Observing atmospheric rivers using multi-GNSS airborne radio occultation: system description and data evaluation
<p>Atmospheric rivers (ARs) are narrow filaments of high moisture flux responsible for most of the horizontal transport of water vapor from the tropics to mid-latitudes. Improving forecasts of ARs through numerical weather prediction (NWP) is important for increasing the resilience of the west...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/18/3361/2025/amt-18-3361-2025.pdf |
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| Summary: | <p>Atmospheric rivers (ARs) are narrow filaments of high moisture flux responsible for most of the horizontal transport of water vapor from the tropics to mid-latitudes. Improving forecasts of ARs through numerical weather prediction (NWP) is important for increasing the resilience of the western United States (US) to flooding and droughts. These NWP forecasts rely on the improved understanding of AR physics and dynamics from satellite, radar, aircraft, and in situ observations, and now airborne radio occultation (ARO) can contribute to those goals. The ARO technique is based on precise measurements of Global Navigation Satellite Systems (GNSS) signal delays collected from a receiver on board an aircraft from setting or rising GNSS satellites. ARO inherits the advantages of high vertical resolution and all-weather capability of spaceborne RO observations and has the additional advantage of continuous and dense sampling of the targeted storm area. This work presents a comprehensive ARO dataset recovered from 4 years of AR Reconnaissance (AR Recon) missions over the eastern Pacific. The final dataset is comprised of <span class="inline-formula">∼</span> 1700 ARO profiles from 39 flights over approximately 260 flight hours from multiple GNSS constellations. Profiles extend from aircraft cruising altitude (13–14 <span class="inline-formula">km</span>) down into the lower troposphere, with more than 50 % of the profiles extending below 4 <span class="inline-formula">km</span>, below which the receiver loses or cannot initiate signal tracking. The horizontal drift of the tangent points that comprise a given ARO profile greatly extends the area sampled from just underneath the aircraft to both sides of the flight track (up to <span class="inline-formula">∼</span> 400 <span class="inline-formula">km</span>). The estimated refractivity accuracy with respect to dropsondes is <span class="inline-formula">∼</span> 1.2 % in the upper troposphere, where the sample points are closely colocated. For the lower troposphere, the agreement is within <span class="inline-formula">∼</span> 7 %, which is the level of consistency expected given the nature of atmospheric variations over the 300–700 <span class="inline-formula">km</span> separation between the lowest point and the dropsonde.</p> |
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| ISSN: | 1867-1381 1867-8548 |