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windbornesystems.com/blog/planetary-boundary-layer-pbl-showcase

Planetary Boundary Layer (PBL) Showcase

Atmospheric sounding diagram with red temperature and green dew-point profiles.
By
John Little, R&D Systems Engineer
Published
Reading time
3 minutes

The (PBL) is the critical region extending from ground level to 1-2 kilometers above Earth's surface - understanding it is essential for weather forecasting, particularly since it's where human activity occurs. In this region, atmospheric conditions such as moisture, temperature, and winds can all change quickly through very localized processes of heat transfer, moisture exchange, and friction. Sampling the PBL is vital not only in populated areas but also in remote regions, as warm, moist air evaporating from oceans can travel thousands of miles before forming clouds and precipitation.

At WindBorne, we like to tinker and experiment with our Global Sounding Balloons () to push the limits of what’s possible. Whether it's new hardware or software design, we thoroughly test our changes to ensure they're scalable before rolling them out to our global balloon constellation. This rigorous testing approach helps us deploy updates in a safe and robust way. Our newest change is one we’re quite excited about: tuning our controller settings to fly our balloons further into the PBL, gathering previously inaccessible data at low altitudes in remote locations. We’re now consistently flying close to the earth and are able to collect data that can be especially valuable for more accurate forecasts.

Managing a balloon in the PBL's turbulent winds and sudden condensation layers generally presents as a significant challenge, but our recent modifications allow us to take closer in these valuable altitudes. These flights can now routinely descend to low elevations - our record turnaround being 14 meters above the ocean! In our onboard flight software, a new PBL Mode will be more daring on descent, but quickly turn around if either high humidity or turbulence hazards are detected. Additionally, our ground control software now uses outputs from WeatherMesh to intelligently decide when the weather is safe enough to perform these deep soundings.

These changes continue to improve our cost and coverage compared to traditional weather data collection. At approximately $100 per sounding, our soundings are about 5x cheaper than and 50x cheaper than aircraft-deployed dropsondes when accounting for full operational costs. In their multiple weeks of flight, our GSBs fly to previously inaccessible locations while gathering dozens of complete vertical atmospheric profiles from the PBL to the mid-.

We’ve been working hard to improve our GSB’s capabilities and are eager to surface more data about our planet.

Here’s a sample of some of our deep atmospheric soundings just from the last two weeks, from all over the globe:

Twelve deep-sounding flights. AGL means above ground level; figure numbers refer to the flight plots below.
FLIGHTFIGURESTARTING LOCATIONSOUNDING LOCATIONSOUNDING DEPTH AGL
W-2799Fig. 1AlaskaTurkmenistan174 m
W-2800Fig. 2AlaskaWestern Pacific499 m
W-2808 AFig. 3New YorkEastern China446 m
W-2808 BFig. 4New YorkPacific44 m
W-2859Fig. 5Palo AltoPakistan112 m
W-2861Fig. 6AlaskaRussia119 m
W-2865Fig. 7South KoreaEastern Pacific590 m
W-2878Fig. 8Cape VerdeMauritania294 m
W-2884Fig. 9Cape VerdeCape Verde / Atlantic249 m
W-2886Fig. 10Cape VerdeChad330 m
W-2890Fig. 11AlaskaNova Scotia14 m
W-2907Fig. 12New YorkCaribbean196 m
Fig. 1: Launched from Alaska. Sounding depth AGL of 174m over Turkmenistan.
Fig. 1: Launched from Alaska. Sounding depth AGL of 174m over Turkmenistan.
Fig. 2: Launched from Alaska. Sounding depth AGL of 499m over the Western Pacific.
Fig. 2: Launched from Alaska. Sounding depth AGL of 499m over the Western Pacific.
Fig. 3: Launched from New York. Sounding depth AGL of 446m over Eastern China.
Fig. 3: Launched from New York. Sounding depth AGL of 446m over Eastern China.
Fig. 4: Launched from New York. Sounding depth AGL of 44m over the Pacific.
Fig. 4: Launched from New York. Sounding depth AGL of 44m over the Pacific.
Fig. 5: Launched from Palo Alto. Sounding depth AGL of 112m over Pakistan.
Fig. 5: Launched from Palo Alto. Sounding depth AGL of 112m over Pakistan.
Fig. 6: Launched from Alaska. Sounding depth AGL of 119m over Russia.
Fig. 6: Launched from Alaska. Sounding depth AGL of 119m over Russia.
Fig. 7: Launched from South Korea. Sounding depth AGL of 590m over Eastern Pacific.
Fig. 7: Launched from South Korea. Sounding depth AGL of 590m over Eastern Pacific.
Fig. 8: Launched from Cape Verde. Sounding depth AGL of 294m over Mauritania.
Fig. 8: Launched from Cape Verde. Sounding depth AGL of 294m over Mauritania.
Fig. 9: Launched from Cape Verde. Sounding depth AGL of 249m over Cape Verde/Atlantic.
Fig. 9: Launched from Cape Verde. Sounding depth AGL of 249m over Cape Verde/Atlantic.
Fig. 10: Launched from Cape Verde. Sounding depth AGL of 330m over Chad.
Fig. 10: Launched from Cape Verde. Sounding depth AGL of 330m over Chad.
Fig. 11: Launched from Alaska. Sounding depth AGL of 14m over Nova Scotia.
Fig. 11: Launched from Alaska. Sounding depth AGL of 14m over Nova Scotia.
Fig. 12: Launched from New York. Sounding depth AGL of 196m over the Caribbean.
Fig. 12: Launched from New York. Sounding depth AGL of 196m over the Caribbean.