Precipitation measurements using VHF wind profiler radars: Measuring rainfall and vertical air velocities using only observations with a VHF radar

Campos, Edwin; Fabry, Frédéric; Hocking, W. K.

doi:10.1029/2006rs003540

Cited by 14 publications

(20 citation statements)

References 23 publications

(44 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The carrier frequency of MUR is 46.5 MHz so that it is mainly sensitive to clear air refractive index fluctuations at half the radar wavelength in size (i.e. the Bragg scale), even in presence of clouds or weak precipitations (less than 4 mm h −1 according to Campos et al, 2007). Therefore, small-scale refractivity turbulence can be monitored by MUR in both clear air and cloudy conditions.…”

Section: Resultsmentioning

confidence: 99%

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

et al. 2013

View full text Add to dashboard Cite

Abstract. The present paper addresses the detection of turbulence based on the Thorpe (1977) method applied to an atmosphere where saturation of water vapor occurs. The detection method proposed by Thorpe relies on the sorting in ascending order of a measured profile of a variable conserved through adiabatic processes, (e.g. potential temperature). For saturated air, the reordering should be applied to a moist-conservative potential temperature, θm, which is analogous to potential temperature for a dry (subsaturated) atmosphere. Here, θm is estimated from the Brunt–Väisälä frequency derived by Lalas and Einaudi (1974) in a saturated atmosphere. The application to balloon data shows that the effective turbulent fraction of the troposphere can dramatically increase when saturation is taken into account. Preliminary results of comparisons with data simultaneously collected from the VHF Middle and Upper atmosphere radar (MUR, Japan) seem to give credence to the proposed approach.

show abstract

Section: Resultsmentioning

confidence: 99%

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

et al. 2013

View full text Add to dashboard Cite

show abstract

“…It is necessary to exclude periods of convective rain that may be present in the datasets from any DSD retrievals. It should be noted that this limitation is not present when using VHF wind profilers (Campos et al 2007).…”

Section: Discussionmentioning

confidence: 99%

“…If the clear-air contribution is known, it can be removed from the Doppler spectrum prior to retrieving DSDs. Several methods for isolating and removing the clearair contribution have been explored, including the use of multiple radar frequencies such as UHF and VHF (Schafer et al 2002;Rajopadhyaya et al 1999), cluster analysis , deconvolution (Rajopadhyaya et al 1993;Lucas et al 2004), fitting model spectra to observed spectra (Wakasugi et al 1986;Kobayashi and Adachi 2005), and using measurements from a single VHF wind profiler to quantify both precipitation signals and the ambient air velocity (Campos et al 2007). …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Analysis of Errors in Drop Size Distribution Retrievals and Rain Bulk Parameters with a UHF Wind Profiling Radar and a Two-Dimensional Video Disdrometer

Kanofsky

Chilson

2008

Journal of Atmospheric and Oceanic Technology

View full text Add to dashboard Cite

Vertically pointed wind profiling radars can be used to obtain measurements of the underlying drop size distribution (DSD) for a rain event by means of the Doppler velocity spectrum. Precipitation parameters such as rainfall rate, radar reflectivity factor, liquid water content, mass-weighted mean drop diameter, and median volume drop diameter can then be calculated from the retrieved DSD. The DSD retrieval process is complicated by the presence of atmospheric turbulence, vertical ambient air motion, selection of fall speed relationships, and velocity thresholding. In this note, error analysis is presented to quantify the effect of each of those factors on rainfall rate. The error analysis results are then applied to two precipitation events to better interpret the rainfall-rate retrievals.It was found that a large source of error in rain rate is due to unaccounted-for vertical air motion. For example, in stratiform rain with a rainfall rate of R ϭ 10 mm h Ϫ1 , a mesoscale downdraft of 0.6 m s Ϫ1 can result in a 34% underestimation of the estimated value of R. The fall speed relationship selection and source of air density information both caused negligible errors. Errors due to velocity thresholding become more important in the presence of significant contamination near 0 m s Ϫ1 , such as ground clutter. If particles having an equivalent volume diameter of 0.8 mm and smaller are rejected, rainfall rate errors from Ϫ4% to Ϫ10% are possible, although these estimates depend on DSD and rainfall rate.

show abstract

“…Standard forms for this equation assume, most of the time, an average scatterer cross section per unit volume (or radar reflectivity) that is constant within the sampling volume of a given range gate. Under these conditions and neglecting the effect of the convolution of the transmitted pulse with the reflectivity profile, the radar equation is given by the following expression [for details on its derivation, see Campos et al (2007); Eq. (18)]:…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Effects of Height-Variable Reflectivity and Antenna Sidelobes on the Radar Equation

Campos

Hocking

Fabry

2008

Journal of Atmospheric and Oceanic Technology

Self Cite

View full text Add to dashboard Cite

Using radar observations to quantify precipitation intensity requires the intervention of the radar equation, which converts the precipitation signal into reflectivity units. This equation generally assumes that the reflectivity is uniform within each sampling gate and that the sidelobes of the antenna pattern are negligible. The purpose here is to provide a more realistic approach that eliminates these assumptions when computing profiles of precipitation intensity (by using a height-variable reflectivity and antenna pattern of significant sidelobes to compute profiles of a radar reflectivity factor). To achieve this, simultaneous observations of collocated vertically pointing radars operating in the VHF and X bands were obtained. Raindrop measurements were used to correct for attenuation in the precipitation signal at the X band. Then the precipitation signal in the VHF radar was simulated by combining this X-band signal and the VHF antenna pattern into a general version of the radar equation. The simulated precipitation signal at VHF compares well with actual measurements of the rain signal (range gates centered at 2.5, 3.0, and 3.5 km) by the VHF radar, and this validates the analysis methods. In conclusion, the analysis indicates that VHF reflectivity at gates above the melting layer is artificially enhanced by the precipitation signal collected in the sidelobe direction. Similar enhancement will be expected wherever there is a strong vertical gradient of reflectivity (i.e., on the order of 10 dB km Ϫ1 or larger).

show abstract

Precipitation measurements using VHF wind profiler radars: Measuring rainfall and vertical air velocities using only observations with a VHF radar

Cited by 14 publications

References 23 publications

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

An Analysis of Errors in Drop Size Distribution Retrievals and Rain Bulk Parameters with a UHF Wind Profiling Radar and a Two-Dimensional Video Disdrometer

Evaluating the Effects of Height-Variable Reflectivity and Antenna Sidelobes on the Radar Equation

Contact Info

Product

Resources

About