Season's Greetings from Lakes Environmental!

Lakes Environmental sends you our best wishes for a wonderful Holiday Season and a successful 2007.

Our offices will be closed for the holiday season on:

• Monday, December 25^th, 2006
• Tuesday, December 26^th, 2006
• Friday, December 29^th, 2006
• Monday, January 1^st, 2007

We wish to thank all our subscribers for taking the time to read our newsletter. We value your feedback and suggestions and look forward to hearing from you in the new year.

We’ve set a number of training dates for 2007, with additional courses to be announced soon!

Courses Filling Up!

Our Toronto AERMOD Course is filling up, register now to book your spot!

AERMOD Courses - New Course Dates Posted for 2007!

*Includes new section regarding MOE Reg. 419/05 (see Outline)

Human Health Risk Assessment Courses

CALPUFF Courses

For more information on the above courses, such as registration information, location, and course outlines, please visit our web site: https://www.weblakes.com/courses.html.

Customized or International Courses

Lakes Environmental offers a variety of on-site, customized courses for all of your air dispersion modeling needs.  For information on pricing and availability, please email us at training@weblakes.com.

AERMOD Potential Temperature Profile
Elevation Above Mean Sea Level (PROFBASE Keyword)

Introduction

The meteorological (ME) pathway in the US EPA AERMOD model input file contains the keyword PROFBASE, which is used to specify the base elevation above mean sea level of the primary met tower for the purpose of calculating a potential temperature profile. It is often not well understood what exactly this means and why it is important, the significance of the elevation of the primary met tower is explained in the following tip.

Potential Temperature

The concept of potential temperature is used by the AERMOD model to simplify calculations. Note that pressure, temperature, and air density are inversely proportional to height changes. Potential temperature allows air temperatures at different altitudes to be compared using a standard level, avoiding the complexity introduced by the change in altitude.

Potential temperature (() is the temperature that a parcel of air would have if it was adiabatically (without adding or removing heat) brought to 1000 mbar of pressure, as shown in the figure below.

Reference Temperature

AERMOD calculates a vertical profile of potential temperatures, primarily for use in the calculation of plume rise. This profile is calculated from a reference temperature, measured at the primary tower, which is typically the surface station.

In order to use this reference temperature to calculate the profile, it must first be converted to a potential temperature. In order to convert the reference temperature into a potential temperature, it is necessary to know at what pressure the temperature was measured, which in turn is dependent on the elevation above mean seal level (MSL). This is why the base elevation of the primary meteorological tower above MSL is required by AERMOD.

We are currently accepting submissions for the Monthly Modeling Tip which appears in our newsletters.  If you have a modeling tip that may benefit a variety of people, please send it to us at support@weblakes.com.   Your name and the name of your organization will appear below the tip providing you with greater exposure.

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Here are a few conferences and trade shows coming up in the next few months: