The Actual Meteorological Database Construction (AMDaC) package is a software package developed for the decoding, filing and quality evaluation of meteorological data. In conformity with the functions specified in operation 3.2 of the MARS Project Call for Proposals General Conditions and Detailed Specifications (August 1990) the AMDaC package is able to:

• decode INTERMEDIATE-hour and MAIN-hour SYNOP-reports (FM 12-VIII) and METAR-reports (FM 15-VIII) from weather stations in the EC-countries, circulating on the Global Telecommunication System (GTS);
• check the quality and correct the obvious errors in the received weather reports;
• store the coded and decoded information in two separate databases with direct access files;
• perform time consistency checks to compare the values of reported parameters with those previously or subsequently reported for the same station;
• correct automatically obvious errors detected while performing consistency checks;
• fill up automatically gaps in the database through interpolation based on time consistency criteria;
• flag errors and dubious observations which can not automatically be corrected, and write these to a log file;
• extraction or calculation and storage of the following parameters in a separate database:
• sunshine duration;
• total 24 hour precipitation (6 UTC - 6 UTC);
• daily mean cloud cover;
• daily mean wind speed at 10 meters;
• daily mean vapor pressure;
• air temperature and vapor pressure at 6, 9, 12, 15 and 18 UTC;
• maximum and minimum temperature;
• total cloud cover during daytime (i.e. 6-18 UTC);
• mean daytime visibility;
• state of the soil;
• calculated daily mean vapor pressure deficit and slope of the saturated vapor pressure vs. temperature curve;
• calculated amount of shadow clouds during daytime (i.e. 6-18 UTC);
• calculated sunshine duration;
• calculated global radiation;
• calculated evapotranspiration according to the modified Penman formula.

The AMDaC package consists of six programs (see also Fig. 1.1):

• EXDEC: this program (1) extracts weather reports needed for the Actual Meteorological Database (AMD) from the input file GTS:I yymmdd .DAT, (2) checks and (whenever possible) corrects the construction of the extracted reports, (3) stores the (corrected) coded observations in the database CODED, (4) decodes the observations and (5) stores the extracted and some derived data in the database DECODED;
• CHECK: this program (1) performs time and space consistency checks on the observations in the CODED and DECODED databases, (2) automatically corrects obvious errors and (3) detects other possible errors which can be corrected later on by the operator through the OBSCON program;
• OBSCON: this program offers an operator the possibility of viewing coded (stored in CODED), decoded and derived element values (both stored in DECODED). Furthermore, errors which were not automatically corrected by the CHECK program can be displayed, and if necessary values can be added to or modified in the database DECODED. For the representation of data various lay-outs are available;
• INTER: this program tries to fill up gaps in the database DECODED through interpolation based on time consistency;
• SELECT: this program (1) selects element values of the AMD stations from the database DECODED, (2) calculates some AMD parameter values and (3) writes all AMD parameter values to the file DAILY:S yymmdd .DAT;
• FINAL: this program performs a final check of the AMD parameter values in the file DAILY:S yymmdd .DAT;

In this manual a description of the AMDaC programs is given.