PACS Upper Air: Upper Air sounding data from San Cristobal (Galapagos) 1.0 General Description Soundings have been released semi-daily at San Cristobal (SNCR) during the Pan American Climate Studies field campaign (PACS). All of the SNCR soundings were made with Vaisala RS80 sondes which utilized GPS tracking to determine the winds. The sonde data were recorded using Vaisala software. This data set contains data from 01 September 1998 thru 06 June 2005. However, there are days within this time period where rawinsonde data is missing or a rawinsonde was not released. The sonde data were quality controlled at the Joint Office for Science Support (JOSS) at NCAR, using methods similar to those used to quality control the TOGA COARE sounding data (Loehrer et al., 1996; their sections 3a-e). See section 5.0 for more details on JOSS quality control procedures for the SNCR Rawinsonde data set. The radiosonde station is at San Cristobal (WMO 84008) which is located at 0.90 S latitude and 89.61 W longitude. 2.0 Parameters in Raw Dataset Parameters Units -------------------------------------- Time Seconds Pressure Millibars Temperature Deg C Dew Point Deg C Relative Humidity % U wind component m/s V wind component m/s Wind Speed m/s Wind Direction Deg Ascension Rate m/s Longitude Deg Latitude Deg Range km Azimuth Angle Deg Altitude Geopotential Meters Pressure Quality Code mb Temp Quality Code Deg C Humidity Quality Code Deg C U comp Quality Code m/s V comp Quality Code m/s UV Quality Code m/s -------------------------------------- 3.0 Conversion to JOSS CLASS format (ASCII text) 3.1 The raw 10 s vertical resolution time, temperature, relative humidity, altitude, pressure, dew point, wind direction, and wind speed were kept without change. 3.2 The ascension rate was calculated for each data point (excluding the surface, where it was given a missing value) based on the altitude and time at two levels, the current 10 s level and the previous 10 s level. If the data point for which the ascension rate was being calculated had missing time or altitude, the ascension rate was not calculated at that level and was flagged as missing. If the data point prior to that for which the ascension rate was being calculated had a missing time or altitude, then the data point two data points prior to the present one was used, and so on until one with non-missing time and altitude was found. If there are no non-missing previous data points the ascension rate is set to missing. 3.3 Due to CLASS format constraints, Dew Points less than -99.9 Deg C were given a value of -99.9 Deg C and were flagged as being questionable. 4.0 JOSS CLASS Format (ASCII text) Description 4.1 Header records The header records (15 total records) contain data type, project ID, site ID, site location, actual release time, nominal release time, and possibly other specialized information. The first five header lines contain information identifying the sounding, and have a rigidly defined form. The following 6 header lines are used for auxiliary information and comments about the sounding, and they vary significantly from dataset to dataset (For the Ron Brown these lines contain information on the radiosonde and other information). This is the last time the dataset was released. It has the format yyyymmddhh). The next line (line 12) contains the Nominal date and time of the release. 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 six standard header lines are as follows: Line Label (fixed to 35 char in length) 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: Time of release, in format: yyyy, mm, dd, hh:mm:ss 12 UTC Nominal Release Time: Nominal release time. 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 six non-standard header lines may contain any label and contents. The label is fixed to 35 characters to match the standard header lines. Sample header records are provided in the sample data file in section 4.3. 4.2 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 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 Missing No. Width Parameter Units 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 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 flag for Pressure Code (see below) 99.0 17 4 F4.1 QC flag for Temperature Code (see below) 99.0 18 4 F4.1 QC flag for Humidity Code (see below) 99.0 19 4 F4.1 QC flag for U Component Code (see below) 99.0 20 4 F4.1 QC flag for V Component Code (see below) 99.0 21 4 F4.1 QC flag for Ascension Rate Code (see below) 99.0 ---------------------------------------------------------------------- Fields 13 and 14 are `variable' because depending on the sounding system the variables used in these positions can vary. For the Ron Brown soundings, these fields have been set to missing. Fields 16 through 21 contain the Quality Control information (flags) generated locally at JOSS. These flags are based on the automated checks. See Sections 5.0 for further information. The JOSS QC flags are as follows: 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') ---------------------------------------------------------------------- 4.3 Sample data The following is a sample portion of a JOSS CLASS format file including header records. The data portion is much longer than 80 characters and, therefore, wraps around to a second line. Data Type: High Resolution Sounding Project ID: PACS Release Site Type/Site ID: San Cristobal SNCR 84008 Release Location (lon,lat,alt): 89 36.60'W, 0 54.00'S, -89.610, -0.900, 8.0 UTC Release Time (y,m,d,h,m,s): 2005, 06, 03, 11:36:00 System Operator/Comments: REV 8.34 using GPS Radiosonde Serial Number: 323111906 Input File: ../raw_data/2005060311.dat / / / Nominal Release Time (y,m,d,h,m,s):2005, 06, 03, 11:36:00 Time Press Temp Dewpt RH Ucmp Vcmp spd dir Wcmp Lon Lat Ele Azim 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 1009.6 22.7 20.8 89.0 -1.7 2.0 2.6 140.0 999.0 -89.610 -0.900 999.0 999.0 8.0 99.0 99.0 99.0 99.0 99.0 9.0 10.0 1004.4 22.5 19.5 83.0 -2.0 2.6 3.3 142.0 4.5 9999.000 999.000 999.0 999.0 53.0 2.0 99.0 99.0 99.0 99.0 99.0 20.0 1002.9 22.4 19.6 84.0 -2.3 3.2 3.9 144.0 1.3 9999.000 999.000 999.0 999.0 66.0 2.0 99.0 99.0 99.0 99.0 99.0 9999.0 1000.0 22.2 19.6 85.0 -2.5 3.5 4.3 145.0 999.0 9999.000 999.000 999.0 999.0 91.0 99.0 99.0 99.0 99.0 99.0 9.0 30.0 998.0 22.0 19.4 85.0 -2.6 3.7 4.5 145.0 999.0 9999.000 999.000 999.0 999.0 108.0 2.0 99.0 99.0 99.0 99.0 9.0 5.0 Quality Control Procedures This dataset underwent the JOSS QC process which consisted of internal consistency checks. The internal consistency checks included gross limit checks on all parameters and vertical consistency checks on temperature, pressure, and ascension rate. 5.1 Automated Quality Control Procedures 5.1.1 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. JOSS conducted the following gross limit checks on the San Cristobal PACS 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 > 1030 mb P B Altitude < 0 m or > 40000 m P, T, RH Q Temperature < -99.9C or > 40C T Q Dew Point < -99.9C or > 30C 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 > 70 m/s U Q > 150 m/s U B V Wind Component < 0 m/s or > 70 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 ---------------------------------------------------------------- 5.1.2 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 values. 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 from surface to 150 mb: > 15 C/km (not applied at p < 150mb) P, T, RH Q > 30 C/km (not applied at p < 150mb) P, T, RH B for pressures < 150 mb: > 100 C/km (not applied at p > 150mb) P, T, RH Q > 10000 C/km (not applied at p > 150mb) 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 ---------------------------------------------------------------- 6.0 References Loehrer, S. M., T. A. Edmands and J. A. Moore, 1996: "TOGA COARE upper-air sounding data archive: development and quality control procedures", BAMS, 77, 2651-2671.