2011-04-15 Matti Leskinen
Nocturnal migration and morning birds northwards 2011-04-14
Kumpula radar large scale reflectivity during the
night and in the morning.
The case on 2011-04-13 is quite similar to
this one.
The case file of 2011-04-11 explains more the
radar measurements.
Additional files show detailed multiparameter images of the
migration episodes.
Weather
Temperature
Humidity
Wind
Wind direction:
0 = from north,
-90 = from west,
+90 = from east.
Kumpula radar large scale reflectivity
Banded structures are related to clouds or other non-biological stuff.
Reflectivity 23 UTC
Nocturnal migration after midnight is reasonably heavy and uniform over
Finland, but over the sea the weak western precipitation bands and clouds
probably reduce the number of migrants.
Reflectivity 00 UTC
Over the Gulf of Finland the main migration is heaviest along a quite
narrow area south of Helsinki-Porvoo region.
Reflectivity 01 UTC
Migration over the sea is over a broader area than 00 UTC, but in SW
the number of migrants is still low, not much birds getting to areas
west of Helsinki.
Reflectivity 03 UTC
Morning migration burst causes high reflectivity over Finland, and
birds are gathered north of the Estonian coast as well.
Reflectivity 05 UTC
The birds migrating over the Gulf of Finland, especially to the
Porkkala region and areas east of Helsinki.
Matti.Leskinen@helsinki.fi
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