The sun shows activity over a large range of length and time scales. The total number of sunspots seen in the sun varies with an eleven year cycle. This cycle itself is not a regular one, its amplitude varies (with no particular regularity) with time. There are instances where almost no sunspots were seen for several decades -- called the Maunder minima. On short time scales the sun shows for more violent events, e.g., solar flares and coronal mass ejections. The solar magnetic activity is one of the most important factors in determining space weather. Hence it is imperative that we develop a model of solar weather forecast. In this talk, I shall describe our preliminary forays in this field where we apply the method of data assimilation to estimate the strength of meridional circulation. I shall provide an introduction to the techniques of data assimilation in general and to Ensemble Kalman Filter in particular.
