Aerosol-Cloud-Precipitation
Interaction at Bodega Bay, CA
BBACPAX: The Bodega Bay Aerosol-CloudPrecipitation in Atmospheric rivers eXperiment
February 12, 2014 – March 9, 2014
The Prather Mobile Laboratory
UCSD
Outline
• Major Occluded Cyclone with entrained Asian Dust
o Overview of meteorology: Feb 26, 2014 to Feb 28, 2014
o Ambient aerosol conditions during storm
o Chemical analysis of precipitation residues
• Influence of Local Pollution on Coastal Clouds: Petaluma Gap Flow
o Flow regime, Analysis from WRF/CHEM
o Aerosol sizes, CCN, S-Band at CZC
• A New Technique for In-line Characterization of Ice Nuclei Chemistry:
CFDC-pCVI-ATOFMS
o Theory of measurement
o Observation of a shift in source airmass: clean marine to dust IN
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
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.
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 mixeddust and clouds.
Back Trajectories which arrive at cloud
echo top during rain came from very
low levels in a clean quiescent region.
Chemical Analysis of Precipitation Residues
0.8
0.7
0.6
Na Al
Fraction
0.5
2/26/2014
K
1000 < Area < 5000
5000 < Area < 10000
Fe
0.4
10000 < Area < 20000
Ti
0.3
Area > 20000
Li
0.2
TiO
Pb
0.1
0
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350
m/z
K Ca
Na
0.8
2/28/2014
2/28/2014
Fe
1000 < Area < 5000
0.7
0.6
Fraction
0.5
Li
0.4
0.3
0.2
0.1
5000 < Area < 10000
Al
10000 < Area < 20000
Ca2O
Area > 20000
(CaO)2
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
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
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
•
•
APS size distribution during 03/06/2014
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
CFDC-pCVI-ATOFMS
Titanium Colorstack Comparison
0.1
CFDC-pCVI-ATOFMS Theory of Operation
0.08
1000
5000
10000
20000
0.06
0.04
Ti+
0.02
0
Aluminum Colorstack Comparison
• Select ions which are
indicative of dust
were enhanced in the
activated IN, but not
in ambient particles.
Ambient before
CFDC after
Ambient after
CFDC
before
PO3- Colorstack Comparison
0.1
0.08
0.06
0.1
5000
10000
20000
Al+
1000
5000
10000
20000
0.08
0.06
CN-
0.04
0.04
0.02
0.02
0
0
Ambient before
CFDC after
Ambient after
CFDC before
Ambient before
CFDC after
Ambient after
CFDC before
Conclusions
• Review:
o A confluence of complex midlatitude dynamics, tropical wv
and Asian dust created a unique
set of storms 02/26 – 02/28 2014
o Although parcels experienced
similar transport, rain at BBY from
02/26 contained more dust-like
ions than rain from 02/28.
Occlusion important?
o PGF made the air at BBY “dirtiest”
during heavy rain.
o WRF, supported by obs. Suggest
that CCN could be transported
to CZC during PGF.
o A new integrated instrument,
CFDC-pCVI-ATOFMS successfully
observed a change in IN
chemistry which resulted from a
change in airmass.
• Future Directions:
o Examine more closely the
relationship between North Pac
Tropical-Extratropical dynamics
and dust transport (C. Pac
Occluded storms are
common).
o Further connect PGF, CCN and
CZC. S-Band radar? What
about other sites with potential
anthropogenic influence?
Climatology of these events?
o Continue to deploy CFDCpCVI-ATOFMS, particularly inflight.