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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, at
night. However, during some daytimes with low relative wind speeds the
PMEL sensor was warmer. We assume that this was a result of solar heating
of the container deck. 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). The IMET RH was almost always within 3% of the two PMEL
RM Young sensors except during the few above mentioned times when the PMEL
temperatures were warmer due to solar heating. There were several occasions
of a few hours when there were no available ship (SCS) data, during those
times the PMEL RM Young sensor was used in this data record
Barometric Pressure:
Barometric pressure was measured with the ship's SCS electronic Vaisala
sensor and the PMEL Qualimetrics model 7105-A sensor. There was also a
handwritten record from the ship's bridge at 6-hour intervals that used
the ship's aneroid barometer (calibrated to sea level by the NWS). When
all three records were closely examined the PMEL sensor best followed the
ship's aneroid barometer record, although it had a constant offset. Since
there was no agreement between the three records, we assumed the recently
calibrated aneroid barometer was the most accurate and used this record
to calibrate the PMEL barometer. The data reported here are 30-minute averages
of the 1-minute data from the PMEL barometer calibrated to sea level with
the ship’s aneroid barometer.
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 30 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 30 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.) There were three periods when the PMEL data system was
down or the skyvane anemometer was broken. During these periods (DOY 81.2-81.4,
83.1-83.15, 90.16-91.1) the relative wind signal from the "mast" anemometer
was used.
The one minute average relative wind speed and direction data were separated into orthogonal components of "keel" and "beam". These components were averaged into 30 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 30 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. There were 4 periods when the IMET record
was not available: a few hours at the beginning and end of the cruise,
a large gap from DOY 80.4 to 91.2 when the IMET wind sensor was damaged
and a short period at the start of DOY 95 when the SCS data system was
down. During the period from DOY 80.4375 to 91.2500 the anemometer on the
ship’s mast above the bridge (recorded on the SCS as "true mast winds")
was used. The mast sensor is located higher than the IMET sensor and also
is affected more by wind blowing over the ship. During periods of no IMET
or mast winds (74.2917 to 75.7917, 95.0000 to 95.0208, and 109.6250 to
109.8750) the hourly hand written records from the ship's "Deck Weather
Logs" were used.
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 30 minute averaged data include all data points. The data
are reported in units of mm/hr. (Note: since the data are 30 minute averages,
summing all 48 points for one day and dividing by two will give total precipitation
in mm for that day.)
DMS measurements:
Ambient air and seawater were immediately analyzed aboard ship for
dimethylsulfide (DMS) concentrations using the same automated collection/purge
and trap system. Air samples were pulled through a Teflon filter and Teflon
tubing which ran approximately 50 m from the top of the aerosol sampling
mast (18 m above sea level, forward of the ship’s bridge) to the analytical
system. One hundred ml/min of the 4 L/min flow were pulled through a KI
solution at the analytical system to eliminate oxidant interferences. The
air sample volume ranged from 0.5 to 1.5 L depending on the DMS concentration.
Seawater samples were collected from the ship's seawater pumping system
which had an inlet located near the ship’s bow at a depth of approximately
4 m. The seawater line ran to the analytical system where 5.1 ml of sample
were valved into a Teflon gas stripper. The samples were purged with hydrogen
at 80 ml/min for 5 min. Water vapor in either the air or purged seawater
sample stream was removed by passing the flow through a -25C Teflon tube
filled with silanized glass wool. DMS was then trapped in a -25C Teflon
tube filled with Tenax. During the sample trapping period, 6.2 pmole of
methylethyl sulfide (MES) were valved into the hydrogen stream as in internal
standard. At the end of the sampling/purge period the coolant was pushed
away from the trap and the trap was electrically heated. DMS was desorbed
onto a DB-1 mega-bore fused silica column where the sulfur compounds were
separated isothermally at 50C and quantified with a sulfur chemiluminesence
detector. The detection limit during ACE-Asia was approximately 0.8 pmole.
The system was calibrated using gravimetrically calibrated DMS and MES
permeation tubes. The precision of the analysis, based on both replicate
analyses of a single water sample and replicate analyses of a standard
introduced at the inlet of the air sample line, was typically +- 8%. The
performance of the system was monitored regularly by running blanks and
standards through the entire analytical and sampling system (including
the Teflon filter and sampling line). Values reported here have been corrected
for recovery losses (0-5%). System blanks were below detection limit. Water
samples are reported in units of nanomoles per liter. Air samples are reported
in units of parts-per-trillion by volume (ppt). The mixing ratios were
calculated at standard temperature (25C) and pressure (1013 mbar) such
that 1 nmole/m3 equals 24.5 ppt. The flux of DMS from the ocean to the
atmosphere in micromoles/square meter/day was calculated for each seawater
DMS measurement using the exchange coefficients of Wanninkhof (1992) and
Liss and Merlivat (1986). The calculated DMS flux includes the seawater
DMS concentration, wind speed and sea water temperature. The true wind
speeds and sea water temperatures were measured aboard the Brown and are
described in detail in separate data files.
Liss, P.S. and L. Merlivat, Air-sea gas exchange rates: Introduction and synthesis, in The Role of Air-Sea Exchange in Geochemical Cycling, edited by P. Buat-Menard, pp. 113-127, D. Reidel, Norwess, Mass., 1986.Wanninkhof, R.H., Relationship between wind speed and gas exchange over the ocean, J. Geophys. Res., 97, 7373-7382, 1992.
Standardization
Zero air was introduced into the sample line upstream of the Fluoropore filter for 10 minutes every hour to establish a zero baseline. An SO2 standard was generated with a permeation tube held at 50˚C. The flow over the permeation tube, diluted to 17.7 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 170 ppt. For 30 minute data the limit of detection is reduced to 30 ppt. Uncertainties in the concentrations based on the permeation tube weight and dilution flows is < 5%. The version 2 data have been corrected for losses in the Teflon inlet valve as determined on the NEAQS 2002 field study.
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 data were also filtered of short duration (less than 15 minute) spikes of high CN concentrations. The filtered one minute data were averaged into 30 minute periods centered on the hour and half-hour. The value of -999 was assigned to any 30 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
Honolulu at the beginning of the cruise and in Yokosuka at the end of the
cruise using radon emitted from a known source.
Carbon monoxide:
Air was continuously pumped at 5 to 10 L/min through a plastic coated
aluminum tubing (Dekoron) sample line that ran from the an inlet at the
top of the aerosol sampling mast (18 m above sea level, forward of the
ship’s bridge) to the analytical system at the forward end of the ship's
main oceanographic laboratory. The analytical system was a PMEL built,
automated GC system consisting of a mole sieve 5A chromatographic column
and a Trace Analytical reduction gas detector. Every seven minutes a 5
ml sample of air from the sample line, air standard from a gas cylinder,
or CO free air from a zero air generator was injected into the system.
The air standards were dried, whole-air mixtures contained in aluminum
cylinders and were calibrated by NOAA/CMDL. The sampling schedule was such
that generally 3 air sample were analyzed per hour. The data presented
on this server consist of one hour averages of the all CO measurements
during that hour. There were several occasions when the ship was running
downwind when it was obvious that ship exhaust was entering the air sample
line; these data points were removed before averaging. There was a 2 day
data gap during day-of-year 101-102 when the uv lamp in the detector was
failing. The detector was fixed by the start of DOY 103.
Light Scattering by Aerosols:
Contact person: Trish Quinn, quinn@pmel.noaa.gov
Measurements of aerosol scattering and hemispheric backscattering coefficients were made with an integrating nephelometer (Model 3563, TSI Inc.) at wavelengths of 450, 550, and 700 nm at approximately 55% RH. Data are reported at the measurement RH, 0degC, and 1013 mb. Values measured directly by the nephelometer were corrected for an offset determined by measuring filtered air over a period of several hours [Anderson and Ogren, 1998]. Data have been corrected for angular non-idealities, including truncation errors and nonlambertian response, of the nephelometer using the method of Anderson and Ogren [1998].
Measurement RH: The measurement RH was controlled to near 55% RH. The RH was measured inside the nephelometer sensing volume. The measurement RH, T, and P values are given in the data file. Also given are the ambient T and RH measured at 18 m asl near the main aerosol inlet on the ship.
Inlet: Two single-stage Berner impactors, one with a D50,aero(55%
RH) of 1.1 um and one with a D50,aero(55% RH) of 10 um were placed upstream
of the nephelometer. An automated valve switched between the two impactors
every 15 minutes so that sampling alternated between sub-1 um and sub-10
um aerosol.
Averaging interval: 30 min
Time stamp: Decimal day of year where DOY 75.5 is noon
on March 16th. Time given is the mid-point of the 30 min averaging
interval.
Time period covered by data: DOY 75.1667 to 109.292 (March
16th - April 19th).
Calibration: The neph was calibrated with air and CO2
during the campaign at the beginning, middle, and end.
Anderson and Ogren, Aer. Sci. Tech., 29, 57 - 69, 1998.Light Absorption by Aerosols:
The absorption coefficient was measured by monitoring the change in transmission through a filter with a Particle Soot Absorption Photometer (PSAP, Radiance Research) at less than 55% RH. Values are reported at 550 nm, 0°C, and 1013 mb. Measured values have been corrected for a scattering artifact, the deposit spot size, the PSAP flow rate, and the manufacturer's calibration as per Bond et al. [1999].
Measurement RH: The sample air supplied to the PSAP was controlled to near 55% RH. The actual RH of the air inside the PSAP is expected to be lower, however, due to the PSAP location and heating within the PSAP.
Inlet: Two single-stage impactors, one with a D50,aero(55% RH) of 1.1 um and one with a D50,aero(55% RH) of 10 um were placed upstream of the PSAP. An automated valve switched between the two impactors every 15 minutes so that sampling alternated between sub-1 um and sub-10 um aerosol.
Averaging interval: 30 min
Time stamp: Decimal day of year where DOY 75.5 is noon
on March 16th. Time given is the mid-point of the 30 min averaging interval.
Time period covered by data: DOY 75.1667 to 109.292 (March 16th
- April 19th).
Bond, T.C., T.L. Anderson and D. Campbell. Calibration and intercomparison of filter-based measurements of visible light absorption by aerosols. Aerosol Sci and Technol., 30, 582-600, 1999.
Aerosol Organic Carbon/Elemental Carbon (OCEC):
Information about the OCEC sampling and data is available in a separate
PDF document.
Aerosol Optical Depth:
Contact person: Trish Quinn, quinn@pmel.noaa.gov
A 5-channel handheld Microtops sunphotometer (Solar Light Co.) operating
at 380, 440, 500, 675, and 870 nm was used. The full angular field
of view is 2.5 deg. The instrument has built in pressure and temperature
sensors and was operated with a GPS connection to obtain position and time
of the measurements. A MATLAB routine, also used by the NASA SIMBIOS
program and Brookhaven National Laboratory, was used to convert the raw
signal voltages from the Microtops to aerosol optical depths. Included
in the conversion is a correction for Rayleigh scattering [Penndorf, 1957],
ozone optical depth, and an air mass that accounts for the Earth's curvature
[Kasten and Young, 1989]. Ozone column amounts used to calculate
the ozone optical depth were based on TOMS data. The instrument was
calibrated using a Langley plot approach [Shaw, 1983] by the manufacturer
prior to the cruise and again at Mauna Loa 5 months after the cruise.
Calibration constants for the 5 wavelengths differed by less than 0.9%
between the two calibrations, which corresponds to approximately 0.01 in
optical depth.
Kasten, F. and A. T. Young, Revised optical air mass tables and approximation formula, Applied Optics, 28, 4735 - 4738, 1989.Penndorf, R. , Tables of refractive index for standard air and the Rayleigh scattering coefficient for the spectral region between 0.2 and 20 um and their application to atmospheric optics, J. Opt. Soc. America, 47, 176 - 182, 1957.
Shaw, G. E., Sun Photometry, Bull. Am. Met. Soc., 64, 4-9, 1983.
Aerosol Chemistry Data - collected with 2 stage impactors
Contact person: Trish Quinn, quinn@pmel.noaa.gov
ASCII Files: ACEASIA_aero_cat.acf and ACEASIA_aero_an.acf
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
Contact person: Trish Quinn, quinn@pmel.noaa.gov
ASCII File: ACEASIA_aero_grav.acf
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
Contact person: Trish Quinn, quinn@pmel.noaa.gov
ASCII File: ACEASIA_aero_elem.acf
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 samples were collected on Teflo filters (1.0 um pore size) mounted in a Berner impactor downstream of a D50,aero 1.1 um jet plate (Berner et al., 1979). Bulk samples were collected on Teflo filters (1.0 um pore size) in a filter pack having an upper D50,aero of 10 um. Supermicron elemental concentrations were determined by difference between the submicron and bulk samples. 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.
The reported Ca does not include sea salt Ca (as determined from soluble
Na
concentrations and the ratio of Ca to Na in seawater).
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.
Feely et al., Geophys. Monogr. Ser., vol. 63, AGU, Washington, DC, 251 - 257, 1991.
Feely et al., Deep Sea Res., 45, 2637 - 2664, 1998.
Sea Surface Temperature and Salinity:
Sea Surface Temperature (SST) and Salinity were measured with the Ship's
Thermosalinograph (Seabird SBEmodel # 21 and serial # 2117166-2531). The
intake depth was at 5.6 meters. There was a period of a few hours on DOY
79 (20-Mar.) when there are missing data due to air bubbles in the inlet
when the ship was going backwards to keep the bow into the wind.
U.S.Dept of Commerce / NOAA / OAR / PMEL / Atmospheric Chemistry