This shapefile was created from the routes-f file as prepared by INSROP
project I.5.8. The points included are the same as in the routes_c (see the I.5.8
folder in Ice and Snow category) shapefile set, which includes points defining the
ship routes as defined in INSROP Working paper no. 108 (1998), prepared by
Work Package 1 (Box B) as part of INSROP Phase 2.
Absolute air humidity in the Arctic is very low. Over the sea surface along
the NSR it ranges from 2 to 3 mbar in winter, and in summer, increases two to six
times. The maximum mean monthly relative humidity is observed in summer
(85-95%). The mnimum is observed in winter (75-85%). Fogs in the Arctic are related
to high relative humidity.
In winter, in spite of oversaturation of the air by water vapor, the frequency
of fogs is small because of low absolute humidity of water masses and a low
number of condensation particles. In places where enough particles of
condensation (smoke, vehicle exhaust) occur, one can observe frost fogs.
In summer, over the northern arctic seas, the air is very close to a point of
saturation by water vapor, and a small decrease in temperature is enough for
fog formation. The fogs in the Arctic very often correlate with wind direction.
This relationship is most visible in summer when advective fogs prevail and the
temperature difference between land and open sea is large. In coastal regions,
the fogs correlate with winds from the open sea. For example, on the west coast
of Novaya Zemlia all fogs are brought in by west winds. There are no fogs when
east winds blow. The opposite phenomenon is observed on the east coast of
Novaya Zemlia. The same relationship between wind and fog is observed in the region
of Mys Shmidta and Poseloc Uelen. On the islands of the northeast Kara Sea,
the frequency of fog is a direct reflection of wind direction.
For most regions of the Arctic, there is an inverse relationship between fog
and wind velocity. Maximum fog events are observed with small or regular wind
velocities (0-7 m/s). But in the regions of Ostrov Dikson, Amderma, and Mys
Shelagskii fog is followed by storm wind. There is a very strong relationship
between fogs and ice edge location in the arctic seas. One can see a maximum
frequency of fog occurrence in the northern parts of the seas where ice massifs are
usually located. The frequency of occurrence increases with increasing ice
concentration. But this relationship is observed only for ice concentrations, which
are less than 80-90%. Above these concentrations the frequency of occurrence
decreases. Over ice with a concentration of 100%, the number of days with fog is
equal to the number of days with fog over a sea with an ice concentration of
40-50%. The maximum duration of fog that creates the lowest visibility is observed
in summer at coastal regions and around islands in the western part of the
Barents Sea, where warm currents meet cold arctic air masses. This is the so-called
"spot character" of fogs.
Fogs caused by evaporation frequently occur in Kola Bay. From December to
February in Kola Bay and other bays of the Barents Sea, there are about 11-13 days
with fog from evaporation. Sometimes there are 22-24 days per month (about 100
days per year). In Murmansk, 50% of the fog events are regular or strong fogs
and about 20% are very strong fogs with visibility of less than 50 m. The
duration of fogs in February may reach 415-425 hours.
Path: <NSR_DATA>\meteorol\i_5_8
GeoDataset type: Shapefile with Point features.
Coordinate system: Latitude/longitude in decimal degrees
Label field: Point
* Probability of fog
335 Points, 9 descriptive fields.
Fields: [<Name>] -- <Alias> (type of field)
[No] -- "No" (Numeric, no decimals)
Point number
[Point] -- "Point" (String, max. 5 characters)
Point identifier
[April] -- "April" (Numeric, no decimals)
[May] -- "May" (Numeric, no decimals)
[June] -- "June" (Numeric, no decimals)
[July] -- "July" (Numeric, no decimals)
[August] -- "August" (Numeric, no decimals)
[September] -- "September" (Numeric, no decimals)
[October] -- "October" (Numeric, no decimals)
Probability of fog