Evaporation Pre-processing - Overview

This module calculates mean monthly potential evaporation (in mm/day) from daily climatic data recorded at meteorological stations.

The following climatic parameters (as daily values) are used for the calculation of potential evapotranspiration with the modified Penman (Penman/Monteith) formula:

In addition to these time series data various time-independent station-related physical parameters are used .

The daily data can be either online (ORACLE) or offline (in the linked database Evap_offline.db). An uploading of the original daily data from Oracle (Table "JORDAN_DAILY_CLIMATE") to the offline database is not implemented. Presently, the program will only update the individual daily data tables for selected climatic parameters (offline) from the daily climate data (Oracle). Runaways (obviously wrong data) are automatically excluded. This operation will operate with rather large data volumes, and is therefore rather critical in cases of poor network performance.

Note: The calculation of daily humidity out of daily dry bulb and wet bulb measurements in included in this process.

Additional to the daily data available at the Ministry of Water and Irrigation monthly climatic data from the Department of Meteorology are included for the period 1985 to 1998. The reason is the insufficient coverage of all Agro-Climatic Zones (ACZ) by stations operated by MoWI. However, this aspect is of primary concern for the irrigation module. The Runoff module processes station-related data, although a more representative coverage of the country would certainly increase the accuracy of model results.

Processing is done for the complete time period. The time period (hydrological years) to be entered relates only to update of records from the ORACLE data base.

The following queries are executed:
  1. The tables of daily records of sunshine, windrun, minimum and maximum temperature and humidity are summarized into monthly values.
  2. All monthly climatic values are combined in a single table "MetData_db".
  3. The values from the Meteorological Department (Table "M_DepMeteo") are added to table "MetData_db".
  4. From monthly data stored in table "MetData_db", monthly potential evaporation is calculated with the Penman Formula and the results are stored in table "mETP" for each station with available data.
    Station-related data from that table are later used by the core runoff model and regionalized with Surfer.

Particularly if connected to ORACLE, processing will take some time. A status bar on the form is indicating which parameter is currently processed.

End of processing is indicated as well.

Note: Export of evaporation data or station data to dBase files is not required any more, as the core rainfall/runoff model is now directly accessing the same linked tables of the Access database.