scholarly journals A Proposed Solution to the Range–Doppler Dilemma of Weather Radar Measurements by Using the SMPRF Codes, Practical Results, and a Comparison with Operational Measurements

2005 ◽  
Vol 44 (9) ◽  
pp. 1375-1390 ◽  
Author(s):  
Juha Pirttilä ◽  
Markku S. Lehtinen ◽  
Asko Huuskonen ◽  
Markku Markkanen
Keyword(s):  
High Resolution ◽  
Pulse Repetition Frequency ◽  
Weather Radar ◽  
Simplified Model ◽  
Measured Spectrum ◽  
Model Calculations ◽  
Incoherent Scatter ◽  
Incoherent Scatter Radars ◽  
Working Principle ◽  
Radar Measurements

Abstract Based on the measurement principles used on incoherent scatter radars, the authors have developed the Simultaneous Multiple Pulse Repetition Frequency (SMPRF) code that is intended to solve the range–Doppler dilemma and that can be used with modern magnetron radars. The working principle of the code is explained in mathematical terms and with the help of a simplified model. Results from the SMPRF and traditional fixed PRF weather radar measurements are compared, and the reasons for the differences are explained. The practical results show that the SMPRF code seems to work in the manner that is predicted by the theoretical and model calculations. The SMPRF code provides enough information to produce a high-resolution measured spectrum for each range gate. The shape of these measured spectra are seldom purely Gaussian. It is possible that more advanced raw products, other than just reflectivity, velocity, and width, can be produced with the help of these high-resolution spectra.

scholarly journals Enhanced incoherent scatter plasma lines

1996 ◽  
Vol 14 (12) ◽  
pp. 1462-1472 ◽  
Author(s):  
H. Nilsson ◽  
S. Kirkwood ◽  
J. Lilensten ◽  
M. Galand
Keyword(s):  
High Plasma ◽  
Collision Term ◽  
Vhf Radar ◽  
Detailed Model ◽  
Model Calculations ◽  
Incoherent Scatter ◽  
Incoherent Scatter Radars ◽  
Plasma Line ◽  
E Region ◽  
Radar Measurements

Abstract. Detailed model calculations of auroral secondary and photoelectron distributions for varying conditions have been used to calculate the theoretical enhancement of incoherent scatter plasma lines. These calculations are compared with EISCAT UHF radar measurements of enhanced plasma lines from both the E and F regions, and published EISCAT VHF radar measurements. The agreement between the calculated and observed plasma line enhancements is good. The enhancement from the superthermal distribution can explain even the very strong enhancements observed in the auroral E region during aurora, as previously shown by Kirkwood et al. The model calculations are used to predict the range of conditions when enhanced plasma lines will be seen with the existing high-latitude incoherent scatter radars, including the new EISCAT Svalbard radar. It is found that the detailed structure, i.e. the gradients in the suprathermal distribution, are most important for the plasma line enhancement. The level of superthermal flux affects the enhancement only in the region of low phase energy where the number of thermal electrons is comparable to the number of suprathermal electrons and in the region of high phase energy where the suprathermal fluxes fall to such low levels that their effect becomes small compared to the collision term. To facilitate the use of the predictions for the different radars, the expected signal- to-noise ratios (SNRs) for typical plasma line enhancements have been calculated. It is found that the high-frequency radars (Søndre Strømfjord, EISCAT UHF) should observe the highest SNR, but only for rather high plasma frequencies. The VHF radars (EISCAT VHF and Svalbard) will detect enhanced plasma lines over a wider range of frequencies, but with lower SNR.

The spectrum of gaseous methane at 77 K in the 1.1 – 2.6 μm region: a benchmark for planetary astronomy

1989 ◽  
Vol 67 (11) ◽  
pp. 1027-1035 ◽  
Author(s):  
A. R. W. McKellar
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Low Temperature ◽  
Spectral Resolution ◽  
Fourier Transform Spectrometer ◽  
Absorption Cell ◽  
Model Calculations ◽  
Testing Model ◽  
Medium Resolution ◽  
Spectrometer Data

The spectrum of CH4 obtained in CH4 plus N2 mixtures at a temperature of 77 K has been recorded with a spectral resolution of 0.14 cm−1 in the region 3800 to 9100 cm−1. The experiments were performed with long paths (66 or 88 m) in a cooled absorption cell using a Fourier-transform spectrometer. Data are presented here at low and medium resolution, and examples of some spectral regions are also shown at high resolution. The complete results are available from the author in an Appendix. Comparisons are made with previous model calculations of CH4 absorption, and with the observed spectrum of Neptune's satellite, Triton. The results should be useful for the interpretation of the spectra of Triton, Titan, and Pluto. They will also be of value for testing model calculations of low-temperature CH4 absorption, which, thus verified, can be used with greater confidence to analyze observations of Jupiter, Saturn Uranus, and Neptune.

scholarly journals Influence of Disdrometer Type on Weather Radar Algorithms from Measured DSD: Application to Italian Climatology

Atmosphere ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 360 ◽  
Author(s):  
Elisa Adirosi ◽  
Nicoletta Roberto ◽  
Mario Montopoli ◽  
Eugenio Gorgucci ◽  
Luca Baldini
Keyword(s):  
Drop Size ◽  
Weather Radar ◽  
Size Distributions ◽  
Regression Methods ◽  
Radar Meteorology ◽  
Quality Checks ◽  
Radar Measurements ◽  
Drop Size Distributions ◽  
First And Second Generation ◽  
Theoretical Considerations

Relations for retrieving precipitation and attenuation information from radar measurements play a key role in radar meteorology. The uncertainty in such relations highly affects the precipitation and attenuation estimates. Weather radar algorithms are often derived by applying regression methods to precipitation measurements and radar observables simulated from datasets of drop size distributions (DSD) using microphysical and electromagnetic assumptions. DSD datasets can be derived from theoretical considerations or obtained from experimental measurements collected throughout the years by disdrometers. Although the relations obtained from experimental disdrometer datasets can be generally considered more representative of a specific climatology, the measuring errors, which depend on the specific type of disdrometer used, introduce an element of uncertainty to the final retrieval algorithms. Eventually, data quality checks and filtering procedures applied to disdrometer measurements play an important role. In this study, we pursue two main goals: (i) evaluate two different techniques for establishing weather radar algorithms from measured DSD, and (ii) investigate to what extent dual-polarization radar algorithms derived from experimental DSD datasets are influenced by the different error structures introduced by the various disdrometer types (namely 2D video disdrometer, first and second generation of OTT Parsivel disdrometer, and Thies Clima disdrometer) used to collect the data. Furthermore, weather radar algorithms optimized for Italian climatology are presented and discussed.

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