National Weather Service (NWS) High Resolution Rawinsonde Data 1.0 General Description This is one of the upper air data sets developed for the Impact of Typhoons on the Ocean in the Pacific (ITOP) 2010. This data set includes 976 high vertical resolution (6-second) MicroArt soundings from the six (6) National Weather Service (NWS) rawinsonde stations in the ITOP 2010 region (Yap, WCI; Ponape, ECI; Koror, Palau WCI; Chuuk, ECI; Majuro, Marshall Island; Guam, Marianna Island). The data cover the period from 1 August 2010 to 31 October 2010. The soundings were typically released twice a day (0000 and 1200 UTC) and any special releases are also included in this data set. This data set currently does not contain soundings from Majuro for the month of September nor Yap for the month of October. The data are in EOL Sounding Composite format (columnar ascii). 1.1 Data Set Contact Steve Williams NCAR/EOL sfw@ucar.edu 2.0 Detailed Data Description 2.0.1 National Weather Service High-Resolution Sounding Algorithms The detailed description of NWS MicroArt sounding collection and instrumentation is located in NWS (1991). 2.1 Detailed Format Description All upper air soundings were converted to the National Center for Atmospheric Research/Earth Observing Laboratory (NCAR/EOL) Sounding Composite Format (ESC). ESC is a version of the National Center for Atmospheric Research (NCAR) CLASS format and is an ASCII format consisting of 15 header records for each sounding followed by the data records with associated QC information. Header Records The header records (15 total records) contain data type, project ID, site ID, site location, release time, sonde type, meteorological and wind data processors, and the operator's name and comments. The first five header lines contain information identifying the sounding, and have a rigidly defined form. The following 7 header lines are used for auxiliary information and comments about the sounding, and may vary from dataset to dataset. The last 3 header records contain header information for the data columns. Line 13 holds the field names, line 14 the field units, and line 15 contains dashes ('-' characters) delineating the extent of the field. The five 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 Release Site Type/Site ID: Description of release site. 4 Release Location (lon,lat,alt): Position of release site, in format described below. 5 UTC Release Time (y,m,d,h,m,s): Time of release, in format: yyyy, mm, dd, hh:mm:ss The release 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'W where ddd is the number of degrees from True North (with leading zeros if necessary), mm.mm is the decimal number of minutes, and W represents W or E for west or east longitude, respectively. Latitude has the same format as longitude, except there are only two digits for degrees and N or S for north/south latitude. The decimal equivalent of longitude and latitude and station elevation follow. The seven non-standard header lines may contain any label and contents. The labels are padded to 35 characters to match the standard header lines. Records for the MicroArt data include the following three non-standard header lines. Line Label (padded to 35 char) Contents 6 Ascension No: 1299 7 Radiosonde Serial Number: 152551614 8 Radiosonde Manufacturer: Vaisala Data Records The data records 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 the QC code 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 places of precision. The contents and sizes of the 21 fields that appear in each data record are as follows: Field Format No. Width Parameter Units Missing Value ------------------------------------------------------------------------ 1 6 F6.1 Time Seconds 9999.0 2 6 F6.1 Pressure Millibars 9999.0 3 5 F5.1 Dry-bulb Temperature Degrees C 999.0 4 5 F5.1 Dew Point Temperature 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 Meters / Second 999.0 11 8 F8.3 Longitude Degrees 9999.0 12 7 F7.3 Latitude Degrees 999.0 13 5 F5.1 Elevation Angle Degrees 999.0 14 5 F5.1 Azimuth Angle Degrees 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 Fields 16 through 21 contain the Quality Control information derived at the NCAR Earth Observing Laboratory (NCAR/EOL). Any QC information from the original sounding is replaced by the following EOL codes: Code Description 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") Sample Data The following is a sample record of ITOP 2010 Sounding Rawinsonde NWS upper air data in EOL ESC format. The data portion is much longer than 80 characters and, therefore, may wrap around to a second line. See section 2.1 for an exact format specification Data Type: National Weather Service Sounding. Project ID: ITOP_2010 Release Site Type/Site ID: PTP Ponape, ECI Release Location (lon,lat,alt): 158 12.00'E, 07 00.00'N, 158.200, 7.000, 39.0 UTC Release Time (y,m,d,h,m,s): 2010, 09, 15, 23:13:00 Ascension No: 1474 Radiosonde Serial Number: 87040691.CSN Radiosonde Manufacturer: VIZ B2 / / / Nominal Release Time (y,m,d,h,m,s):2010, 09, 16, 00:00:00 Time Press Temp Dewpt RH Ucmp Vcmp spd dir Wcmp Lon Lat Ele Azi Alt Qp Qt Qrh Qu Qv QdZ sec mb C C % m/s m/s m/s deg m/s deg deg deg deg m code code code code code code ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 0.0 1008.8 23.9 23.1 95.0 -1.2 1.0 1.6 129.8 999.0 158.200 7.000 52.7 130.3 39.0 1.0 1.0 1.0 1.0 1.0 9.0 6.0 1003.9 24.0 22.4 90.7 -1.5 1.8 2.3 140.2 7.2 158.200 7.000 52.7 130.3 82.0 1.0 1.0 1.0 4.0 4.0 99.0 12.0 999.7 23.8 21.9 89.2 -1.8 2.5 3.1 144.2 6.2 158.200 7.001 52.4 141.8 119.0 1.0 1.0 1.0 4.0 4.0 99.0 18.0 994.9 24.0 21.6 86.6 -2.1 3.3 3.9 147.5 7.0 158.200 7.001 50.6 152.7 161.0 1.0 1.0 1.0 4.0 4.0 99.0 24.0 991.2 24.0 21.6 86.3 -2.4 4.0 4.7 149.0 5.5 158.200 7.002 47.6 162.3 194.0 1.0 1.0 1.0 4.0 4.0 99.0 30.0 987.4 23.8 21.4 86.2 -2.6 4.6 5.3 150.5 5.5 158.200 7.002 43.5 170.5 227.0 1.0 1.0 1.0 4.0 4.0 99.0 2.2 Data Remarks For the MicroArt station data the use of the raw 6-sec resolution elevation and azimuth angle data to derive the winds sometimes led to large oscillations in wind speed, due to the presence of oscillations in the elevation angle data, particularly at low elevation angles. The general approach to correct this problem was to remove the out-lier radiosonde position data before computing the wind components (Williams et al. 1993). For both the azimuth and elevation angles from 360 sec to the end of the sounding, a ninth order polynomial was fit to the curve. The residuals were calculated and compared to the observed values. The outliers of the residuals were then removed. Then to help correct the more extensive problems at low elevation angles within 10 degrees of the limiting angles (LA) some additional smoothing was applied. If the elevation angle was between (LA + 7.5) and (LA + 10), the new elevation angle was computed with a 2 min linear fit. If the elevation angle was between (LA + 5) and (LA + 7.5), the new elevation angle was computed with a 3 min linear fit. If the elevation angle was less than (LA + 5), the new elevation angle was computed with a 4 min linear fit. If the number of observations with low elevation angles was greater than 20% of the total number of observations for the sounding no frequency smoothing occurred. Then, for the elevation angle only, a finite Fourier analysis was performed on the residuals. Periods from 90-190 sec were removed and those below 30 sec were flattened. Finally, a 2 min second order polynomial was then fit to the position to derive the u and v wind components, except for the beginning and end minute (or 1.5 minutes if over 50 mb) which used a 3 min fit. If there were less than 15% of the total number of points, not counting the beginning or end of the flight, on one side of the point for which the wind value was being computed, a linear fit was used. For further information on this methodology and its changes since Williams et al. (1993) please see Williams, et al. (1998). 2.3 Station List ID SITE STATE COUNTRY LONG LAT ELEV (m) SONDE TYPE ------------------------------------------------------------------------- PTY Yap WCI 138.1 9.5 22.0 Vaisala PTP Ponape ECI 158.2 7.0 39.0 VIZ B2 PTR Koror, Palau WCI 134.5 7.3 30.0 VIZ B2 PTK Chuuk (Truk) ECI 151.8 7.4 3.0 VIZ B2 PMK Majuro, Marshall Island 171.3 7.1 4.0 VIZ B2 pgac Guam, Marianna Island 144.8 13.5 75.0 VIZ B2 3.0 Quality Control Processing This dataset underwent an automated QC process. The dataset underwent internal consistency checks which included two types of checks, gross limit checks on all parameters and rate-of-change checks on temperature, pressure and ascension rate. Some further information on the QC processing conducted by EOL can be found in Loehrer et al. (1996) and Loehrer et al. (1998). 3.1 Gross Limit Checks These checks were conducted on each sounding and data were automatically flagged as appropriate. Only the data point under examination was flagged. EOL conducted the following gross limit checks on the T-REX NWS sounding dataset. In the table P = pressure, T = temperature, RH = relative humidity, U = U wind component, V = V wind component, B = bad, and Q = questionable. __________________________________________________________________ Parameter(s) Flag Parameter Gross Limit Check Flagged Applied __________________________________________________________________ Pressure < 0 mb or > 1050 mb P B Altitude < 0 m or > 40000 m P, T, RH Q Temperature < -90C or > 45C T Q Dew Point < -99.9C or > 33C RH Q > Temperature T, RH Q Relative Humidity < 0% or > 100% RH B Wind Speed < 0 m/s or > 100 m/s U, V Q > 150 m/s U, V B U Wind Component < 0 m/s or > 100 m/s U Q > 150 m/s U B V Wind Component < 0 m/s or > 100 m/s V Q > 150 m/s V B Wind Direction < 0 deg or > 360 deg U, V B Ascent Rate < -10 m/s or > 10 m/s P, T, RH Q _________________________________________________________________ 3.2 Vertical Consistency Checks These checks were conducted on each sounding and data were automatically flagged as appropriate. These checks were started at the lowest level of the sounding and compared neighboring 6-sec data points (except at pressures less than 100 mb where 30-sec average values were used. In the case of checks ensuring that the values increased/decreased as expected, only the data point under examination was flagged. However, for the other checks, all of the data points used in the examination were flagged. All items within the table are as previously defined. _____________________________________________________________________ Vertical Consistency Parameter(s) Flag Parameter Check Flagged Applied _____________________________________________________________________ Time decreasing/equal None None Altitude decreasing/equal P, T, RH Q Pressure increasing/equal P, T, RH Q > 1 mb/s or < -1 mb/s P, T, RH Q > 2 mb/s or < -2 mb/s P, T, RH B Temperature < -15 C/km P, T, RH Q < -30 C/km P, T, RH B > 50 C/km (not applied at p < 250mb) P, T, RH Q > 100 C/km (not applied at p < 250mb) P, T, RH B Ascent Rate change of > 3 m/s or < -3 m/s P Q change of > 5 m/s or < -5 m/s P B _____________________________________________________________________ 3.3 Visual Checks All soundings were visually examined utilizing the EOL XQC tool which allows data quality flags to be adjusted. Visual examination is conducted only up to 50mb. 3.4 Data Quality Comments Majuro ------ PMK_201008292306 - bad winds from 350-180mb PMK_201010011108 - bad winds from 175-80mb PMK_201010042314 - no data above 945mb, little wind. PMK_201010052312 - no wind above 265mb PMK_201010061106 - no data above 170mb PMK_201010062312 - no data above 180mb; no wind above 520mb PMK_201010071119 - no winds PMK_201010072306 - no winds; no data above 180mb PMK_201010081224 - no winds; no data above 180mb PMK_201010082304 - no winds; no data above 245mb PMK_201010091112 - bad winds; no data above 230mb PMK_201010092312 - no winds; no data above 125mb PMK_201010101105 - no winds; no data above 150mb PMK_201010102308 - no winds PMK_201010111132 - no winds; no data above 105mb PMK_201010112303 - bad winds PMK_201010121112 - no winds; no data above 215mb PMK_201010122317 - no winds; no data above 180mb PMK_201010131109 - no winds PMK_201010132306 - no winds PMK_201010141112 - no winds PMK_201010142313 - no winds PMK_201010161103 - no data above 200mb PMK_201010171108 - no winds; no data above 290mb PMK_201010212333 - winds somewhat noisy Chuuk ----- PTK_201008051126 - no data above 185mb; bad T/DP 590-295mb PTK_201008192304 - bad winds above 170mb PTK_201008281117 - no data above 720mb; T/RH bad above 790mb PTK_201009151103 - no data above 475mb PTK_201009262350 - T/RH bad above 420mb PTK_201010011114 - no data above 515mb PTK_201010132308 - no data above 250mb PTK_201010141111 - no data above 203mb; bad winds PTK_201010221104 - winds mostly bad Ponape ------ PTP_201008292300 - No winds PTP_201009112301 - No data above 920mb PTP_201010091102 - No winds PTP_201010221101 - No data above 850mb Koror ----- PTR_201008011104 - Bad winds above 635mb PTR_201008061104 - No data above 640mb PTR_201008092302 - Bad winds from 690-320mb PTR_201009102303 - Bad winds from 860-570mb PTR_201009281104 - No data above 910mb PTR_201010041102 - No data above 120mb PTR_201010091102 - No data above 420mb PTR_201010121101 - Bad winds 820-620mb PTR_201010132304 - No data above 960mb PTR_201010212302 - No data above 140mb Yap --- PTY_201008062327 - No data above 295mb PTY_201008082306 - No data above 600mb PTY_201008132304 - Bad winds PTY_201008141105 - Bad winds PTY_201008201104 - Bad winds PTY_201008222307 - Bad winds PTY_201009082304 - No data above 350mb PTY_201009121104 - No data above 550mb PTY_201009282310 - No data above 135mb Guam ---- pgac_201008152309 - No data above 160mb pgac_201008211103 - No data above 170mb pgac_201008312307 - Winds bad above 180mb pgac_201009032309 - No data above 250mb pgac_201009041104 - No data above 210mb; no good winds above 430mb pgac_201009042326 - No data above 150mb pgac_201009091109 - No data above 200mb pgac_201009101107 - No data above 135mb pgac_201009111103 - No data above 140mb pgac_201009151112 - No data above 285mb pgac_201009251103 - Bad winds below 420mb pgac_201010042302 - Bad winds 620-435mb; No data above 325mb pgac_201010211103 - Bad winds 620-330mb pgac_201010212302 - No data above 435mb pgac_201010282302 - No data above 200mb 4.0 References Loehrer, S. M., T. A. Edmands, and J. A. Moore, 1996: TOGA COARE upper-air sounding data archive: development and quality control procedures. Bull. Amer. Meteor. Soc., 77, 2651-2671. Loehrer, S. M., S. F. Williams, and J. A. Moore, 1998: Results from UCAR/JOSS quality control of atmospheric soundings from field projects. Preprints, Tenth Symposium on Meteorological Observations and Instrumentation, Phoenix, AZ, Amer. Meteor. Soc., 1-6. NWS, 1991: 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., S. M. Loehrer, and D. R. Gallant, 1998: Computation of high-resolution National Weather Service rawinsonde winds. Preprints, Tenth Symposium on Meteorological Observations and Instrumentation, Phoenix, AZ, Amer. Meteor. Soc., 387-391.