Split and Merge

In the tracking process using the area overlapping method (OverlapAreaTracker), TATHU is able to define split and merge events for CS. The ConvectiveSystem class has an attribute to indicate these events - event. In total, 5 types are considered:

https://raw.githubusercontent.com/uba/tathu/master/docs/sphinx/img/system-events.png — Figure 5 - CS events: (a) continuity, (b) split and (c) merge. The dashed lines represent the systems at time t − ∆t. Adapted from Vila et al. (2008) [1].

Spontaneous Generation: the CS is identified in one image, however, it is not present in the previous image or does not meet the minimum area overlapping criterion. This is the default event;
Natural Dissipation: It’s the end of the system’s lifecycle, not identified or tracked in the current image;
Continuity: the CS is identified in an image and is present in the previous image, i.e. meets the minimum area overlap criterion;
Split: at time t, there is an CS that satisfies the minimum area overlap criterion with two or more systems at time t − ∆t;
Merge: at time t − ∆t, there are two or more CS that obey the minimum area overlap criterion with only one system at time t.

Computationally:

class LifeCycleEvent(Enum):
    '''
    Enumeration that represents the life cycle events of convective systems.
    '''
    SPONTANEOUS_GENERATION = 0
    NATURAL_DISSIPATION = 1
    CONTINUITY = 2
    SPLIT = 3
    MERGE = 4

class ConvectiveSystem(object):
    def __init__(self, geom):
        # (...)
        self.event = LifeCycleEvent.SPONTANEOUS_GENERATION

After the tracking process, each instant of time will have an associated description of the event. We can list these events from an SQL query, for example:

SELECT event, date_time FROM systems WHERE name='2f790224-9146-400c-b9c6-e11b685d4a3e';

Result:

event	date_time
SPONTANEOUS_GENERATION	2017-04-08 01:30:00
CONTINUITY	2017-04-08 02:00:00
CONTINUITY	2017-04-08 02:30:00
CONTINUITY	2017-04-08 03:00:00
CONTINUITY	2017-04-08 03:30:00
CONTINUITY	2017-04-08 04:00:00
MERGE	2017-04-08 04:30:00
MERGE	2017-04-08 05:30:00
CONTINUITY	2017-04-08 06:00:00
CONTINUITY	2017-04-08 06:30:00
CONTINUITY	2017-04-08 07:00:00
CONTINUITY	2017-04-08 07:30:00
CONTINUITY	2017-04-08 08:00:00
CONTINUITY	2017-04-08 08:30:00
CONTINUITY	2017-04-08 09:00:00
CONTINUITY	2017-04-08 09:30:00
CONTINUITY	2017-04-08 10:00:00
CONTINUITY	2017-04-08 10:30:00
CONTINUITY	2017-04-08 11:00:00
CONTINUITY	2017-04-08 11:30:00
CONTINUITY	2017-04-08 12:00:00
CONTINUITY	2017-04-08 12:30:00
CONTINUITY	2017-04-08 13:00:00
MERGE	2017-04-08 13:30:00
SPLIT	2017-04-08 14:00:00
CONTINUITY	2017-04-08 14:30:00
CONTINUITY	2017-04-08 15:00:00
CONTINUITY	2017-04-08 16:00:00

Footnotes