UMRBPP ETA Model Location Time Series (MOLTS) Derived Soundings Data Set 1.0 General Description The Eta Model Location Time Series Derived Soundings is one of the model output data sets provided in the Upper Missouri River Basin Pilot Project (UMRBPP) The full Eta MOLTS data set covers most of North America east of the Rocky Mountains (up to 574 locations). The UMRBPP Eta MOLTS Derived SOundings Data Set contains data from only the six sites in the Black Hills region of South Dakota. MOLTS are hourly time series output at selected locations that contain values for various surface parameters and `sounding' profiles at Eta model levels and are derived from the Eta model output. The MOLTS output files were converted into JOSS Quality Control Format (QCF) the same format used for atmospheric rawinsonde soundings processed by JOSS. The MOLTS output provided by JOSS on-line includes only the initial analysis output (i.e. no forecast MOLTS) and only state parameters (pressure, temperature, humidity, and wind). The full output, including the forecast MOLTS and all output parameters, in its orignal format (BUFR) is available from the NCAR/Scientific Computing Division. This data set covers the UMRBPP period (1 April to 5 May 1999). 2.0 Detailed Data Description The National Centers for Environmental Prediction (NCEP) began operations for the Eta model in June 1993 with a resolution of 80 km and 38 levels. The top level was 50 mb. In late 1994, the domain of the Eta model was increased and the resolution became 48 km with 38 levels. The Eta analysis and forecast fields are generated every 12 hours at 0000 and 1200 UTC daily. MOLTS are hourly vertical profile and surface time series derived from the Eta model output. The complete MOLTS output includes a changable number of informational items, parameters for each level and parameters at the surface. Output are available each hour beginning at the initial analysis (the only output available from JOSS) and ending at the 48 hour forecast. JOSS converts the raw format files into JOSS QCF format which is the same format used for atmospheric sounding data such as NWS soundings. A description of JOSS QCF format is included within section 2.1. JOSS calculated the total wind speed and direction from the u and v wind components. JOSS calculated the mixing ratio from the specific humidity (Pruppacher and Klett 1980) and the dew point from the mixing ratio (Wallace and Hobbs 1977). Then the relative humidity was calculated from the dew point (Bolton 1980). The altitude was not one of the available output parameters from the Eta MOLTS. JOSS did not conduct any quality control on this output. 2.1 Detailed Format Description 2.1.1 Header records The header records (15 total records) contain output type, project ID, the location of the nearest station to the MOLTS location (this can be a rawinsonde station, an ARM/CART station, a wind profiler station, a surface station, or just the nearest town), the location of the MOLTS output, and the valid time for the MOLTS output. The 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. 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 Output Type: Description of type of data. 2 Project ID: ID of weather project. 3 Nearest Station (lon,lat): Description of the nearest location. 4 Output Location (lon,lat,alt): Position of MOLTS output in format described below. 5 Valid Time (y,m,d,h,m,s): Time of release in UTC, in format: yyyy, mm, dd, hh:mm:ss 6 CAUTION: A warning that this is not actual rawinsonde data, but rather model output. 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 label is fixed to 35 characters to match the standard header lines. Sample header records are provided in the sample data file in section 2.1.3. 2.1.2 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 MOLTS output, these columns 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 automatic or visual checks made. See Sections 3.0 and 4.0 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') 2.1.3 Sample data The following is a sample portion of an JOSS QCF file including header records. The data portion is much longer than 80 characters and, therefore, wraps around to a second line. Data Type: ETA MOLTS Project ID: GCIP class format derived sounding Launch Site Type/Site ID: BUOY S OAHU PAC 51002 Launch Location (lon,lat,alt): 157 48.00'W, 17 12.00'N, -157.80, 17.20, 0.0 GMT Launch Time (y,m,d,h,m,s): 1995, 11, 07, 00:00:00 Nearest Location (lon,lat): BUOY S OAHU PAC 51002 157.80W 17.20N Caution: This is not actual rawinsonde data, it is output from the NCEP ETA model initial analysis. / / / / Nominal Launch Time (y,m,d,h,m,s): 1995, 11, 07, 00:00:00 Time Press Temp Dewpt RH Uwind Vwind Wspd Dir dZ Lon Lat Rng Ang Alt Qp Qt Qh Qu Qv Qdz sec mb C C % m/s m/s m/s deg m/s deg deg km deg m code code code code code code ------ ------ ----- ----- ----- ------ ------ ----- ----- ----- -------- ------- ----- ----- ------- ---- ---- ---- ---- ---- ---- 9999.0 1012.0 26.1 20.2 69.9 -6.1 1.9 6.4 107.0 999.0 -157.800 17.200 999.0 999.0 0.0 99.0 99.0 99.0 99.0 99.0 9.0 9999.0 1011.0 26.1 20.9 72.9 -6.1 -2.1 6.5 71.0 999.0 -157.800 17.200 999.0 999.0 99999.0 99.0 99.0 99.0 99.0 99.0 9.0 9999.0 1007.0 25.9 20.6 72.7 -6.1 -2.1 6.5 71.0 999.0 -157.800 17.200 999.0 999.0 99999.0 99.0 99.0 99.0 99.0 99.0 9.0 . . . etc. 2.3 Data Remarks No remarks. 3.0 Quality Control Processing No quality control was performed by JOSS. 4.0 References Bolton, D., 1980: The Computation of Equivalent Potential Temperature. Mon. Wea. Rev., 108, 171-180. Pruppacher, H. R., and J. D. Klett, 1980: Microphysics of Clouds and Precipitation. D. Reidel Publishing Company. 714 pp. Wallace, J. M., and P. V. Hobbs, 1977: Atmospheric Science: An Introductory Survey. Academic Press. 467 pp.