Baseliner: An open-source, interactive tool for processing sap flux data from thermal dissipation probes

Estimating transpiration from woody plants using thermal dissipation sap flux sensors requires careful data processing. Currently, researchers accomplish this using spreadsheets, or by personally writing scripts for statistical software programs (e.g., R, SAS). We developed the Baseliner software to help establish a standardized protocol for processing sap flux data. Baseliner enables users to QA/QC data and process data using a combination of automated steps, visualization, and manual editing. Data processing requires establishing a zero-flow reference value, or "baseline", which varies among sensors and with time. Since no set of algorithms currently exists to reliably QA/QC and estimate the zero-flow baseline, Baseliner provides a graphical user interface to allow visual inspection and manipulation of data. Data are first automatically processed using a set of user defined parameters. The user can then view the data for additional, manual QA/QC and baseline identification using mouse and keyboard commands. The open-source software allows for user customization of data processing algorithms as improved methods are developed.