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4. %nakedsoftware.org opensource license, copyright 2010 stephane.poirier@oifii.org % %developed by Stephane Poirier, M.Sc. Optical Physics, Remote Sensing Application Software Developer (1991-2010) % %this function is part of oifii.org's ar\sp\ Microwave- derived 30-year Canada-Alaska Daily Temperature and Snowcover Databases library % %this function is part of oifii.org's ar\sp\'this folder' application (lauched with ar\sp\'this file'.m) %oifii.org's ar\sp\affiche_carte application is part of the oifii.org's ar\sp set of applications which %may also contain similar variant versions of this function with identical filename. % %A geophysical research paper about this work has been submitted in June 2009 for publication in JGR-Atmosphere %Royer, A. and Poirier S., Surface temperature spatial and temporal variations in North America from homogenized %satellite SMMR-SSM/I microwave measurements and reanalysis for 1979-2008, Journal of Geophysical Research - Atmosphere, %Submitted June 2009, http://www.oifii.org/tsatdb/Royer- Poirier_Microwave-derived-daily-surface- temperature_JGR2009JD012760_R2.pdf % %This study's database can be downloaded from the author web site at: %http://www.oifii.org/tsatdb/Royer-Poirier_Microwave-derived- daily-surface-temperature-db_1979-2008.zip % %this function is used to display the raw microwave raster data (NSIDC's SMMR and SSMI satellite, ref. nsidc.org) % %usage: % 20yymmmdd % %version 0.0, 20yymmmdd, spi, initial function draft % %nakedsoftware.org opensource license, copyright 2010 stephane.poirier@oifii.org

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7. %for easegrid north, calls ieasegrid(iopt,thelon,thelat,ascale) function [alon,alat]=pix2latlon(x,y1) if nargin<1 disp('usage: pix2latlon(x,y1)'); return; end % % function [lon, lat]=pix2latlon(x,y,head) % %Given an image pixel location (x,y) (1..nsx,1..nsy) %computes the lat,lon coordinates (lon,lat). The lat,lon returned %corresponds to the lower-left corner of the pixel. (Note % that is the upper-left in matlab image coordinates). If lat,lon %of pixel center is desired use (x+0.5,y+0.5) where x,y are integer %valued pixels % %Note: while routine will attempt to convert any (x,y) %values, only (x,y) values with 1 <= x <= nsx+1 and 1 <= y <= nsy+1 %are contained within image. % % INPUTS: % x,y - input pixel location % % OUTPUTS: % lon,lat - longitude, latitude % R=6371.228; C=25.067525; nsx=721; nsy=721; iopt=11; xdeg=360; ydeg=360; ascale=2*R/C; bscale=R; a0=-360; b0=-360; % y=y1; y=nsy-y1+1; % convert from matlab coordinates to SIR coordinates if iopt == -1 % image only (can't transform!) thelon=(x-1.0)/ascale+a0; thelat=(y-1.0)/bscale+b0; alon=thelon; alat=thelat; elseif iopt == 0 % rectalinear lat/long thelon=(x-1.0)/ascale+a0; thelat=(y-1.0)/bscale+b0; alon=thelon; alat=thelat; elseif (iopt == 1) | (iopt == 2) % lambert thelon=(x-1.0)/ascale+a0; thelat=(y-1.0)/bscale+b0; [alon,alat]=ilambert1(thelon,thelat,ydeg,xdeg,iopt); elseif iopt == 5 % polar stereographic thelon=(x-1.0)*ascale+a0; thelat=(y-1.0)*bscale+b0; [alon,alat]=ipolster(thelon,thelat,xdeg,ydeg); elseif (iopt == 11) | (iopt == 12) | (iopt == 13) % EASE thelon=x-xdeg-1.0-(xdeg+a0); thelat=y-ydeg-1.0-(ydeg+b0); [alon,alat]=ieasegrid(iopt,thelon,thelat,ascale); else disp(['*** unknown SIR transformation']); end %if... end %function