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Investigation:

CD-10 (Wofsy / Kirchhoff / Camargo / A. Nobre)

LBA Dataset ID:

LBA_CD10_MAXARANGUAPE

Originator(s):

1. KIRCHHOFF, V.W.J.H.
2. AIRES, C.B.
      3. ALVALA, P.C.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

This data set reports the concentrations of carbon monoxide (CO) and carbon dioxide (CO2), wind direction, wind speed, and air temperature measured at the Maxaranguape Atmospheric Observatory in northeast Brazil, January 4, 2003 - December 27, 2006. The data are 30-minute averages. The concentrations observed at Maxaranguape are representative of upstream atmospheric boundary conditions for the Amazon basin and could be used in conjunction with Santarem data and other data sets to estimate regional budgets for these gasses (Kirchhoff et al., 2003). There is one comma-delimited ASCII text file with this data set.

Beginning Date:

2003-01-04

Ending Date:

2006-12-27

Metadata Last Updated on:

2011-05-19

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO CD-10 CO, CO2 and Meteorological Data, Maxaranguape, Brazil :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1012

Documentation/Other Supporting Documents:

LBA-ECO CD-10 CO, CO2 and Meteorological Data, Maxaranguape, Brazil :  http://daac.ornl.gov/LBA/guides/CD10_CO_CO2_Maxaranguape.html

Citation Information - Other Details:

Kirchhoff, V.W.J.H., C.B. Aires, and P.C. Alvala. 2011. LBA-ECO CD-10 CO, CO2 and Meteorological Data, Maxaranguape, Brazil. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/1012

Keywords - Theme:

Parameter Topic Term Source Sensor
CARBON DIOXIDE ATMOSPHERE ATMOSPHERIC CHEMISTRY TOWER IRGA (INFRARED GAS ANALYZER)
CARBON MONOXIDE ATMOSPHERE ATMOSPHERIC CHEMISTRY TOWER CARBON MONOXIDE ANALYZER
SURFACE AIR TEMPERATURE ATMOSPHERE ATMOSPHERIC TEMPERATURE METEOROLOGICAL STATION TEMPERATURE SENSOR
SURFACE WINDS ATMOSPHERE ATMOSPHERIC WINDS TOWER ANEMOMETER

Uncontrolled Theme Keyword(s):  CARBON DIOXIDE, CARBON MONOXIDE, TROPICAL MARINE BOUNDARY LAYER, WIND DIRECTION, WIND SPEED

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  RIO GRANDE DO NORTE -5.49600 -5.49600 -35.26050 -35.26050

Related Publication(s):

Kirchhoff, V.W.J.H., C.B. Aires, and P.C. Alvala. 2003. An experiment to determine atmospheric CO concentrations of tropical South Atlantic air samples. Quarterly Journal of the Royal Meteorological Society 129(591):1891-1902.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data Description: Mixing ratios of CO and CO2, wind direction, wind speed and temperature measured at the Maxaranguape Atmospheric Observatory from January 4, 2003 - December 27, 2006. The data are provided as a single comma-delimited ASCII text file.



File name: CD10_Maxaranguape_CO_CO2_2003-2006.csv



Column Heading Units/format Description

1 Day_of_year Decimal day of the year with hour indicated by fraction based on UTC (1.5 = noon on Jan 1st)

2 Seq_date_2002 Decimal day since January 1st 2002 based on UTC (local time is GMT-4)

3 Date yyyy/mm/dd Sampling date

4 Hour Hour is the start of the half hourly sampling period on a 24 hour clock on UTC: (local time is GMT -4)

5 Wind_spd m s-1 Mean wind speed in meters per second (m s-1) computed as a vector average on 30 min intervals

6 Wind_dir degrees Mean wind direction in degrees computed as a vector average on 30 min intervals

7 T_air degrees C Mean air temperature in degrees Celsius for the 30 min sampling period

8 Std_dev_T_air degrees C Standard deviation of the mean air temperature

9 CO2_mix_ratio ppmv CO2 mixing ratio in micromoles/mole (ppmv)

10 Std_dev_CO2_ratio ppmv Standard deviation of the calculated mean CO2 ratio

11 Npts_CO2 Number of one minute averages included in the half-hourly reported CO2 ratio

12 CO_mix_ratio ppbv Carbon monoxide (CO) mixing ratio reported in nanomoles/mole (ppbv)

13 Std_dev_CO_ratio ppbv Standard deviation of the calculated mean CO ratio

14 Npts_CO Number of one minute averages included in the half-hourly reported CO ratio. The maximum number will be less than 30 because of the periodic zeroingof the periodic zeroing

Missing data are represented by -999



Example data records



Day_of_year,Seq_date_2002,Date,Hour,Wind_spd,Wind_dir,T_air,Std_dev_T_air,CO2_mix_ratio,Std_dev_CO2_ratio,

Npts_CO2,CO_mix_ratio,Std_dev_CO_ratio,Npts_CO

3.5833,368.5833,2003/01/04,14,-999,-999,-999,-999,-999,-999,-999,92.6,8.5,22

3.6042,368.6042,2003/01/04,14.5,-999,-999,-999,-999,-999,-999,-999,93.6,7.2,26

3.625,368.625,2003/01/04,15,-999,-999,-999,-999,-999,-999,-999,84.7,6,21

3.6458,368.6458,2003/01/04,15.5,-999,-999,-999,-999,-999,-999,-999,93.1,6.4,23

3.6667,368.6667,2003/01/04,16,-999,-999,-999,-999,-999,-999,-999,92.2,7.7,25

3.6875,368.6875,2003/01/04,16.5,-999,-999,-999,-999,-999,-999,-999,95.9,3.5,22

3.7083,368.7083,2003/01/04,17,-999,-999,-999,-999,-999,-999,-999,91.8,5,23

3.7292,368.7292,2003/01/04,17.5,-999,-999,-999,-999,-999,-999,-999,97.2,3.1,26

3.75,368.75,2003/01/04,18,-999,-999,-999,-999,-999,-999,-999,91.7,3,21

...



Data Application and Derivation:

The mixing ratios of CO and CO2 observed at Maxaranguape are representative of upstream boundary condition for the Amazon basin and will be used in conjunction with the Santarem data and other data sets to estimate regional budgets for these gases.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Detection limits for CO were based on 2x the standard deviation of the repeated CO-free gas samples. The detection limit was approximately 10 ppb. Precision was based on the standard deviations of repeated sample and calibration gas measurements. The precision was approximately 10 ppb. See Kirchhoff et al (2003) for more details.

Process Description:

Data Acquisition Materials and Methods:

The Maxaranguape site is located near the ocean on the northeast coast of Brazil, approximately a one-hour drive from the INPE Natal site. The wind magnitude is strong, generally above 10 m/s, and the preferential direction is between about 100 and 140 degrees,most of the time, thus bringing pristine South Atlantic air masses to the site. However, during a few hours of the night time period, and only on a few days of the month, the direction may change to values larger than 180 degrees, when the wind may blow over city limits before it reaches Maxaranguape, and thus can bring pollution to the site (larger CO2 concentrations, and lower O3 values correlate with the wind direction change).



Wind speed and direction were measured by wind vane and propeller anemometer mounted 3 m above the building roof. Wind speed and direction were computed as vector averages on 30-minute intervals. Air temperature was measured by a thermistor housed in an aspirated radiation shield and half hourly mean and standard deviation are reported.



CO2 was measured using a LiCor 6262. Water vapor was removed from the sample stream with a Nafion dryer. The CO2 analyzer was operated in differential mode with the reference cell purged with purified air with a constant CO2 mixing ratio close to ambient level. Four times per day the analyzer was calibrated by supplying a high, medium, and low mixing ratio calibration gas that spanned the range of ambient levels. The sample mixing ratios were computed from non-linear calibration curves fit to the standards. Mixing ratios were computed from 60-second averages and subsequently averaged to half-hour intervals reported here along with the standard deviation and number of samples included. Intervals with too few observations were rejected.



Carbon monoxide was measured using a Thermoenvironmental Instruments 48CTL gas-filter correlation infra red absorption analyzer. Water vapor in sample air and standard gas was held constant by passing the sample stream through a 2C cold trap to remove condensate from the ambient sample. The instrument zero was tracked by passing ambient air over an oxidizing catalyst (Sofnocat) to remove carbon monoxide. The instrument was zeroed for 3 minutes every 15 minutes, and interpolated zeros were subtracted from the sample and calibration signals. Every 6 hours the instrument gain was determined using calibration standards with ~100 and ~500 ppbv. Sample mixing rations were determined by computing a second order least-squares fit to the zero and calibration signals. Signals were initially averaged to 1 minute intervals to compute mixing ratio, and these were further averaged to 30-minute intervals. Data are reported as the 30-minute mean and standard deviation along with the number of observations included in the average.

References:

Kirchhoff, V.W.J.H., C.B. Aires, and P.C. Alvala. 2003. An experiment to determine atmospheric CO concentrations of tropical South Atlantic air samples. Quarterly Journal of the Royal Meteorological Society 129(591):1891-1902.doi:10.1256/qj.02.142

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