A Day in the Life

by Frank Flocke (NCAR/ACD)

I thought it might be fun for folks outside of our community to know what we scientists do during a large experiment like this and will start describing what a typical day in the field looks like.

Jeff Stith looks at weather conditions for flight planning. Photo by Alison Rockwell (NCAR/EOL)

The more exciting (and often busier) days are the ones where an actual science flight takes place. Daily planning meetings including weather briefings, facility status updates, aircraft and instrument updates still take place early in the morning. After that the pilots are briefed on the plan and how it has changed from the (often ‘strawman’) flight plan that was filed the evening before. The forecast for where the storms will form are more precise the morning of the flight, which often necessitates tweaking of the plans from the day before.

Kip Eagan, aircraft mechanic, prepares the NSF/NCAR GV for a research flight. Photo by Alison Rockwell (NCAR/EOL)

In the meantime, the aircraft support crew turn research power on and start the main data computer in the aircraft and the scientists start what we call ‘pre-flight.’ This typically takes about 3 hours and everyone turns on their instruments to give them enough time to warm up and get everything to work at peak performance. Scientists also use the pre-flight time install temporary equipment such as gas cylinders, fill cryogens such as dry ice and liquid nitrogen needed on some instruments, which need to be freshly replenished before flight.

Since we are targeting convection typical take-off times are late-morning to mid-day. Flights can be as long as eight hours, which is the maximum endurance of NCAR’s GV aircraft. The NASA DC-8 can stay out longer than that, but probably will not for this experiment. Flights after dark are not planned.

Researchers prepare their on-board instruments pre-flight and several scientists will be on the research flight to monitor their instruments as well. Photo by Alison Rockwell (NCAR/EOL)

Some of the scientists fly on the aircraft with their instruments, because they need constant attention and care during flight. Some scientists stay on the ground and monitor (and sometimes operate) their instruments remotely via a satellite communication channel to the aircraft. There is also a constant chat room connection between scientists on the aircraft and the ground. This way, colleagues can ask their counterparts on the plane to check on unattended instruments or make some minor adjustments, if needed. This saves seats on the aircraft and makes room for more instruments.

The chat connection is also used for an even more important activity: to help guide the aircraft to the target storms and send modified flight coordinates up and discuss sampling maneuvers as the storms move and evolve while the aircraft is sampling them. More about this in a separate blog in a few days…

When the aircraft return after a science flight there is a brief period of up to one hour after landing where the scientists go back on board and go through the shutdown sequences of their instruments, make final calibrations, and copy the data collected during the flight off the on-board computers. Temporary equipment and supplies used up during the flight might also be removed before the planes are put away for the night.

To the extent possible, the collected sampling data needs to be processed  immediately (or at least within 24h) to produce what we call ‘field data’ (kind of a quick-look product with sufficient, but not ‘final data’ accuracy). This data helps the scientists to see what was learned and what may have been missed during the science flight and this information can then be applied to the strategy for sampling during the next flight.

Flight days are long days that can easily exceed 14 hours or so. We can fly two flights in a row, and occasionally we even had 3 consecutive flight days on some missions, but this cannot be done often as it is easy to understand how very taxing this can be.

What is a Convective Cloud?

Convective clouds develop through a sequence of events. First, incoming solar radiation heats the surface of the Earth, warming the air and causing water to evaporate into the air. That warm moist air then rises (due to basic principles of physics that warm air rises), creating upward air movement and bringing with it gases, dust particles, and chemicals from lower levels. As that moist air rises, it cools and condenses – creating many, tiny water droplets and ice crystals, forming cumulus clouds. The cloud particles then grow and eventually fall from the sky in different forms – snow, hail, rain, etc. – depending on the temperature.

When you see or hear a thunderstorm, it is really a mature convective cumulus cloud. So what you might call a boisterous thunderstorm is in fact a deep convective cloud!

Convection is a key aspect to this study because it provides the vertical transport of air and chemicals from the lower level to the upper level of the troposphere. The troposphere is the lowest of the five layers of the atmosphere, and is where all of the weather that we experience on a daily basis occurs.

DC3 is taking a closer look at the physical and chemical processes that occur to air parcels while in the deep convective clouds, as well as what happens to the transported chemicals as the cloud system dissipates.

What is DC3?

Scientists at the National Center for Atmospheric Research (NCAR) and other organizations are targeting thunderstorms in Alabama, Colorado, and Oklahoma this spring to discover what happens when clouds suck air up from Earth’s surface many miles into the atmosphere. This study is made possible by the National Science Foundation.

Thunderstorms, such as this one in eastern Colorado, can affect the atmosphere for many miles. (Photo by Bob Henson.)

The Deep Convective Clouds and Chemistry (DC3) experiment, which is scheduled to run from 15 May – 30 June 2012, will explore the influence of thunderstorms on air just beneath the stratosphere, a little-explored region that influences Earth’s climate and weather patterns. Scientists will use three research aircraft, mobile radars, lightning mapping arrays, and other tools to pull together a comprehensive picture.