Missing data
Breaks in the lines on the temperature graphs occur where there are missing data. For the purpose of this illustration, annual averages are calculated only where there is a complete year of monthly values available on the NIWA Climate Database. In the case of Albert Park, some data are missing due to persistent vandalism of equipment there. In other cases, the most common reason for missing data is a faulty gauge.
Length of records
Albert Park extends back in time much earlier than 1950, but we focus here on the period where Albert Park overlaps with other Auckland sites.
Mangere closed in July 1998 so a full year figure cannot be calculated for this site for 1988.
From mid-1998 onwards, Auckland Aero data are used in the Auckland composite record.
Period of trend
The calculated trend line (linear regression best fit) depends on the period of record used. For example, Albert Park has a steeper warming trend over 1950-1975 than over 1950-1989.