Bloom Index

Overview

The bloom index algorithm produces one value per day, a numeric code. The basic steps of the algorithm are

1. Average the chlorophyll data to nightly values.

2. Compute the rate of change and rate of growth.

3. Loop thru the time series. Conditions which would constitute the start of an event would be a large rate of growth (>0.45). If the rate of growth is larger than 0.80, then it may be an advection event. If an event lasts longer than a given number of days, then the event classifies as a bloom event. Conditions which will cause the event to end include

   1. Invalid data.

   2. An advective rate of growth immediately followed by a sizably large decrease, which leads us to believe that it really was an advection event.

   3. If the mean growth rate over the window falls below zero, then we the event has been on a long downhill slide.

   4. If the running cumulative sum of delta chl falls below zero, then we have less chlorophyll than when we started.

Input

1. chlorophyll time series in micrograms/liter

2. The window length in days is required. This provides a period of time over which an event must sustain itself before being labeled a bloom.

Ancillary Requirements

None.

MATLAB m-file

compute_bloom_index.m

Output