Heat content (equivalent
potential temperature) and moisture content (total
water mixing ratio) are conserved as an air parcel rises/descends.
Mixing between two parcels occurs on a line between their characteristic
properties, and the distance along the line shows the proportions of the
2 kinds of air in the mixture (Paluch, JAS 36, 1979).
Shear in the layer can mean that air from different origins is combining,
causing the mixing line to curve (Craig, 1946). The color of the
line in the mixing diagram indicates the wind direction, for a guess at
the shear. Also check out the trajectories
the air took on that day and the SST
map.
The well-mixed MABL is a cluster of points. The extension of
the mixing line to the surface-quantities line is a guess at the SST the
BL is feeling.
In the inversion, MABL air is mixing with free atmosphere air. The measurement
altitude is labelled in hundreds of meters.
Each mixing diagram shows the direction that a 2 C increase in temperature,
20 mb increase in pressure, and .5 g/kg increase in total mixing ratio
within the air parcel would take, were the other quantities held constant.
It's not exact, since I am not sure how to calculate the total mixing ratio
change with T and P.
| Point Conception | Cape Mendocino | Point Sur | Cape Blanco |
| June
19, individual profiles
Average North: Line mixing between homog air above BL and surface. South: Same, but intrusion of moisture above BL. Separation above/below BL. |
June
07, individual
Average Offshore: Mixing line w/ homog layers to surface. At Cape: IBL |
June
02, individual
Average Fairly mixed with moist intrusions aligned w/ surface. Homog in BL. Surface SST may need to be corrected. |
July
01, indivdual
Average In BL, mixing to a colder surface separated by inversion from mixing line to homog mass above. Moisture intrusions above BL in some profiles. |
| June
23, individual
Average North: Homog mass above, cooling to surface below inversion, mixing above (drying only?) South: Same, but homog at surface and less distinct. |
June
12, individual
Average Offshore: Mixing line w/ homog layers in between, perhaps above IBL, and at upper levels. Mostly moistening. Mixing line in cloud, IBL. At Cape: colder SST. |
June
11, individual
Average Offshore: Mixing line between 2 homog masses. Near shore: Mixing with moister air above. Moisture intrusions. |
|
| June
29, individual
Average Layered intrusions of moisture above the BL. Mixing along a mixing line below. |
June
26, individual
Average Offshore: Mixing line with homog intermediate regions. Mixing to reach the surface if it changes. At Cape: Homogenized but intrusions of moister air. |
June
21, individual
Average Mixing line to surface, homog below inversion, mixing in 100 m to surface. Moisture intrusion in higher cloud. |
|
| June
17, individual
Average Mixing line, few homog regions except at upper levels. Mixing to a moister/ warmer location above, separated by inversion. |
Please send comments or questions to me at kate@coast.ucsd.edu
