National Weather Service (NWS) High Resolution L3 Radiosonde Data 1.0 General Description This is one of the upper air data sets developed for the Dynamics of the Madden-Julian Oscillation (DYNAMO) 2011-2012 project. This data set includes 903 high vertical resolution soundings from the National Weather Service (NWS) rawinsonde stations at Guam (297 soundings; 6-second resolution) in the Mariana Islands and Yap (267 soundings; 1-second resolution) and Koror (339 soundings; 1-second resolution) both in the Western Caroline Islands. These data were converted into the EOL Sounding Composite format (columnar ascii). Soundings were typically released twice daily during this period. However, Yap was once daily until 16 November 2011 (and had no soundings from 30 October to 7 November 2011 and from 19-28 March 2012) and Koror had outage problems from 14-22 December. This data set contains data from 1 October to 31 March 2012 for Yap and Koror and only 1-31 October 2011 and 1 December 2011 to 31 March 2012 data for Guam. 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 at Guam include the following three non-standard header lines. Line Label (padded to 35 char) Contents 6 Ascension No: 1531 7 Radiosonde Serial Number: 87047718.CSN 8 Radiosonde Manufacturer: VIZ B2 Records for the RRS data at Koror and Yap include the following non-standard header lines: Line Label (padded to 35 char) Contents 6 Ascension Number: 422 7 Radiosonde Serial Number: 85221265 8 Balloon Manufacturer/Type: Other / GP26 9 Balloon Lot Number/Weight: 1012011 / 0.700 10 Radiosonde Type/RH Sensor Type: Sippican Mark IIA with chip thermistor, pressure / Sippican Mark IIA Carbon Hygristor 11 Surface Observations: P: 1008.1, T: 999.0, RH: 94.0, WS: 3.6, WD: 193.0 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 DYNAMO 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/Ascending Project ID: DYNAMO Release Site Type/Site ID: PTYA Yap, WCI / 91413 Release Location (lon,lat,alt): 138 04.90'E, 09 29.83'N, 138.082, 9.497, 27.0 UTC Release Time (y,m,d,h,m,s): 2011, 11, 08, 23:14:44 Ascension Number: 452 Radiosonde Serial Number: 85216911 Balloon Manufacturer/Type: Other / GP26 Balloon Lot Number/Weight: 1012011 / 0.700 Radiosonde Type/RH Sensor Type: Sippican Mark IIA with chip thermistor, pressure / Sippican Mark IIA Carbon Hygristor Surface Observations: P: 1009.1, T: 27.0, RH: 88.0, WS: 0.0, WD: 360.0 Nominal Release Time (y,m,d,h,m,s):2011, 11, 09, 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 1008.4 31.8 27.7 79.0 -1.6 1.3 2.1 129.1 999.0 138.082 9.497 999.0 999.0 27.0 1.0 1.0 1.0 1.0 1.0 9.0 1.0 1006.9 31.6 27.1 77.2 -1.4 0.9 1.7 122.7 13.0 138.082 9.497 999.0 999.0 40.0 1.0 3.0 1.0 1.0 1.0 99.0 2.0 1006.1 31.4 27.0 77.3 -1.5 0.9 1.7 121.0 7.0 138.081 9.497 999.0 999.0 47.0 1.0 3.0 1.0 1.0 1.0 99.0 3.0 1005.4 31.2 26.9 77.8 -1.6 1.0 1.9 122.0 7.0 138.081 9.497 999.0 999.0 54.0 1.0 3.0 1.0 1.0 1.0 99.0 4.0 1004.7 31.0 26.5 77.1 -1.7 1.1 2.0 122.9 6.0 138.081 9.497 999.0 999.0 60.0 1.0 3.0 1.0 1.0 1.0 99.0 5.0 1004.0 30.8 26.1 76.1 -1.8 1.1 2.1 121.4 7.0 138.081 9.497 999.0 999.0 67.0 1.0 3.0 1.0 1.0 1.0 99.0 : : : 2.2 Data Remarks For the Guam 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 27.0 Sippican Mark IIA PTR Koror, Palau WCI 134.4 7.3 34.0 Sippican Mark IIA pgac Guam, Marianna Island 144.8 13.5 75.0 VIZ B2 Yap and Koror utilize GPS windfinding. Guam utilizes radio theolodite windfinding. We have utilized the processed PTU and GPS data from the RRS sounding systems to generate these files. The raw position, temperature and RH data are normalized by linear interpolation into 1 second processed data. The raw pressure data are normalized by least square interpolation into 1 second processed data. The pressure data are smoothed over 11 seconds of corrected pressure and the result is applied to the 6th corrected pressure within the 11 second spread. The temperature data are smoothed over 9 seconds of uncorrected temperature and the result is applied to the 5th uncorrected temperature within the 9 second spread. There must be at least 2 good raw temperature elements with the 9 second spread. The following corrections were applied by the RRS sounding system. Pressure correction - pressure correction is used to compensate for offsets of the radiosonde pressure sensor as compared to the station's pressure sensor. The pressure offset is determined during the radiosonde baseline operations. The correction is applied to the uncorrected pressure prior to pressure smoothing. This correction is defined as: Pc = Pu * (Pstn/Psonde) where Pc is the corrected pressure Pu is the uncorrected pressure Pstn is the station pressure Psonde is the radiosonde surface pressure Temperature correction - temperature correction is used to compensate for solar radiation. The correction is applied to the smoothed temperature. These corrections are proprietary to Sippican. 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 DYNAMO 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. 3.4 Data Quality Comments Koror ----- No Koror soundings were taken from 12 UTC 15 October through 00 UTC 22 October. Yap --- No Yap soundings were taken from 30 October to 7 November due to a tracking antenna failure. Yap sounding were once per day (at 00 UTC) from 1-29 October and 8-15 November due to a failure of their hydrogen gas generator. No Yap soundings were taken from 00 UTC 19 March to 00 UTC 28 March. The Yap sounding at 20120208230739 from ~115-40mb the pressure data are highly questionable. Guam ---- At this time, no high resolution sounding data are available from Guam for November 2011. No additional corrections were required for these data between the L2 and L3 versions. The data set was moved to L3 on 10 July 2013. 4.0 References 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.