Resample Type:

• None - no resampling.
• Average - the mean value within resample period (fixed-window averaging without overlap). This is also known as a 'box-car' or ensemble average.
• Minimum/Maximum - Temporarily disabled - the most extreme minimum and maximum values within resample period. (Time stamps of the minimum/maximum values are not provided at this time, only the bin-centered time stamp. This option may become available again once additional time-stamps provided and performance with QAQC is improved.)

Resample Period:

• Minute
• Hour
• Day

When resampling is selected:

• The timestamps in the data series correspond to the centre of each resampling interval. (Data downloaded prior to 13 Feb 2013: timestamps were at beginning of interval). The resample interval always begins and ends at an integer multiple of the resample period, so minutes on the minute, hours on the hour, days on the day, etc.
• If the date/time range on the search has limits that are within a resampling interval, the date/time endpoints are extended to include the entire resampling interval. For example, when daily resampling is selected from 03:00:00.000 on Monday to 20:00:00.000 on Thursday, the date range is extended to 00:00:00.000 on Monday to 23:59.59.999 on Thursday.
• Note that tides are not filtered out in resampled products.
• No anti-alias filtering is done. This is why only averaging and min/max are offered at this time. Box-car / ensemble averaging is an easily understood and ubiquitous process that is actually a partially effective low-pass anti-alias filter. For more information, see this page on data reduction and time-averaging.
• Average and Minimum/Maximum values will not be provided if less than a certain percentage (default 80%) of the expected samples per resampling interval are present (either because of data gaps or low data quality). (Data downloaded before 21 Mar 2013: No data completeness or quality assurance was tested for.)
• All averages are calculated by adding all individual samples and then divide by the total number of samples. (Data downloaded before 13 Feb 2013: hourly and daily averages were weighted over 15-minute periods, that is, the average of each 15-minute period was calculated individually, and the hourly and daily averages were calculated from the 15-minute averages.)

More options may be available in the future. For more complex subsampling, CodeRunner (see CodeRunner Help ) is an alternative resource.