Flora

Celebrity Flora Underway pCO2 Data

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Who We Are 

| Rik Wanninkhof, Ph.D.

Senior Technical Scientist

| Denis Pierrot, Ph.D.

Oceanographer

About the Celebrity Flora

In 2000, Royal Caribbean International started a collaboration with the University of Miami’s Rosenstiel School of Marine and Atmospheric Science (RSMAS), the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), the Office of Naval Research (ONR), and the National Aeronautics and Space Administration (NASA) to have one of its ships, the Explorer of the Seas, equipped with a whole array of scientific instruments geared toward monitoring the atmosphere and the ocean.

In February of 2019, our group installed an autonomous instrument on the Celebrity Flora to measure CO2 in the surface water, primarily in the Caribbean region. Since then, CO2 instruments were installed on two additional cruise ships: Equinox and Allure of the Seas. In 2019, a CO2 instrument was installed aboard the new Celebrity Cruise ship, Flora, specifically designed for tours in the Galapagos Islands. The installation was completed during the Flora’s inaugural cruise across the Atlantic in June. Repeating loops around and through the Galapagos Islands started in July, 2019.

The installations continue a partnership with RSMAS, who not only provides the seawater supply infrastructure to which our systems are connected but also the computer network to allow constant access to the system computers and data. The pCO2 instrument on the Allure of the Seas takes 100 water measurements about every 4 hours. Data files are transferred to AOML every day so that the system operation can be monitored. The final data are processed after a cruise is completed and then posted to international databases and to this web site.

About the Website

This web site provides access to the fugacity of CO2 (fCO2) data collected on this ship. Note, fCO2 is the partial pressure pCO2 corrected for non-ideality of the CO2 gas; they are numerically similar (fCO2 ≃ 0.995 pCO2). The processed data are organized by year and by cruise. For each cruise, the color coded fCO2 values are plotted along the ship’s cruise track on a chart. Next to each chart are links to the comma-delimited data file and the associated Readme file. To download a data file, select the year from the drop-down list box and click. Choose a chart and cruise, right-click on the link to its data file or Readme file, and select the download option. Please consult with and acknowledge the AOML Ocean Carbon Cycle group if data is used for publication or presentation (contacts in Master Readme, or Denis.Pierrot@noaa.gov).

The Master Readme provides meta data that is applicable for all data gathered from this ship. The individual Readme files next to the charts provide meta data specific to the associated cruise. The Real-Time Display link displays plots of the raw xCO2 data as a function of time and location. These plots are suitable for monitoring but are not suitable for environmental interpretation since the Real-Time data has not been processed nor quality controlled.

Celebrity Flora Underway pCO2 Data

+Choose Data by Year

Celebrity Flora 2019 May – August Data
Celebrity Flora 2019 September – December Data
Celebrity Flora 2020 January – April Data

Celebrity Flora Master Readme

Introduction

The information presented in this file is applicable to all the data sets collected on the Celebrity Flora on this webpage. Any temporary changes in this information will be noted in the readme files for the individual expeditions.

Statement for use of data:

These data are made available to the public and the scientific community in the belief that their wide dissemination will lead to greater understanding and new insights. The availability of these data does not constitute publication of the data. We rely on the ethics and integrity of the user to ensure that the AOML ocean carbon group receives fair credit for its work. Please consult with us prior to use so we can ensure that the quality and limitations of the data are accurately represented.

Platform Information:

In 2019, the Ocean Carbon Group at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) installed an autonomous instrument to measure CO2 levels in surface water aboard the Celebrity Flora, a ship specifically designed for tours in the Galapagos Islands. This installation continues a collaboration among Royal Caribbean International (RCI), NOAA, and RSMAS that started in 2002.

Vessel Name: Celebrity Flora

Class of Data: Surface ocean carbon dioxide concentrations

Scientists responsible for the technical quality of this pCO2 dataset:

Rik Wanninkhof and Denis Pierrot
NOAA/AOML/Ocean Chemistry and Ecosystems Division
4301 Rickenbacker Causeway
Miami, FL 33149
Rik.Wanninkhof@noaa.gov
Denis.Pierrot@noaa.gov

Contact persons for this dataset:

Denis Pierrot
NOAA/AOML/Ocean Chemistry and Ecosystems Division
4301 Rickenbacker Causeway
Miami, FL 33149
Denis.Pierrot@noaa.gov

Component Specifications and Accuracies

The accuracies of all components, when operating optimally, are such that the calculated seawater fCO2 has an accuracy of 2 uatm or better and the calculated mole fraction of CO2 (XCO2) in air has an accuracy of 0.1 uatm.

Infrared Analyzer:
LI-COR model 840A
Licor_840A_Manual.pdf
CO2 resolution: 0.01 umol/m
CO2 accuracy: ±1ppm at 350 ppm

Equilibrator Pressure
Setra model 270
http://www.setra.com/ProductDetails/270_Baro.htm
Resolution: 0.015 hPa
Accuracy: ±0.15 hPa
(manufacturer specifications: ±0.05% FS, where FS = 80-110 kPa)

Equilibrator Temperature:
Hart model 1521
http://www.instrumart.com/assets/1521_manual.pdf
Resolution: 0.001°C
Accuracy: ±0.025°C

Sea Surface Temperature and Salinity (maintained by other scientists):
SeaBird model SBE-45
http://www.seabird.com/pdf_documents/manuals/45_017.pdf
Temperature resolution: 0.0001°C
Temperature accuracy: ±0.002°C
Salinity resolution: 0.0002‰
Salinity accuracy: ±0.005‰/span>

SeaBird model SBE-38
http://www.seabird.com/pdf_documents/manuals/38_013.pdf
Temperature resolution: 0.00025°C
Temperature accuracy: ±0.001°C

Instrument Description and Configuration

The general principle of operation of the instrument can be found in Wanninkhof and Thoning (1993), Ho et al. (1995), Feely et al. (1998), and Pierrot et al. (2009). Seawater flows through an equilibrator chamber where CO2 exchanges between water and the air above it. Small changes in seawater CO2 concentration are rapidly translated into changes in CO2 concentration in the air of the chamber (headspace). The mole fraction of CO2 in the headspace gas is measured using a non-dispersive infrared (NDIR) analyzer from LICOR®.

The effects of water vapor on the sample analyses are kept to a minimum by removing as much water as possible. The water is first condensed out of the sample gas stream by cooling to ~5 °C using a thermoelectric device. Then water is further removed using Nafion® gas dryers before reaching the IR analyzer. The counterflow gas in the dryer is pre-dried outside air. Typical water content of the analyzed gas is less than 3 millimoles/mole with approximately 90% of the water being removed.

The infrared analyzer is calibrated regularly using four standard gases (200 – 600 ppm CO2 in air) from Apel-Riemer Environmental Inc. (Miami, FL). Before use in the field, these standards were calibrated using primary reference gases from the laboratory of Dr. Charles D. Keeling and from the NOAA Earth System Research Laboratory (Boulder, CO), which are directly traceable to the WMO scale. The zero gas of ultra-high purity air is analyzed regularly also. Any value outside the range of the standards should be considered approximate (±5 ppm). While individual data points above the highest standard or below the lowest standard may less accurate, the general trends would be indicative of the seawater chemistry. The standards used on a particular cruise are listed in the individual readme file.

Sea water is drawn into the ship through a dedicated inlet near the bow in the starboard-side engineering technical room. A temperature sensor (SBE38) is located between the inlet and the sea water pump, which pushes water through the instruments in the port-side fresh water room and out a dedicated exit valve. The transit from the inlet to the pCO2 equilibrator takes ~140 seconds and the water warms approximately 0.2 degree Celsius.

Seawater is pushed through a spray head into an equilibration chamber with a 0.4 L continuously flushed water pool and a 0.6 L gaseous headspace. Water flow rate is 2.0-2.5 L/min. The equilibrator headspace gas is recirculated through the analyzer and back during EQU analyses at 80 – 100 ml/min.

It is hoped that the system will also measure the CO2 content of ambient air; however, a suitable route for the air inlet tubing has yet to be found. The data file structure will include columns for the air analyses, but these columns will not contain meaningful data till an air inlet is installed.

The GPS position and data from other sensors are provided to the CO2 analytical system by the RSMAS Marine Technology Group, who also maintain the scientific sea water infrastructure. Data is transferred within the ship and between the ship and land via a virtual private network provided by the RCI and RSMAS. The CO2 data is transmitted back to land each day to monitor the analytical system’s performance.

A typical sequence of continuous analyses is:

STEP TYPE REPETITIONS
1 – Standards (all four) – 1
2 – EQU – 100

The amount of time between analyses depends on whether the analyses are of the same type of gas (e.g., STD, EQU) or not. When switching between different gases, the connecting tubes and analyzer are flushed for an initial interval called the ‘PRE-FLUSH’ time plus an interval called the ‘REGULAR FLUSH’ time. Between successive measurements of the same type of gas, the system is flushed for only the ‘REGULAR FLUSH’ time. The gas flow is then stopped. After the ‘STOP FLOW’ time interval, which is 10 seconds for all analyses, the output of the NDIR analyzer is read. The pre-flush time is set to 180 seconds and the regular flush time is set to 60 seconds for standard analyses. Both the pre-flush and regular flush times are 120 seconds for equilibrator headspace analyses. With these settings, a complete set of standards is done every 5 hours and a full day contains about 490 analyses of the equilibrator headspace.

Calculations

The measured xCO2 values are linearly corrected for instrument response using the standard measurements (see Pierrot et al., 2009).

For the equilibrator headspace the fCO2eq is calculated assuming 100% water vapor content:

fCO2 = xCO2 P (1-pH2O) exp[(B11+2d12)P/RT]

where fCO2 is the fugacity in ambient air or equilibrator headspace, pH2O is the water vapor pressure at the sea surface or equilibrator temperature, P is the equilibrator or outside atmospheric pressure (in atm), T is the SST or equilibrator temperature (in K) and R is the ideal gas constant (82.057 cm&^3·atm·deg^-1·mol^-1). The exponential term is the fugacity correction where B11 is the first virial coefficient of pure CO2

B11 = -1636.75 + 12.0408 T – 0.0327957 T^2 + 3.16528E-5 T^3

and

d12 = 57.7 – 0.118 T</span?

is the correction for an air-CO2 mixture in units of cm^3·mol^-1 (Weiss, 1974).

The fugacity as measured in the equilibrator is corrected for any temperature difference between sea surface temperature and equilibrator chamber using the empirical correction outlined in Takahashi et al. (1993).

fCO2(SST) = fCO2(teq)exp[0.0423(SST-teq)]

where fCO2(SST) is the fugacity at the sea surface temperature and fCO2(teq) is the fugacity at the equilibrator temperature. SST and teq are the sea surface and equilibrator temperatures in degrees C, respectively.

The amount of time between the sea water passing by the SST (SBE38) sensor and the water flowing through the equilibrator is estimated before assigning an SST value to each analysis. The patterns in the temperature records for the equilibrator and for SST over time are compared, and a time offset that optimizes the match of these patterns is determined. The time offset is applied to the SST measurements. A linear interpolation between the time-adjusted SST data yields the SST value assigned to each CO2 analysis and used in the fugacity calculations.

Data File Structure

List of variables included in this dataset:

COLUMN

HEADER

EXPLANATION

1.

EXPOCODE

Expedition code, where ‘????’
is the NODC ship identifier,
and YYYYMMDD is the UTC date that
the ship starts the expedition

2.

Group_Ship

AOML__Flora, (if present)

3.

Cruise_ID

Dependent upon expedition’s name, (if present)

4.

YD_UTC

Decimal year day

5.

DATE_UTC_ddmmyyyy

UTC Date

6.

TIME_UTC_hh:mm:ss

UTC Time

7.

LAT_dec_degree

Latitude in decimal degrees (negative values are in southern hemisphere)

8.

LONG_ dec_degree

Longitude in decimal degrees (negative values are in western hemisphere)

9.

xCO2_EQU_ppm

Mole fraction of CO2 in the equilibrator headspace (dry) at equilibrator temperature, in parts per million

10.

xCO2_ATM_ppm

Mole fraction of CO2 in outside air in parts per million, (if present)

11.

xCO2_ATM_interpolated_ppm

xCO2 in outside air associated with each water analysis. These values are interpolated between the bracketing averaged good xCO2_ATM analyses, in parts per million, (if present)

12.

PRES_EQU_hPa

Barometric pressure in the equilibrator headspace, in hectopascals (1 hPa = 1 millibar)

13.

PRES_ATM@SSP_hPa

Pressure measured by outside barometer, corrected to sea level, in hectopascals

14.

TEMP_EQU_C

Water temperature in equilibrator, in degrees centigrade

15.

SST_C

Sea surface temperature from the ship’s remote temperature sensor, in degrees centigrade [interpolated, see note above]

16.

SAL_permil

Salinity from the thermosalinograph (SBE45), on the Practical Salinity Scale

17.

fCO2_SW@SST_uatm

Fugacity of CO2 in sea water, in microatmospheres (100% humidity)

18.

fCO2_ATM_interpolated_uatm

Fugacity of CO2 in air corresponding to the interpolated xCO2, in microatmospheres (100% humidity), (if present)

19.

dfCO2_uatm

Sea water fCO2 minus interpolated air fCO2, in microatmospheres, (if present)

20.

WOCE_QC_FLAG

Quality control flag for fCO2 values (2 = good value, 3 = questionable value)

21.

QC_SUBFLAG

Quality control sub flag for fCO2 values provides explanation for atypical data, when QC_FLAG = 3

The quality control flags are provided as an aid to the interpretation of the CO2 data. Stringent minimum and maximum values for numerous parameters (e.g.temperature difference between the equilibrator temperature and SST) have been established by CO2 researchers (see Pierrot et al., 2009). These ranges were chosen so that if each parameter were within their stringent range, the resulting CO2 data would almost certainly be good. If a parameter is outside its range or if a parameter is estimated from surrounding good values, the quality flag of that data record is set to 3 (questionable value). The resulting CO2 data could be good; however, investigators should determine whether these data are valid for their purposes.

References

DOE (1994). OE (1994). Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water; version 2. DOE.

Feely, R. A., R. Wanninkhof, H. B. Milburn, C. E. Cosca, M. Stapp and P. P. Murphy (1998).  A new automated underway system for making high precision pCO2 measurements onboard research ships. Analytica Chim. Acta 377: 185-191.


Ho, D. T., R. Wanninkhof, J. Masters, R. A. Feely and C. E. Cosca (1997). Measurement of underway fCO2 in the Eastern Equatorial Pacific on NOAA ships BALDRIGE and DISCOVERER, NOAA data report ERL AOML-30, 52 pp., NTIS Springfield.


Pierrot, D., C. Neill, K. Sullivan, R. Castle, R. Wanninkhof, H. Luger, T. Johannessen, A. Olsen, R. A. Feely, and C. E. Cosca (2009). Recommendations for autonomous underway pCO2 measuring systems and data-reduction routines. Deep Sea Research II, 56: 512-522.


Wanninkhof, R. and K. Thoning (1993) Measurement of fugacity of CO2 in surface water using continuous and discrete sampling methods. Mar. Chem. 44(2-4): 189-205.


Weiss, R. F. (1970). The solubility of nitrogen, oxygen and argon in water and seawater. Deep-Sea Research 17: 721-735.


Weiss, R. F. (1974). Carbon dioxide in water and seawater: the solubility of a non-ideal gas. Mar. Chem. 2: 203-215.


Weiss, R. F., R. A. Jahnke and C. D. Keeling (1982). Seasonal effects of temperature and salinity on the partial pressure of CO2 in seawater. Nature 300: 511-513.


Takahashi, T., J. Olafsson, J. G. Goddard, D. W. Chipman, and S. C. Sutherland (1993). Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: a comparative study, Global Biogeochem. Cycles, 7, 843-878.

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