Here is code, try this-
data a1;
set a;
row = compress (row, '" " ');
fdate= compress (fdate, '" " ');
nav_pn= compress (nav_pn, '" "');
pdc= compress (pdc, '" "');
oldfcst= compress (oldfcst, '" "');
curfcst= compress (curfcst, '" "');
rcrdtype= compress (rcrdtype, '" "');
run;