Modelling of Diurnal Profile of Surface Air Temperature and Surface Dissolved Oxygen of Lake Water

Abstract

Fourier analysis method can be used as a mathematical tool for modelling the diurnal profile of surface air temperature and surface dissolved oxygen (DO) of lake water. For developing the model, initially Lake Rudrasagar, Tripura, India has been chosen as the study site. Within the scope of this communication, due to availability of collected data the developed mathematical model has been verified for Subhas Sarobar, Kolkata. It is observed that the diurnal profile of DO and surface air temperature of both the lakes studied almost follows similar trends of sinusoidal variation.Keywords: Diurnal profile, dissolved oxygen, sinusoidal variation, surface air temperature.ONE-dimensional harmonic analysis with regard to timeseries data has potential applications in oceanography, hydrology 1-4 as well as in geosciences and geology. The two-dimensional extension of harmonic analysis finds significant applications in meteorology and climatology. Fourier analysis may also be termed as spectral analysis which decomposes a new time-dependent regular sensation directly into several sinusoidal features, each of which simply characterized by special amplitude and period valuations. The actual portion involving variance inside initial time-series can be established and every single term of the harmonic analysis can also be worked out. Model designing during the last few years has become a challenging task among researchers and engineers, for scientifically prediction of the future scenario 5 . In hydrodynamics, mathematical simulation has become a vital feature of researches in this regard. In order to generate a mathematical model, experimental data analysis is the fundamental criterion for following the process over the time-space domain. Fourier analysis method has been chosen as the mathematical tool for generating the required model to study the sinusoidal variation of surface air temperature and surface dissolved oxygen (DO) of lakes. Several major physico-chemical characteristics of lake water are controlled by temperature for the Lake Rudrasagar 6 which is in turn responsible for maintaining the lake water quality suitable for human consumption. The progressive variation in air temperature also shows a strong seasonal relationship with lake water temperature 7 . DO concentration regulates the respiration of these organisms. If strong turbulence is not observed in a lake, then photosynthesis by aquatic plants is the only vital source of DO. There exist strong correlations between surface air temperature and surface DO for the lakes Rudrasagar and Subhas Sarobar. Incoming solar radiation may also put a signature on diurnal profile of surface air temperature and surface DO of lake water 8 . The study site, i.e. Lake Rudrasagar (2329N and 9001E) falls in Melaghar Block under Sonamura SubDivision of Tripura, the third smallest state of India. This natural lake is 50 km away from the state capital, Agartala. It has three sources of inflow and one outflow. Inflows are Noacherra, Durlavnarayan cherra and Kemtali cherra, whe...