Connecting an Offshore Dry Air Stratospheric Intrusion with the Outbreak of Soberanes Fire 2016
Publication Date
2-1-2024
Document Type
Article
Publication Title
Journal of Applied Meteorology and Climatology
Volume
63
Issue
2
DOI
10.1175/JAMC-D-23-0043.1
First Page
209
Last Page
226
Abstract
This study investigates the connection between the arrival of dry stratospheric air and the Soberanes Fire (2016). The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) and Goddard Earth Observing System Forward Processing model (GEOS-FP) are used for back-trajectories and offshore deep stratospheric intrusion in conjunction with the ignition and outbreak of the fire. The back-trajectory analysis indicates that most air reaching the vertical column was critically dry, exhibiting relative humidity values below 10%. As the fire ignited, dry air arrived from due west at heights of 1–3 km about 24 h prior. During the overnight fire growth, dry air arrived from the northwest to northnorthwest at heights of 3.5–5.5 km 48–72 h prior. The synoptic and GEOS-FP analyses demonstrate offshore mid-to-low stratospheric intrusion. On 21 July 2016, an enclosed upper-level low approached the California–Oregon border along the northwesterly subtropical jet stream hours before the fire outbreak. The GEOS-FP results of potential vorticity, specific humidity, and ozone along the back-trajectories to the west and northwest of the fire suggest a stratospheric intrusion event into the mid-to-low troposphere at the back-trajectory start points, and vertical velocity indicates sinking motion. The specific humidity analyzed at the arrival time shows the transport of the abnormally dry air to the Soberanes Fire. Results suggest a connection between dry stratospheric air transported to the Soberanes Fire at ignition and overnight accelerated growth, supported by a dark bank in satellite water vapor imagery. The prediction of low-level transport of dry stratospheric air to the coastal communities could help to predict the occurrence of wildfire outbreaks, or periods of accelerated fire growth.
Funding Number
NA22SEC4810015
Funding Sponsor
National Oceanic and Atmospheric Administration
Keywords
Dry intrusions, Ozone, Potential vorticity, Wildfires
Department
Meteorology and Climate Science
Recommended Citation
Jodie Clark and Sen Chiao. "Connecting an Offshore Dry Air Stratospheric Intrusion with the Outbreak of Soberanes Fire 2016" Journal of Applied Meteorology and Climatology (2024): 209-226. https://doi.org/10.1175/JAMC-D-23-0043.1