VESSEL: R/V Atlantis
DEPARTED: Woods Hole, Massachusetts on 30 AUGUST, 2017
ARRIVED: Woods Hole, Massachusetts on 24 September, 2017
Link to more NAAMES3 pages
(2017) Parameter Information
goal of this cruise was to measure nascent ocean derived aerosols.
The Sea Sweep (Bates et al., 2012) was deployed at six stations
during the cruise. The Sea Sweep consists of a frame of stainless
steel (ss) flatbar 0.61 m wide, 0.91 m long, and 0.91 m high. The
upper 0.15 m (bow and stern) and 0.46 m (port and starboard sides) of
the frame are covered with ss sheet metal. The top is enclosed with
ss sheet metal hood in a cone shape extending 0.3 m above the frame.
The Sea Sweep frame is supported by two inflatable pontoon floats
(1000 Denier Reinforced) 3 m long attached to aluminum tubing. The
frame was adjusted in the pontoons so that the opening at the bow and
stern was 1.0 cm above the water under calm conditions.
hoses are attached to the Sea Sweep cone top. One hose (1.3 cm ID
Pliovic (TM) reinforced (braided)) provides compressed air at a flow
of 50 L min-1
to two ss diffusion stones (2 um porosity, 2.54 cm diameter, 24 cm
long). The diffusion stones are horizontally mounted on the bottom of
the Sea Sweep frame 0.75 m below the sea surface. A second hose (5.1
cm ID NutriFLEX Pliovic [TM]) provides a laminar flow air curtain
directed downward at the bow and stern ends of the frame. A blower is
used to produce a flow of 2 m3
of particle-free air (charcoal and hepa filtered) to form this
curtain. The curtain and side walls prevent ambient air from entering
the Sea Sweep. The curtain provides an outward flow of about 1 m3
(1 m sec-1
face velocity) and an equal dilution flow to the bubbled air in the
enclosed space under the hood. The third hose (5.1 cm ID NutriFLEX
Pliovic [TM]) brings 1 m3
of Sea Sweep "sample" air to the PMEL aerosol sampling mast
18 m above the sea surface. This is the same mast and flow rate used
during ambient air sampling. The transmission efficiency of the PMEL
sampling mast for particles with aerodynamic diameters less than 6.5
um (the largest size tested) is greater than 95% [Bates
et al., 2002].
To check for particle losses, simultaneous measurements of the
aerosol number size distribution resulting from bubbled seawater were
made at the top of the Sea Sweep cone and at the base of the sampling
mast with two Aerodynamic Particle Sizers (APS). These measurements
showed no measurable loss of particles in either the hose or the
Sea Sweep was deployed off the port bow of the RV
during NAAMES3. The ship was positioned with the wind off the
starboard bow and steamed slowly (0.2 m sec-1)
forward during sampling to ensure a continual renewal of ocean
surface water. The forward motion was relative to the current. During
some deployments, the ship steamed slowly backwards to keep the water
flow under Sea Sweep at 0.2 m sec-1.
The ship motion was adjusted visually to keep some bubbles trailing
behind Sea Sweep while most of the bubbles were captured in the hood.
The ship blocked the true wind. During Sea Sweep sampling the aerosol
sampling mast and instruments sampled Sea Sweep so there were no
ambient aerosol measurements.
chemical and physical Sea Sweep data "concentrations" are
based on the measured mass/number per volume of air sampled. The
"concentrations" are a function of the number of bubbles
collected in the Sea Sweep hood. The data should only be compared in
relative terms. We normalize the chemistry data to the sodium
concentration to compare measurements during and between stations.
T.S., P.K. Quinn, A.A. Frossard, L.M. Russell, J. Hakala, T.
M. Kulmala, D.S. Covert, C.D. Cappa, S.-M. Li, K.L.
Hayden, I. Nuaaman,
R. McLaren, P. Massoli, M.R. Canagaratna,
T.B. Onasch, D. Sueper, D.R. Worsnop, and W.C. Keene, Measurements of
ocean derived aerosol off the coast of California, J.
Geophys. Res., 117,
D00V15, doi:10.1029.2912JD017588, 2012.
and Meteorological Measurements
Position (Latitude and Longitude):
the one minute files the position is treated somewhat differently
from all the other data. The position given is the ship's position at
the start of the one minute 'averaging' period. All other data are a
true average. The PMEL GPS was the primary source, the Ship's GPS was
used when there were missing data in the ship's record.
Speed, Course and Gyro:
ship's GPS speed in
(Speed Over Ground) and GPS Course in
(Course Over Ground) are the one minute averages from the GPS (the
PMEL GPS as the primary source, the Ship's GPS was the secondary
source). To make the one minute averages the 1-second recorded motion
vector was separated into east and north components that were
averaged into one minute bins. The one minute components were then
combined into the ship Velocity Vector. The GyroCompass in
compass degrees is
the one minute average heading. The primary source was the PMEL GPS
compass (Si-TEX Vector Pro), the ship gyro compass data were used
when the primary data were missing. The 1-second data were separated
into an east and north component before averaging and then
recombined. NOTE: The GPS-Course is the direction the ship is moving.
The GyroCompass is the direction the ship's bow is pointing. When the
ship is moving at 6 or more knots they generally are the same. Due to
water currents, at slow speeds there can be quite a difference
between the two. When the ship is stationary, the two are totally
primary source for the relative wind data was the PMEL Vaisala WX520
sonic anemometer, located on the aerosol sampling mast. For periods
of missing data from the PMEL data sources average of the ship's two
sensors at the bow met
used. The one second relative wind speed and direction data were
separated into orthogonal components of "keel" and "beam".
These components were averaged into 1 minute averages, and then
recombined to relative wind vectors. Wind speed is reported in meters
per second and wind direction is in degrees with -90 being wind
approaching the ship on the port beam, 0 degrees being wind
approaching the ship directly on the bow, and +90 degrees being wind
approaching the ship on the starboard beam.
Components/ True Wind Speed/ True Wind Direction:
primary source for the true wind data was the average of the ship's
two WX520 sensors on the bow met tower (19.5 m above sealevel). For
periods of missing data the PMEL Vaisala WX520 sonic anemometer,
located on the aerosol sampling mast (17 m above sealevel) was used.
The ship’s measurements at the bow tower were used as the
primary measurement as they were least affected by wind flow over the
ship’s superstructure. True
wind speed and direction were calculated from the relative wind
taking into account the ship's motion from the GPS and the ship
heading from the GPS compass. The true wind vector is given as wind
speed in m/s and wind direction in compass degrees. The WindU and
WindV are the east and north components of the wind vector (in m/s).
minute averages in degrees C. The following data sources were used.
The PMEL rotronics sensor on the aerosol sampling mast the PMEL
Vaisala WXT520 sensor on the sampling aerosol mast (both at 17 m
above sealevel) and
the two ship owned Vaisala WXT520 sensors on the ship's IMET bow
tower (both at 19.5 m above sealevel). These 4 sensors generally
agreed to better than 0.5 deg C. For this project the average of the
ship's WXT520 sensors on the bow tower were used, During periods of
missing data in the ship's sensors the PMEL WXT520 data was used.
minute averages in %. The following data sources were used. The PMEL
rotronics sensor on the aerosol sampling mast, the PMEL Vaisala
WXT520 sensor on the sampling aerosol mast (both
at 17 m above sealevel) and
the two ship owned Vaisala WXT520 sensors on the ship's IMET bow
tower (both at 19.5
m above sealevel).
These 4 sensors generally agreed to better than 5 (RH) %. For this
project the average of the Ships WXT520 sensors on the bow tower were
used, During periods of missing data in the Ships sensors the PMEL
WXT520 data was used.
minute averages in units of mb. There were two sources of raw data,
the PMEL WXT520 sensor (corrected to sea level) and the two ship's
WXT520 sensors on the bow tower. For this project the average of the
Ships WXT520 sensors on the bow tower were used. During periods of
missing data in the ship's sensors the PMEL WXT520 data was used.
minute averages in units of watts per square meter. Total solar
radiation was measured with an Epply Black and White Pyranometer
(horizontal surface receiver -180, model 8-48, serial number 12946)
and an Epply precision pyranometer (horizontal surface receiver -180,
twin hemispheres, model PSP, serial number 133035F3) that were
mounted on the top of AERO van. Both instruments were calibrated by
The Epply Laboratory on October 11, 1994. There were times when the
sampling mast shaded one or both sensors. There were also times when
the ship's mast/bridge shaded the sensors. The shaded data have not
been edited out of the 1 minute data record. The data reported here
are from the model 8-48, serial number 12946 radiometer and are in
watts per square meter and are the average value over the 1 minute
was pulled from 16 m above sea level through a 1/4 inch teflon line
at approximately 1 m3min-1
into a Thermo Environmental Instruments Model 49c ozone analyzer. The
air inlet was appoximently 2 meters below the aerosol inlet. The data
are reported as one minute averages in units of ppb.
PMEL radon instrument is a "dual flow loop, two filtered radon
detector". The general features of the instrument are described
and Zahorowski, Baseline radon detectors for shipboard use:
Development and deployment in the First Aerosol Characterization
Experiment (ACE1), J. Geophys. Res.,
103, 16,743-16,751, 1998. The instrument response is due to radon
gas, not radon daughters (all of the existing radon daughters are
filtered out before entering the decay/counting tank). The instrument
registers the total number of decay counts per 30 minute interval on
a filter (wire screen) arising from the decay of radon in the tank.
The volume of the decay/counting tank was 905 l and the sample flow
rate into and out of the tank was typically 70 l/min. The response
time of the radon instrument is limited to about 30 minutes by the
radiological decay time constants of the radon daughters on the wire
screen filter. Thus, the start time given in the data file is 15
minutes prior to midpoint of the counting interval. The instrument
was calibrated with a known radon source in Seattle before the cruise
and a second calibration was performed after the instrument was
shipped back to PMEL . Radon concentrations are given in mBq m-3.
Surface Temperature and Salinity:
Surface Temperature (SST) in degrees C is from the ship’s
Hull Probe (SBT48), Salinity
in PSU is from the
The temperature probe and water inlet for the thermosalinograph were
5.3 meters below the water line. The
underway chlorophyll is from the University of Maine, MISC
aerosol particles were sampled at 18 m above sea level through a
heated mast. The mast extended 5 m above and forward of the aerosol
measurement container. The inlet was a rotating cone-shaped nozzle
that was automatically positioned into the relative wind to maintain
nominally isokinetic flow and minimize the loss of supermicrometer
particles. Air entered the inlet through a 5 cm diameter hole, passed
through a 7 degree expansion cone, and then into the 20 cm inner
diameter sampling mast. The flow through the mast was 1 m3 min-1. The
transmission efficiency of the inlet for particles with aerodynamic
diameters less than 6.5 um (the largest size tested) is greater than
95% [Bates et al., 2002].
bottom 1.5 m of the mast were heated to establish a stable reference
relative humidity (RH) for the sample air of in the controlled range
%RH. Twenty one 1.6 cm inner diameter stainless steel tubes extending
into the heated portion of the mast were connected to downstream
aerosol instrumentation with either conductive silicon tubing or
stainless steel tubing for analysis of organic aerosol.
Two data files, Sea Sweep and Ambient. See notes on Sea Sweep above.
of the twenty one 1.6 cm diameter tubes was used to supply ambient
air to TSI 3010 (CN_Direct) and TSI 3025A (UFCN_Direct) particle
counters. Another one of tubes was used to supply ambient air to a
TSI3785 (UFCN_Chem) particle counter. A separate 1/4" line was
used to supply air from the top of the mast directly to a TSI 3760
particle counter. The 3760, 3010, 3025 and 3785 measure all particles
larger than roughly 12, 12, 3 and 5 nm respectively. The total
particle counts from each instrument were recorded each second. The
data were filtered to eliminate periods of calibration and instrument
malfunction and zero air periods, and periods of obvious ship
contamination from the R/V Atlantis (based on relative wind and high
CN counts). The "best" filtered values were chosen to
represent CN>12 (CN) and ultra-fine (UFCN) particle
concentrations. The best CN values are primarily from CN_Direct with
data from CN_Stack used to fill in periods where the CN_Direct data
were not available. Similarly, the UFCN values are primarily from
UFCN_Direct with the UFCN_Chem data used to fill in periods where
UFCN_Direct data were not available. These "best" data were
averaged into one minute periods. One second data are available upon
request. The value of -999 was
assigned to any one minute
period without data.
Chemistry Data (Ion Chromatograph):
Two data files, Sea Sweep and Ambient. See notes on Sea Sweep above.
and seven-stage multi-jet cascade impactors (Berner et al., 1979)
sampling air at 25-35%
RH were used to determine the mass size distribution of Cl-, NO3-,
SO4=, Na+, NH4+, K+, Mg+2, and Ca+2. Sampling periods ranged from 2
to 13 hours. The RH of the sampled air stream was measured a few
inches upstream from the impactors. The 2-stage impactors cut the
samples into submicrometer (Daero < 1.1 um at 30%
RH), and supermicrometer (1.1 um < Daero < 10 um) samples.
Aerosol mass size distributions from the 7-stage impactors (size cuts
at: 0.18, 0.31, 0.55, 1.1, 2.0, 4.1 and 10 um) are available for
impaction stage at the inlet of the impactor was coated with silicone
grease to prevent the bounce of larger particles onto the downstream
stages. Tedlar films were used as the collection substrate in the
impaction stage and a Millipore Fluoropore filter (1.0-um pore size)
was used for the backup filter. Films were cleaned in an ultrasonic
bath in 10% H2O2 for 30 min, rinsed in distilled, deionized water,
and dried in an NH3- and SO2-free glove box. Filters and films were
wetted with 1 mL of spectral grade methanol. An additional 5 mLs of
distilled deionized water were added to the solution and the
substrates were extracted by sonicating for 30 min. The extracts were
analyzed by ion chromatography [Quinn et al., 2000]. All handling of
the substrates was done in the glove box. Blank levels were
determined by loading an impactor with substrates but not drawing any
air through it.
are reported as ug/m3 at STP (25C and 1 atm). Values below the
detection limit are denoted with a -8888 in the .acf file or zero in
the .itx and .ict files, missing data are denoted with a -9999 in the
.acf and .ict files and NaN in the .itx file.
et al., Sci. Total Environ., 13, 245 - 261, 1979.
et al., J. Geophys. Res., 105, 6785 - 6805, 2000.
Carbon (Sunset Laboratory thermal/optical analyzer)
um, sub-1.1 um and sub-10 um samples were collected on pre-combusted
quartz fiber filters using 2, 2 and 1 stage impactors, respectively,
for organic carbon (OC) and elemental carbon (EC) analysis [Bates
2004]. A charcoal diffusion denuder was deployed upstream of the
submicrometer and sub-0.18 um impactors to remove gas phase organic
species. OC and EC concentrations were determined with a Sunset
Laboratory thermal/optical analyzer. Three temperature steps were
used to evolve OC under O2-free
conditions for quantification. The first step heated the filter to
230 Deg C; the second step heated the filter to 600 Deg C (AMS
vaporizer temperature); and the final step heated the filter to 870
Deg C. After cooling the sample down to 550 Deg C, a He/O2
mixture was introduced and the sample was heated in four temperature
steps to 910 Deg C to drive off EC. The transmission of light through
the filter was measured to correct the observed EC for any OC that
charred during the initial stages of heating. No correction was made
for carbonate carbon so OC includes both organic and carbonate
carbon. The percentage of carbonate carbon is unknown. EC was below
the detection limit for all samples. Super-micrometer OC
concentrations were determined by difference between submicrometer
and sub-10 um impactor samples without denuders.
in-situ Light Scattering and Absorption, Scattering and Absorption
angstrom exponents, Single Scatter Albedo, and RH dependence of
suite of instruments was used to measure aerosol light scattering and
absorption. Two TSI integrating nephelometers (Model 3563) measured
integrated total scattering at wavelengths of 450, 550, and 700nm
(Anderson et al, 1996; Anderson and Ogren, 1998). Sample flow was
taken from the AeroPhysics sampling van inlet. One nephelometer
(neph_sub10) always measured aerosols of aerodynamic diameter Dae <
10 micrometers; the second nephelometer (neph_sub1) measured only
aerosol of aerodynamic diameter Dae < 1 micrometer. When possible,
both nephelometers were operated at a sensing volume RH of
This RH was controlled by controlling the temperature of the
insulated cabinet that the nephelometers were in.
10 and 1 micrometer cut-offs were made with Berner multi-jet cascade
impactors. Two Radiance Research Particle Soot Absorption Photometers
were used to measure light absorption by aerosols at 467, 530, and
660nm (Bond et al., 1999; Virkkula et al.,2005) under 'dry' (<25%
RH) conditions for sub 10 (psap_sub10) and sub 1 (psap_sub1)
micrometer aerosols at the outlet of the respective nephelometers.
the PMEL Data Sever the ~30%
RH, neph_sub10 data are in the TOTSCAT file, the ~30%
RH, neph_sub1 data are in the SUBSCAT file. The psap_sub10 and
psap_sub1 data are in the PSAP file.
separate humidity controlled system measured submicrometric light
scattering at two different relative humidities, approximately 25% RH
and 85% RH (neph_sub1_lo and neph_sub1_hi) with two TSI integrating
3-wavelength nephelometers operated in series downstream of a Berner
impactor. There are no backscattering values available from the _hi
or _lo nephelometers as the backscatter shutter mode was set to
"total" due to problematic backscatter shutters. The first
nephelometer measured scattering of the ~50% conditioned aerosol from
the AeroPhysics sampling van inlet at approximately 25% RH after
drying of the sample flow using a PermaPure, multiple-tube nafion
dryer model PR-94. Downstream of this nephelometer a humidifier was
used to add water vapor to the sample flow (6 microporous teflon
tubes surrounded by a heatable water-jacket). The sample was
conditioned to approximately 85% RH, scattering was measured by the
second TSI neph. Humidity was measured by using a chilled mirror dew
point hygrometer downstream of the second neph.
the PMEL Data Sever the neph_sub1_lo data are in the SUBSCATloRH
file, the neph_sub1_hi data are in the SUBSCAThiRH file.
COLLECTION AND PROCESSING
from both systems were collected and processed at 1 sec resolution
but are reported as 60-second averages. Data from each instrument are
corrected and adjusted as described below, allowing for derivation of
extensive parameters (light scattering and absorption) and intensive
parameters (single scatter albedo, Angstrom exponent). Light
absorption is box-car averaged by the instrument over a window
all parameters, the bad value code is "NaN" (-9999 in the
.acf fles). Intensive parameters are set to NaN when the extensive
properties used in their calculation fell below the measurement noise
threshold. Both extensive and intensive properties are set to NaN
(-9999) during certain events, such as during filter changes,
instrument calibration, obvious instrument failure etc. Negative
values of absorption might occur during periods of absorption signals
near or in the range of the instrument noise, and are partly shifted
into the negative range due to scattering correction.
are p_STP=1013.2 hPa, T_STP=273.2 K.
OF MEAN VALUES
from the TSI integrating nephelometers, Neph sub10 and Neph sub1, and
f(RH=low) and f(RH=high) are processed as follows:
gas (air and CO2) calibrations were made before the field campaign
using the standard TSI program. During the campaign zero (particle
free air at ambient ater vapor conc.) and CO2 span checks were made
at three to four day intervals. The resulting zero offset and span
factors were applied to the data.
TSI nephelometers measure integrated light scattering into 7-170
degrees. To derive total scatter (0-180degrees) and hemispheric
backscatter (90-180degrees) angular truncation correction factors
were applied as recommended by Anderson and Ogren (1998).
and hemispheric backscatter were adjusted to STP. (NOTE: There are
no backscattering values available from the f(RH=low) and f(RH=high)
nephelometers as discussed above.)
from the Radiance Research Particle Soot Absorption Photometers,
PSAPs sub1, sub10, and _lo,
processed as follows:
values of light absorption are corrected for spot size, flow rate,
artifact response to scattering, and error in the manufacturer's
calibration, all given by Bond et al. (1999). Except the spot size,
all corrections were made after data collection, i.e. they are not
integrated into the PSAP firmware. However, the PSAP's were
flow-calibrated prior to the campaign, and a flow correction was
applied based on routine flow checks during the cruise.
absorption is adjusted to STP
f(RH) of scattering data is processed as follows:
values of light scattering at low RH and high RH were corrected to
exponent describing the f(RH) dependence of scattering was
determined using the scattering values of neph_lo_1min (fRH-optics)
and neph_hi_1min (fRH-optics) and applying a linear regression of
on the Kasten & Hanel formula
[Wang et. al.,2006]
fRH values given on the data server (SUBFRH) are at the measured high
and low RH values. The gamma factor calculated from the equation
above is available upon request.
Angstrom exponent for scattering at (450,550,700nm),
Bs, Gs and Rs are light scattering values that apply to 450, 550 and
700 nm, respectively and where these values have been smoothed by
averaging over a 30-sec wide window.
Angstrom exponent for absorption at (467,530,660nm),
Ba, Ga and Ra are light absorbtion values that apply to 467, 530 and
660 nm, respectively and where these values have been smoothed by
averaging over a 30-sec wide window.
single scatter albedo of the sub-micron aerosol was calculated as
= Neph1_scat / (Neph1_scat + PSAP1_abs)
light absorption values and scattering have been averaged over 60
seconds. SSA is given for 532nm, i.e. the nephelometer data was
wavelength-shifted to match the PSAP wavelength using the
nephelometer based Angstrom exponent.
sub 1 micron and sub 10 micron Scattering Angstrom exponents can be
found on the PMEL Data Server in the SUBSCATANG and TOTSCATANG files.
The sub 1 micron and sub 10 micron Absorption Angstrom exponents can
be found in the SUBABSANG and TOTABSANG files. The sub 1 micron and
sub 10 micron single scatter albedo values can be found in the SUBSSA
and TOTSSA files.
T.L., D.S. Covert, S.F. Marshall, M. L. Laucks, R.J. Charlson, A.P.
Waggoner, J.A. Ogren, R. Caldow, R. Holm, F. Quant, G. Sem, A.
Wiedensohler, N.A. Ahlquist, and T.S. Bates, "Performance
characteristics of a high-sensitivity, three-wavelength, total
scatter/backscatter nephelometer", J. Atmos. Oceanic Technol.,
13, 967-986, 1996.
T.L., and J.A. Ogren, "Determining aerosol radiatve properties
using the TSI 3563 integrating nephelometer", Aerosol Sci.
Technol., 29, 57-69, 1998.
T.C., T.L. Anderson, and D. Campbell, "Calibration and
intercomparison of filter-based measurements of visible light
absorption by aerosols", Aerosol Sci. and Tech., 30, 582-600,
Virkkula, N. C. Ahquist, D. S. Covert, P. J. Sheridan, W. P. Arnott,
J. A Ogren,"A three-wavelength optical extinction cell for
measuring aerosol light extinction and its application to determining
absorption coefficient", Aero. Sci. and Tech., 39,52-67, 2005
Virkkula, N. C. Ahquist, D. S. Covert, W. P. Arnott, P. J. Sheridan,
P. K. Quinn,D. J. Coffman, "Modification, calibration and a
field test of an instrument for measuring light absorption by
particles", Aero. Sci. and Tech., 39, 68-83, 2005
et. al, Aerosol optical properties over the Northwestern Atlantic
Ocean during NEAQS-ITCT 2004, and the influence of particulate matter
on aerosol hygroscopicity, submitted to J. Geo. Phys. Res., 2006
Droplet Measurement Technologies CCN Counter (DMT CCNC) was used to
determine CCN concentrations of 50, 75, 100, and 150 nm Sea Sweep
particles at supersaturations ranging from 0.1 to 0.8%. A TSI SMPS
was used to size-select particles of a given diameter, which were
then sampled in parallel by the CCNC and a TSI 3010 particle counter.
Details concerning the characteristics of the DMT CCN counter can be
found in Roberts and Nenes  and Lance et al. . The CCN
counter was calibrated before and during the experiment as outlined
by Lance et al. . The uncertainty associated with the CCN
number concentrations is estimated to be less than +/- 10% [Roberts
and Nenes, 2005]. Uncertainty in the instrumental supersaturation is
less than +/- 1% for the operating conditions of this experiment
[Roberts and Nenes, 2005].
data are reported in the NAAMES1_CCN-MONO-SeaSweep_v0 files (in acf,
netCDF, ICARTT and IGOR formats). The data are in 10 second time
intervals and include CCN concentration (in n/cm^3), CCN/CN ratio,
Supersaturation (in %), and particle diameter selected (in nm)
S., J. Medina, J.N. Smith, and A. Nenes, Mapping the operation of the
DMT continuous flow CCN counter, Aer. Sci. Tech., 40, 242 - 254,
G.C. and A. Nenes, A continuous-flow streamwise thermal gradient CCN
chamber for atmospheric measurements, Aer. Sci. Tech., 39, 206 - 221,
Number Size Distributions:
There are four
main data files, ambient(<=35%RH)
and Sea Sweep.
of the 21 1.6 cm diameter tubes was used to supply ambient air to a
short differential mobility particle sizer (Aitken-DMPS) and a medium
differential mobility particle sizer (Accumulation-DMPS). The two
DMPSs were located in a temperature-controlled box at the base of the
mast. When possible the temperature was controlled such that the RH
of the sample stream was maintained at 25-35%
RH. The Aitken-DMPS was a University of Vienna (Reischle) short
column instrument connected to a TSI 3760A particle counter operating
with a positive center rod voltage to sample particles with a
negative charge. Data were collected in 10 size bins from 20 to 200
nm diameter. The Aitken-DMPS operated with an aerosol flow rate of 1
L/min and a sheath air flow rate of 10 L/min. The Accumulation-DMPS
was a University of Vienna (Reischle) medium column connected to a
TSI 3760A particle counter operating with a positive center rod
voltage to sample particles with a negative charge. Data were
collected in 7 size bins from 200 to 800 nm diameter. The
Accumulation-DMPS operated with an aerosol flow rate of 0.5 L/min and
a sheath air flow rate of 5 L/min. The relative humidity of the
sheath air for both DMPS was controlled resulting in a measurement RH
in the DMPSs 25-35
distributions were collected every 5-minutes from a mobility scan
that started at even 5 minute intervals and lasted ca. 4.75 minutes.
mobility distributions from the Aitken-DMPS, Accumulation-DMPS were
inverted to a number distribution by assuming a Fuchs-Boltzman charge
distribution resulted from the Kr85 charge neutralizer (Stratman, F.
and A. Wiedensohler, 1997). The overlapping channels between the two
instruments were eliminated in the inversion. The data were corrected
for diffusional losses and size dependent counting efficiencies based
on pre-ACE-2 intercalibration exercises at IfT. Data are reported in
geometric diameter (micrometers) in units of dN/dlogDp (cm-3) at an
RH of 30%
same 1.6 cm diameter tube was used to supply ambient air to the APS
(TSI 3321) located in the lower temperature controlled box at the
base of the mast. The temperature was controlled to maintain the RH
of the aerosol sample stream of 25-35
APS data reported here are in 34 size bins with the nominal
manufacturers aerodynamic diameters ranging from 0.96 to 10.37 um.
Data are reported in aerodynamic diameter (micrometers) in units of
dN/dlogDp (cm-3) at an RH of 25-35
%. Additionally, modifications were made to the APS to account for
the internal heating of the sample in the APS by its sheath flow and
waste heat, which could reduce the measurement RH below
First, the sheath flow was conditioned outside the instrument case
before reintroduction into the sheath and acceleration nozzle.
Second, the inlet tube was insulated to reduce heating at that point.
While the temperature at the APS's sensing volume was not measured
during sampling, laboratory testing prior to the cruise showed a
significant reduction in the internal heating. Before the
modifications, the differential temperature between the inlet and the
sensing volume was about 3 Deg C, but after the modifications, the
same differential temperature was reduced to less than 1 Deg C.
data were filtered to eliminate periods of calibration and instrument
malfunction. The value of -999 is assigned to any period without
v0 data were missing the last two days, they were added in the v1
v1 data are given in the following file types: DMPS size
distributions where the sizes are geometric diameters, APS size
distributions where the sizes are aerodynamic diameters, and a
combined DMS/APS number size distribution (nsd) where the sizes are
in geometric diameter. The APS data were converted from aerodynamic
diameters to geometric diameters using densities calculated from
measured chemistry. The combined mass size distribution (msd) was
calculated from the number size distribution (nsd) using the same
densities. All data were filtered to eliminate periods of calibration
and instrument malfunction. The value of -999 is assigned to any
period without data. Data are reported in units of dN or dM/dlog(base
10)Dp (cm-3) at an RH of 30%.
Format: comma-delimited ASCII. Date-Time UTC, Julian Decimal Date,
Lat and Longt. followed by the dmps, aps size bins as described
above. The first two rows of data contain the bin numbers and the
midpoint diameters in micrometers of each bin, respectively.
F. and A. Wiedensohler. A new data inversion algorithm for DMPS
measurements. J. Aerosol Sci., 27, 339-340, 1997.
U.S.Dept of Commerce /