I think your input data should be x,y,z,error
you could do z=error
and you could try something like: echo "-45 -23 0.2 1" | gmt psxy -R-50/-40/-25/-21 -JX10c -Ctemp.cpt -Ey+w0.2+p0.75p,solid+cf -Bya1+l"[mm/yr]" -BSWne -Bxa1 > test.ps
which results in:
Hi Joaquim,
I have started to change all my GMT 5 version to GMT6. I must say it saves so much time specifically fiddling to insert a text for the intended places. Simply awesome. GMT6 rocks !!!
Yes, I did try to feed the plot command 4 parameters repeating the third one before I sent my question to the community but it still failed, then when I insert +cf as recommended by @MarceloBanik, it is now working.