Month: January 2020

By Ellen Gray /NASA’S WALLOPS FLIGHT FACILITY, VIRGINIA/

After a cloudy and rainy morning, by 1:50 pm the sun had come out and the skies were clear for take-off at NASA’s Wallops Flight Facility in Virginia. The P-3 Orion research aircraft outfitted with eleven instruments to measure conditions inside snow clouds was heading north to a storm system over New York and Vermont for the second science flight of the Investigation of Microphysics and Precipitation for Atlantic Coast Threatening Snowstorms, or IMPACTS field campaign.

NASA’s high-flying ER-2 was already in the air. Based out of Hunter Army Air Field in Savannah, Georgia, it had an extra hour to fly so that the two planes—the ER-2 at 60,000 feet and the P-3 starting at 18,000 feet—would arrive at the same time and fly along the same path to make simultaneous measurements.

Since we were flying into bad weather, I was worried about a bumpy ride—and we got it. Our flight path led us out over the ocean first to approach Long Island from the south. At thirty minutes after take-off Claire Robinson from NASA’s Langley Research Center prepped the first of two dropsondes to drop from a tube at the back of the plane into the storm over the ocean. A dropsonde is a small instrument package in what looks like a paper-towel roll. It has a parachute and a radio transmitter that sends data on temperature, humidity and wind speed as it falls, giving a vertical profile of the atmosphere from the plane to the ground.

While Claire was watching her monitor for the plane to be over the right spot, we hit turbulence that made it feel like we were going over bumps on a roller-coaster. It got bad enough we needed to return to our seats in the ten minutes between the first and second dropsondes. The turbulence evened out fairly quickly though, especially once we were back over land where the upward movement of air was less severe. Bumps returned periodically throughout the flight, but it ended up being smoother overall than expected.

After the dropsondes were away we continued north over Connecticut and western Massachusetts where we turned left to start the first of three bowtie flight patterns, two over southeastern New York and one over Vermont. Bowties are these large triangular patterns that approach the storm from many different angles.

“The atmosphere is not a layer cake,” said atmospheric scientist Sandra Yuter from North Carolina State University, when I spoke with her before the flight. She’s in charge of plotting the flight paths to maximize the science measurements based on the forecasts two-days ahead of time, which she then sends to the pilots and aircraft coordinators who will iterate on it to make the final flight plan.

The atmosphere is instead more like a cake with a marbled interior—swirls and wiggly lines sliced one way, large patches and different swirls when sliced another. “We’re not expecting the same cross-sections in different parts of the storm,” Sandra said. “Bowties give you those multiple angles.”

At the top of the first bowtie over New York, we started out at 18,000 feet, high above the freezing level (0°C). (About half-way through we descended to 16,000 feet at the request of Air Traffic Control.) Mike Poellot of the University of North Dakota and today’s Flight Scientist, sitting in the cockpit to coordinate between the science team and the pilots, asked over the headset, “Cloud probes what are you seeing?”

In the main cabin, Greg Sova, a grad student at the University of North Dakota and Starboard Wing Instrument Operator, answered the first of many such check-ins. On his monitor, streams of tiny pictures from his instrument scrolled by. The tiny pictures were of cloud, ice, and snow particles, most less than a millimeter big, that had just been imaged at ~300 mph.

On that first pass of the bowtie, he was seeing from the cloud probes, “Columns and dendrites but a lot of shattering.”

Columns and dendrites are types of snow crystals and were also common in later check-ins as we continued on. So were aggregates, a bunch of snowflakes stuck together in a mass, thin needles, and at lower altitude, spheres that were probably water droplets as we did the second bowtie at lower altitude where the air temperature was warmer. Sometimes it was mix of all three. At times it would switch back and forth as we passed through air with different characteristics—remember that marble cake analogy?

At one point on the northern bowtie over Vermont, Greg reported that we’d passed from seeing more liquid droplet spheres to being back in crystals of snowflake plates, dendrites, with a column or two. Then he added, “And as soon as I said that we’re back into small spheres.”

While the P-3 flew through the clouds, the ER-2 paced us from high above with its suite of remote sensing instruments. The two planes were in sync, for the most part passing over the same legs of the bowties less than 5 minutes apart. Each bowtie took about an hour, and a little after 6:00 pm we dropped to 12,000 feet for the flight home, while the storm system continued east.

“I think was good mission,” Mike said when we got back. “The instruments seem to work well, aircraft coordination seemed to go well, and we definitely got into some weather. A lot of precipitation down low that was occurring, and I think it was more along the lines of what we’re looking to do in this project.”

In the days that follow, the instrument teams will begin processing the data they collected, while the forecasters look out for the next storm on the horizon.

By Ellen Gray /NASA’S WALLOPS FLIGHT FACILITY, VIRGINIA/

The IMPACTS team is what makes the field campaign happen. Over 200 people are contributing to the project from aircraft crews and managers, to support and logistics staff, to the scientists running the instruments and asking the big questions. They include veteran pilots and mission managers, university and NASA researchers who’ve done field campaigns before, and graduate students on their first campaign.

Field campaigns provide valuable training and perspective in researchers’ early careers. We caught up with three students who are on the rotating roster for the IMPACTS forecasting team. Their responses have been edited for clarity.

My name is Sebastian Harkema. I’m a first year PhD candidate at the University of Alabama in Huntsville. This is my first field campaign in general so I’m super excited about this. I’m actually studying snowfall so I’m going to be using the IMPACTS data as part of my PhD for the next three years. Specifically, I’m looking at thundersnow, so I’m hoping to use some of the instrumentation to look at that and to understand how lightning and snowfall can be used in nowcasting—predicting heavy snowfall, where the models really have trouble in that near-term period where forecasters really need that information.

Being a forecaster is different. Going from research to being an actual forecaster is kind of challenging. Because when you’re a researcher you’re staring at a TV screen or a monitor all day. For forecasting you’re doing that but it’s in a completely different environment. As for my schedule, showing up at 5:45 am in the morning, having to put a presentation together by 8:45 am and presenting at 9 am, that’s a challenge unto itself, let alone trying to understand what is going on in the atmosphere. So I definitely give a lot of credit to all the forecasters throughout the United States, and the world—Props to you guys! It’s a lot of hard work and I definitely appreciate it a lot more than I did in the past.

I’m Ben Kiel and I’m a Masters student at Stonybrook University in New York. With IMPACTS, I’m helping out with storm forecasts, if there are storms to forecast for. It’s been quite a bit of challenge I would have to say. We were hoping for more storms than what we’ve had so far. It’s kind of funny, most people want good weather, we want bad weather.

This one that we’re looking going after Saturday is one where, if the pattern was more active it’s one we wouldn’t prefer to chase because it’s a messy system. There’s a lot of dry air getting into it. It’s a very warm system. There’s going to be a lot of rain. At least there will be snow aloft. There’s certainly things we can learn from snow aloft, because that’s how this rain is forming as it’s staring out as snow and then falling down and then turning into rain. So we’ll take it.

My main focus will not actually be directly related to IMPACTS. I’m actually working with IMPACTS mission scientist Brian Colle, I’ll be doing a project related to machine learning. It’s a different sort of problem, trying to figure out or explain why our weather models are so variable. We’re trying to find better explanations so that we can pinpoint and improve them. So that’s not necessarily directly related to the IMPACTS project but the data that comes from here will probably certainly get ingested into my work as time goes on. All of these projects end up connected in some way that one acts as a validation for the other. We’ll see what happens there. I’m looking forward to it.

My name is Phillip Yeh and I grew up in Parsippany, New Jersey, and I’m currently at Stonybrook University as a PhD student. My focus for my PhD project will likely be using the data that we gather from the IMPACTS project to understand these snow bands associated with these snow storms here in the North East.

I am helping with forecasting for the IMPACTS project. So forecasting involves many things. A lot of it involves looking at the weather models and trying to figure out where the storm is going to be, especially in regard to the timing of the storm, in regard to where the rain/snow line is going to set up, and in regard to where we should be flying the plane. This is my first field campaign. I think the biggest thing I’m looking forward to is the opportunity to fly on the P-3 and the second biggest thing is being able to launch weather balloons, which I’ll do when I leave Wallops and go back to Stonybrook where we’re doing that.

I’ve always loved snow ever since I was young, and often times watched as a snow storm runs too far to the south or to the north and just misses us, or occasionally when the snow hits us perfectly, and also seeing how the forecast models may struggle with getting the location of a storm right.

 

By Ellen Gray / NASA’S WALLOPS FLIGHT FACILITY, VIRGINIA/

Nothing to be done.

When your field campaign depends on chasing winter storms you have to wait for the weather to arrive in its own time. For the science team of the Investigation of Microphysics Precipitation for Atlantic Coast-Threatening Snowstorms, or IMPACTS, campaign that means carefully watching the weather forecasts and then making the most of it when it arrives.

IMPACTS is a field campaign all about snow. This week, we’re with the team at NASA’s Wallops Flight Facility in Virginia, where the P-3 research plane is outfitted with instruments ready to fly into winter storms over the next six weeks in order to learn more about how snowstorms behave. A second plane, NASA’s ER-2 based out of Hunter Army Air Field in Savannah, Georgia, for the campaign, will fly high above the clouds with satellite-simulating instruments aboard to measure the snow clouds from above.

One of the big questions is why do snow clouds organize themselves into bands of heavy and light snow fall? The ultimate goal is to improve forecasts of where and how much snow will fall, especially over the densely populated U.S. East Coast where storms are nicknamed “Snowpocalypse” and “Snowmageddon” because of the disruption they can cause.

At the daily 9:00 am weather briefing on Wednesday, the team looked at several different weather models – the same ones used by the National Weather Service, the Weather Channel and other forecasters – to find the next storm they want to target.

“High pressure is finally moving out! Whooo!” said Sebastian Harkema, the lead forecaster, to open the briefing.

If you’re familiar with your local weather news, high pressure usually accompanies sunny skies and clear conditions – the opposite of what the science team is looking for. Instead they’re interested in flying into the bad weather. And there’s a developing storm system that will move across Pennsylvania and up toward Massachusetts, New York and Vermont on Saturday and Sunday.

The big question of the day is, do they schedule one flight through it, or two on back-to-back days?

The advantage of flying twice would be more data collected. However, the human factor of flying two days in a row means that between flights is a 12-hour mandatory crew rest, so the timing of the second flight may not be the best time to sample the second part of the storm – and there’s a chance that the snowing part of the storm may have passed by the time they get out there.

The advantage of doing one flight is that the science team can pick the time and place they think will have the best snow.

The other logistical consideration is the mobile team of researchers from the University of Illinois, Champaign-Urbana, who are driving their vehicles on highways and back roads to be below the storm while the P-3 and ER-2 aircraft fly above it. From the ground they are sending up balloon sondes – instruments to measure the temperature and humidity from the ground to the clouds. They’d likely only be able to make one of two locations, since they’d have to drive through the very snow or cold rain the science team was measuring to get to the second spot three states away.

In the end, the team waits for the next run of the models, which come out every 6 hours, before making a decision. At the times and locations that look the most promising – Central Pennsylvania, the tri-corner where Massachusetts, New York and Vermont meet – they look at how wet or dry the air is and the likely temperatures, trying to discern the best spots to sample snow.

“It’s a messy storm,” said IMPACTS Principal Investigator Lynn McMurdie of the University of Washington. The temperatures are on the warm side, and there’s indications of tendrils of dry air throughout, which can stop precipitation. It’s unclear in some spots whether they’d find rain or wet snow.

The verdict: one flight on Saturday to pick the best time and place. Three days out, they’re looking at Vermont, but they won’t make any final decisions until they have a better forecast to help narrow the timing and location down in the next day or so. Still, the flight planners are already working up a preliminary plan so they’ll be ready to refine it when conditions become more clear tomorrow.