Merge pull request #7 from eurec4a/conventions-revision

Updated conventions to reflect conversation in issue #2

README.md

@@ -5,37 +5,35 @@ For example circles and straight legs were purposefully conducted maneuvers duri
 a distinct sampling behaviour of the various instruments can be assumed. For future analyses
 based on specific kinds of flight segments (e.g. only based on circles) it is desired to use a
 common set of start- and end-times to assure consistency between the studies. This repository
-provides the start- and end-times of the flight-segments for each RF together with some  very
-general information about the RF or special events during the RF.
+provides files listing the start- and end-times of  flight segments for each platform for each flight. The files also contain general information and/or notes about special events during the RF.
 
 Flight segments need not be unique or complete: a given time during a flight may belong to
 any number of segments or none at all. Segments may overlap (i.e. a segment of kind `circling`
-may include several segments of kind `circle`) although a time window should belong to only
-one segment of a given kind.  
+may include several segments of kind `circle`). This allows flights to be segmented
+in multiple ways and at multiple levels of granulatiry.
 
-### Primary flight segment kinds
-Data providers are encouraged to use following the segment kinds to describe broad flight phases.
-Reporting and validation tools within this repo will be based on this list. Each segment should
-include only one of the following in its list of kinds.
+
+### Common vocabulary - broad sampling strategy
+Following are names of segments assembled from a range of platforms describing broad sampling strategies. Many will contain subsets
+e.g. `cloud` segments will likely contain `subcloud layer` and `cloud layer` segments.
+Data providers are encouraged to use these names, especially those in the first, where applicable.
+Feel free to add the the list (e.g. with a Github pull request) if needed.
 * ground
+* transit
 * circle
 * cloud
 * calibration
 * profile
-* level
 * axbt
 * rectangle
 * sawtooth
 * racetrack
 * clover
 
-### Secondary flight segment kinds
-Segments may be of arbitrary kind; where the following kind labels are applicable data providers are encouraged
-to use the same kinds across platforms.
-
+### Common vocabulary - subsets/refinements and super-sets
 * circling: describes multiple consecutive circles.
-* profile-upward: provides further detail for `profile` segments
-* profile-downward: provides further detail for `profile` segments
+* upward: primarily ascending, could be used as further detail for `profile` segments
+* downward: primarily descending, could be used as further detail for `profile` segments
 
 The following kinds describe level flight legs sampling atmospheric structure:
 * surface level
@@ -44,8 +42,9 @@ The following kinds describe level flight legs sampling atmospheric structure:
 * cloud layer
 * inversion level
 * above cloud
+* in cloud (these may be many and short)
 
-### Platform-specific kinds
+### Platform-specific subsets
 Platforms are free to adopt other conventions exploiting the ability for a segment to have more than one kind associated with it.
 
 The ATR uses the following sub-kinds of certain `level` segments:
@@ -57,3 +56,7 @@ HALO uses the following sub-kinds of the `calibration` kind:
 * radar_calibration_wiggle
 * radar_calibration_tilted
 * baccardi_calibration
+
+## Conventions
+Flight segmentation is designed to be flexible and unstructured, but we propose that data providers follow the convention that
+_a time or time window may not belong to more than one segment of the same kind_