Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
68 Cards in this Set
- Front
- Back
|
Above Ground Level (AGL)
|
An expression used with height measurements to indicate the measurement is for the heigh above the ground at that location (in constrast to above mean sea level or above radar level).
|
|
|
Advanced Weather Interactive Processing System (AWIPS)
|
The AWIPS is the hardware and software the NWS uses to acquire, process, view, and store data from numerous sources (including those products received from the RPG).
|
|
|
Angular Beam Width
|
The angle in degrees measured across the axis of the radar beam between half power points.
|
|
|
Anomalous Propagation (AP)
|
The abnormal bending of the radar beam as it passes through the atmosphere.
|
|
|
Attenuation
|
The reduction in power of a signal due to refraction, scattering, or absorption of energy.
|
|
|
Backscattered Signal
|
The scattering of radiant energy at 180 degrees to the direction of the transmitted wave; scattering from a target back toward the antenna.
|
|
|
Base Data Distribution System (BDDS)
|
A subcomponent of the WSR-88D system that was added as part of the Open Radar Product Generator system upgrade. The BDDS provides real-time access to base data for NWS partners to provide value added products for their customers.
|
|
|
Base Product
|
The WSR-88D products that display the three base moments: Reflectivity, Velocity, and Spectrum Width.
|
|
|
Base Reflectivity (Z)
|
A reflectivity product at a specific elevation which has been obtained directly from the base reflectivity data.
|
|
|
Beam Width
|
The distance between half-power points of the radar beam. Can also be a measure of the concentration of power of a radar beam.
|
|
|
Below Beam Effects
|
The inaccurate radar measurements caused by incomplete sampling of the atmosphere. For example, evaporation or growth of precipitation below the beam will not be detected.
|
|
|
Bounded Weak Echo Region (BWER)
|
A core of weak equivalent reflectivity in a thunderstorm which identifies the location of a strong updraft with a mesocyclone.
|
|
|
Bow Echo
|
A rapidly moving crescent shaped echo which is convex in the direction of motion. Bow echoes are typically associated with strong straight-line winds.
|
|
|
Clutter Suppression
|
Clutter suppression is a quality assurance process performed at the WSR-88D RDA to remove ground clutter contamination caused by non-meteorological ground return.
|
|
|
Cognitive Task Analysis (CTA)
|
A study conducted to capture how experts at a particular task think, what they know, how they organize and structure information, and what they seek to understand better.
|
|
|
Composite Reflectivity (CZ)
|
A WSR-88D volumetric product which displays the highest reflectivities detected above a given area on the earth's surface.
|
|
|
DBZ (dBZ)
|
A decibel of the equivalent radar reflectivity factor, where:
dBZ = 10*Log(equivalent reflectivity). |
|
|
Dealiasing
|
Process of removing underdesirable aliases from the velocity field.
|
|
|
Decibel db
|
A logarithmic expression for the ratio of two quantities, such as the ratio of power transmitted to the power received at the antenna [i.e.,
db = 10*Log(Power Trans/Power Rec)]. |
|
|
Derived Product
|
The WSR-88D derived products are all the products generated from the three base moments of the base data using meteorological algorithms.
|
|
|
Digital Mesocyclone Detection (DMD)
|
The Digital Mesocyclone Detection (DMD) product is similar to the MDA, with the key difference being that DMD is a rapid update product that is available after each elevation scan (while the MDA is available only at the end of each volume scan).
|
|
|
Displaced Real-Time (DRT)
|
A term used to describe the process of setting the system clock backwards on a WES-enabled Linux workstation so that archived data from the Advanced Weather Interactive Processing System can be displayed as when it was originally received.
|
|
|
Display Two Dimensions (D2D)
|
The visualization software used to display data on AWIPS.
|
|
|
Doppler Dilemma
|
The problem encountered in arriving at a balance between maximum velocity determination and maximum detection range.
|
|
|
Doppler Effect
|
The observed change in the frequency of sound or electromagnetic waves due to the relative motion of the source and observer.
|
|
|
Downburst
|
A strong downdraft associated with thunderstorms which induces an outflow of damaging winds on or near the surface.
|
|
|
Ducting
|
A special condition of superrefraction in which the radar beam becomes trapped within a layer of the atmosphere. A condition of warm, dry air overlying relatively cool, moist air may result in ducting.
|
|
|
Echo
|
Energy backscattered from a target and received by the RDA, displayable in the base and derived products.
|
|
|
Elevation Angle
|
The angle between the horizon and a point above the horizon.
|
|
|
Gust Front
|
An outflow boundary which consists of winds meeting gust criteria. On the surface, its passage resembles that of a cold front.
|
|
|
Hook Echo
|
A classical radar echo which is often shaped like a figure six. The hook echo is associated with tornadic activity.
|
|
|
Layer Composite Reflectivity Maximum (LRM)
|
One of the derived radar product that computes the composite reflectivity maximum for three predefined layers of the atmosphere.
|
|
|
Line Echo Wave Pattern (LEWP)
|
A line of radar echoes which has been subjected to an acceleration along one portion of the line. This results in a mesoscale wave pattern in the line.
|
|
|
Maximum Unambiguous Range
|
The maximum range to which a transmitted pulse of radar energy can travel and return to the radar before the next pulse is transmitted
|
|
|
Melting Level
|
The level where frozen precipitation particles melt into water during their decent to the surface. The melting level usually appears about 1,000 ft. above the bright band on radar displays.
|
|
|
Mesocyclone
|
A three-dimensional region in a storm that rotates cyclonically, meets a series of criteria related to its intensity and temporal consistancy, and is closely correlated with severe weather.
|
|
|
Microburst
|
A damaging wind event that results from a downburst and is often less than 2 sq. miles in extent.
|
|
|
Nyquist Velocity
|
The velocity value up to which Doppler radar can detect inbound and outbound velocities unambiguously.
|
|
|
Outflow Boundaries
|
The leading edge of horizontal air flow resulting from cooler, denser air sinking and spreading out at the surface. Outflow boundaries often are cased by the downdraft of thunderstorms.
|
|
|
Partial Beam Filling
|
The effect that occurs when a target fills only a small portion of the radar beam.
|
|
|
Post-Mortem
|
A detailed examination or evaluation of a significant event from which some lessons may be learned to improve future performance. In AWOC, post-mortems most often refer to meteorological events.
|
|
|
Pulse
|
A single short duration transmission of electromagnetic energy.
|
|
|
Pulse Pair Processing
|
A method of determining the Doppler shift by comparing the returned frequency shift of consecutive pulses.
|
|
|
Pulse Repetition Frequency (PRF)
|
The rate at which the pulses of electromagnetic energy are transmitted by the radar; the number of pulses per second.
|
|
|
Pulse Storms
|
A particular classification of convective storms that are typically short-lived, lack well-defined storm structure, and can produce damaging winds near the ground as the storms collapse and dissipate.
|
|
|
Quasi-Linear Convective System (QLCS)
|
A multicellular thunderstorm complex that, generally, has a linear appearance (i.e., MCS, squall line) but also exhibits localized storm-scale vorticies that can behave very similar to low-level mesocyclones and are capable of producing tornadoes.
|
|
|
Radar
|
An acronym for Radio Detection and Ranging; it's also an electronic instrument used to detect atmospheric scatters such as precipitation.
|
|
|
Radar Data Acquisition (RDA)
|
The RDA is the component of the WSR-88D system that includes the radar transmitter, antenna, receiver, and associated hardware that produced the base data sent to the RPG for processing.
|
|
|
Radial Velocity (V)
|
The component of velocity parallel to the radar beam.
|
|
|
Range Folding (RF)
|
The display of multiple trip return which differs from the actual location of the target. A multiple trip return appears at the difference of the true range and a multiple of the unambiguous range.
|
|
|
Range Resolution
|
The ability of the radar to distinguish between two targets at different ranges from the radar, but at the same azimuth.
|
|
|
Rankine Vortex
|
Velocity profile for a symmetric circulation in which the inner core is in solid body rotation.
|
|
|
Refraction
|
The process in which the direction of energy propagation is changed as the result of a change in density. Large changes is the refractive index of the atmosphere can cause subrefraction and superrefraction.
|
|
|
Second-Trip Echo
|
A radar echo received from a target beyond the normal maximum range of detection.
|
|
|
Side Lobes
|
Concentrated elements of focused power outside the main radar beam. Backscatter from side lobes can be displayed as if it were in the main beam. Ground clutter is a common result from side lobes.
|
|
|
Signal-to-Noise Ratio (SNR)
|
A ration of the intensity of the minimum signal capable of being detected to the amount of interference generated by the radar.
|
|
|
Spectrum Width (SW)
|
A measure of dispersion of velocities within the radar sample volume, it can also be defined as the standard deviation of the velocity spectrum.
|
|
|
Subrefraction
|
Atmospheric conditions which cause a straightening of the radar beam upward.
|
|
|
Supercell Thunderstorm
|
A classification of thunderstorm that is often associated with severe and tornadic thunderstorms. Supercells have strong, rotating thunderstorm updrafts, among other storm features, that allow them to last longer than most common thunderstorms.
|
|
|
Superrefraction
|
Bending of the radar beam in the vertical which is greater than under standard refractive conditions. This causes the beam to be lower than indicated, and often results in extensive ground return as well as an overestimation of cloud top heights.
|
|
|
Teletraining
|
A delivery method of distance education where the instructor and students are in different locations, viewing training visuals on monitors (or projectors) and utilizing teleconferencing technology for audio communication.
|
|
|
Three-Body Scatter Spike (TBSS)
|
An area of enhanced reflectivity that is often seen down the radar beam radial from an area of significant hail. In addition to enhanced reflectivity, TBSSs often have near-zero radial velocities and high spectrum width values.
|
|
|
Thunderstorm Downdraft
|
The region of a thunderstorm where air descends towards the surface. Downdrafts can occur in a thunderstorm because the air in that region is relatively stable or because the wind fields in the thunderstorm force air towards the surface.
|
|
|
Thunderstorm Updraft
|
The portion of a thunderstorm where relatively unstable air flows into the storm and rises. A stronger, or faster, a thunderstorm updraft usually results in stronger, more intense severe weather associated with that thunderstorm.
|
|
|
Tornadic Vortex Signature (TVS)
|
The radar "signature" of a vortex indicative of a tornado or tornadic circulation. The WSR-88D employs an algorithm that uses the base moment data to detect these circulations.
|
|
|
Unambiguous Range
|
The range to which a transmitted pulse wave can travel and return to the radar before the next pulse is transmitted.
|
|
|
Velocity Aliasing
|
This occurs as a result of an incorrect value(s) for radial velocities when the actual velocity exceeds the Nyquist velocity.
|
|
|
Velocity Couplet
|
Adjacent maxima of radial velocities of opposite sign that indicate the presence of rotation or divergence in Doppler radial velocities.
|
