Of Coyotes and Hurricanes

Hello everyone! Today we will be discussing hurricanes and Coyotes!
I promise, that combination is going to make sense.
First, let’s start with hurricanes. The transitional boundary between hurricanes and the open ocean relates to the heat, moisture, which in turn relate to the intensity of the storm and thus is rather important. This boundary is not the easiest thing to study, however. Making observations with a manned aircraft below one kilometer (0.62 miles) altitude brings about danger in the form of large waves and other hazardous conditions. Most manned hurricane reconnaissance aircraft don’t fly below three  kilometers (1.86 miles) altitude. While ocean buoys, dropsondes, and radar are used, this low altitude region remains understudied. I’ll be explaining dropsondes more in a minute, but for now, let’s move on to the Coyotes.
No, no, not that kind of coyote. Not the mammal. The unmanned aircraft system! Raytheon Missile Systems make aircraft called Coyotes. These can be sent into the regions of hurricanes not safe for manned aircraft, giving us more data.
That brings us to today’s article, “Coyote unmanned aircraft system observations in Hurricane Edouard (2014)”, published in September 2016 in the American Geophysical Union’s journal Earth and Space Science. Written by J. J. Cione, E. A. Kalina, E. W. Uhlhorn, A. M. Farber, and B. Damiano, this article discussed Coyotes being used in a hurricane and how they performed. 
Hurricane Edouard as seen on September 2014. Image Credit: NASA Goddard MODIS Rapid Response Team
Hurricane Edouard as seen on September 2014. Image Credit: NASA Goddard MODIS Rapid Response Team
The Coyote unmanned aircraft system (UAS) were sent into Hurricane Edouard in 2016 twice, once on September 16th, once the following day. This marked the first time a UAS was sent into a hurricane using a manned aircraft to deliver it. There had been three previous uses of UAS in such storms before: Tropical Storm Ophelia in 2005, Typhoon Longwang in the same year, and Hurricane Noel in 2007. All of these were land-based operations.
Coyotes are pretty small, measuring 0.79 meters (two feet, seven inches) in length, with a wingspan of 1.47 meters (just shy of four foot ten), and weighing only 6 kilograms (just over 13 pounds). A Coyote can carry up to 1.8 kilograms (3.97 pounds) in instruments. For these experiments, the wings of the Coyote were folded, and then the UAS was placed inside a canister. This is deployed in-flight and slowed by an attached parachute. After about 15 seconds, the flight is fairly stabilized: the Coyote comes out of the canister, wings unfolding, and starts taking measurements. The Coyote’s airspeed, flight path, and altitude are controlled remotely by the manned aircraft. In this case, that was the Lockheed WP-3D Orion “Hurricane Hunter”.
The first Coyote flight in Hurricane Edouard was September 16th, 2014. The Coyote stayed in flight for 27 minutes, sending back data from in and around the eye of the storm. Unfortunately, it did not have a great signal for sending this data, and not all information was retrieved. The flight the following day was much more successful: the flight lasted a record 68 minutes, and as the WP-3D, which was receiving signal, stayed closer than the day before, much more data was transmitted.
The Coyotes are equipped to measure temperature, atmospheric pressure, and relative humidity. From the information Coyotes send back, wind measurements can also be determined. Depending on where the Coyote was in the storm, the UAS measured wind speeds between 2 and 51.5 meters per second (4.47 to  115 miles per hour). Temperature was generally around 21 Celsius (69.8 Fahrenheit).
The Coyote measurements were compared to those taken by the WP-3D and dropsondes. You may be familiar with ‘radiosondes’; the instrumentation attached to weather balloons that float up and collect data. Dropsondes are gravity-assisted radiosondes, so to speak; instead of floating up, they measure the same things a weather balloon would–after being dropped from an aircraft and falling down. The Coyote data agreed well with those of the other devices in all areas, suggesting they could be quite useful for future hurricane studies. Starting in 2016, Coyotes are also expected to be able to measure sea surface temperature, which would be a wonderful addition to the measurements they already take.


Cione, J. J., E. A. Kalina, E. W. UhlhornA. M. Farber, and B. Damiano (2016), Coyote unmanned aircraft system observations in Hurricane Edouard (2014), Earth and Space Science,  3, 370380, doi:10.1002/2016EA000 187 
Today’s main article.
Lang, Steven and Rob Gutro. NASA Sees Hurricane Edouard Enter Cooler Waters. National Aeronautics and Space Administration. 19 September 2014. Web.
A page with a series of short articles about Hurricane Edouard. This particular one was the source for the picture used above.
Newman, Paul. ed. Lynn Jenner. “What the Heck is a Dropsonde?” National Aeronautics and Space Administration, Goddard. 31 July 2016. Web.
A short article which describes dropsondes and their use.
OMAO NOAA. Lockheed WP-3D Orion. Office of Marine and Aviation Operations, National Oceanic and Atmospheric Administration. 13 May 2013. Web.
A page on the WP-3D Orion “Hurricane Hunter” aircraft, which I also link to within today’s post.
Raytheon. Coyote. Raytheon Company, 2016. Web.
A very brief description of the Coyote UAS by Raytheon, with many links and an image of the Coyote. The main video they link to is from my local news station, which I find an amusing coincidence. This page is also linked to within the text of my post.

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