Snow monitoring network
DEOS sensors help DelDOT set snow reimbursement thresholds
9:12 a.m., Dec. 19, 2014--When Delaware Department of Transportation (DelDOT) representatives need real-time data about winter weather conditions in Delaware, they turn to the Delaware Environmental Observing System (DEOS), housed in the University of Delaware’s College of Earth, Ocean, and Environment.
For the last seven years, the DEOS-operated “Snow Monitoring Network” — which recently expanded to 26 snow-depth sensors in DelDOT’s 12 maintenance zones — has helped DelDOT accurately calculate snow total data throughout the state.
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The data is used to set reimbursement thresholds for neighborhood association snow removal costs. DelDOT district offices also use the data to determine — in real-time — where services are needed, including when to begin plowing bus routes, which is done after the accumulation total reaches 6 inches or more in a maintenance zone.
“The DEOS system is a valuable tool. DelDOT relies heavily on the sensor data collected for the snow storms during the winter months for its maintenance and operations division,” said Gloria Acevedo, DelDOT Maintenance and Operations Snow Removal Reimbursement Program manager.
In 2013, DelDOT disbursed approximately $2.5 million in reimbursements to neighborhood associations statewide for snow removal based on DEOS sensor data.
Reimbursement thresholds are measured in 4-inch increments. In maintenance zones with more than one measuring station, DelDOT uses the highest accumulation recorded by any of the DEOS stations within that zone for a given event.
Maintenance zones in New Castle County are equipped with three sensors, while Kent and Sussex county districts contain two sensors. Additional sensors monitor snow depth in Chester County, Pennsylvania.
How it works
For most big snow events, the DEOS team monitors the sensors for the duration of the event, sometimes lasting as long as 36 hours, and communicates regularly with Acevedo, who posts the accumulation totals provided by DEOS to the DelDOT website.
“Initially we measured just the amount of snow on the ground but now we measure a snowfall accumulation much like the National Weather Service,” said Dan Leathers, professor of geography and Delaware’s state climatologist.
Accurate to within four-tenths of an inch, the sensors calculate snow depth by sending pulses of sound waves down to the ground. When the sound waves hit the ground, or snow, they bounce back and an algorithm computes the travel time, which tells researchers how far the sensor is from a solid surface. As the depth of the snow changes, the travel time decreases and the differences in snow depth are recorded as snow accumulation.
DEOS team members monitor the sensors to ensure that quality data is coming in across the state and they place this data on the DEOS website where it is available to DelDOT, as well as the general public.
In additional to snowfall, DEOS weather stations provide time-specific data on air temperature, wind speed, wind gusts, wind direction, relative humidity, barometric pressure and rainfall.
In severe weather, these kinds of details are often a first-alert that can help emergency managers make timely, informed decisions about needed services.
“In 2013 a burst of snow in the early morning put down 5-6 inches of snow in a narrow band about 10 miles wide in Delaware. When the sensors recorded the measurement, DelDOT actually called us and said ‘is that real?’” Leathers said.
Looking ahead to winter 2015
Early forecasts for winter 2015 have pointed to a strong El Niño, which often has big implications in North America, but Leathers said at present it looks like a weak pattern that might not mean much for Delaware.
When asked about predictions for snow, Leathers joked that he expects “less than last year,” which was the second snowiest Delaware winter on record. Snow totals across the state for winter 2013 ranged from 35-55 inches — more than three times the normal average. The highest recorded snow totals in Delaware occurred during winter 2009-10 when the state was blanketed with 72 inches of snow.
“From a purely statistical point of view, it’s unlikely we will have two big years in a row,” he said. “With moderate temperatures and just a slight chance of above normal precipitation in the National Weather Service extended forecast, we could experience above normal precipitation this winter and still only get light snowfall because it’s too warm.”
To learn more about how DEOS capabilities have evolved over the last decade, click here.
Article by Karen B. Roberts