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Atmospheric Temperature:
Air temperature (degrees C) was measured with the ship's IMET RM Young
sensor and recorded on the ship’s scientific computer system (SCS). The
sensor was located on the ship's meteorological mast on the bow, 14 meters
above the sea surface. This signal agreed well with the PMEL RM Young sensor,
located 14 meters above the sea surface on top of the PMEL Aero Van . There
were several occasions of a few hours where there were no available ship
(SCS) data. During those times the PMEL RM Young sensor was used in this
data record.
Relative humidity:
The relative humidity (%) reported here was measured with the ship's
IMET sensor (SCS) and the PMEL RM Young sensor. The values
reported here are the average of the two values expect during the few times
when only the PMEL or the ship SCS sensor data were available. During
those times the available sensor is reported.
Barometric Pressure:
Barometric pressure was measured with the ship's SCS electronic Vaisala
sensor. Selected hourly reports of the ships handwritten, hourly
reports in the Deck Weather log were compared to the SCS sensor and most
values were found to agree within a milibar.
Insolation:
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 15 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 15 minute sampling period.
Relative Wind
The primary source for the relative wind data was the PMEL "Skyvane"
anemometer that was located at the top of the aerosol sampling mast. We
assume that the relative wind information is primarily used to determine
periods of ship contamination, thus we are using the anemometer that is
closest to the sample inlet. This anemometer also was used as an input
to the algorithm that turned off the sample pumps during periods of ship
contamination.)
The one minute average relative wind speed and direction data were separated into orthogonal components of "keel" and "beam". These components were averaged into 15 minute averages, and then recombined to relative wind vectors. Wind speed is reported 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.
Wind Components/ True Wind Speed/ True Wind Direction:
True wind speed and direction were calculated from measurements obtained
with the Ships IMET wind sensor. This sensor was mounted 14 meters above
the sea surface on the ship's meteorological sampling mast at the bow.
The true North and East components of the wind vector were calculated and
then averaged into 15 minute intervals in m/s. The true wind vector was
calculated from these components and is given as wind speed in m/s and
wind direction in compass degrees.
Rainfall Rate:
The rainfall rate was measured with a Scientific Technology Inc. ORG-100
Optical Precipitation Intensity Sensor. The instrument was mounted on the
railing of Aero van and was used along with wind direction, wind speed
and CN to control the aerosol chemistry pumps. The dynamic range of the
sensor is 0.5 to 1600 mm/h. Spikes in the signal may be associated with
sea spray. The 15 minute averaged data include all data points. The data
are reported in units of mm/hr. (Note: since the data are 15 minute averages,
summing all 48 points for one day and dividing by 4 will give total precipitation
in mm for that day.)
SO2 Measurements aboard Ronald H. Brown during ACE-Asia
Version 1.1, February 24, 2003 (file: NEAQS2002_atmchem_1m.acf)
Inlet and Instrument :
Air was pulled from 18 m above sea level down the 20 cm ID powder-coated
aluminum aerosol sampling mast (6 m) at approximately 1 m3min-1. At the
base of the sampling mast a 0.5 Lmin-1 flow was pulled through a 0.32 cm
ID, 1m long Teflon tube, a Millipore Fluoropore filter (1.0-um pore size)
housed in a Teflon filter holder, a Perma Pure Inc. Nafion Drier (MD-070,
stainless steel, 61 cm long) and then through 2 m of Telfon tubing to the
Thermo Environmental Instruments Model 43C Trace Level Pulsed Fluorescence
Analyzer. The initial 1 m of tubing, filter and drier we located in the
humidity controlled (55%) chamber at the base of the mast. Dry zero air
(scrubbed with a charcoal trap) was run through the outside of the Nafion
Drier at 1 Lmin-1. The analyzer was run with two channels (0-10 ppb full
scale and 0-100 ppb full scale) and a 20 sec averaging time. Data were
recorded every minute.
Standardization:
Zero air was introduced into the sample line upstream of the Fluoropore
filter for 10 minutes every 6 hours to establish a zero baseline. An SO2
standard was generated with a permeation tube held at 50C. The flow over
the permeation tube, diluted to 4.0 ppb, was introduced into the sample
line upstream of the Fluoropore filter for 10 minutes every 6 hours. The
limit of detection for the 1 min data, defined as 2 times the standard
deviation of the signal during the zero periods, was 100 ppt. Uncertainties
in the concentrations based on the permeation tube weight and dilution
flows are <5%.
Ozone:
Air was sampled from 18 m above sea level down the 20 cm ID powder-coated
aluminum aerosol sampling mast (6 m) at approximately 1 m3min-1.
At the base of the sampling mast a 0.5 Lmin-1 flow was pulled
through a 0.32 cm ID, 2m long Teflon tube into a TECO 49 ozone analyzer
that had been calibrated to a NIST traceable analyzer at NOAA-CMDL.
Data were recorded as one minute averages. A small portion of the
data have been deleted (consisting mostly of times that the inlet air was
passed through a zero filter - usually when the relative wind was well
behind the beam of the ship).
PMEL/UW CN and UFCN measurements:
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. Air was pulled through this 5 cm diameter inlet nozzle at 1 m3 min-1 and down the 20 cm inner diameter mast. The lowest 1.5 m of the mast was heated to reduce the relative humidity (RH) to a value of not less than 55% and partially dry the aerosol. Twenty one 1.6 cm inner diameter conductive tubes extending into this heated zone were used to subsample the main air flow for the various aerosol instruments at flows of 30 l min-1.
One of the twenty one 1.6 cm diameter tubes was used to supply ambient air to TSI 3010 and TSI 3025A particle counters. 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 and 3025 measure all particles larger than roughly 13, 12 and 3 nm respectively. The counts from the three detectors are referred to here as CN>13 (TSI3760), CN>12 (TSI3010), and CN>3 (TSI3025). The total particle counts from each instrument were recorded each minute. The data were filtered to eliminate periods of calibration and instrument malfunction and periods of ship contamination (based on relative wind and high CN counts). The value of -999 was assigned to any one minute period without data.
Radon:
The PMEL radon instrument is a "dual flow loop, two filtered radon
detector". The general features of the instrument are described in Whittlestone
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 arising from the decay of radon in the tank. The time given in the
data file is the time of the start of the counting interval. As 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 was about 13 minutes. The radon detector was standardized in
Charleston at the beginning of the cruise using radon emitted from a known
source.
Sea Surface Temperature and Salinity:
Sea Surface Temperature (SST) and Salinity were measured with the Ship's
Thermosalinograph. The intake depth was at 5.6 meters.
Aerosol Chemistry Data - collected with 2 stage impactors
Two-stage multi-jet cascade impactors (Berner
et al., 1979) sampling air at 55 ± 5% RH were used to determine
the sub- and supermicron concentrations of Cl-, NO3-, SO4=, methanesulfonate
(MSA-), Na+, NH4+, K+, Mg+2, and Ca+2. Sampling periods ranged from 4 to
6 hours. The RH of the sampled air stream was measured a few inches
upstream from the impactor. The 50% aerodynamic cutoff diameters,
D50,aero, were 1.1 and 10 um. Submicron refers to particles with
Daero < 1.1 um at 55% RH and supermicron refers to particles with 1.1
um < Daero < 10 um at 55% RH.
The 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., 1998]. 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.
Non-sea salt sulfate concentrations
were calculated from Na+ concentrations and the ratio of sulfate to sodium
in seawater.
Concentrations are reported as ug/m3 at STP
(25C and 1 atm).
Berner et al., Sci. Total Environ., 13, 245 - 261, 1979.
Quinn et al., J. Geophys. Res., 105, 6785 - 6805, 2000.
Aerosol Gravimetrically-determined Mass - collected with 2 stage
impactors
Two-stage multi-jet cascade impactors (Berner
et al., 1979) sampling air at 55 ± 5% RH were used to determine
sub- and supermicron aerosol mass concentrations. The RH of the sampled
air stream was measured a few inches upstream from the impactor.
The 50% aerodynamic cutoff diameters, D50,aero, were 1.1 and 10 um.
Submicron refers to particles with Daero < 1.1 um at 55% RH and supermicron
refers to particles with 1.1 um < Daero < 10 um at 55% RH.
The 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.
Films and filters were weighed at PMEL with
a Cahn Model 29 and Mettler UMT2 microbalance, respectively. The
balances are housed in a glove box kept at a humidity of 33 ± 2%.
The resulting mass concentrations from the gravimetric analysis include
the water mass that is associated with the aerosol at 33% RH.
The glove box was continually purged with
room air that had passed through a scrubber of activated charcoal, potassium
carbonate, and citric acid to remove gas phase organics, acids, and ammonia.
Static charging, which can result in balance instabilities, was minimized
by coating the walls of the glove box with a static dissipative polymer
(Tech Spray, Inc.), placing an anti-static mat on the glove box floor,
using anti-static gloves while handling the substrates, and exposing the
substrates to a 210Po source to dissipate any charge that had built up
on the substrates. Before and after sample collection, substrates were
stored double-bagged with the outer bag containing citric acid to prevent
absorption of gas phase ammonia. More details of the weighing procedure
can be found in Quinn and Coffman [1998].
Concentrations are reported as ug/m3 at STP
(25C and 1 atm).
Berner et al., Sci. Total Environ., 13, 245 - 261, 1979.
Quinn et al., J. Geophys. Res., 105, 6785 - 6805, 2000.
Aerosol Trace Elements Data
Concentrations of Al, Si, Ca, Ti, and Fe were
determined by thin-film x-ray primary and secondary emission spectrometry
[Feely et al., 1991; Feely et al., 1998]. Submicron and sub-10 um
samples were collected on Teflo filters (1.0 um pore size) mounted in Berner
impactors having a D50,aero of 1.1 um and 10 um jet plates,
respectively (Berner et al., 1979). Supermicron elemental concentrations
were determined by difference between the submicron and sub-10 um concentrations.
This method of sample collection allows for the sharp size cut of the impactor
while collecting a thin film of aerosol necessary for the x-ray analysis.
Sampling periods ranged from 6 to 24 hours.
Blank levels were determined by loading an
impactor or filter pack with a filter but not drawing any air through it.
Concentrations are reported as ug/m3 at STP
(25C and 1 atm).
Berner et al., Sci. Total Environ., 13, 245 - 261, 1979.Aerosol Organic Carbon/Elemental Carbon (OCEC):
Feely et al., Geophys. Monogr. Ser., vol. 63, AGU, Washington, DC, 251 - 257, 1991.
Feely et al., Deep Sea Res., 45, 2637 - 2664, 1998.
Information about the OCEC sampling and data is available in a separate PDF document.
U.S.Dept of Commerce / NOAA / OAR / PMEL / Atmospheric Chemistry