Note 1: Each record also contains additional information on wind speed and general weather conditions that are not processed by PCRAMMET.
Note 2: The mixing height records input to PCRAMMET must contain the morning and afternoon mixing heights for the day being processed. Quality checks are not performed on mixing height data input to PCRAMMET, and so it is recommended that the user review this data for completeness. A blank in a mixing height field is interpreted as a zero, i.e., the mixing height is assumed to be at the surface.
See below the description of each element in the mixing height data file:
Upper Air Station Number -
The Weather Bureau Army Navy (WBAN) station identification number identifying the NWS upper air observation station used to calculate mixing heights. The List of Upper Air Stations available from NCDC tabulates such WBAN numbers. The station must be representative of the site to be modeled.
Year - The last two digits of the year of record for the mixing height data.
Month - The month number corresponding to a given set of mixing heights.
Day - The calendar day number corresponding to a given set of mixing heights.
Nocturnal Urban Mixing Height -
The minimum mixing height for a given day calculated from the 1200 GMT upper air sounding on that day, using morning surface temperature augmented by 5°C to account for urban heating.
Afternoon Mixing Height -
The maximum mixing height for a given day calculated from the afternoon surface temperatures and the 1200 GMT upper air sounding for that day.
Each record of the mixing height data file corresponds to the following:
Mixing height record for December 31 of the year preceding the year of record;
Mixing height record for January 1 of the year of record;
Mixing height record for January 2 of the year of record;
.
.
.
Mixing height record for December 30 of the year of record;
Mixing height record for December 31 of the year of record;
Mixing height record for January 1 of the year following the year of record (or duplicate of the December 31 record with year, month, day changed).
The method for calculating hourly mixing heights from the twice daily mixing heights uses the methods suggested by Holzworth (1972). This method interpolates the mixing heights using the afternoon mixing height from the preceding day and both mixing heights from the following day. For this reason, the mixing heights for the last day of the year preceding the year of record must be included as the first mixing height record. Also, the mixing heights for the first day of the year following the year of record must be included as the last mixing height record. If these data are not available, the data for the first and last days of the year of record can be substituted, respectively.
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