TIHMMI: a low-cost mobile system to simultaneously map urban air and surface temperatures

PICONE, NATASHA; LEE, JOSEPH; KETLER, RICHARD; NESIC, ZORAN; CHRISTEN, ANDREAS; CAMPO, ALICIA M.

Nueva York

Conferencia; ICUC 10; 2018

City College of New York, AIUC y American Meteorological Society

Most studies of the extent and energetics of urban heat islands are either studies of the canopy-layer urban heat island (CLUHI) derived from simultaneous air temperature measurements in urban and rural environments or studies of thesurface urban heat island (SUHI). The measurement of the CLUHI is often based on fixed stations or traverses on single vehicles, with high temporal resolution, but limited spatial detail. The study of the SUHI in contrary is usuallybased on thermal satellite data, hence has excellent geospatial, but limited temporal detail. Generally, a simultaneous measurement of CLUHI and SUHI is not attempted.We developed TIHMMI (Temperature ? Infrared - Humidity - Mobile Mapping Instrument) as a low-cost and opensource Arduino based sensor system designed to simultaneously map air and surface temperature in cities. The goal was to provide an affordable and light traverse system that is replicable, and can be easily built. The system can then simultaneously map and measure air and surface temperatures as it moves, mounted on bikes, motorcycles or cars, through cities. A central application of the system is teaching ? it serves as a tool to showcase innovative crowdsourced data collection, geospatial data visualization, and analysis in courses related to urban climate/meteorology and GIS. Students in classes can build, operate and analyze multiple systems simultaneously. The system is developed in a collaboration between the University of British Columbia (Canada), University of Freiburg (Germany), and CIG-IGEHCS (CONICET/UNCPBA, Argentina) with support from the Mozilla Foundation.The components TIHMMI are: an Arduino Mega microcontroller, a global positioning system (GPS) antenna, an actively ventilated thermocouple, a relative humidity probe and thermistor-based temperature sensor, a bolometer (infrared temperature) all mounted on a custom-made board. All data are sorted on-board on a microSD card. The GPS (Adafruit Ultimate GPS Logger Shield with GPS Module) allows a precise geolocation (latitude/longitude, speed, altitude) of each measurement every 2 seconds. The Thermocouple, its radiation shield and active ventilation allow to obtain precise air temperature data. The digital sensor (AM2302/DHT22) retrieves relative humidity (and a second temperature) for additional information related to thermal indices. Infrared Temperature Sensors (Melexis MLX90614 Non-Contact Sensors) measure infrared emittance of selected urban surface facets (usually pointed on the road surface, or sideways from the vehicle to sample wall temperatures) and transform them into brightness temperatures. The system requires 12 volts of power which can be supplied by a car cigarette lighter socket or a portable battery.We illustrate the use of the system in teaching classes at the UNCPBA in Tandil, Argentina. The high temporal and spatial resolution data generated highlights the differences between SUHI and CLUHI at different times, and with different urban form in Tandil. Additionally, the temperature and humidity data allow calculation of geolocated comfort indices, or in future comparative studies of surface temperature with simultaneous satellite datasets.