9. Pacificon 2021 Picoballoon and Radiosonde Presentation

   David WB6TOU, Martin W6MRR, and myself gave a presentation at the Pacificon, which is the annual ARRL Pacific Division ham radio conference held in San Ramon in the fall. Our presentation was titled "Picoballooning in the Bay Area: High Altitude Balloons, Picoballoons, and Radiosondes." Download the slides here.

   We also used this opportunity to launch the new SF-HAB website, which is a collection of how-tos, resources, and blog posts about our ballooning activities.

   The first third of the presentation was David talking about balloon mechanics, including how to prestrech, fill, measure, and release SBS-13 and cheap Aliexpress picoballoons. David launched two SBS-13 picoballoons from the Central Valley in winter 2021, one of which went 2.5 times around the world ...

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10. Receiving Monterey Bay Radiosondes

    Taking a look at SondeHub one evening in early July 2021, I noticed some radiosondes down in the Monterey Bay, about 75 miles south of San Francisco. There seemed to be one per day in the afternoon on most days. The Naval Postgraduate School launches radiosondes very infrequently for their meteorology program, but these seemed to be launched from Watsonville or Salinas, not the main NPS campus in downtown Monterey.

    

    Then, on Monday July 12th, there was a flurry of radiosondes launched. I received a total of 5 of them from my station in Los Gatos. This station does not have good coverage in the direction of Monterey, and only starts receiving radiosondes when they rise up to 5,000 ...

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11. Two Radiosonde Recoveries in San Francisco

    The prevailing winds here in California blow from west to east, from the Pacific Ocean towards the Sierra Nevada mountains. Radiosondes launched from Oakland International Airport float in these winds, landing east of Oakland in the Central Valley, or south in the hills east of San Jose. I never recover the ones that land in the Central Valley, as driving 2 hours each direction during rush hour to recover a balloon is a bit too far for me. Only rarely do they land in populated areas in the Bay Area, and almost never on the Peninsula or in the city of San Francisco.

    This map (code below) shows the landing locations of all the radiosondes launched from Oakland since November ...

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12. Telemetry from an Oakland Radiosonde Floater

    In the beginning of March, something happened to the regular cadence of radiosonde launches from Oakland Airport. No balloon was launched on March 11th 2300 UTC, nor the next standard launch window on March 12th 1100 UTC (5am Pacific time). The SDM Ops Status Messages had a 10142 error for Oakland, which is ground equipment failure. I'm guessing that something broke or got jammed on their autolauncher, or maybe they ran out of hydrogen gas.

    By the afternoon of March 12th, the issue appeared to be resolved, and there was three launches in quick succession. The first and third balloons, S3231708 and S2321334, were normal, but the middle balloon slowly rose and leveled out around 35,000 meters (~115,000 ...

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13. An Atmospheric River of Radiosondes

    I recently installed a new antenna (see below), and checking SondeHub a few hours later I noticed a bunch of balloons west of Sacramento. Well, that's pretty interesting. There aren't any regular launches near Sacramento, so this must be something special. They seemed to be launched frequently, because when I stopped receiving one balloon I immediately start receiving the next.

    

    These balloons were far away! I guess this new antenna works a lot better than the old one. Trying to back out the launch location, it seemed like they were being launched from Beale AFB, which is directly east of Yuba City. Maybe a military project? The military does launch a lot of radiosondes, but those are usually in Arizona ...

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14. Two Months of Radiosonde Balloon Reception

    It's been two months since my first radiosonde recovery. In this post, I perform some analysis of the receiving stations at my apartment in San Francisco and my vacation home/parents place in Los Gatos. I also include the python code needed to generate your own plots.

    San Francisco Station

    Immediately after I got home from my first recovery, I converted my regular amateur radio station at my apartment to receive radiosondes. The external antenna is a Diamond X-50NA, which is a great amateur radio 5/8 wave 2m/70cm dual-band antenna. Coax up to the roof is about 80 ft of LMR-400, which is calculated at around 1.5 dB loss at 145 MHz and 2.5 dB at ...

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15. Two Radiosonde Payload Recoveries, and RS-41SGP Teardown

    I've been watching SondeHub for the past two months to, every day since my first recovery, but the winds have not been cooperating! Lots of radiosondes went into the hills east of San Jose, out into the ocean, into the Santa Cruz mountains, all the way down to Gilroy, or splashed down in the bay, but none have landed in populated areas within an hours drive of my home in San Francisco. I realized how lucky I was that the first radiosonde I successfully tracked actually landed in a populated place.

    In a typical city, approximately 35-50% of the land is dedicated to cars: residential roads, arterials, freeways, and parking lots. So when a balloon lands in populated areas of ...

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16. Oakland Radiosonde Investigation, Launch, and Recovery

    I've recently stumbled upon the radiosonde_auto_rx project. I've always been interested in tracking radiosondes, and even watched a radiosonde launch in Inuvik, NWT a few years back. Worldwide, there are over 800 launches every twelve hours of every day, and this data feeds into weather forecast models.

    The radiosonde_auto_rx project is built around decoding many different types of radiosondes with a software-defined receiver. The preferred receiver is a RTL-SDR Blog v3, and I already had an extra one of those (because they are so inexpensive!).

    Most radiosondes worldwide use 400-406 MHz as their downlink, but the United States also uses some frequencies around 1680 MHz. Reading the documentation on which frequencies are in use, it appeared ...

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17. Radiosonde Launch from Inuvik, NWT

    In September 2016 I visited the Environment Canada Weather Station in Inuvik, NWT. I arrived just as they were preparing for the 2300z weather balloon launch, and they let me hang around and take some pictures.

    Every twelve hours around the globe, approximatley 800 radiosondes are launched. These weather balloons record temperature, pressure, humidity, and location from the surface all the way up to 100k feet, or higher. These measurement are fed into weather models for long-term weather forecasting. These launches happen worldwide at 1100 and 2300 UTC, which gives the balloon enough time to be up at altitude around noon and midnight UTC.

    This is the Vaisala RS92-SGPD radiosonde, which measures location, pressure, temperature, and humidity as the balloon ...

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