Urban Aerosols: Who CARES?: Best laid plansJuly 19th, 2010 by Mike Obland, NASA LaRC
It is 6:30 AM and you are waiting for the morning weather briefing to start, in which the meteorological conditions for the next few days are laid out and the science teams go over their flight plans for the day. You were up late last night putting the final touches on the flight plan for today’s science flight, making sure that you hit as many science objectives as you could. “I included several coordinated flight legs with the G-1 aircraft,” you think, “and I verified that the Terra satellite path takes it nicely across the pollution plumes near San Francisco and San Jose, giving us good data to verify the satellite results.”
But looking at the weather forecasts that were updated just before you woke up this morning has you worried. Will that predicted layer of ocean stratus blanketing San Francisco burn off in time to allow your instruments an unobstructed view of the aerosols below? What about those high cirrus clouds predicted to be hugging the mountains right above your G-1 coordinated leg? Will they limit the usefulness of your data?
Looking out the window, conditions look good here at the airport, but who knows what they will be like in 3 hours when your aircraft is getting ready to lift off. You could cancel the flight based on current predictions, but you run the risk of missing the science objectives that you are here for. Or, you could go forward with the flight and your science objectives may never materialize, leaving you with less useful data and fewer funds to use on potentially better flights.
As you ponder all of this, you find out that shifting wind patterns favor a different flight pattern for the G-1 and its instruments. If you are going to coordinate with them, you will need to quickly change your flight plan to something very different, but you need to minimize the number of changes you make. After all, your plan has to be checked by the pilots and submitted to Air Traffic Control at least 2 hours before a flight. The clock is ticking.
This is a day in the life of a flight planner. Planning a flight involves balancing all of these factors, changing and unpredictable weather and aerosol conditions, sometimes fickle aircraft and instrument systems, crew rest time, and competing science interests, to obtain the best set of measurements possible for future study. Flight planners have to have detailed knowledge of the discipline of atmospheric science, so that they can weigh the science objectives against each other and determine what produces the most results for the taxpayer dollars, which is why the flight planners here (Rahul Zaveri and Beat Schmid for the DOE G-1, Chris Hostetler and Rich Ferrare for the NASA B-200) have so many years of research experience behind them.
Even with years of experience, though, flight planning is more of an art than a science, and you have to learn to get a “gut feeling” sometimes about the right path to choose. Fortunately, we have many successful days and on the rare days that we do not achieve science objectives for that day, the data are usually useful for some other purpose (such as cloud studies, for example).
Usually once or twice during a month-long campaign, in the midst of unpredictable weather patterns, erratic pollution conditions, and instrument operation and aircraft timing issues, we will achieve a “golden day” where all of the conditions and aircraft timing are nearly perfect. Those are the days that are then studied for years to come. You never know when these days will come, but you know they will, so whether you fly on any given day or have to cancel for any myriad of reasons, you have to move forward after the decision is made. Speaking of which, it is time to start putting together tomorrow’s flight plan!