MnrAq

Annex 5 243
temporal coverage QA/QC). This analysis provides a derivation for the relationship between coverage and
uncertainty in the days spent at sea, which, in combination with the per-hour uncertainty estimates, is applied
to calculate the total uncertainty in the annual CO 2 emissions estimate.
Estimate of uncertainty of the input parameters and method
The assumptions used to estimate the uncertainty in the annual fuel consumption of an average ship in a given
ship type and size category are listed in Table 19.
Table 19 – Estimated parameters for the uncertainty in the inputs
to the annual emissions calculation
Period Input parameter Mean Standard deviation
Per annum (observed and Ratio of days at sea to days at port Taken from LRIT to AIS analysis derived relationship
unobserved)
per year
When observed on AIS Average emissions per hour at sea Read in from the per-hour uncertainty analysis
Average emissions per hour in port
When not observed on AIS
Average emissions per hour at sea
Average emissions per hour in port
Results
The output of the simulation of the per-year uncertainty analysis, using the outputs from the per-hour uncertainty
analysis, can be seen in Figure 30 and Figure 31. Both plots depict the bulk carrier size category 60–99,999
dwt. The first of the two plots characterizes the uncertainty in 2007, a year when the average ship in that type
and size category was observed on AIS for just 14% of the year. This contrasts with the second plot, which is
calculated for 2012, when the AIS coverage of the average ship was 65% and the uncertainty greatly reduced.
Figure 30: Uncertainty around the annual emissions (x-axis is ‘00,000 tonnes of CO 2 ;
y-axis is frequency) from a Monte Carlo simulation of an “average”
Panamax bulk carrier (60,000–99,999 dwt capacity) in 2007