Carbon monoxide climatology derived from the trajectory mapping of global MOZAIC-IAGOS data
A three-dimensional gridded climatology of carbon monoxide (CO) has been developed by trajectory mapping of global MOZAIC-IAGOS in situ measurements from commercial aircraft data. CO measurements made during aircraft ascent and descent, comprising nearly 41 200 profiles at 148 airports worldwide...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/10263/2016/acp-16-10263-2016.pdf |
| Summary: | A three-dimensional gridded climatology of carbon monoxide (CO) has been
developed by trajectory mapping of global MOZAIC-IAGOS in situ measurements
from commercial aircraft data. CO measurements made during aircraft ascent
and descent, comprising nearly 41 200 profiles at 148 airports worldwide
from December 2001 to December 2012, are used. Forward and backward
trajectories are calculated from meteorological reanalysis data in order to
map the CO measurements to other locations and so to fill in the spatial
domain. This domain-filling technique employs 15 800 000 calculated
trajectories to map otherwise sparse MOZAIC-IAGOS data into a quasi-global
field. The resulting trajectory-mapped CO data set is archived monthly from
2001 to 2012 on a grid of 5° longitude × 5°
latitude × 1 km altitude, from the surface to 14 km altitude.<br><br>The mapping product has been carefully evaluated, firstly by comparing maps
constructed using only forward trajectories and using only backward
trajectories. The two methods show similar global CO distribution patterns.
The magnitude of their differences is most commonly 10 % or less and
found to be less than 30 % for almost all cases. Secondly, the method has
been validated by comparing profiles for individual airports with those
produced by the mapping method when data from that site are excluded. While
there are larger differences below 2 km, the two methods agree very well
between 2 and 10 km with the magnitude of biases within 20 %. Finally, the
mapping product is compared with global MOZAIC-IAGOS cruise-level data,
which were not included in the trajectory-mapped data set, and with
independent data from the NOAA aircraft flask sampling program. The
trajectory-mapped MOZAIC-IAGOS CO values show generally good agreement with
both independent data sets.<br><br>Maps are also compared with version 6 data from the Measurements Of
Pollution In The Troposphere (MOPITT) satellite instrument. Both data sets
clearly show major regional CO sources such as biomass burning in Central
and southern Africa and anthropogenic emissions in eastern China. While the
maps show similar features and patterns, and relative biases are small in
the lowermost troposphere, we find differences of ∼ 20 % in
CO volume mixing ratios between 500 and 300 hPa. These upper-tropospheric
biases are not related to the mapping procedure, as almost identical
differences are found with the original in situ MOZAIC-IAGOS data. The total
CO trajectory-mapped MOZAIC-IAGOS column is also higher than the MOPITT CO
total column by 12–16 %.<br><br>The data set shows the seasonal CO cycle over different latitude bands and
altitude ranges as well as long-term trends over different latitude bands.
We observe a decline in CO over the northern hemispheric extratropics and the
tropics consistent with that reported by previous studies using other data
sources.<br><br>We anticipate use of the trajectory-mapped MOZAIC-IAGOS CO data set as an a
priori climatology for satellite retrieval and for air quality model
validation and initialization. |
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| ISSN: | 1680-7316 1680-7324 |