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Table of Contents - The Atmospheric Studies Group at TRC

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Section 6: SMERGE Surface D<strong>at</strong>a Meteorological Preprocessor<br />

6.1.1 Generic Multi Time Interval Surface D<strong>at</strong>a File<br />

For sub-hourly or any time interval surface observ<strong>at</strong>ion d<strong>at</strong>a th<strong>at</strong> do not conform to any <strong>of</strong> the d<strong>at</strong>a sets<br />

above, a user can develop a generic comma delimited d<strong>at</strong>a file and process it through a stand alone<br />

program, SURFCSV to cre<strong>at</strong>e a SURF.DAT file with one single st<strong>at</strong>ion. <strong>The</strong> purpose <strong>of</strong> SURFCSV is to<br />

read a comma delimited form<strong>at</strong> meteorological d<strong>at</strong>a file, extract the surface d<strong>at</strong>a <strong>at</strong> fixed intervals and<br />

output as SURF.DAT v2.1 with beginning and ending times th<strong>at</strong> span the interval requested. This<br />

program is different to the Generic option (Section 6.1.1) <strong>of</strong>fered in SMERGE which only processes<br />

hourly surface observ<strong>at</strong>ion d<strong>at</strong>a which must be in the exact comma-delimited form<strong>at</strong> as shown in <strong>Table</strong> 6-<br />

1. SURFCSV on the other hand is not part <strong>of</strong> SMERGE and must be executed separ<strong>at</strong>e <strong>of</strong> the GUI.<br />

Unlike the Generic form<strong>at</strong>, SURFCSV does not require the user to have the d<strong>at</strong>a in specific columns but<br />

allows much more flexibility through the use <strong>of</strong> a user control input file where the user specifically st<strong>at</strong>es<br />

wh<strong>at</strong> d<strong>at</strong>a is available, wh<strong>at</strong> column the said d<strong>at</strong>a is in and accounts for any time period interval to the<br />

nearest minute. SURFCSV will then process the comma delimited file and cre<strong>at</strong>e a surface d<strong>at</strong>a file<br />

which can be read directly into CALMET. No QA steps are employed so the user must take responsibility<br />

for the adequacy <strong>of</strong> the d<strong>at</strong>a. Furthermore, the single observ<strong>at</strong>ion nearest the end <strong>of</strong> the output interval<br />

selected may be used if the exact time <strong>at</strong> the end <strong>of</strong> an interval is not in the file (missing d<strong>at</strong>a). No<br />

averaging is done.<br />

<strong>The</strong> d<strong>at</strong>a record can be <strong>of</strong> any user defined time increment, i.e., from one minute to multi-hours. <strong>The</strong> user<br />

is required to give an output starting time and output ending time specifying the d<strong>at</strong>a record to the nearest<br />

minute interval. <strong>The</strong> d<strong>at</strong>a interval to the nearest minute is also specified. <strong>The</strong> user has the choice to use<br />

two different d<strong>at</strong>e/time stamp form<strong>at</strong>s, either YYYY-MM-DD hh:mm or, MM/DD/YYYY hh:mm. It is<br />

up to the user to make sure the time and d<strong>at</strong>e stamp conform to either <strong>of</strong> these form<strong>at</strong>s. This can be done<br />

using Excel. <strong>The</strong> SURFCSV control file requests specific inform<strong>at</strong>ion as to which column the wind speed,<br />

wind direction, temper<strong>at</strong>ure, rel<strong>at</strong>ive humidity, pressure, cloud cover and cloud ceiling height can be<br />

found. A choice <strong>of</strong> units is available for each variable which saves the user time in having to first convert<br />

the d<strong>at</strong>a into the correct form<strong>at</strong>, prior to processing.<br />

<strong>The</strong> comma delimited form<strong>at</strong> required for SURFCSV is specifically designed to allow users to make use<br />

<strong>of</strong> spreadsheets where the raw d<strong>at</strong>a can most easily be observed and sorted. Unlike the hourly Generic<br />

form<strong>at</strong> where missing d<strong>at</strong>a in the file must be replaced with the missing value indic<strong>at</strong>or <strong>of</strong> 9999.00 for<br />

real numbers and 9999 for integers, missing values are autom<strong>at</strong>ically replaced in SURFCSV.<br />

<strong>Table</strong> 6.8 provides a sample control input file required for SURFCSV, while <strong>Table</strong> 6.9 provides detailed<br />

inform<strong>at</strong>ion <strong>of</strong> the control input file. A sample CSV.DAT file is shown in <strong>Table</strong> 6.10. Note th<strong>at</strong> the first<br />

line <strong>of</strong> the sample control input file (<strong>Table</strong> 6.8) must remain unchanged as it provides the default file<br />

name and version number. <strong>The</strong> second line refers to the number <strong>of</strong> lines <strong>of</strong> comment records which<br />

follows immedi<strong>at</strong>ely afterward. <strong>The</strong> rest <strong>of</strong> the parameters are detailed in <strong>Table</strong> 6.9. Note th<strong>at</strong> both the<br />

input control file must be called SURFCSV.INP and the comma delimited d<strong>at</strong>a file (6.10), CSV.DAT, so<br />

this processor is best run using a "b<strong>at</strong>ch" file th<strong>at</strong> renames files specific to an applic<strong>at</strong>ion. D<strong>at</strong>a records<br />

6-18

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