Skip to main content

Visit the Photochemical Assessment Monitoring Site

Measurements made at the Rutgers Photochemical Assessment Monitoring (PAM) site are used to assesses air quality and lower atmospheric conditions in Central New Jersey. The site is equipped with a wide array of surface and remote sensor measurements and is located on Horticulture Farm #3. A twenty meter tower equipped with temperature, relative humidity, and wind measurements at two meters, ten meters, and twenty meters provide continuous monitoring of the surface layer, which is thin layer of atmosphere closest to the surface. Exchanges between the surface and atmosphere take place in the surface layer.

The PAM Site is also equipped with a comprehensive, state-of-the-art system that measures the incoming solar and infrared radiation fields and the net radiation exchange (incoming minus outgoing). The incoming solar radiation field is comprised of a direct component, which is the solar radiation coming from the direction of the sun’s disk, and a diffuse component, which is the solar radiation coming from all other directions. Measurements across the full range of incoming solar wavelengths, termed “broadband”, and across small increments in the spectrum, termed “narrowband” are made at the site.

A vertically-pointing laser, known as a laser ceilometer, measures the lowest cloud-base height every 15 seconds. Winds and temperatures in the lowest 3-5 kilometers of the atmosphere are monitored continuously. A profile of the wind speed and direction is measured by a vertically-pointing Doppler radar operating at a frequency of 915 MHZ. This radar measures the velocity of turbulent eddies as they pass above the site being moved with the wind along three different beams, one vertical and two slightly off vertical. Once per hour large speakers pointed toward the sky, toward zenith we call it, broadcast sound waves that are a form of turbulence. As these sound waves move away from the speakers and into the lower atmosphere, we use the Doppler radar to measure their speed, which is directly related to the atmospheric temperature. As the sound passes through different layers of the lower atmosphere and its speed changes slightly in response to temperature changes, we can construct a temperature profile. Knowledge of the temperature profile is important because it impacts the vertical exchanges between the surface and lower atmosphere.