Fig. 5

Estimation by VAM and linear regression. This figure depicts the estimation of annual mean in 1997 by VAM with the midpoint method and by VAM with gamma fitting via MLE, which are shown by a green dot and red dot, respectively. Annual means estimated by the midpoint method and MLE from 1998 to 2008 are illustrated by the orange line and green line. Estimated annual means are also fit to a linear regression which is shown by dotted lines, whereas the mean estimation in 1997 is not included