Water Column Temperature Statistics    

Data source:	Resource Assessment and Conservation Engineering (RACE) Eastern Bering Sea
summer survey water temperatures collected during the down cast of the net.
Thanks to the many years of data collection by the RACE groundfish group.

Data notes: 
The statistics were calculated after the top 5.5 meters of the data were removed.
The surface layer is greatly influenced by the daily weather and was removed to better
delineate the summer long temperature patterns.

80s data includes 1982-1989 plus 1990 vessel 78. (Only inflexion points were recoded.)
For each profile a record was generated for 5.5m based on the nearest record above and below.
Since many of the 80s profiles ended after the last inflexion point, a record was added
to the profile when gear_depth  >  deepest profile depth + 5m.  The record consisted
of gear_depth and the last temperature of the profile.

90s data includes 1991-2006 plus 1990 vessel 37.  Temperatures occurring at the same depth
were averaged.  The down cast usually includes some bouncing around of the gear before it
smoothly descends.  Averaging the temperatures at the same depth alleviates
some of the surface noise.

Data identifiers taken from racebase.haul:
cruise, vessel, haul, stationid, start_lati (latitude), start_long (longitude), start_time

Data:
toptemp - top of the water column temperature 
topdepth - top depth of the water column 
90s data - The next available depth after removing the top 5.5m.
80s data - Usually the inserted record at 5.5m.
bottemp - bottom temperature (last temperature in profile)
botdepth - bottom depth 
90s data - The bottom depth is lowest depth found in the profile.
80s data - The bottom depth is lowest depth of the revised profile.
top2bot = surface temperature - bottom temperature

maxtemp - maximum temperature 
mintemp - minimum temperature
temprange = maximum temperature - minimum temperature
max2 - maximum depth of 2 degrees and colder
min2 - minimum depth of 2 degrees and colder
ext2 = maximum depth of 2 degrees - minimum depth of 2 degrees
maxzero - maximum depth of 0 degrees and colder
minzero - minimum depth of 0 degrees and colder
extzero = maximum depth of 2 degrees - minimum depth of 0 degrees

toplaytemp - Average temperature of top layer
toplaydepth - The lower depth of top layer.  Temperatures from the top depth to this
depth stay less than or equal to 1 degree.

botlaytemp - Average temperature of bottom layer
botlaydepth - The upper depth of bottom layer.  Temperatures from this depth to the 
bottom depth stay less than or equal to 1  degree.

midlayext = botlaydepth - toplaydepth
In 23% of the casts midlayext are negative of which 20.5% of the casts are mixed
top to bottom and the rest have overlapping mixed layers.
midlayslope = (toplaytemp - botlaytemp) / (midlayext) where midlayext > 0

Delta calculations:
A weeding algorithm was applied to the 90s data to approximate 1 meter intervals.
First each point was assigned to a 1 meter bin by rounding depth to the nearest whole meter.
Next only one point from each bin was kept, the point closest to the whole meter.
    
On the interval 5.5m-30m       
negdelta30  - maximum decrease degree C. per meter while descending the water column
 (increasing temperatures are set to null)
negdepth30 - mid depth of the interval where maximum decrease in temperature occurred

same for 30m-75m       (shallow stations are set to null)
negdelta75 
negdepth75 

same for 75m-bottom       
negdelta90 
negdepth90 

maxdelta =  maximum decrease degree C. per meter while descending the water column on the 
interval from 5.5m to the bottom. (increasing temperatures are set to null)
maxddelta = mid depth of the interval where the maxdelta was found
posmaxdelta = maximum increase in degree C. per meter while descending the water column on
	the interval from 5.5m to the bottom.(decreasing temperatures are set to null)
posmaxddepth = mid depth of the interval where posmaxdelta was found.