fixed a memory leak

src/core.py

@@ -427,7 +427,7 @@ def search(
 
                 iframe = int(round(((tpeak-t0) - ioff*deltat_cf) / deltat_cf))
                 frame = frames[:, iframe]
-                imax = num.argmax(frame)
+                imax = imaxs[iframe]
 
                 latpeak, lonpeak, xpeak, ypeak, zpeak = \
                     grid.index_to_location(imax)
@@ -500,6 +500,9 @@ def search(
 
             io.save([tr_stackmax, tr_stackmax_indx], ifm_path_template)
 
+            del frames
+            del frame
+
         logger.info('end processing time window group: %s - %s' % (
             util.time_to_str(tmin_win),
             util.time_to_str(tmax_win)))