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Table of Contents - The Atmospheric Studies Group at TRC

Table of Contents - The Atmospheric Studies Group at TRC

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Section 8: CALMET Model Files<br />

8.5 Overw<strong>at</strong>er D<strong>at</strong>a Files (SEA1.DAT, SEA2.DAT, ...)<br />

If the modeling applic<strong>at</strong>ion involves overw<strong>at</strong>er transport and dispersion, the CALMET boundary layer<br />

model requires observ<strong>at</strong>ions <strong>of</strong> the air-sea temper<strong>at</strong>ure difference, air temper<strong>at</strong>ure, rel<strong>at</strong>ive humidity and<br />

overw<strong>at</strong>er mixing height. If the overw<strong>at</strong>er temper<strong>at</strong>ure method is used, vertical temper<strong>at</strong>ure gradient<br />

inform<strong>at</strong>ion is also necessary, however defaults are specified in the CALMET.INP file. <strong>The</strong> special<br />

overw<strong>at</strong>er observ<strong>at</strong>ions, along with wind speed and direction, are contained in a set <strong>of</strong> files named<br />

SEAn.DAT, where n is a st<strong>at</strong>ion number (1,2,3,...). If SEAn.DAT files are not used, the overw<strong>at</strong>er st<strong>at</strong>ion<br />

and its standard surface parameters (e.g., wind speed and direction, etc.) can be tre<strong>at</strong>ed as a regular<br />

surface st<strong>at</strong>ion. Additionally, any overw<strong>at</strong>er site th<strong>at</strong> should not be used in the overw<strong>at</strong>er temper<strong>at</strong>ure<br />

interpol<strong>at</strong>ion scheme should be placed in the SURF.DAT file instead <strong>of</strong> a SEA.DAT file. For instance, a<br />

user may want to include wind inform<strong>at</strong>ion from a lake buoy but not have the buoy influence<br />

temper<strong>at</strong>ures over the ocean.<br />

<strong>The</strong> overw<strong>at</strong>er d<strong>at</strong>a files are structured to allow the use <strong>of</strong> d<strong>at</strong>a with arbitrary time resolution. For<br />

example, hourly or daily air-sea temper<strong>at</strong>ure difference d<strong>at</strong>a, if available, can be entered into the files.<br />

Otherwise, monthly or seasonal d<strong>at</strong>a can be used. However, any st<strong>at</strong>ion th<strong>at</strong> is reporting non-missing<br />

wind speed and direction should use hourly d<strong>at</strong>a resolution or inaccuracies will be introduced into the<br />

wind field. <strong>The</strong> inaccuracy results from the fact th<strong>at</strong> the variables retain their current values each hour<br />

until a new observ<strong>at</strong>ion is encountered, <strong>at</strong> which time they are upd<strong>at</strong>ed. Thus, long periods <strong>of</strong> missing<br />

wind d<strong>at</strong>a between valid observ<strong>at</strong>ions should receive hourly records with the wind d<strong>at</strong>a set to missing. A<br />

similar argument applies to temper<strong>at</strong>ure and vertical temper<strong>at</strong>ure gradient inform<strong>at</strong>ion if the overw<strong>at</strong>er<br />

temper<strong>at</strong>ure method is used. All times must m<strong>at</strong>ch the base time zone <strong>of</strong> the CALMET run (variable<br />

IBTZ).<br />

<strong>The</strong> loc<strong>at</strong>ion <strong>of</strong> the overw<strong>at</strong>er site is specified for each observ<strong>at</strong>ion. This allows the use <strong>of</strong> d<strong>at</strong>a collected<br />

from ships with time-varying loc<strong>at</strong>ions. <strong>The</strong> d<strong>at</strong>a for each observ<strong>at</strong>ion st<strong>at</strong>ion (fixed or moving) must be<br />

stored in a separ<strong>at</strong>e overw<strong>at</strong>er d<strong>at</strong>a file.<br />

<strong>Table</strong> 8-13 contains a sample overw<strong>at</strong>er input file, which contains hourly overw<strong>at</strong>er d<strong>at</strong>a. A description<br />

<strong>of</strong> each input variable and form<strong>at</strong> is provided in <strong>Table</strong> 8-14.<br />

8-77

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