radar measurements exist and exceed those related to the methodology itself and to the disdrometer sampling error, supporting the finding that there is an error associated with the gamma DSD assumption.

scholarly journals On the Relationship between Intensity and Rainfall Distribution in Tropical Cyclones Making Landfall over China

2017 ◽  
Vol 56 (10) ◽  
pp. 2883-2901 ◽  
Author(s):  
Zifeng Yu ◽  
Yuqing Wang ◽  
Haiming Xu ◽  
Noel Davidson ◽  
Yandie Chen ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Rain Rate ◽  
Vertical Wind Shear ◽  
Intensity Change ◽  
Total Rainfall ◽  
Rainfall Distribution ◽  
Rain Area ◽  
Maximum Rainfall ◽  
Rain Rates ◽  
The Relationship

AbstractTRMM satellite 3B42 rainfall estimates for 133 landfalling tropical cyclones (TCs) over China during 2001–15 are used to examine the relationship between TC intensity and rainfall distribution. The rain rate of each TC is decomposed into axisymmetric and asymmetric components. The results reveal that, on average, axisymmetric rainfall is closely related to TC intensity. Stronger TCs have higher averaged peak axisymmetric rain rates, more averaged total rain, larger averaged rain areas, higher averaged rain rates, higher averaged amplitudes of the axisymmetric rainfall, and lower amplitudes of wavenumbers 1–4 relative to the total rainfall. Among different TC intensity change categories, rapidly decaying TCs show the most rapid decrease in both the total rainfall and the axisymmetric rainfall relative to the total rain. However, the maximum total rain, maximum rain area, and maximum rain rate are not absolutely dependent on TC intensity, suggesting that stronger TCs do not have systematically higher maximum rain rates than weaker storms. Results also show that the translational speed of TCs has little effect on the asymmetric rainfall distribution in landfalling TCs. The maximum rainfall of both the weaker and stronger TCs is generally located downshear to downshear left. However, when environmental vertical wind shear (VWS) is less than 5 m s−1, the asymmetric rainfall maxima are more frequently located upshear and onshore, suggesting that in weak VWS environments the coastline could have a significant effect on the rainfall asymmetry in landfalling TCs.

scholarly journals A study on the characteristics and influencing factors of reservoir sedimentation in Wanjiazhai Reservoir

2018 ◽  
Vol 246 ◽  
pp. 01046
Author(s):  
Zhihui Ren ◽  
Ting Wang ◽  
Yuanjian Wang ◽  
Shaojun Qu
Keyword(s):  
Water Level ◽  
Reservoir Operation ◽  
Temporal Distribution ◽  
Measured Data ◽  
Sediment Deposition ◽  
Reservoir Sedimentation ◽  
Spatial And Temporal Distribution ◽  
Timely Manner ◽  
Reservoir Area ◽  
The Impact

Based on measured data of the Wanjiazhai Reservoir in different periods, the characteristics of the spatial and temporal distribution of sedimentation in the reservoir area were preliminarily analyzed and the impact of reservoir operation on this distribution was discussed. Primary conclusions are as followed: in terms of temporal distribution, sedimentation continuously accumulated over the period from 2000 to 2017, with the sediment deposition ratio dramatically decreasing between 2011 and 2017; in terms of spatial distribution, the sedimentation in the reservoir area was mainly concentrated downstream of the WD54 section, with the highest concentration being downstream of the WD23 section. The characteristics of sedimentation distribution in the reservoir area were closely related to inflow and sediment conditions and reservoir operation water level. When the water level was lower than 952 m, the sediment deposition ratio was lower than 0. To further improve the sediment deposition form in the reservoir area, lowering water level and ejecting the sediment are recommended in a timely manner.

scholarly journals Automated rain rate estimates using the Ka-band ARM zenith radar (KAZR)

2015 ◽  
Vol 8 (9) ◽  
pp. 3685-3699 ◽  
Author(s):  
A. Chandra ◽  
C. Zhang ◽  
P. Kollias ◽  
S. Matrosov ◽  
W. Szyrmer
Keyword(s):  
Rain Rate ◽  
Tropical Indian Ocean ◽  
Rain Gauge ◽  
Signal Attenuation ◽  
Ka Band ◽  
Automated Algorithm ◽  
Atmospheric Radiation Measurement ◽  
Microphysical Processes ◽  
The Tropics ◽  
Rain Rates

Abstract. The use of millimeter wavelength radars for probing precipitation has recently gained interest. However, estimation of precipitation variables is not straightforward due to strong signal attenuation, radar receiver saturation, antenna wet radome effects and natural microphysical variability. Here, an automated algorithm is developed for routinely retrieving rain rates from the profiling Ka-band (35-GHz) ARM (Atmospheric Radiation Measurement) zenith radars (KAZR). A 1-dimensional, simple, steady state microphysical model is used to estimate impacts of microphysical processes and attenuation on the profiles of radar observables at 35-GHz and thus provide criteria for identifying situations when attenuation or microphysical processes dominate KAZR observations. KAZR observations are also screened for signal saturation and wet radome effects. The algorithm is implemented in two steps: high rain rates are retrieved by using the amount of attenuation in rain layers, while low rain rates are retrieved from the reflectivity–rain rate (Ze–R) relation. Observations collected by the KAZR, rain gauge, disdrometer and scanning precipitating radars during the DYNAMO/AMIE field campaign at the Gan Island of the tropical Indian Ocean are used to validate the proposed approach. The differences in the rain accumulation from the proposed algorithm are quantified. The results indicate that the proposed algorithm has a potential for deriving continuous rain rate statistics in the tropics.

Partial Shading in Building Integrated PV System: Causes, Effects and Mitigating Techniques

2015 ◽  
Vol 6 (4) ◽  
pp. 712 ◽  
Author(s):  
Zainal Salam ◽  
Zulkifli Ramli ◽  
Jubaer Ahmed ◽  
Muhammad Amjad
Keyword(s):  
Economic Benefits ◽  
Pv System ◽  
Comprehensive Overview ◽  
Partial Shading ◽  
Holistic Understanding ◽  
Mitigation Techniques ◽  
Physical Reasons ◽  
The Impact

This paper is aimed to provide a holistic understanding on the issues related to partial shading: its causes, the theoretical and physical reasons behind it, its implications on the BIPV system. Furthermore  the possible mitigation techniques using the software (MPPT) and hardware solutions are discussed. Finally an example is given to illustrate the impact of partial shading and the economic benefits of employing various partial shading mitigation techniques into the BIPV system To aid the unfamiliar readers in this subject, a brief but comprehensive overview of important PV concepts are also given.

scholarly journals Improving the Water-Use Efficiency and the Agricultural Productivity: An Application Case in a Modernized Semiarid Region in North-Central Mexico

2020 ◽  
Vol 12 (19) ◽  
pp. 8122
Author(s):  
Julián González-Trinidad ◽  
Hugo Enrique Júnez-Ferreira ◽  
Carlos Bautista-Capetillo ◽  
Laura Ávila Dávila ◽  
Cruz Octavio Robles Rovelo
Keyword(s):  
Crop Yields ◽  
Water Productivity ◽  
Agricultural Productivity ◽  
Free Water ◽  
Field Capacity ◽  
Semiarid Region ◽  
Future Research ◽  
Drought Period ◽  
Water Volumes ◽  
The Impact

The increasing population demands a greater quantity of food. In order to satisfy the world’s demand, one of the main challenges worldwide consists of modernizing the current irrigation systems. This research shows an experience carried out in a modernized irrigation module in Central-North Mexico following these objectives: to evaluate the impact of the modernization of the irrigation module, to analyze the agricultural productivity, and to assess a group of parameters related with the agricultural production (system conduction and distribution efficiencies, water productivity, among others) and the water volumes after and before the modernization. After a drought period, a methodology was performed in commercial parcels in 2013 to increase the yield of different crops. Some of the activities were: soil leveling, estimation of the soil properties (field capacity, wilting point, bulk density, pH, and organic matter), optimum fertilization applications, use of a model to scheduling irrigation, measure volumes extracted at the parcel level. With the modernization and the method used, around 1800 and 2000 m3 ha−1 were saved with respect to the initial granted volume by the Comisión Nacional del Agua and increase in the global efficiency was also achieved (from 55% to 85%). All crop yields increased, i.e., for corn from 2.5 kg/m3 to 3.8 kg/m3. The impact of modernization accompanied with an effective operation allowed a significant increase of the crop yield and water productivity. Despite a controlled distribution of water being carried out, future research should contemplate free water demand scenarios and automation irrigation for improving the module operation.

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