Weather

NASA hunts ice in storms off the NC coast

NASA's DC-8 Airborne Laboratory has been seen recently off the NC coast, hunting microscopic ice that can build up in aircraft engines causing failures.

Posted 2022-07-24T23:24:14+00:00 - Updated 2022-07-25T13:26:10+00:00

DC-8 Airborne Laboratory in flight during research mission (NASA)

Tony Rice

, NASA Ambasador

An eagle-eyed viewer spotted a NASA plane off the North Carolina coast, circling through a storm from Ocracoke to Wilmington.

NASA's DC-8 Airborne Laboratory studying icing in large storms off the North Carolina coast between Ocracoke and Wilmington (Courtesy: FlightAware)

It is part of ongoing research into high ice water content (HIWC), tiny ice crystals that develop in deep convective storms. These ice crystals are difficult to detect and can cause big problems as they build up in engines as pilots fly through and even around these storms.

Deep convective storms form when warm moist air rises and condenses as it cools. Ice forms around tiny particles in the atmosphere, around 100 microns in size or about the size of baking flour. Updrafts push those ice crystals, where they can remain suspended for hours, above 30,000 feet, cruise altitude for passenger airliners.

Vertical cross-sectional schematic of radar reflectivity factor (RRF) with high ice water content (HIWC) RADAR sampling altitudes superimposed. (NASA, Rice)

While millimeter-sized rain drops, hail and wet snowflakes are very reflective, making them visible to weather radars aboard passenger and other aircraft flying above 30,000 feet, these micron-sized ice crystals are not, making them invisible to pilots until the engines begin losing power as ice builds up inside.

A team of researchers from Australia, France and NASA's Langley Research Center in Hampton, Va., have an idea of how to help pilots spot HIWC conditions by combining remote satellite data from geostationary weather satellites like Europe's Meteosat, Japan's MTSAT, and NOAA's GOES along with measurements of the total water content of the air around the plane, with a lot of math.

Understanding the capability of radar to detect high altitude icing is the goal of a NASA flight campaign about to begin in Fort Lauderdale, Florida. For the next three weeks, NASA researchers will be flying a DC-8 research plane, outfitted with state-of the-art radar and sophisticated meteorological probes to detect ice crystal icing conditions.

Current weather radar can detect rain, hail or ice particles, but is limited in its ability to discern which types and sizes of ice crystals are in the atmosphere. When ice crystals hit warm aircraft engines, they start to melt and evaporate, cooling the engine core surfaces to temperatures below freezing. This enables the melted ice crystal water to refreeze, causing ice to accumulate inside the engine core. Ice in this location may cause temporary power loss or engine blade damage.

The Florida flight campaign is the first NASA mission and the third in a series of investigations by industry and government researchers to develop a better understanding of ice crystal icing conditions. “We are collecting radar signatures of the icing environment while the meteorological probes measure the actual ice water content and sizes of the ice crystals that the plane flies through,” says Steve Harrah, principal investigator. “The goal is to develop design requirements for a new radar process that can detect ice crystal icing and discern these conditions from non-hazardous clouds and low ice particle concentrations. With this new information, pilots should be able to avoid danger in the future.”

Data collected from NASA’s research will define requirements for future commercial radar products, provide the avionics industry with good scientific principles and measures for the detection of ice crystal icing conditions, and add additional data for engine icing standards updated earlier this year.

Photo credit: NASA/Peter Merlin — Understanding the capability of radar to detect high altitude icing is the goal of a NASA flight campaign about to begin in Fort Lauderdale, Florida. For the next three weeks, NASA researchers will be flying a DC-8 research plane, outfitted with state-of the-art radar and sophisticated meteorological probes to detect ice crystal icing conditions. Current weather radar can detect rain, hail or ice particles, but is limited in its ability to discern which types and sizes of ice crystals are in the atmosphere. When ice crystals hit warm aircraft engines, they start to melt and evaporate, cooling the engine core surfaces to temperatures below freezing. This enables the melted ice crystal water to refreeze, causing ice to accumulate inside the engine core. Ice in this location may cause temporary power loss or engine blade damage. The Florida flight campaign is the first NASA mission and the third in a series of investigations by industry and government researchers to develop a better understanding of ice crystal icing conditions. “We are collecting radar signatures of the icing environment while the meteorological probes measure the actual ice water content and sizes of the ice crystals that the plane flies through,” says Steve Harrah, principal investigator. “The goal is to develop design requirements for a new radar process that can detect ice crystal icing and discern these conditions from non-hazardous clouds and low ice particle concentrations. With this new information, pilots should be able to avoid danger in the future.” Data collected from NASA’s research will define requirements for future commercial radar products, provide the avionics industry with good scientific principles and measures for the detection of ice crystal icing conditions, and add additional data for engine icing standards updated earlier this year. Photo credit: NASA/Peter Merlin

The ultimate goal of this research is to better understand the conditions where ice crystals form, especially in high concentrations, and test out that idea that might enable pilots to better avoid otherwise invisible hazardous weather.

They are using NASA's Airborne Science Laboratory, tail number N817NA, a 50+ year old DC-8 that can put 15 tons of science instruments and scientists where the science is, at altitudes between 1,000 and 42,000 feet for up to 12 hours.

The plane began service for Italy's flagship airline Alitalia in 1969 where it flew for a decade, then for Braniif Airways before NASA acquired it in 1985. NASA modified it for use in atmospheric science like the current campaign as well as validating instruments before they are launched on satellites and calibrating them after.

instruments aboard NASA's flying research lab for studying icing conditions. (NASA Glen & LaRC)

The aircraft HIWC campaign equipped the with sensors that continuously measure temperature, pressure, humidity and even the size of those particles that turn into ice crystals.

NA817NA spent Sunday flying at lower altitudes through weather south of Cozumel, Mexico. We could see more of NASA off the North Carolina coast as this HIWC campaign continues through the end of the month.