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Aerosol-Cloud-Precipitation Interaction at Bodega Bay, CA

Aerosol-Cloud-Precipitation Interaction at Bodega Bay, CA. BBACPAX: The Bodega Bay Aerosol-Cloud-Precipitation in Atmospheric rivers eXperiment February 12, 2014 – March 9, 2014 The Prather Mobile Laboratory UCSD. Outline. Major Occluded Cyclone with entrained Asian Dust

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Aerosol-Cloud-Precipitation Interaction at Bodega Bay, CA

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  1. Aerosol-Cloud-Precipitation Interaction at Bodega Bay, CA BBACPAX: The Bodega Bay Aerosol-Cloud-Precipitation in Atmospheric rivers eXperiment February 12, 2014 – March 9, 2014 The Prather Mobile Laboratory UCSD

  2. Outline • Major Occluded Cyclone with entrained Asian Dust • Overview of meteorology: Feb 26, 2014 to Feb 28, 2014 • Ambient aerosol conditions during storm • Chemical analysis of precipitation residues • Influence of Local Pollution on Coastal Clouds: Petaluma Gap Flow • Flow regime, Analysis from WRF/CHEM • Aerosol sizes, CCN, S-Band at CZC • A New Technique for In-line Characterization of Ice Nuclei Chemistry: CFDC-pCVI-ATOFMS • Theory of measurement • Observation of a shift in source airmass: clean marine to dust IN

  3. Major Occluded Cyclone with Entrained Asian Dust • System Occluded over Central Pacific, entraining Asian dust • Instability in the polar jet caused 2 incipient short waves: 2 surface lows (Feb 26, Feb 28) • Feb 26 system advected leftover moist tongue from a stalled AR • AR conditions at BML during both rounds • Global aerosol models predicted elevated dust over CA during round 1, much less dust during round 2. • Precip totals at BML • Feb 26: 2.00 in • Feb 28: 0.95 in MODIS True Color and AOT 02/24/14 @ 20 UTC

  4. Ambient Aerosols During Storm(s) • ATOFMS LVN (250 nm < Da < 3000 nm) continuously sampled aerosol particles in ambient air before during and after Feb 26 and Feb 28 rain events.

  5. Long-Range Transport NE-Pac on 02/25: Event 1 NE-Pac on 02/26: Event 2 Back Trajectories which arrive at cloud echo top during rain more likely passed through a region of mixed-dust and clouds. Back Trajectories which arrive at cloud echo top during rain came from very low levels in a clean quiescent region.

  6. Chemical Analysis of Precipitation Residues 2/26/2014 Na Al K Fe Ti Li TiO Pb 2/28/2014 Fe Ca K 2/28/2014 Na Al Ca2O (CaO)2 Li

  7. Influence of Local Pollution on Coastal Clouds • Prior to the start of rainfall and during the early stages of the storm on Feb 26, “Petaluma Gap Flow” (PGF) significantly affected air quality at BML. • While Gap Flow was active, CCN # conc. Spiked, coincident with the heaviest BB rain at CZC. • High-res (3 km) WRF-Tracer simulation identified PGF regime, and suggests that particles from CV, SF-Bay may reach CZC CZC BBY Surface Observations from Meso-West 02/26/2014 @ 10 am PST

  8. Upslope IWV (and CCN) to Rainy Coastal Range? 02/26/2014 (UTC) Observations at BBY by the UCSD-SIO Mobile Laboratory and at CZC (top) by NOAA-HMT S-Band Radar WRF-Tracer (top 2) and Observations (lower 3) of Transport and PM2.5

  9. IN Chemistry Responds to a Change in Airmass Source • On March 6, 2014 Offshore winds shifted from a westerly near-surface local marine transport regime to a subsiding northwesterly regime. • MODIS and GEOS-5 suggested that the northwesterly source region would be dust laden. MODIS True-color and AOT near 0000 UTC 03/06 • Integrated CFDC-pCVI-ATOFMS samples observations were performed before and after the estimated time of airmass change (1700 UTC) • This methodology should allow ATOFMS (LVN) to isolate IN chemistry APS size distribution during 03/06/2014

  10. CFDC-pCVI-ATOFMS CFDC-pCVI-ATOFMS Theory of Operation Ti+ Ambient before CFDC after Ambient after CFDC before • Select ions which are indicative of dust were enhanced in the activated IN, but not in ambient particles. Al+ CN- Ambient before CFDC after Ambient before CFDC after Ambient after CFDC before Ambient after CFDC before

  11. Conclusions • Review: • A confluence of complex mid-latitude dynamics, tropical wv and Asian dust created a unique set of storms 02/26 – 02/28 2014 • Although parcels experienced similar transport, rain at BBY from 02/26 contained more dust-like ions than rain from 02/28. Occlusion important? • PGF made the air at BBY “dirtiest” during heavy rain. • WRF, supported by obs. Suggest that CCN could be transported to CZC during PGF. • A new integrated instrument, CFDC-pCVI-ATOFMS successfully observed a change in IN chemistry which resulted from a change in airmass. • Future Directions: • Examine more closely the relationship between North Pac Tropical-Extratropical dynamics and dust transport (C. Pac Occluded storms are common). • Further connect PGF, CCN and CZC. S-Band radar? What about other sites with potential anthropogenic influence? Climatology of these events? • Continue to deploy CFDC-pCVI-ATOFMS, particularly in-flight.

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