• How are the statistics computed for the 'Query by Box' type
queries ?
- Pixel filtering: We assume that there can be some outlier pixels present in the area of study (for e.g. due to noise or incomplete quality checks). These pixels are not of interest in the computation of the statistics and are therefore omitted in the mean, max, min and std dev. calculations. In order to filter these outlier pixels we proceed with a two step approach: first the mean μ and the standard deviation σ2 are computed over all the data in the selected box, and then the values outside the range μ±2σ are rejected. The mean, max, min and std. dev. are then re-computed on the remaining values.
- Mean and Standard Deviation computation: We apply two different methods to compute the mean and standard deviation values over a selected box: 1) Arithmetic mean over N pixels representing the average of the product data set assuming normal distribution. This method is applied to all Physical variables, Indicators and PAR; 2) Geometric mean representing the average of the product assuming log-normal distribution (i.e. if logX is normally distributed, see Campbell 1995). This method is applied to Chlorophyll-a, Primary Production and Diffuse Attenuation Coefficient.
• Why are some physical variables not represented for the whole European window ? All physical variables (with the exception of the SST) are climatology numerical model output resulting from different models around Europe (see Physical variables), and therefore some regions are still missing. In the near future all European regions will be covered with inter-annual data.
• Is it possible to have access to the raw data ? Due to the proprietary rights of the satellite and model data we cannot give access to the raw data. If you need such data for scientific purposes you can send us a request by email explaining the nature of your research.
• Why are the indicators not represented for the whole European window ? The indicators are calculated for shallow and coastal areas, i.e. where the depth is not greater than 100 metres (see Available Results).
• Can I save the images in any other format than PDF ? Images (maps and graphs) can also be saved in PNG (Portable Network Graphic) format: right click on the image and then 'Save Image As'.
• How often is AMIS updated with the latest data ? We try to update AMIS every year.
