Orthogonal decomposition methods for inclusion of climatic data into environmental studies

Scenario approach is widely used in numerical modeling for the assessment of current and prospective states of environmental and ecological systems. The results of modeling essentially depend on the representation of the underlying hydrodynamics. We suggest a methodology for a quantitative description of the behavior of a dynamic system for a long time interval in a compressed, generalized form. Following it, the necessary information, intended to be used for the construction of scenarios, is extracted from a database containing measured and/or calculated data on hydrodynamic state functions.The proposed methodology is a development of ideas of principal component analysis and factor analysis. Calculations are made with the help of a method of orthogonal decomposition of functional spaces formed by multi-variate, multi-dimensional state functions from the database. A two-level data structuring with allowance for given goal criteria is firstly produced. This provides an efficient realization of the methodology practically without restrictions upon the amount of data and component content of the database. The targeted structuring is just the element which differs the methodology proposed from the traditional approaches to data decomposition.The NCEP/NCAR reanalysis database for 56 years (1950–2005) is used to demonstrate the possibilities of the methodology. The method of orthogonal decomposition results in the subspaces which correspond to the processes on different scales: from global climatic processes to weather noises. These subspaces serve as informative bases for analysis of the climatic system behavior. Moreover, the subspaces are key elements for the construction of deterministic–stochastic scenarios to obtain an atmospheric background for problems of environment protection and design, ecological risk/vulnerability assessment and control, etc.