Gateway 700SE Personal Computer

Overall camera operation is controlled by a PC running a current Windows based operating system. The cameras are connected to the PC through RS-232 serial ports. Images are acquired every 30 minutes and archived on the hard drive. Image files are copied onto removable media for eventual storage off-site. Power to the cameras is supplied by a 24V AC power supply. Power and signals are carried by conduit protected cable mounted on WXII property. The equipment is housed in a climate controlled room next to the tower and protected by several layers of uninterruptible power sources.

WXII Television Tower

Cameras and visibility equipment need protection from hazards such as falling ice and lightning strikes. Each camera is protected in a heated enclosure that is mounted near the tower. Each enclosure is protected from ice by a shield that is angled to divert falling ice from making direct impacts on the shield. After a lightning related surge damaged both cameras in 2002, the wiring between cameras and the PC was upgraded to include communications using the RS-422/485 standard for greater signal isolation

Optec NGN-2 Ambient Nephelometer

One of the major upgrades planned for Haze Cam during 2004 is the addition of visual range measurements.  To achieve that goal, an Optec NGN-2 ambient nephelometer has been purchased from Air Resource Specialists Inc.  The nephelometer will be installed on-site at Sauratown Mountain and will provide measurements of light scattering due to particles and aerosols in the atmosphere.  Due to the open-air design of the NGN-2, ambient temperature and relative humidity is taken into account, an important consideration due to the frequency of saturated fog conditions. In some areas, nephelometers are used to provide surrogate measurements for fine particle (PM2.5) monitoring. In this application, the nephelometer output (B-scat)  will be related to visual range measurements through a mathematical relationship. 

Field Measurements

Air quality and meteorological measurements displayed on Haze Cam are taken at a variety of monitoring sites in Forsyth County, North Carolina. Ozone readings from the Union Cross site are obtained with a state of the art ozone analyzer. Fine particulates are measured by a continuous PM2.5 sampler at the Hattie Avenue site in downtown Winston-Salem. Winds are measured by a real-time meteorological system and the temperature/dew point readings come from a similar unit in place at a Forsyth County monitoring station. A complete assessment and description of the Forsyth County air monitoring is completed each year and changes are made when necessary. A data file containing the air quality and meteorological readings is automatically sent by FTP to the web server directly from the monitoring stations. A script on the web server parses the data file for display.