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Featured Articles

These are examples of CSU-CHILL data selected from meteorologically interesting cases. The data plots generally have had some basic level of post-processing applied (i.e., calculations of derived fields, utilization of specialized base maps, etc.)

Dual-Doppler mesocyclone observations: 20 July 2013
A low altitude mesocyclone developed near Aurora, CO, a location where horizontal winds could be synthesized from the radial velocity measurements made by the CSU-CHILL X-band radar and the operational NWS KFTG radar. The narrow (0.3 deg) beam width developed by the CHILL X-band system permitted high resolution observations to be made at ranges of 80 - 90 km.
Dual polarization hail signature development at low elevation angles: 27 July 2013
PPI scans at an elevation angle of 0.5 degrees were conducted as reflectivity rapidly intensified beneath a thunderstorm. Decreases in differential reflectivity (Zdr) and co-polar HV correlation coefficient (rhoHV) indicated that hailstones composed an increasing fraction of the intensifying precipitation core.
High Kdp values observed by the CSU-CHILL and KFTG radars: 21 July 2013
The lower levels of a thunderstorm that was producing intense rainfall were jointly observed by the CSU-CHILL and NWS KFTG dual polarization radars on 21 July 2013. One-way specific propagation differential phase (Kdp) magnitudes of ~8 deg / km were documented by both radars.
Thunderstorm passage over a tipping bucket rain gauge: 4 September 2013
Rain rates of ~60mm per hour were recorded by a Denver flood control district rain gauge during a thunderstorm passage on 4 September 2013. The CSU-CHILL radar made low elevation angle PPI sweeps at roughly one minute time intervals as the echo core passed the gauge. Time histories of the S-band reflectivity and specific propagation differential phase data at the gauge's azimuth / range location have been prepared.
Cell intensification following a boundary passage: 30 August 2013
Brief intensification was observed when fine line echoes in the boundary layer interacted with a small, pre-existing thunderstorm. Animations of the X-band dual-polarization data show evidence of higher concentrations of oblate rain drops during the intensification period.
S and X-band rhoHV observations in hail: 3 August 2013
Dual frequency data was collected during a hailstorm that affected the Greeley area on 3 August 2013. Indications of X-band rhoHV reductions due to Mie scattering effects appear to be present at a location of confirmed hail damage.
Initial plots from flooding rainfall in Aurora, Colorado: 13 September 2013
Preliminary plots of the CSU-CHILL dual-polarization data collected during a small time segment of a widespread flooding event have been developed.
An RHI scan sequence through thunderstorm outflow: 27 July 2013
The approach and passage of a thunderstorm gust front at the CSU-CHILL radar site was observed through a series of RHI scans that repeated at ~1 minute time intervals. Time lapse loops of the 3 GHZ (S-band) reflectivity and radial velocity data have been prepared.
Attenuation observed at 9 GHz (X-band): 15 July 2013
The X-band attenuation due to a thunderstorm's heavy rainfall core prevented the detection of more distant echoes. The evolution of the attenuation "shadow" is shown using selected time lapse loops.
Dual-Doppler observations of a Bounded Weak Echo Region (BWER): 17 June 2013
Synchronized dual Doppler scanning was done by the CSU-CHILL and Pawnee radars during a 20hr project on thunderstorm electrification. A storm observed on 17 June 2013 contained a Bounded Weak Echo Region (BWER) in association with the main updraft.
Time variations in bright band height: 12 April 2013
RHI sweeps were repeated at time intervals of ~47 seconds as an area of weakening rain showers approached the CSU-CHILL radar on 12 April 2013. (The radar was operating in X-Band only configuration). Fluctuations in the height of the Zdr bright band were noted as various localized reflectivity maxima descended through the melting level.
Selected dual-Doppler observations of a snow band: 15 April 2013
A well-defined snow band extended across the greater Denver area during the morning hours of 15 April 2013; portions of this band were located within the eastern lobe of the dual-Doppler domain defined by the CSU-CHILL and NWS KFTG radars. Example plots of the synthesized wind fields along with X-band polarimetric data from CSU-CHILL have been prepared.
High time resolution RHI's through a snow band: 4 March 2013
RHI scans repeated at ~1 minute intervals were done as a snow band approached the CSU-CHILL radar site. Small scale convective elements were observed in the upper portions of the echo system.
Dual frequency observations of a dry cold front: 15 August 2012
The fine line echo associated with a dry cold frontal passage at the CSU-CHILL radar site was observed at radar frequencies of both 3 and 10 GHz (S and X-Bands). The narrower X-Band beam provided a better resolution of small scale structures along the frontal echo.
Selected dual polarization observations in a supercell thunderstorm: 8 June 2012
A weakening supercell thunderstorm approached the CSU-CHILL radar site on the evening of 7 June 2012 (local date) during DC3 project operations. RHI scans were taken through the weak echo region (WER) and the adjacent hail shaft.
Dual wavelength hail detection: 26 September 2012
Systematic differences between the reflectivities observed at wavelengths of 11 and 3 cm were used to identify an area of hail on 26 September 2012. Supporting plots of the 11 cm wavelength differential reflectivity (Zdr) and hail differential reflectivity (Hdr) have been generated.
A comparison of dual polarization KFTG and CSU-CHILL Kdp fields: 26 September 2012
The Denver / Front Range WSR-88D radar was upgraded to dual polarization configuration in early September, 2012. During the afternoon hours of 26 September 2012, thunderstorms producing intense rain rates and sub-severe diameter hail moved through the Platteville, Colorado area. Plots of the Kdp fields observed in the Platteville storm by the KFTG and CSU-CHILL radars have been prepared.
Cold frontal passage: 3 October 2012
A strong, essentially dry cold front passed the CSU-CHILL radar site near 2200 UTC on 3 October 2012. The progression of the fine line echo and wind shift associated with front is shown in a time lapse of low elevation angle PPI scans.
Varying outflow boundary motion: 11 September 2012
Shower activity locally modified the motion of a pre-existing outflow boundary. The evolution of the boundary's motion is shown with a time lapse sequence of low elevation angle PPI images.
X-Band attenuation example: 30 July 2012
Regions of both stratiform and convective rain were observed during dual frequency test operations on 30 July 2012. Complete attenuation of the X-band / 3 cm wavelength signal occurred in an area of thunderstorm precipitation.
Initial dual frequency observations of rain: 17 July 2012
The CSU-CHILL dual frequency feedhorn was reinstalled on 5 July 2012. Preliminary plots of convective rain observed simultaneously at wavelengths of 11 and 3 cm have been prepared.
Anvil level dual Doppler horizontal winds: 15 June 2012
Winds synthesized from a dual Doppler volume scan done by the CSU-CHILL and Pawnee radars during the DC3 project are presented.
Thunderstorm outflow and rainfall near the surface over Ft. Collins: 1 August 2011
Radial velocity patterns and a rainfall time history plot are presented.
Time lapse imagery of sky conditions near the Hewlett fire on 16 May 2012
Digital camera images at one minute time intervals between 2020 and 2149 UTC taken from the CSU-CHILL radar site.
Bounded weak echo region (BWER) example: 9 June 2011
A marginally severe thunderstorm was observed with both PPI and RHI scans during the early UTC hours of 9 June 2011. Plots of the storm's three-dimensional structure have been generated.
Damaging hailstorm at Cheyenne, WY: 12 July 2011
A series of low elevation angle dual-polarization PPI scans were recorded by the CSU-CHILL radar as a severe hailstorm struck Cheyenne, WY. Time lapse loops of several radar data fields have been prepared.
X-Band Kdp observations in a snowstorm: 3 February 2012
Selected plots from dual frequency test operations conducted during a widespread snowstorm have been collected.
Initial CSU-CHILL X-band operations: January 2012
Example plots from test operations conducted with the dual frequency feed horn are presented.
Thundersnow: 14 November 2009
An echo line developed in association with a convergence zone generated by a westerly wind surge. This echo line produced observations of both snow and lightning at Denver International Airport. Locally reduced rhoHV and enhanced Ldr values were observed near the surface in the convective echo cores.
Cold air surge at the surface: 2 November 2011
A series of RHI scans were taken after a cold frontal passage. The increasing northerly surface winds following this frontal passage can be seen in a sequence of radial velocity images.
Differential attenuation patterns: 19 August 2011
Thunderstorm precipitation produced an axis of heavy rain that became radially-aligned with the CSU-CHILL radar. Differential attenuation along beam paths through this heavy rain caused a negative Zdr bias.
Fine line passage at Denver International Airport: 30 August 2011
The passage of a fine line echo coincided with the timing of a wind direction shift reported in the surface weather observations.
Time lapse observations of outflow phenomena: 11 August 2011
The low-level outflow patterns generated by rainshowers and weak thunderstorms are shown by animations of CHILL PPI plots and digital camera images.
Damaging hailstorm at Denver International Airport: 13 July 2011
Hail damage was inflicted on multiple aircraft at Denver International Airport during the evening hours of 13 July 2011. Selected CSU-CHILL dual-polarization data images from this storm have been generated.
Polarimetric radar identification of frozen hydrometeors in thunderstorm precipitation: 6 August 2010
The radar characteristics of individual range gates are used to place thunderstorm precipitation into one of three categories: (1) primarily rain; (2) mixed rain and hail; and (3) primarily hail. The areal coverage of these categories varies with time during a series of low elevation angle PPI sweeps through a thunderstorm.
Evolution of radial velocity and rain rate fields in low elevation PPI sweeps of a thunderstorm: 30 July 2010
A series of 1.5 degree elevation angle PPI scans document intensifying outflow and increasing rain rates as a storm reaches the CSU-CHILL radar site.
An RHI scan through a severe thunderstorm: 21 June 2010
A single RHI sweep through a severe thunderstorm reveals several signatures in the radial velocity and dual-polarization data fields.

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Technical Notes

These articles deal with engineering topics of interest to users of CSU-CHILL data.

Using Time-series data from CSU-CHILL (TN-009)
Short article describing the time-series data extraction tool
X-band Solid State Transmitter Monitor User's Guide (TN-008)
User's Guide to the solid-state X-band transmitter monitor developed at CSU-CHILL.
Clock Generator User's Guide (TN-007)
User's Guide to the programmable clock-generator design developed at CSU-CHILL.
Frequency Synthesizer User's Guide (TN-006)
User's Guide to the programmable Frequency Synthesizer design developed at CSU-CHILL.
Radar Echoes from Wind Turbines (TN-004)
Wind Turbines have become increasingly common in recent years. Their Doppler spectral characteristics are presented, along with an animation showing the repetitive patterns present in the turbine spectra. An audio presentation of the same data is also available, clearly showing the temporal variation of the echo. A brief discussion on the effects of wind turbine proliferation on radar meteorology is also presented.
Coherent Leakage (TN-003)
This is a short discussion on coherent leakage, discussing the various causes of coherent leakage in weather radar receivers. Some troubleshooting tips are also provided.

More Technical Notes

Recent Observations

More Recent Observations articles

Ongoing Data Analysis

More Ongoing Data Analysis articles

Casebook

The CSU-CHILL Casebook contains summaries of CHILL operations, categorized by keywords, project names and by date of operation.

Casebook Archives


modified on 19 March 2014 at 15:48 ••• 37,697 views