412
1: . ti. WIPPIRMANN
3. K , PHOFII FS I N BAR(KI.INIC CASES
The baroclinicity has been determined for only a very few of the measured
wind profiles. Figures 2, 3, and 4 show three examples. which are described
in a paper by Wippermann and Yordanov (1972). Also the K , profile for
Scilly I (circles in Fig. 2) fits the universal profiles obtained by the PHL
niodel for two neighbouring baroclinicities; only the lowest two points differ
very much.
As discussed in the paper mentioned before. a sharp minimum can occur
in the K, profile when a certain baroclinicity is given (the thermal wind has
t o have a component in the direction of the geostrophic wind at the ground).
Figures 3 and 4 give two examples of boundary layers in which a rather thin
FIG 3. .The minimum (due to harochicity) in the vertical profile of the rddj diffusion
coefficicnt as obiained by the PRL model and by ohservcltians.
layer is formed with a reduced eddy diffusion coefticient K , due to the
baroclinicity. For the K, profile Helgoland I1 (Fig. 4) this nlinimunl is
situated at 325 rn, it may act as a harrier against turbulent mixing in thc
vertical direction; such minima could be important for the diffusion from
very tiill stacks. They are due to the baroclinicity of the PBL only, they iire
not related to a temperature inversion.
1: . ti. WIPPIRMANN
3. K , PHOFII FS I N BAR(KI.INIC CASES
The baroclinicity has been determined for only a very few of the measured
wind profiles. Figures 2, 3, and 4 show three examples. which are described
in a paper by Wippermann and Yordanov (1972). Also the K , profile for
Scilly I (circles in Fig. 2) fits the universal profiles obtained by the PHL
niodel for two neighbouring baroclinicities; only the lowest two points differ
very much.
As discussed in the paper mentioned before. a sharp minimum can occur
in the K, profile when a certain baroclinicity is given (the thermal wind has
t o have a component in the direction of the geostrophic wind at the ground).
Figures 3 and 4 give two examples of boundary layers in which a rather thin
FIG 3. .The minimum (due to harochicity) in the vertical profile of the rddj diffusion
coefficicnt as obiained by the PRL model and by ohservcltians.
layer is formed with a reduced eddy diffusion coefticient K , due to the
baroclinicity. For the K, profile Helgoland I1 (Fig. 4) this nlinimunl is
situated at 325 rn, it may act as a harrier against turbulent mixing in thc
vertical direction; such minima could be important for the diffusion from
very tiill stacks. They are due to the baroclinicity of the PBL only, they iire
not related to a temperature inversion.