STorm scale Operational and Research Meteorology-Weather-data Assimilation and Verification Experiment(STORM-WAVE) Fixed Class Format Upper Air Sounding Data Set 1.0 General Description This is one of the upper air sounding data sets developed for the GEWEX (Global Energy and Water Cycle Experiment) Continental scale International Project (GCIP). STORM-WAVE was conducted from 1 April thru 30 June 1995 and executed by the US Weather Research Program(USWRP) in the central United States. This effort creates a unique high resolution research quality data set utilizing national, regional, and state data sources for model verification and sensitivity study during a critical part of the hydrologic water year. In addition, STORM-WAVE will help evaluate data during the National Weather Service modernization program. STORM-WAVE contains data from 34 National Weather Service upper air sites listed below. The data set encompasses soundings launched at the regular 12 hour intervals: 00Z and 12Z as well as additional special ascensions specifically for Norman, OK (OUN) and Amarillo, TX(AMA). The final data set consists of six second vertical resolution soundings. STORM-WAVE's aerial coverage extends approximately from 85W to 109W degrees longitude and 30N to 45N degrees latitude. Id Station Name State Lat/Lon deg Elev.(m) Record Length total files ****************************************************************************** ABR Aberdeen SD 45.50 -98.40 397 950401-950630 182 ABQ Albuquerque NM 35.00 -106.60 1615 950401-950630 180 AMA Amarillo TX 35.20 -101.70 1094 950401-950630 203 BMX Birmingham AL 33.20 -86.80 178 950401-950630 176 BIS Bismarck ND 46.80 -100.70 505 950401-950630 184 MPX Minneapolis MN 44.80 -93.60 288 950602-950627 51 CRP Corpus Christi TX 27.80 -97.50 14 950401-950630 179 DVN Davenport IA 41.60 -90.60 229 950401-950630 164 DAY Dayton OH 39.90 -84.10 298 950401-950630 182 DRT Del Rio TX 29.40 -100.90 314 950401-950630 182 DNR Denver CO 39.80 -104.90 1611 950401-950630 181 DTX White Lake MI 42.70 -83.50 329 950401-950630 172 DDC Dodge City KS 37.80 -100.00 790 950401-950630 189 ELP El Paso TX 31.80 -106.40 1199 950401-950630 182 FWD FT WORTH TX 32.80 -97.30 198 950401-950630 199 GJT Grand Junction CO 39.10 -108.50 1475 950401-950630 180 GRB Green Bay WI 44.50 -88.10 214 950401-950630 181 JAN Jackson MS 32.30 -90.10 91 950401-950630 182 LCH Lake Charles LA 30.10 -93.20 5 950401-950630 182 LND Lander WY 42.80 -108.70 1695 950401-950630 181 ILX Central Illinois IL 40.20 -89.30 178 950401-950630 185 LIT North Little Rock AR 34.80 -92.30 172 950401-950630 186 MAF Midland TX 32.00 -102.20 873 950401-950630 201 UMN Monett MO 36.90 -93.90 438 950401-950517 84 BNA Nashville TN 36.20 -86.60 180 950329-950630 189 OUN Norman OK 35.20 -97.40 357 950401-950630 209 LBF North Platte NE 41.10 -100.70 849 950401-950630 183 RAP Rapid City SD 44.00 -103.10 966 950401-950630 178 SHV Shreveport LA 32.50 -93.80 83 950401-950630 168 SIL Slidell LA 30.40 -89.80 10 950331-950630 177 SGF Springfield MO 37.20 -93.40 390 950519-950630 83 STC St Cloud MN 45.50 -94.10 315 950401-950531 120 TOP Topeka KS 39.10 -95.60 270 950401-950630 176 OAX Omaha NE 41.30 -96.40 350 950330-950630 183 There is a total of 34 stations ****************************************************************************** All stations are in the GIST domain On May 17th,1995 Monett(UMN) moved to Springfield(SGF). On June 1st,1995 St Cloud(STC) moved to Chanhassen(MPX). Minneapolis and Chanhassen are synonymous. 2.0 Detailed Data Description 2.0.1 National Weather Service Sounding Algorithms The detailed description of NWS sounding collection and instrumentation is located in Section 2.2 below. 2.1 Detailed Format Description All upper air soundings were originally converted to UCAR/Office of Field Project Support(OFPS) Class Format(OCF). OCF is an ASCII format where a sounding file consists of 15 header records followed by that sounding's data records containing quality control (QC) information. Header Records -------------- The Header records (15 total records) contain data type, project ID, site ID, site location, release time, and comments. The first five header lines hold information identifying the sounding, and have a rigidly defined form. The ensuing 6 header lines are used for auxiliary information and comments about the sounding, and may vary from data set to data set. The next line (line 12) contains the Nominal date and time of the launch. The last 3 header lines contain headers for the data columns, enhancing readability. Line 13 holds the field names, line 14 the field units, and line 15 dashes ('-' characters) delineating the field's extent. The six standard header lines are as follows: Line Label (padded to 35 char) Contents 1 Data Type: Description of type and resolution of data. 2 Project ID: ID of weather project. 3 Launch Site Type/Site ID: Description of launch site. 4 Launch Location (lon,lat,alt): Position of launch site, in format described below. 5 GMT Launch Time (y,m,d,h,m,s): Time of launch, in format: yyyy, mm, dd, hh:mm:ss 12 GMT Nominal Launch Time (y,m,d,h,m,s): Nominal launch time. The launch location is given as: lon (deg/min), lat (deg/min), lon (dec. deg), lat (dec. deg), alt (m) Longitude in deg/min is in the format: ddd mm.mm'X where ddd is the number of degrees (with leading zeros if need be), mm.mm is decimal minutes, and X represents W or E for west or east longitude respectively. Latitude has the same format, except there are only two digits for degrees and X represents N or S for north/south latitude. An example of line 4 would thus be: Launch Location (lon,lat,alt): 096 06.60'W, 39 49.80'N, -96.11, 39.83, 384 The seven non-standard header lines may contain any label and contents. As mentioned above line 12 has been used in the sounding composite for the nominal launch date and time. Data Records ------------ The data records (1 record per 6 second interval including surface) each contain time from release, pressure, temperature, dew point, relative humidity, U and V wind components, wind speed and direction, ascent rate, balloon position data, altitude, and quality control flags (see QC description). Each data line contains 21 fields, separated by spaces, with a total width of 130 characters. The data are right-justified within the fields. All fields have one decimal place of precision with the exception of latitude and longitude, which have three decimal place precision. The contents and sizes of the fields are detailed below. The 21 fields that appear in each data line are as follows: Field Format No. Width Parameter Unit Missing Flag 1 6 F6.1 Time Seconds 9999.0 2 6 F6.1 Pressure Millibar 9999.0 3 5 F5.1 Dry-bulb Temperature Degrees C 999.0 4 5 F5.1 Dew Point Degrees C 999.0 5 5 F5.1 Relative Humidity Percent 999.0 6 6 F6.1 U Wind Component Meters / Second 9999.0 7 6 F6.1 V Wind Component Meters / Second 9999.0 8 5 F5.1 Wind Speed Meters / Second 999.0 9 5 F5.1 Wind Direction Degrees 999.0 10 5 F5.1 Ascension Rate (dZ) Meters / Second 999.0 11 8 F8.3 Longitude Degrees 9999.0 12 7 F7.3 Latitude Degrees 999.0 13 5 F5.1 Variable (see below) 999.0 14 5 F5.1 Variable (see below) 999.0 15 7 F7.1 Altitude Meters 99999.0 16 4 F4.1 QC for Pressure Code (see below) 99.0 17 4 F4.1 QC for Temperature Code (see below) 99.0 18 4 F4.1 QC for Humidity Code (see below) 99.0 19 4 F4.1 QC for U Component Code (see below) 99.0 20 4 F4.1 QC for V Component Code (see below) 99.0 21 4 F4.1 QC for Ascension Rate Code (see below) 99.0 where Format is the FORTRAN format that could be used to write the field, and Missing Flag is the missing data flag for that field. Note that the missing data flag consists of just enough 9s to fill the field. Note also that there is a space (FORTRAN format 1X) between each field. A FORTRAN 77 FORMAT statement that conforms to the above would be: 100 format(2(2(F6.1,1X),3(F5.1,1X)),F8.3,1X,F7.3,2(1X,F5.1),1X, + F7.1,6(1X,F4.1)) Fields 13 and 14 are "variable" because true CLASS soundings use these fields for range in km and angle in degrees, respectively, which is information unavailable for NWS soundings. NWS soundings do, however, have elevation in degrees and azimuth in degrees, which are used to fill these fields. Processing programs should simply copy the contents of these fields. Fields 16 through 21 contain the OFPS derived Quality Control information. Any QC information from the original sounding is ignored. Currently, field 21 will always be missing. The codes used are as follows: Code Meaning 99.0 Unchecked (QC information is "missing.") ("UNCHECKED") 1.0 Checked, datum seems physically reasonable. ("GOOD") 2.0 Checked, datum seems questionable on physical basis. ("MAYBE") 3.0 Checked, datum seems to be in error. ("BAD") 4.0 Checked, datum is interpolated. ("ESTIMATED") 9.0 Checked, datum was missing in original file. ("MISSING") 2.2 Data Remarks NWS soundings during STORM-WAVE were of two types:Space Data radiosondes (Amarillo, TX and El Paso, TX) and the remaining sites, VIZ radiosondes. Amarillo and El Paso began using VIZ radiosondes June 1st, 1995. 2.21 Missing Data The missing sounding list only refers to the normal 00Z and 12Z launch times. There may be soundings for these days that were launched at different times. Format of sounding name: YYMMDD HH where YY - year(95), MM - months(04 thru 06), DD - day(01 thru 31) and when applicable HH - hour(00Z or 12Z). When a sounding is not followed by HH, then both the 00Z and 12Z soundings for that date are missing. If a station is missing from the list then its sounding record is complete. Albuquerque is missing soundings: 950407 00Z, 950411, 950419 12Z, and 950623 12Z. Amarillo is missing soundings: 950411 12Z thru 950412 12Z, 950513 12Z, and 950626 12Z. Birmingham is missing soundings: 950529 thru 950531, 950606 12Z, and 950624 00Z. Chanhassen is missing soundings: 950601, 950624 12Z, and 950628 thru 950630. Corpus Christi is missing soundings: 950520 12z thru 950523 00Z. Davenport is missing soundings: 950405 00Z, 950408 00Z, 950415 12Z, 950419, 950421 00Z, 950424 12Z, 950425 12Z, 950429 00Z, 950501 12Z, 950502 00Z, 950504 12Z, 950508 12Z, 950514 12Z, 950522 00Z, and 950609 thru 950612. Del Rio is missing soundings: 950408 12Z and 950413 00Z. Denver is missing sounding: 950518 00Z. Detroit is missing soundings: 950401 12Z, 950506 00Z, 950606 12Z thru 950607, and 950626 thru 950629. Dodge City is missing soundings: 950429 12Z,950525 thru 950529, and 950628 12Z thru 950629 12Z. Fort Worth is missing soundings: 950429 12Z, 950501 thru 950502 00Z, and 950511. Grand Junction is missing soundings: 950531 00Z, 950609 00Z, and 950630 12Z. Green Bay is missing sounding: 950626 12Z. Jackson is missing soundings: 950423 12Z, 950601, and 950609 00Z. Lake Charles is missing sounding: 950401 12Z. Lander is missing sounding: 950430 12Z. Lincoln is missing sounding: 950522 12Z. Midland is missing soundings: 950402 12Z, 950404 00Z, 950420 12Z, 950527 12Z, and 950601 00Z. Monett is missing soundings: 950409 00Z, 950419 thru 950424, 950427 thru 950428 00Z, and 950518 thru 950519. 950518 thru 950519 occurred while Monett operations moved to Springfield. Rapid City is missing soundings: 950420 12Z, 950506 12Z, 950511 00Z, 950519 12Z, and 950622 00Z. Shreveport is missing soundings: 950421 12Z, 950427 00Z, 950428 thru 950429 12Z, 950515 12Z, 950524 12Z, and 950620 12Z thru 950628 00Z. Slidell is missing soundings: 950502 00Z, 950601 thru 950604 00Z, and 950618 12Z. Springfield is missing soundings: 950523, 950601, 950608, and 950610 12Z. St Cloud is missing soundings: 950509. Topeka is missing soundings: 950531 12Z, 950613 thru 950619 00Z, 950623 12Z thru 950627 12Z, and 950630 12Z. Valley is missing sounding: 950420 12Z. OFPS applied a correction to the Space Data radiosonde relative humidity calculations. In the resistance and RH calculations, the NWS Micro-ART sounding system used, instead of the observed temperature, the observed temperature divided by 100. The OFPS applied a correction re-deriving the resistance ratio, using the observed temperature divided by 100 and the observed RH, iterating the so termed "1A" and "1B" coefficients. Now using the new calculated resistance ratio, the observed temperature and the "1A" coefficients only, the new RH was determined. Also, OFPS implemented a correction to the VIZ radiosonde RH calculations. Using the observed temperature and RH and iterating both the "1A" and "1B" coefficients the resistance ratio was re-derived. Using the calculated resistance ratio, the observed temperature and only the "1A" coefficients , the new RH was computed. In both radiosonde types, deriving winds using raw 6-sec resolution elevation and azimuth angle data containing elevation angle oscillations occasionally led to large oscillations in wind velocity, specifically at low elevation angles. The general approach correcting this problem was removing outlier radiosonde position data before computing the wind components. This process required fitting a ninth order polynomial to the azimuth and elevation angle data from 360 seconds to the end of the sounding, then comparing the calculated residuals and observed values, and finally removing the outliers when detected. Applying some additional smoothing helped rectify the more extensive problem occurring when low elevation angles were within 10 degrees of the limiting angles (LA). When the elevation angle was between (LA + 7.5) and (LA + 10), the new elevation angle was computed using a 2 min linear fit. When the elevation angle was between (LA + 5) and (LA + 7.5), the new elevation angle was computed using a 3 min linear fit. When the elevation angle was less than (LA + 5), the new elevation angle was computed employing a four minute linear fit. No frequency smoothing occurred when the number of low elevation angle observations was greater than 20% of the total number of observations. A Finite Fourier Series analysis performed using the elevation angle's residuals allowed the removal of 90-190 second periods and smoothing periods below 30 seconds. Obtaining the u and v wind components entailed fitting a 2 min second order polynomial to the position except for the beginning and end minute (or 1.5 minutes if over 50 mb) which used a 3 min fit. A linear fit was employed when there were less than 15% of the total number of points, not including the beginning or end of the flight, on one side of the point undergoing the wind value calculation. 3.0 Quality Control Processing This data set required a two-stage QC process. First, an internal consistency check which included two types of inspections: "reasonable" limit checks on all parameters and rate-of-change checks on temperature, pressure and ascension rate. Secondly, each sounding endured a visual examinaton verifying those parameters that are too variable for automatic checks: wind speed, wind direction and moisture. In addition, this stage of the QC process allowed confirmation of the automatic check's QC flags. 4.0 Reference Micro-ART Observation and Rework Programs Technical Document, National Weather Service, National Oceanic and Atmospheric Administration, Washington, D.C., March 1991. Williams, S.F., C.G. Wade, and C. Morel, 1993: A Comparison of High Resolution Radiosonde Winds: 6-second Micro-ART Winds versus 10-second CLASS LORAN Winds. Preprints, Eighth Symposium on Meteorological Observations and Instrumentation, Anaheim, California, Amer. Meteor. Soc., 60-65. Williams, S.F., January 1995: Tactical Data Collection And Management Plan for the Enhanced Seasonal Observing Period (ESOP-95). University Corporation For Atmospheric Research (UCAR) Office Of Field Project Support (OFPS).