SMRU Fine-Scale Harbour Seal Usage GIS files 

This version 2016-12-06
Prepared by Clint Blight, SMRU
E-mail: cjb22@st-andrews.ac.uk

This is a basic "READ ME" for the GIS files of fine-scale harbour seal
at-sea usage estimates for a region around Orkney and the North coast
of Scotland. These were produced for Marine Scotland by the Sea Mammal
Research Unit. (MSQ-0174, Contract Research Fund - Ref CR/2014/11)

A modelling process has been used to combine harbour seal telemetry 
data (from 2003-2015), terrestrial count data (from 2008 to 2015) 
and environmental covariates to produce estimated at-sea usage and 
associated 95% confidence intervals for harbour seals (Phoca vitulina). 
The region of interest for this study was an area around Orkney and the 
North coast of Scotland, represented in these files a 200 column 
by 212 row grid of 600 m by 600 m cells specified using the UTM 
Zone 30N (WGS84) projection (EPSG:32630).

Corner coordinates of the grid:

               Easting     Northing       Longitude     Latitude
 Upper Left  ( 443000.000, 6613600.000) ( 4d 0'41.31"W, 59d39'23.67"N)
 Lower Left  ( 443000.000, 6486400.000) ( 3d58'42.27"W, 58d30'51.93"N)
 Upper Right ( 563000.000, 6613600.000) ( 1d52'55.47"W, 59d39'20.56"N)
 Lower Right ( 563000.000, 6486400.000) ( 1d55' 7.03"W, 58d30'48.95"N)

These predictions can be interpreted as the average number of
harbour seals in each 600 m by 600 m grid cell at any point in time. 
Age and sex-structure of tagged animals may not be representative of
their populations as demographic data were aggregated. Count data is 
not representative of breeding populations. Such telemetry datasets 
represent variable temporal sampling effort. The effect of anthropogenic 
activities on seal spatial distributions were not considered. 

The estimation of mean seal usage (and corresponding uncertainty)
is an involved process. The resulting gridded values should thus be
interpreted with care. For further details on how these usage estimates
were generated please refer to the relevant Scottish Marine and 
Freshwater Science Report - "Fine-scale harbour seal at-sea usage 
mapping around Orkney and the North coast of Scotland" by Esther L. Jones,
Sophie Smout, Clint Blight, Carol Sparling and Bernie McConnell.

N.B. As with previous 5 km x 5 km usage maps, usage has the largest
spatial extent possible. At-sea locations use kernel smoothing to
change point locations to a usage surface. This can create usage
inland, so to accurately sum usage in an area, ensure that all local
onshore and offshore grid cells are summed.   


The values in these GIS files
-----------------------------

CellID
  A unique ID for each 600 m by 600 m cell within the 200 x 212 
  UTM 30N (WGS84) projected grid

Land
  The GSHHS derived land mask used during some of the processing steps
  (N.B. as per caveat above, the values for nearby land cells should be  
  considered whenever summing the at-sea usage in an area)

PvSeaUsage
  Harbour seal (Phoca vitulina) at-sea usage estimated value
  
PvSeaLower
  Harbour seal (Phoca vitulina) at-sea usage 95% lower confidence interval
  
PvSeaUpper
  Harbour seal (Phoca vitulina) at-sea usage 95% upper confidence interval


The Shapefiles
---------------

 All the cells from the original UTM 30N grid are represented as square
 polygons in the original UTM zone 30N WGS84 projection. (N.B. As such
 they may not appear as squares when shown using other projections)

 There are four separate sets of shapefiles (.shp,.dbf,.prj and .shx), one 
 each for PvSeaUsage,PvSeaLower,PvSeaUpper and Land values.

 Each shapefile file has two fields/attributes:  
    One named after the parameter in question, the other being the "CellID" 

 E.g. At-sea harbour seal usage values:
        PvSeaUsage.dbf has attributes "PvSeaUsage" and "CellID"
        PvSeaUsage.prj projection data (UTM Zone 30N WGS84) 
        PvSeaUsage.shp polygon coordinates
        PvSeaUsage.shx index information


The GeoTIFF files
-----------------

 N.B. These are GeoTIFF files containing 64-bit floating point 
 values and are intending for use in a GIS rather than standard
 image viewing software.
   
 The GeoTIFF files are named as per the attributes of the shapefiles above:  
    CellID.tif, Land.tif, PvSeaUsage.tif, PvSeaLower.tif & PvSeaUpper.tif

 They provide the values on the original UTM 30N (WGS84) 600 m x 600 m grid.
 The projection information is embedded in the TIFF headers and also supplied 
 separately (UTM30N.prj, UTM30N_OGC.wkt, UTM30N_PROJ4_string.txt)

 ArcGIS layer files (PvSeaUsage.lyr, PvSeaLower.lyr and PvSeaUpper.lyr) and
 a QGIS 2.18 Style file (PvAtSeaQgisRasterStyle.qml) are also supplied to 
 assist those who may wish to recreate the same sort of colouring as was used
 for the maps in the associated report. (That was a continuous scale with 
 specified colours at 0.0, 0.1, 0.5, 1.0 and 2.0.) 
 
 E.g. At-sea harbour seal usage values are in PvSeaUsage.tif
 and running the gdalinfo utility on that file gives:
 
	Driver: GTiff/GeoTIFF
	Files: PvSeaUsage.tif
	Size is 200, 212
	Coordinate System is:
	PROJCS["UTM Zone 30, Northern Hemisphere",
		GEOGCS["WGS 84",
			DATUM["unknown",
				SPHEROID["WGS84",6378137,298.257223563]],
			PRIMEM["Greenwich",0],
			UNIT["degree",0.0174532925199433]],
		PROJECTION["Transverse_Mercator"],
		PARAMETER["latitude_of_origin",0],
		PARAMETER["central_meridian",-3],
		PARAMETER["scale_factor",0.9996],
		PARAMETER["false_easting",500000],
		PARAMETER["false_northing",0],
		UNIT["metre",1,
			AUTHORITY["EPSG","9001"]]]
	Origin = (443000.000000000000000,6613600.000000000000000)
	Pixel Size = (600.000000000000000,-599.999999999995570)
	Metadata:
	AREA_OR_POINT=Area
	Image Structure Metadata:
	COMPRESSION=LZW
	INTERLEAVE=BAND
	Corner Coordinates:
	Upper Left  (  443000.000, 6613600.000) (  4d 0'41.31"W, 59d39'23.67"N)
	Lower Left  (  443000.000, 6486400.000) (  3d58'42.27"W, 58d30'51.93"N)
	Upper Right (  563000.000, 6613600.000) (  1d52'55.47"W, 59d39'20.56"N)
	Lower Right (  563000.000, 6486400.000) (  1d55' 7.03"W, 58d30'48.95"N)
	Center      (  503000.000, 6550000.000) (  2d56'51.53"W, 59d 5'21.58"N)
	Band 1 Block=200x5 Type=Float64, ColorInterp=Gray
	Min=0.000 Max=5.647
	Minimum=0.000, Maximum=5.647, Mean=0.057, StdDev=0.163
	NoData Value=-1.6999999999999999e+308
	Metadata:
		STATISTICS_MAXIMUM=5.6470434500803
		STATISTICS_MEAN=0.057085930784607
		STATISTICS_MINIMUM=0
		STATISTICS_STDDEV=0.16297899544702
