The current public versions of LIS-7 and LDT support the following data assimilation (DA) observation dataset types (i.e., for CDF matching option):
Data Assimilation (DA) Input Preprocessing
One method for reducing systematic biases between the observational data to be assimilated and the model's state estimates to be updated with that data is known as "CDF matching". The cumulative density function, or aka the "CDF", characterizes the cumulative probability of a random variable (say, X) up to a specific point that is equal to the desired area under the associated PDF curve, for example left of that specific point.
Currently, LDT can estimate the statistics required to do a simple bias-correction or scaling approach between similar observational data and model state estimates to reduce bias between the two during assimilation update step. LDT generates the mean, standard deviation and cumulative (probability) density function (CDF) values, which LIS-7 ingests to perform the final CDF "matching" between the observations and the model estimates.