NEXRAD RADAR OBSERVATIONS LEVEL II and III The Next Generation Weather Radar system (NEXRAD) will consist of approximately 160 Weather Surveillance Radar-1988 Doppler (WSR-88D) throughout the United States and selected overseas locations. This system is a joint effort of the United States Departments of Commerce, Defense, and Transportation to meet the needs of the participating agencies. Level III products will be recorded at 114 sites as stations are commissioned and sent to the National Climatic Data Center (NCDC) for archiving; level II recorders will be placed at all WSR-88D sites. Table 1 contains a list of sites from which Level II data and level III products will be available. Contact NCDC for information on the availability of Nexrad products, or data from any site. The first WSR-88D was installed in 1990 near Oklahoma City, Oklahoma, and the last will be completed in 1996. WSR-88D systems generate three meteorological quantities: reflectivity, mean radial velocity, and spectrum width. From these quantities, computer processing generates numerous meteorological analysis products. Three functional components make up the WSR-88D: Radar Data Acquisition (RDA), Radar Product Generator (RPG), and the Principal User Processor (PUP) (See Figure 1). The RDA consists of a tower, pedestal, antenna, fiberglass radome, klystron transmitter, receiver, status and control processor, and signal processor. The RPG calls upon algorithms that convert base data from the RDA into hundreds of meteorological and hydrological products (39 categories) of various resolutions, data level intervals, and elevation angles in both graphic and alphanumeric form. Selected products are stored on a Write Once Read Many (WORM) optical disk that is sent to the National Climatic Data Center for archive and distribution to customers. This retrieval takes place at a PUP that displays products generated at the RPG. The PUP consists of a microcomputer with graphics tablet, system and application terminals, color graphics printer, color graphic monitors and communication system. Color graphics can be used to display products such as reflectivity, mean radial velocity, echo top height, and precipitation accumulation amounts. Hard copies and acetate overlays are made from the color graphics printer to be sent to customers. A volume scan strategy is selected automatically by the RDA or manually by the operator and determined by operational needs so that the WSR-88D may continually scan the environment in a sequence of pre-programmed 360 degree azimuthal sweeps at various elevation angles. Four separate scan strategies are used now with the possibility of others being implemented in the future. Volume Coverage Pattern 11 (VCP 11) is a precipitation mode. VCP 11 is short pulse, 14 elevation angles with a 5 minute update rate using separate surveillance and doppler scans at the 2 lowest angles. The lowest seven angles are contiguous (See Figure 2). The resulting data are used in algorithms to determine storm tracks, shear and mesocyclones. Other algorithms determine precipitation amounts and obtain wind profiles. Volume Coverage Pattern 21 (VCP 21), a second precipitation mode, is used to observe more distant storms; it uses a short pulse, 9 elevation angles and a 6 minute update rate. There are separate surveillance and doppler scans at the two lowest elevation angles with the lowest five angles being contiguous (See Figure 3). Volume Coverage Pattern 31 (VCP 31) is a clear air mode and is used to detect early formation of convective precipitation, air mass discontinuities and to obtain wind profiles. It is long pulse, 5 elevation angles with a 10 minute update rate. There are separate surveillance and doppler scans on the lowest three elevation angles (See Figure 4). Volume Coverage Pattern 32 (VCP 32) is the same as VCP 31 but with a short pulse (See Figure 4). Precipitation mode is automatic upon detection of precipitation at any elevation angle, or it may be manually selected at times. Return to clear air mode must be manually selected at the Unit Control Position. Three precipitation categories are available. Precipitation category 1 - significant precipitation detected. Precipitation category 2 - small amounts of precipitation detected. Precipitation category 0 - no precipitation for 1 hour. The capability exists to design additional VCPs to optimize performance of the WSR-88D for particular locations or weather scenarios. There are a total of 24 level III products routinely available from NCDC which include 7 graphic products in clear air mode, 11 in precipitation mode, 5 graphic overlays and 1 alphanumeric product. Digital precipitation and radar coded message are products that are unavailable from NCDC at this time. Each product will include state, county & city background maps. Level III graphic products are available only as color hard copy, gray scale hard copy or acetate overlay copies. A list of these products appears in Federal Meteorological Handbook (FMH) No. 11, part A, pages 5-3 and 5-4, and a complete description of each product is in FMH-11, part C, pages 2-1 through 2-101. A brief description and possible uses of these products are included in Table 2. Also, a color example of base reflectivity appears in Figure 5 along with an explanation of the legend that will accompany each product, Figure 6. Level II data are digital base data output from the RDA's signal processor in polar format containing status messages, performance/maintenance data, volume scan strategy, clutter filter bypass map, and wideband communication console messages. The meteorological elements included are base reflectivity, base velocity, and base spectrum width. Initially level II recorders were placed at selected sites for use when significant weather events were taking place. As the system developed it became apparent that level II data would be important in properly calibrating the radars, in research applications, and to test revised algorithms. Current plans call for level II recorders to be placed at all WSR-88D sites. EXABYTE tape drives and 8mm tapes are used as recording devices and media. Each tape can hold approximately 4.7 gigabytes of data and, depending on operational mode of the radar and recorder model used, one tape may be filled about every 1.8 days for each site. These tapes are received at the NCDC from individual sites and are processed on a series of 8505 EXABYTE drives, reblocked, cataloged, inventoried, and archived. The normal charge for level II orders is $100 per tape, plus an $11 service and handling charge per order. SPECIAL NOTE: The WSR-88D is a very complex system. Program modifications and engineering changes are common. Early models experienced difficulties in the recording of level II data and even today tapes are received that contain spurious, erroneous, or illegal configurations. The user is cautioned that these anomalies may be encountered while reading the archived tapes, and in some cases, data gaps are evident. NCDC will be glad to assist in solving problems encountered in reading the tapes but technical questions about the data themselves must be addressed to the: NWS/Operational Support Facility Applications Branch 1200 Westheimer Dr. Norman, OK 73069 Telephone: (405) 366-6530 FAX: (405) 366-6550 The NCDC also distributes the software, including source codes, to display the WSR-88D level II data. Reflectivity, velocity, and spectrum width are displayed while the level II tape is being read and written to disk, or images can be displayed after the data have been written to disk. The WSR-88D Visualization Software (WVS) runs on SUN, IBM, HP, and SGI unix-based workstations. A copy of WVS may be obtained either by mail, on 8mm tape, or via ftp. For mail-order, a charge of $25 will be assessed to cover the cost of the tape and $11 to process the order. To receive a complete copy of the RADAR WEATHER OBSERVATIONS Environmental Information Summaries C-10, or WSR-88D LEVEL II BASE DATA VISUALIZATION SOFTWARE, or TAPE DOCUMENTATION TDF 65-68 for level II data. Please contact: National Climatic Data Center 151 Patton Avenue, Room 120 Asheville, NC 28801-5001 Phone: (704) 271-4800 FAX: (704) 271-4876 Internet: orders@ncdc.noaa.gov NCDC also has numerous products,including NEXRAD inventories, available via World Wide Web (WWW): http:// www.ncdc.noaa.gov. For a further understanding of WSR-88D Doppler radar, please refer to FMH-11 (Parts A through D): FMH-11 Part A System Concepts, Responsibilities, and Procedures FMH-11 Part B Doppler Radar Theory and Meteorology FMH-11 Part C Products and Algorithms FMH-11 Part D Unit Description and Operational Analysis REFERENCES 1. Federal Meteorological Handbook-11 Part A System Concepts, Responsibilities, and Procedures Part B Doppler Radar Theory and Meteorology. Part C WSR-88D Products and Algorithms. Part D WSR-88D Unit Description and Operational Applications. 2. "Recording, Archiving, and Using WSR-88D Data" American Meteorological Society Bulletin April 1993, Timothy D. Crum, Ron L. Alberty, and Donald W. Burgess. 3. "A Description of the Initial Set of Analysis Products Available from the NEXRAD WSR-88D System" American Meteorological Society Bulletin July 1993, Gerard E. Klazura and David A. Imy. TABLE 1 WSR-88D SITES STATION CALL LVL II LVL III ABERDEEN, SD KABR ** *** ALBANY, NY KENX ** *** ALBUQUERQUE, NM KABX ** *** ALPENA, MI KAPX ** *** ALTUS AFB (FREDERICK), OK KFDR ** AMARILLO, TX KAMA ** *** ANCHORAGE, AK PAHG ** ANDERSEN AFB, GUAM PGUA ** ATLANTA, GA KFFC ** *** AUSTIN/SAN ANTONIO, TX KEWX ** *** BEALE AFB, CA KBBX ** BETHEL, AK PABC ** BILLINGS, MT KBLX ** *** BINGHAMTON, NY KBGM ** *** BIRMINGHAM, AL KBMX ** *** BISMARCK, ND KBIS ** *** BOISE, ID KCBX ** *** BOSTON/TAUNTON, MA KBOX ** *** BROOKHAVEN (NEW YORK CITY), NY KOKX ** *** BROWNSVILLE, TX KBRO ** *** BUFFALO, NY KBUF ** *** BURLINGTON, VT KBTV ** *** CAMP HUMPHREYS, KOREA RKSG ** CANNON AFB, NM KFDX ** CEDAR CITY, UT KICX ** *** CHARLESTON, SC KCLX ** *** CHARLESTON, WV KRLX ** *** CHEYENNE, WY KCYS ** *** CHICAGO, IL KLOT ** *** CINCINNATI/DAYTON, OH KILN ** *** CLEVELAND, OH KCLE ** *** COLUMBIA, SC KCAE ** *** COLUMBUS AFB, MS KGWX ** CORPUS CHRISTI, TX KCRP ** *** DAVENPORT (QUAD CITIES), IA KDVN ** *** DENVER/FRONT RANGE, CO KFTG ** *** DES MOINES, IA KDMX ** *** DETROIT, MI KDTX ** *** DODGE CITY, KS KDDC ** *** DOVER AFB, DE KDOX ** DULUTH, MN KDLH ** *** DYESS AFB, TX KDYX ** EDWARDS AFB, CA KEYX ** EGLIN AFB, FL KEVX ** EL PASO, TX KEPZ ** *** ELKO, NV KLRX ** *** EUREKA, CA KBHX ** *** FAIRBANKS, AK PAPD ** FLAGSTAFF, AZ KFSX ** *** FORT CAMPBELL, KY KHPX ** FORT HOOD, TX KGRK ** FORT POLK, LA KPOE ** FORT RUCKER, AL KEOX ** FORT WORTH/DALLAS, TX KFWS ** *** GEORGETOWN, BAH MGGT ** GLASGOW, MT KGGW ** *** GOODLAND, KS KGLD ** *** GRAND FORKS, ND KMVX ** *** GRAND ISLAND (HASTINGS), NE KUEX ** *** GRAND JUNCTION, CO KGJX ** *** GRAND RAPIDS, MI KGRR ** *** GRAND TURK, BWI MGDT ** GREAT FALLS, MT KTFX ** *** GREEN BAY, WI KGRB ** *** GREER, SC KGSP ** *** GRIFFISS AFB, NY KRMX ** HOLLOMAN AFB, NM KHSX ** HOUSTON, TX KHGX ** *** INDIANAPOLIS, IN KIND ** *** JACKSON, MS KJAN ** *** JACKSONVILLE, FL KJAX ** *** KADENA AB, OKINAWA RODN ** KAMUELA, HI PDON ** KEESLER AFB, MS KBIX ** KEY WEST, FL KEYW ** *** KING SALMON, AK PAKC ** KNOXVILLE/MORRISTOWN, TN KMRX ** *** KUSAN AB, KOREA PBCS ** LA CROSSE, WI KARX ** *** LAJES AB, AZORES ** LAKE CHARLES, LA KLCH ** *** LANDER/RIVERTON, WY KRIW ** *** LAS VEGAS, NV KESX ** *** LAUGHLIN AFB, TX KDFX ** LINCOLN (CENTRAL ILLINOIS), IL KILX ** *** LITTLE ROCK, AR KLZK ** *** LORING AFB, ME KCBW ** LOS ANGELES, CA KVTX ** *** LOUISVILLE, KY KLVX ** *** LUBBOCK, TX KLBB ** *** MARCH AFB, CA KRIX ** MARQUETTE, MI KMQT ** *** MAXWELL AFB, AL KMXX ** MEDFORD, OR KMAX ** *** MELBOURNE, FL KMLB ** *** MEMPHIS, TN KNQA ** MIAMI, FL KAMX ** *** MIDDLETON ISLAND, AK PAIH ** MIDLAND/ODESSA, TX KMAF ** *** MILWAUKEE (SULLIVAN TOWNSHIP), WI KMKX ** *** MINNEAPOLIS, MN KMPX ** *** MINOT AFB, ND KMBX ** MISSOULA, MT KMSX ** *** MOBILE, AL KMOB ** *** MOLOKAI, HI PTEJ ** MONTEREY (SAN FRANCISCO BAY), CA KMUX ** *** MOODY AFB, GA KVAX ** MOREHEAD CITY, NC KMHX ** *** NASHVILLE, TN KOHX ** *** NEW ORLEANS/SLIDELL, LA KLIX ** *** NOME, AK PAEC ** NORFOLK/RICHMOND, VA KAKQ ** *** NORTH PLATTE, NE KLNX ** *** OMAHA, NE KOAX ** *** PADUCAH, KY KPAH ** *** PENDLETON, OR KPDT ** *** PHILADELPHIA, PA KDIX ** *** PHOENIX, AZ KIWA ** *** PITTSBURGH, PA KPBZ ** *** PLEASANT HILL (KANSAS CITY), MO KEAX ** *** POCATELLO, ID KSFX ** *** PORTLAND, ME KGYX ** *** PORTLAND, OR KRTX ** *** PUEBLO, CO KPUX ** *** RALEIGH/DURHAM, NC KRAX ** *** RAPID CITY, SD KUDX ** *** RENO, NV KRGX ** *** ROANOKE, VA KFCX ** *** ROBINS AFB, GA KJGX ** SACRAMENTO, CA KDAX ** *** SAINT LOUIS, MO KLSX ** *** SALT LAKE CITY, UT KMTX ** *** SAN ANGELO, TX KSJT ** *** SAN DIEGO, CA KNKX ** *** SAN JOAQUIN VALLEY, CA KHNX ** *** SAN JUAN, PR MCBR ** SEATTLE, WA KATX ** *** SHREVEPORT, LA KSHV ** *** SIOUX FALLS, SD KFSD ** *** SITKA, AK PAEI ** SOUTH KAUAI, HI PRCW ** SOUTH SHORE, HI PDHB ** SPOKANE, WA KOTX ** *** SPRINGFIELD, MO KSGF ** *** STATE COLLEGE, PA KCCX ** *** STERLING (WASHINGTON DULLES), VA KLWX ** *** TALLAHASSEE, FL KTLH ** *** TAMPA, FL KTBW ** *** TINKER AFB, OK KTIK *** TOPEKA, KS KTWX ** *** TUCSON, AZ KSRX ** *** TULSA, OK KINX ** *** TWIN LAKES/NORMAN, OK KTLX ** *** VANCE AFB, OK KVNX ** VANDENBERG AFB, CA KVBX ** WICHITA, KS KICT ** *** WILMINGTON, NC KLTX ** *** YUMA, AZ KYUM ** *** ** - WSR-88D Site that will send Nexrad Level II data to NCDC *** - WSR-88D Site that will send Nexrad Level III data to NCDC TABLE 2 NEXRAD LEVEL III PRODUCTS *Base Reflectivity (R) Base Spectrum Width (SW) *Base Velocity (V) Composite Reflectivity (CR) Echo Tops (ET) **Hail Index Overlay (HI) **Mesocyclone Overlay (M) One-hour Precipitation (OHP) Severe Weather Probability Overlay (SWP) Storm Structure (SS) (Alphanumeric product) *Storm Total Precipitation (STP) **Storm Tracking Information Overlay (STI) **Tornadic Vortex Signature Overlay (TVS) VAD Wind Profile (VWP) Vertically Integrated Liquid (VIL) *Nexrad Level III products making up the standard package **Overlay Products that will be accompanied by alphanumeric read-out *Base Reflectivity (R) - A display of echo intensity measured in dBZ. This product is used to detect precipitation, evaluate storm structure, locate boundaries and determine hail potential. Base Spectrum Width (SW) - A measure of velocity dispersion within the radar sample volume. The primary use of this product is to estimate turbulence associated with mesocyclones and boundaries. *Base Velocity (V) - A measure of the radial component of the wind either toward the radar (negative values) or away from the radar (positive values). Negative values are represented by cool colors (green) while positive values are represented by warm colors (red). This product is used to estimate wind speed and direction, locate boundaries, locate severe weather signatures and identify suspected areas of turbulence. Composite Reflectivity (CR) - A display of maximum reflectivity for the total volume within the range of the radar. This product is used to reveal the highest reflectivities in all echoes, examine storm structure features and determine intensity of storms. Echo Tops (ET) - An image of the echo top heights color coded in user-defined increments. This product is used for a quick estimation of the most intense convection and higher echo tops, as an aid in identification of storm structure features and for pilot briefing purposes. **Hail Index Overlay (HI) - A product designed to locate storms which have the potential to produce hail. Hail potential is labelled as either probable (hollow green triangle) or positive (filled green triangle). Probable means the storm is probably producing hail and positive means the storm is producing hail. **Mesocyclone Overlay (M) - This product is designed to display information regarding the existence and nature of rotations associated with thunderstorms. Numerical output includes azimuth, range, and height of the mesocyclone. One-hour Precipitation (OHP) - A map of estimated one hour precipitation accumulation on a 1.1 X 1.1 nmi grid. This product is used to assess rainfall intensities for flash flood warnings, urban flood statements and special weather statements. Severe Weather Probability Overlay (SWP) - A measure of a storms relative severity as compared with those storms around it. The values are directly related to the horizontal extent of vertically integrated liquid (VIL) values greater than a specified threshold. This product is used as a quick identification of the strongest storms. Storm Structure (SS) (Alphanumeric product) - A table displaying information on storm attributes which include maximum reflectivity, maximum velocity at lowest elevation angle, storm overhang, mass weighted storm volume, storm area base and top, storm position and storm tilt. *Storm Total Precipitation (STP) - A map of estimated storm total precipitation accumulation continuously updated since the last one-hour break over the entire scope. This product is used to locate flood potential over urban or rural areas, estimate total basin runoff and provide rainfall data 24 hours a day. **Storm Tracking Information Overlay (STI) - A product which shows a plot of the past hours movement, current location, and forecast movement for the next hour or less for each identified thunderstormcell. This product is used to determine reliable storm movement. **Tornadic Vortex Signature Overlay (TVS) - A product which shows an intense gate to gate azimuthal shear associated with tornadic- scale rotation. It is depicted by a red triangle with numerical output of location and height. VAD Wind Profile (VWP) - A graphic display of wind barbs plotted on a height staff in 500 ft or 1000 ft increments. The current (far right) and up to 10 previous plots may be displayed simultaneously. This product is an excellent tool for meteorologists in weather forecasting, severe weather and aviation. Vertically Integrated Liquid (VIL) - The water content of a 2.2 X 2.2 nmi column of air which is color coded and plotted on a 124 nmi map. This product is used as an effective hail indicator, to locate most significant storms and to identify areas of heavy rainfall. PRICE LIST: NEXRAD LEVEL III PRODUCTS ALL ORDERS MUST BE PAID IN ADVANCE. MASTERCARD/VISA/AMEX ACCEPTED. MAKE PAYMENT TO: "COMMERCE/NOAA/NCDC" IN U.S. FUNDS. MUST BE DRAWN ON A U.S. BANK OR U.S. AFFILIATE OF FOREIGN BANK. PRICES SUBJECT TO CHANGE WITHOUT NOTICE. CALL TO CONFIRM CURRENT PRICES. FEDERAL AGENCIES MAY SUBMIT U.S. GOVERNMENT PURCHASE ORDER. $22.00 - CHARGE FOR EACH PRODUCT $65.00 - CHARGE FOR STANDARD PACKAGE (AVAILABLE IN PRECIPITATION MODE ONLY) ADD THE FOLLOWING PRICES IF CERTIFICATION (FOR COURT USE) IS NEEDED: GENERAL (WITHOUT SEAL) $26.00 - LIMIT 70 PAGES EACH. DEPT OF COMMERCE SEAL $33.00 - LIMIT 40 PAGES EACH. $5.00 - SERVICE AND HANDLING PER ORDER RUSH SURCHARGE: 50 PERCENT OF THE ORDER'S COST (NOT INCLUDING THE $5.00 SERVICE AND HANDLING CHARGE) OR $45.00, WHICHEVER IS GREATER. ARCHIVE III PRODUCTS PRECIPITATION MODE PRODUCT NAME RANGE RESOLUTION (ID/NO.) (NAUTICAL (NAUTICAL MILES) MILES) *Base Reflectivity (R/19) 124 nmi 0.54 nmi Base Spectrum Width (SW/28) 32 nmi 0.13 nmi Base Spectrum Width (SW/30) 124 nmi 0.54 nmi Base Velocity (V/25) 32 nmi 0.13 nmi *Base Velocity (V/27) 124 nmi 0.54 nmi Composite Reflectivity (CR/38) 248 nmi 2.2 nmi Echo Tops (ET/41) 124 nmi 0.54 nmi **Hail Index Overlay (HI/59) 124 nmi **Mesocyclone Overlay (M/60) 124 nmi One-hour Precipitation (OHP/78) 124 nmi 1.1 nmi Severe Weather Probability Overlay (SWP/47) 124 nmi 2.2 nmi Storm Structure (SS/62) (Alphanumeric Product) *Storm Total Precipitation (STP/80) 124 nmi 1.1 nmi **Storm Tracking Information Overlay (STI/58) 186 nmi **Tornadic Vortex Signature Overlay (TVS/61) 124 nmi VAD Wind Profile (VWP/48) Vertically Integrated Liquid (VIL/57) 124 nmi 2.2 nmi *Nexrad Level III products making up the standard package **Overlay Products that will be accompanied by alphanumerics ARCHIVE III PRODUCTS CLEAR AIR MODE PRODUCT NAME RANGE RESOLUTION (ID/NO.) (NAUTICAL (NAUTICAL MILES) MILES) Base Reflectivity (R/19) 124 nmi 0.54 nmi Base Spectrum Width (SW/28) 32 nmi 0.13 nmi Base Spectrum Width (SW/30) 124 nmi 0.54 nmi Base Velocity (V/25) 32 nmi 0.13 nmi Base Velocity (V/27) 124 nmi 0.54 nmi Composite Reflectivity (CR/36) 248 nmi 2.2 nmi VAD Wind Profile (VWP/48)