Trace gas datasets - naming conventions and data formats

File naming conventions

Data files are stored under the “tropac” subdirectory on the NIWA anonymous FTP site in a series of sub-directories classified first by gas species and then by sampling site or platform (aircraft, ship, etc).

Subfolders for different species are as follows:

aerosols

currently empty, but will contain aerosol data

ch4

methane data

co

carbon monoxide data

co2

carbon dioxide data

mdl

currently empty but will contain computer model results and code

nmhc

Non-methane hydrocarbon data (C2H2, C2H4, C2H6, C3H6, C3H8,

C6H6, C6H7, iC4H10, nC4H10, iC5H12, nC5H12 )

n2o

nitrous oxide data

o2

currently empty but will contain oxygen data

o3

surface ozone data

papers

reports and publications available for downloading

 

At the next level down subfolders for different sites or platforms are currently as follows:

arh

Arrival Heights (Scott Base), Antarctica

bhd

Baring Head clean air station

lau Lauder atmospheric research station

pac

Sampling across the Pacific Ocean on Blue Star Line ships (BSL) between New Zealand and the United States, and Fuji TransWorld (FTW) ships between New Zealand and Japan.

suv

University of the South Pacific, Suva, Fiji

 

Data files follow a naming convention as follows:

The filename prefix is the site or platform code as above and generally duplicates the subdirectory name. For large amounts of data, the filename prefix also specifies a date range or release date (e.g. for hourly data separated by year this could be “1990”, “1991” etc.).

For measurement/sample data, the file extension specifies the gas species measured, and can also specify the measurement technique as follows:

code

Species

Measurement

Units

co2nd

Carbon dioxide

NDIR

ppm

co2gc

Carbon dioxide

GC

ppm

co2d13

Carbon dioxide

d13C

dimensionless ‰

co2d14

Carbon dioxide

D14C

dimensionless ‰

ch4

Methane

GC

ppb

ch4d13

Methane

d13C

dimensionless ‰

ch4d14

Methane

D14C

dimensionless ‰

Co_m

Carbon monoxide

Manometric

ppb

Co_g

Carbon monoxide

GC

ppb

cod13

Carbon monoxide

d13C

dimensionless ‰

cox14

Carbon monoxide

14CO molec/cc(STP)

number density

dicma

Sea water dissolved inorganic carbon

Manometric (extraction line)

µmole/kg-seawater

n2o

Nitrous oxide

GC

ppb

o3

Surface ozone

UV photometry

ppb

 

A file extensions .mts is for monthly series (i.e. interpolated values for mid-point of each month)


File formats

Unless noted otherwise in “readme.txt” files, data files are ASCII text files organised as columns of data with one or more spaces as column separators. The standard format used for “grab sampling” is as follows:

 

 

Field

width

example

 

platform/ site code

3

BHD

Sampling time (start of)

 

 

 

year

4

1989

 

month

2

11

 

day

2

27

 

hour

2

13

 

minute

2

43

Sampling location

 

 

 

latitude (decimal degrees)

6

-41.42

 

longitude (decimal degrees)

7

174.87

 

altitude (m)

5

85

Result

 

 

 

 

value

7

1745.1

 

error

6

4.2

Flags

 

 

 

 

sampling conditions flag

1

2

 

collection/ storage flag

1

0

 

measurement flag

1

1

other

 

 

 

 

sampling duration (min)

5

1

 

(unique) sample-ID

6

G1847

 

analysis-ID (optional)

12

891214/56

 

 

 

 

 

wind speed (m/s)

3

22.1

 

wind direction (degrees)

3

175

 

 

 

 

 

source file for data used (for CO2)

12

SIPICK1998a.DAT

 

Use of the 3 data flags depends on the nature of the sampling and analysis used to obtain the measurement. Please consult the scientists cited in the appropriate “readme.txt” file for details.

Data formats for continuous measurements and other more extensive datasets are described in the appropriate “readme.txt” or “readme.doc” files.