WDTB Glossary

8-Bit Products - Radar base products that display data in 256 levels, in contrast with other products that display data in 16 (4-bit) or 8 (3-bit) data levels.

Advanced Warning Operations Course (AWOC) - The Advanced Warning Operations Course is a blended learning course designed to provide every NWS Forecaster (Meteorologist and Hydrologist) training on advanced warning decision making techniques.

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).

Algorithm - A step-by-step procedure for solving a mathematical problem. The WSR-88D relies on algorithms while producing derived products.

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 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 Blockage - The physical obstruction of the radar beam, usually at close range, caused by building, mountains, etc.

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.

BUFKIT - BUFKIT is a forecast profile visualization and analysis tool kit developed by the staff at the National Weather Service to view model output profiles and forecast parameters at high vertical and temporal resolutions.

Build Training - Training for NWS Forecasters (Meteorologist and Hydrologist) on software and hardware updates to the AWIPS, RPG, RDA, etc.

Clutter Suppresion - 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 undersirable 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).

Display Two Dimensions (D2D) - The visualization software used to display data on AWIPS.

Distance Learning Operations Course (DLOC) - The Distance Learning Operations Course is a blended learning course designed to provide all new NWS Forecasters (Meteorologist and Hydrologist) training on the use of the WSR-88D when making forecast and warning decisions.

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.

Facilitators - The facilitator is the person at a local NWS office who provides assistance, support and guidance to students throughout a course. Facilitators are usually the SOO, DOH, Training Officer, or other designate in the office.

Flash Flood Guidance (FFG) - Flash Flood Guidance is a tool used by meteorologists to predict flash flooding of urban areas, creeks and streams.

Flash Flood Monitoring and Prediction (FFMP) - The Flash Flood Monitoring and Prediction (FFMP) system is an integrated suite of multi-sensor applications which detects, analyzes, and monitors precipitation and generates short-term warning guidance for flash flooding automatically within AWIPS.

Frequency - The number of recurrences of a periodic event per unit time. Radar waves have a frequency specified per second.

Ground Clutter - Echoes that result from physical obstructions such as buildings, trees, and mountains.

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.

Instructional Component (IC) - An organizational unit for training material in the different tracks of AWOC for which a student must pass an exam to receive credit. Each IC is made up of one or more lessons which cover the objectives for that topic.

Layer Composite Reflectivity Maximum (LRM) - One of the derived radar product that computes the composite reflectivity maximum for three predefined layers of the atmosphere.

Learning Management System (LMS) - A service provided to organizations that require distance education and e-learning delivery, tracking, and evaluation in a cost effective manner.

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.

Mesocyclone Detection Algorithm (MDA) - The Mesocyclone Detection Algorithm (MDA) was developed by NSSL to develop a more robust algorithm than the Mesocyclone algorithm that was deployed with the WSR-88D.

NOAA E-Learning - NOAA E-Learning is the Learning Management System implemented throughout NWS, NOAA, and Department of Commerce.

Nyquist Velocity - The velocity value up to which Doppler radar can detect inbound and outbound velocities unambiguously.

Open Radar Data Acquisition (ORDA) - A software and hardware update to the Radar Data Acquisition unit using open source technology and replacing equipment that was deployed when the WSR-88D was originally fielded.

Open Radar Product Generator (ORPG) - A software and hardware update to the Radar Product Generator that used open source technology and replaced equipment that was deployed when the WSR-88D was originally fielded.

Operational Build (OB) - "OB" refers to specific versions of AWIPS. After AWIPS was fielded, the developers switched to a more open source architecture to the system. As a result, the release versions were renamed "Build" to "Operational Build" to highlight the change.

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.

Radar Product Generator (RPG) - The RPG, which is a component of the WSR-88D, is a multi-function unit that ingests base data, processes that data, and produces products for viewing by users.

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.

Scanning Strategy - A programmed combination of antenna motions and switched PRFs. A Volume Coverage Pattern for the WSR-88D is an example of a scanning strategy.

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.

Situation Awareness (SA) - The process of acquiring the perception of the elements in the environment within a volume space, the comprehension of their meaning, and the projection of their status in the near future.

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.

Subject Matter Experts (SME) - Subject Matter Experts are those who provide expertise in the content of an instructional area. SMEs can either contribute to or develop the training.

Subrefraction - Atmospheric conditions which cause a straightening of the radar beam upward.

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.

System for Convection Analysis and Nowcasting (SCAN) - An integrated suite of multisensor applications which detects, analyzes, and monitors convection and generates short-term probabilistic forecast and warning guidance for severe weather automatically within AWIPS.

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.

Terminal Doppler Weather Radar (TDWR) - The Terminal Doppler Weather Radar (TDWR) is a dedicated meteorological surveillance radar deployed by the FAA near many of the larger airports in the U.S.

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.

Turbulence - Irregular, random fluctuations in the wind velocity field in the horizontal and vertical planes.

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.

Vertically Integrated Liquid (VIL) - The algorithm that estimates the total amount of liquid suspended in a vertical column of the atmosphere.

Virga - This phenomenon is precipitation that falls from a cloud but evaporates before reaching the earth's surface.

VISITView - An application used for NWS teletraining development and delivery.

Volume Coverage Pattern (VCP) - The particular scanning strategy employed by the WSR-88D to best sample the atmosphere based on the current conditions.

Warning Decision Making (WDM) - Warning Decision Making refers to the process of how a forecaster makes the decision to issue (or not issue) a warning on a particular storm, as well as mentally processing all of the data inputs that go into making that decision.

Weather Event Simulator (WES) - The Weather Event Simulator is an application that provides case playback and simulation capabilities from archived AWIPS data. The WES is effectively a data pump and a training interface for AWIPS.

Weather Event Simulator Scripting Language (WESSL) - WESSL is an application that utilizes scripts written to enhance the capabilities of WES by adding interaction, maps, and other non-AWIPS visuals and text to the simulation experience.

Weather Surveillance Radar - 88 Doppler (WSR-88D) - The dedicated meteorological surveillance radar deployed by the NWS that significantly improved the quality of reflectivity data available and added the capability of Doppler velocity and spectral width data.