The Variability and Tail Behavior of Compound Climatic Normal Conditions

Two major regions devastated by climate change are Africa and Asia. However, little is known about the characteristics of the different compound climatic modes within the specified regions which is key to managing climate risks. The joint behavior of mean rainfall and temperature in Nigeria, South Africa, Ethiopia and India are thus studied in this paper. The main objective is to understand the dynamics in the tails of the joint normal conditions (using histograms) and to further zoom into different compound climatic zones namely, dry-hot, extreme dry-cold and wet-warm zones which are extracted based on selected quantile pairs for rainfall and temperature. Particular attention is given to the climatic signals of the strong dry-hot divisions, a core characteristic of droughts and heatwaves. The signals in this zone are modeled using simple harmonic motions (sinusoidal model) and white noise techniques in order to develop a locally adapted bivariate rain-temperature model that can further be incorporated into the actuarial climate risk framework. Three variants of the sinusoidal model are applied on the basis of the following noise types - non-adjusted Gaussian noise, mean-variance adjusted Gaussian noise and skew-normal noise. The quantile estimates indicate close fits at differing regions when compared to the empirical model suggesting the need for a mixture model based on the sinusoidal model variants.