Drones in Limón!

Our new sounding launch crew arrived a few days ago and we now have a drone with an IMET sensor for measuring temperature, humidity and pressure that can fly to 300 m.  We tested it yesterday from the beach in Cahuita.  We are excited to see how the surface layer (lower 100 m) evolves throughout the day and over different surfaces such as water, beach and grass.

Thanks Beata Latos from the Polish Academy of Sciences, Institute of Geophysics for joining the OTREC team and bringing her drone!

Playa Negra, Cahuita, Costa Rica

Once, twice, thrice: Flying past the same convective system three times

I'm writing this post from the Atlanta airport, where I am waiting for my connecting flight home from Costa Rica. I had a great week participating in OTREC - it was so great that I delayed my departure for a day so that I had a chance to go on a second research flight - this time, on the NCAR/NSF G-V, on Thursday August 22, 2019.

Me outside the plane in my stylish high visibility safety vest.

The G-V was pretty different than the NOAA P-3 I had flown on earlier this week (see my previous blog post about that flight)! It flew more than twice as high (41,000-45,000 ft. vs. 10,000-20,000 ft), was a smoother ride (though a smaller plane), and was much more luxurious. I particularly liked the seats that swiveled, so you could get a bird’s eye view out of the expansive windows, or could turn around to face a workstation where you could monitor the latest data from the flight.

The swivel chairs! Great for observing clouds through the window. 

After about an hour delay due to fog at the airport, we took off and flew the “B1” pattern, in which we flew back and forth in a box near the Colombia coast and then back and forth in a box in the Caribbean near the Panama and Costa Rica coasts. The first part of our flight, in the Colombian box, the skies were very clear, with just some scattered shallow cumulus. The radar returns looked like static – there were no clouds to see! But this meant that we had a great view of ships, the Andes Mountains in Colombia, and the Panama Canal.

Mostly clear skies. Near the center of the image is a ship (you can see its wake in the water).

The Colombian coastline, and the Andes Mountain Range in the distance. 

The Panama Canal

But then as we crossed over to the Caribbean, convection picked up. A deep convective system had formed, with cloud tops just about at our flight level. As we maneuvered around the convection and continued on our flight pattern, we ended up flying past that same convective system three times, allowing us to view it from three different angles. Viewing it from the side was almost like getting an inside look at the structure of the convective system.

Our first pass, to the east of the convective system, with near textbook structure.  

Radar returns as we flew over the edge of the anvil cloud - the pinks indicate cloud particles!

Our second pass, from the north of the convective system. Notice how there are multiple thunderstorms embedded within  the system.

Photo of our flight path (red dot in the upper right shows our current location) with infrared satellite imagery in the background. The bright right blob in the top right of the image (the smaller of the two) is the convective system we flew past three times.  

Headed towards our third pass by the convective system, this time  to its south and west. 

On our last pass, we had a perfect view of the “overshooting tops”.  Most of the cloudy air stops rising when it is no longer more buoyant than the surrounding atmosphere, which for deep convection occurs when the rising air runs into the more stable air in the tropical tropopause layer. The cloudy air then diverges outward, forming a spreading anvil cloud. But some of the rising air has enough momentum to bubble up a bit further; these are known as “overshooting tops” and are the bubbles of cloud above the otherwise flat top of the cloud.

About to enter the cloud shield. We were flying just at the level of the cloud tops. Notice the extra bit of cloud bubbling up above the otherwise flat anvil cloud top.

Overshooting convection. 

All in all, it was a great flight and a great end to my time with OTREC in Costa Rica!

A gorgeous sunset to end my time with OTREC. 

OTREC joins the hunt for a hurricane!

On Sunday August 18, 2019, I had the exciting opportunity to participate in my first ever research flight. 

Me, with the NOAA P-3 in the background after the flight

Over the weekend, OTREC collaborated with NOAA’s Hurricane Research Division (HRD) to investigate a tropical disturbance that has been identified as “Invest 95E” by the National Hurricane Center – which means that this disturbance has the potential to develop into a hurricane and is something worth investigating.  I got to fly on the NOAA P-3 airplane (NOAA-42, affectionately named “Kermit”).  This airplane is one of the famous “Hurricane Hunters”, which regularly fly into hurricanes to take in situ observations that are vital for the forecasters at the National Hurricane Center, as well as flying research missions. The picture below shows all the hurricanes that the plane has flown through – more than 100! It truly is an impressive aircraft that can withstand flying through almost any type of condition and is outfitted with a lot of specialized equipment for monitoring hurricanes.

A sticker for each hurricane that this airplane has flown through. The most recent one was Hurricane Michael (2018), which devastated the Florida Panhandle near where I live in Tallahassee, FL.

Since HRD was interested in researching the “genesis”, or formation, of a hurricane, and OTREC is about organization of convection, this was a perfect opportunity for the two teams to work together. Unlike the NCAR/NSF Gulfstream-V (G-V) aircraft that is being used in OTREC, the P-3 flies much slower (it is powered by four huge propellers) and much lower to the ground. On this flight, the P-3 flew between 10,000 and 20,000 ft and “hunted” the center and measured precipitation around the disturbance, while the G-V flew much higher, at more than 40,000 ft, to sample the environment around the disturbance. This combination provides a much more complete picture of the environment around the disturbance than a single plane could provide. Since this system might turn into a hurricane later this week, it was a very exciting opportunity to observe the convection as it organized and as a circulation formed.

Me looking official with my headset aboard the NOAA P-3. 

I arrived at NOAA’s pre-flight briefing at the early hour of 4:45 AM, and we took off at 7 AM. Our first objective was to locate the center of the circulation. Luckily, there was a recent overpass of the disturbance by “ASCAT”, which is a satellite that measures surface winds. The satellite observations gave us a good initial guess for where the center was. Throughout the flight, we released dropsondes, which measure the characteristics of the atmosphere (temperature, humidity, pressure, and winds) as they fall from the plane, and “Airborne EXpendable BathyThermographs (AXBTs)”, which measure the characteristics of the upper ocean after they fall into the ocean.  Since a warm upper ocean is important for hurricane formation, we wanted to measure those characteristics as well -- we measured sea surface temperatures of 28 degrees C (about 82 F). 

The P-3 also has many other instruments, including a tail Doppler radar (TDR). This is different from the HIAPER cloud radar on the G-V; instead of looking down to measure clouds, the P-3’s tail Doppler radar scans vertically from the back of the plane at two different angles to get an inside look at the structure of the convection. The P-3 also has a “lower fuselage radar”, mounted on the belly of the plane, that scans horizontally. It was really cool to watch the real time measurements from these radars and connect what I could see from the radar with what the clouds looked like outside my window!

Approaching a thunderstorm (left of image). Photo taken from the window of the NOAA P-3 at 9:25 AM local time (15:25 UTC) on August 18, 2019. Position 11.5 N, 94.7 W

Photo of the onboard display showing the flight track (green line), flight level winds (barbs) and image from the lower fuselage radar. We were flying around the thunderstorm indicated by the green, yellow, and orange colors in the radar image.

Getting closer to the thunderstorm, with clouds around us in all directions. Photo taken from the window of the NOAA P-3 at 9:27 AM local time (15:27 UTC) on August 18, 2019. Position 11.4 N, 94.6 W. 

Photo of the onboard display showing the returns from the tail Doppler radar. The left and right images are scans at different angles. The colored radar returns on the right side of each image show the precipitation in the thunderstorm we were flying past (ignore the values at the bottom of the images, that is the ground). The radar is located on the tail of the plane which is in the center of the image. 

The tropical disturbance was not particularly well organized while we were flying around in it. There was a weak circulation but most of the convection was displaced to the west of the center. Much of the time I saw plenty of convective clouds outside my window,

A healthy distribution of convective clouds. Photo taken from the window of the NOAA P-3 at 9:51 AM local time (15:51 UTC) on August 18, 2019. Position 10.2 N, 93.1 W.

but there were other times where it was much clearer and I could see the ocean surface!

Cirrus above, scattered trade cumulus clouds below, but lots of clear sky through which to view the ocean surface. Photo taken from the window of the NOAA P-3 at 11:50 AM local time (17:50 UTC) on August 19, 2019. Position 11.5 N, 91.8 W. 

Comparing the winds at the flight-level of the P-3 with the winds at the flight-level of the G-V (higher up) shows that the winds were blowing in different directions at the different heights. Take a look at the figure below, showing the flight paths of the P-3 at a low altitude (in yellow) and the G-V at a high altitude (in red). If you look on the left side of the graph, you can see that the winds measured by the P-3 are coming from the southwest, while the winds measured by the G-V are coming from the northeast. This indicates vertical wind shear, which makes it harder for a hurricane to form.

Flight tracks of the NCAR/NSF G-V (in red) and NOAA P-3 (in yellow) on August 18, 2019. The wind barbs indicate the flight level winds (red for the G-V, black for the P-3) The P-3 flew between 10,000 and 20,000 feet, while the G-V flew above 40,000 feet. Note that the middle diagonal section of the G-V (red) track is not the actual track there, there is missing data.

It will be interesting to see what happens in the next few days – today, the convection seems to be better organized! The National Hurricane Center predicts that it has a 80% chance of developing in the next 2 days. The data that the P-3 and G-V collected will be valuable in understanding why the system does or does not form a hurricane.

All in all, despite the very early start (I am not a morning person!) it was an incredibly exciting and fascinating day! I am very grateful to NOAA/HRD for letting me tag along on their flight, and to the OTREC team for letting me participate in the field campaign. Below are my two favorite photos from the flight. 

Mostly clear skies just off the coast of Costa Rica, shortly after takeoff. Some scattered shallow cumulus clouds, cirrus overhead, and a developing thunderstorm (left of image). Photo taken from the window of the NOAA P-3 at 7:17 AM local (13:17 UTC) on August 18, 2019. Position 10.9 N, 86.2 W.

A thunderstorm with overshooting convection above the spreading anvil, with thick clouds at flight level (10,000 ft) and cirrus overhead. Photo taken from the window of the NOAA P-3 at 8:12 AM local (14:12 UTC) on August 18, 2019. Position 12.0 N, 90.4 W.

Aloft, Set, Go!

Aloft, Set, Go!

OTREC mission 1 (RF01)

The NCAR G-V cruising the East Pacific Ocean 43,000 ft a.m.s.l.

         OTREC flight missions have officially begun. The rumors are true, and the data we gathered confirm it; RF01 (fancy acronym for mission 1) was a success! Even a few hours before taking off, GOES satellite imagery already anticipated a thrilling mission, with cloud tops reaching well-above 40,000 ft above mean sea-level (a.m.s.l.) near the active regions of the ITCZ (Inter-Tropical Convergence Zone), right where our experimental cross-sections (sequence B2) were traced.

       Personally, I admit I am a heavy-sleeper. In most cases, not even an earthquake is able to wake me up if it happens in the middle of the night. Very few things are able to make me "rise-and-shine" at 3 am.  Among very few, I'll mention a soccer World Cup final match, following the track of Hurricane Katrina (2005), and my first flight as part of the OTREC crew this past August 8, 2019. The NCAR G-V took off around 6:30 am local time (12:30 UTC).  You know what they say: the early bird always gets the best view above the clouds. No? Well, for this "bird", the image below proves my point:

A view of Costa Rica's East Pacific Coast as the G-V climbed in altitude after taking off from the Liberia International Airport

How high did we go? The GV reached 43,000 ft, but the overall level of excitement of our team had no upper limit. Just look at the level of excitement of three of the members of the New Mexico Tech science team in the picture below, before we took off!  

From left to right: Dr. Stipo Sentic, Dr. Ana Juracic, and Dr. Zeljka Fuchs

And we took off, quickly climbing to the desired altitude. You've gotten this far to the end of the page. You want to see more images. Here they are:

 After a short episode of mild turbulence and zero visibility, we finally were above the clouds!

 The GV around the time the first dropsonde was launched (13:27 UTC)

 Sun glint made it significantly challenging to capture detailed cloud features in most cases

 Bubbling convection

 Quite a breathtaking view. It looks like we're in space!

 Looking down, some of these clouds were bubbling with convection.

 The south part of box pattern B2 had mostly low clouds. Turbulence, however, was present.

 Cloud tops well-above 43,000 ft

 Small developing convective system.

 A similar storm system, but already developed.

 We were still at 43,000 ft when this photo was taken. Really high cloud tops, possibly on a mature stage of convective activity.

 Cloud tops easily reached our cruising altitude at many stages of the flight. Result: zero visibility.

 Yes, the above photo shows a ship! However, if you take a closer look, you can see white caps at the surface of the ocean. Trust me, photographing white caps at 43,000 ft is not easy!

Going back home after a successful flight!

The photographer in action. Donations are always welcome (a joke!).

Photos and blog post by: José Martínez-Claros