Basic parameters like surface pressure (height of 1000 hPa) do not reveal the whole physical background of a situation and can therefore not explain details seen in the cloud features of satellite images.
We will analysis the Phase diagrams for the hurricane to analyse the thermal characteristics. Understanding the phase of cyclones gives a broader, yet insightful, perspective on the overwhelming distribution of all cyclones. Cyclones aren't simply tropical or extra tropical; there is a great continuum of cyclone types, with a significant fraction of them having characteristics of both tropical and extra tropical cyclones.
Additional parameters and parameter combinations which are helpful in the diagnosis of development and feature diagnosis in addition to the basic parameter of the surface pressure (height 1000 hPa) are:
Analysis Phase Animation
The process of extra-tropical transition involves a gradual change of structure from warm core and symmetrical to cold core and asymmetrical.
This phase change can be best represented graphically using the parameters of :-
We will review the diagnostics of Alex using these phase diagrams
The significance of the temperature advection allows us to analysis the development of Alex through it's transition and the later frontal development through the transition as well as the Phase of the system.
Jets (Isotachs) and PVA at 300 hPa
An analysis of the vorticity fields associated with Hurricane Alex and the subsequent development and how the jet stream interacts with the development areas.
In this section we analyse the re-intensification of Alex in more detail using a PV approach (Hoskins et al.1985). The use of PV in meteorology was first introduced by Rossby (1940), and its popularity has recently grown because of its attractive properties of conservation and invertability.
Summary of the investigations in this chapter
To balance the hydrostatic equation, warm core systems have winds that decrease with height, whereas in cold core systems winds increase with height. The relative core temperature is measured using the variation in thermal winds in the lower troposphere between 900-600 hPa. To gauge the depth of the core structure the process can be repeated between 600-300 hPa and a comparison made between the two values.
The development of frontal characteristics of the system are found from
12 UTC on 6 August as cold advection begins to develop over
NewFoundland at 500 hPa. The upper level trough develops and extends through the sequence, enhancing the
advection and developing true frontal characteristics.
A large area of advection associated with the jet, this jet is seen to accelerate as it moves across the Atlantic.