ABSTRACT
Therefore there are four different factors that restrict the number of independent measurements we need to make, and how many independent values of f(y) we can retrieve: the correlation length of f(y), the width of the kernel K(x-y), and the number ng of points where we measure g(x). The correlation length of f(y) is determined by nature; the width of the kernel, by the physics of the remote-sensing problem and the design of the sensor; while the number of measurements we make is under our control. Finally, the signal-to-noise ratio s g
independent values of f(y) we can retrieve. We need to consider all of these factors to determine what fraction of the variance of f(y) we can retrieve.
