Use of Data Logger Devices in the Collection of Site- Specific Weather Information. Peter de Bruijn, RPF. June Fire Report FR

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1 Wildland Fire Operations Research Group (WFORG) 1176 Switzer Drive Hinton AB T7V 1V3 Use of Data Logger Devices in the Collection of Site- Specific Weather Information Fire Report FR Peter de Bruijn, RPF June 2010 Copyright 2010, FPInnovations

2 This report provides an overview of our experiences with the USB-502 data logger equipment used during an exploratory research project in the late summer of 2009 around Kamloops, British Columbia. It provides useful tips for the use and installation of the equipment during future applications of the device. Introduction Wind events, in particular those associated with the passage of frontal boundaries, are the primary cause of wildland fire blow-up situations. In the absence of wind, instances of wildland fire blow-up conditions have been correlated to the occurrence of super adiabatic lapse rates. This occurs when the environmental lapse rate (ELR) exceeds the dry adiabatic lapse rate (DALR) of a 9.8-degree-Celsius change in temperature per 1000-meter change in elevation and is indicative of unstable atmospheric conditions. Temperature lapse rate data are used in the U.S. Haines Index; they are used little in Canada because of the coarseness of data collection points; there are only four such collection locations in British Columbia with twice daily measurements. The Remote Automated Weather Station (RAWS) network has greatly increased the ability to obtain more relevant local weather information. However, because distances between individual stations can still be in excess of 100 kilometres, potentially important information of actual local conditions cannot always be captured. The USB-502 tool can be used to give ready access to more localized and timely information, which has been a longstanding desire expressed by fire managers. Objectives FPInnovations was approached by the British Columbia Ministry of Forests and Range, Wildfire Management Branch, Aviation Management, to conduct exploratory research into collecting localized lapse-rate information. More specifically, to determine if trends in the lapse rate could be used as a possible tool for a more timely prediction of blow-up fire conditions later in the burning period. The USB-502 was used to collect temperature and humidity data. Methods USB-502 data loggers were used in this exploratory research project. They are manufactured by the Measurement Computing Corporation of Norton, Massachusetts, USA. Website: USB-502 Specifications: Temperature measurement range: from -35 to 80 C at 0.5 increments Relative humidity measurement range: 0-100% at 0.5% increments Software configurable sample rate: 10 sec, 30 sec, 1 min, 5 min, 15 min, 30 min, 1 h, 2 h, 6 h, 12 h Sampling recording memory: maximum samples for temperature and relative humidity Battery: ½ AA 3.6 V lithium; typical lifespan: 1 year Dimensions: 103 mm long x 26.4 mm wide x 26.4 mm high Approximate cost: C$ each Page 1 FR

3 Several of the devices and accompanying computer software were provided by the University of Alberta, Edmonton. The USB-502 data logger records temperature and relative humidity and provides dew-point data. The unit plugs into a standard USB computer port. The desired recording interval can be programmed in seconds when activating the device with the accompanying software. The unit is capable of storing up to five months of data, depending on which recording interval is selected. It records in degrees Celsius or Fahrenheit with a resolution of 0.5 degrees Celsius. Downloading stored data is achieved by plugging the unit into a USB port and using the device software. Data are instantly displayed in a graph or Excel format for further manipulation. Page 2 FR

4 USB-502 data loggers were located around the Kamloops area at various elevations ranging from 362 meters on the Thompson River valley floor to 1775 meters at the summit of Greenstone Mountain for a period of approximately 14 days. The recording interval was set at 5 minutes, resulting in over data recordings per device during the period. Each device was placed inside a PVC tube to protect against the elements; mounted vertically, the tube was capped on one end (top) to protect against precipitation. A large hole on the middle face (front) and an open bottom ensured adequate ventilation and easy observation of the LED indicators on the unit. Page 3 FR

5 Experiences The USB-502 data logger provided a detailed temperature and relative humidity history for each recording location during the pilot project. It is a sensitive instrument and therefore correct positioning in the outdoors is critical to recording true weather data. Location Standards for weather stations from the Weather Guide for the Canadian Forest Fire Danger Rating System should be taken into consideration but may not always be practical in short-term applications in the field. Following are some findings and suggestions from our own experience with the USB-502: 1. Direct sunlight on the unit will exaggerate temperature readings; sunlight exposure should be avoided where possible with any type of weather protective housing (e.g., Stevenson screen). 2. Wherever possible, units should be positioned in the shade, and openings on protective housing should be facing north. 3. Irrigation practices in adjacent areas may affect relative humidity readings and should be taken into account when placing the units. 4. Slight differences in the recording accuracy between different units are to be expected and the units should be calibrated prior to use. This can be easily determined by placing all units in the same location under the same conditions for a period of time; observed differences can be noted and applied during the data manipulation process. 5. More precise temperature recording increments of 0.25 C or 0.1 C are desirable. 6. On several occasions we observed notable differences in temperature readings between vertically separated recording stations, indicating the presence of a temperature inversion or thermal belt. Placing a series of data loggers along a vertical profile on a particular fire incident could provide timely information about the existence of such conditions in the immediate area if the units were connected to a transmitting device. Discussion The USB-502 was found to be accurate and dependable. Its low cost and user friendliness make it affordable and viable for locations without weather recording stations where it is desirable to have access to site-specific temperature and relative humidity information. For further information contact Peter de Bruijn RPF Page 4 FR

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