Python: Cubic Spline Regression For A Time Series Data

I have the data as shown below. I want to find a CUBIC SPLINE curve that fits the entire data set (link to sample data). Things I've tried so far: I've gone through scipy's Cubic

Solution 1:

I made a 3D scatterplot of the data, converting the timestamps to "elapsed time in seconds" from the first timestamp, the image is below. It appears to me that the data has a sort of 3D equivalent of an outlier, here shown as an entire line of data that is considerably below most of the other data. This will make creating a 3D surface fit of any kind difficult.