The most comprehensive description of Gaussian processes can be found in

[1] Gaussian Processes for Machine Learning Carl Edward Rasmussen and Christopher K. I. Williams The MIT Press, 2006. ISBN 0-262-18253-X.

which is available free online. The chapter on Gaussian Process Regression is particularly relevant to albatross.

The scikit learn documentation is good place to look for a high level overview.

Sparse Gaussian Processes

[2] Sparse Gaussian Processes using Pseudo-inputs Edward Snelson, Zoubin Ghahramani

Though the code uses notation closer to that used in this (excellent) overview of similar methods:

[3] A Unifying View of Sparse Approximate Gaussian Process Regression Joaquin Quinonero-Candela, Carl Edward Rasmussen