Bug fix to ProjectFileAccess.m script. previous version did not load stable delta-T variavble from .xml Project file (see update 2022.7.7). Fix now allows user to open existing Project file.
New updates improve automatic delta-T-max "baseline" point selection:
- New option in initial configuration window allows user to define threshold for stable nighttime delta-T conditions. This approach is based on Oishi et al., AgForMet 2008 (doi:10.1016/j.agrformet.2008.06.013). Default threshold value is 0.005 (or 0.5%), but should be evaluated by individual users based on their own data.
Nighttime stability is determined using the following function:
S = N / V
where S is stability, N is the standard deviation of nighttime delta-T values within the user-defined time range (this is the same time range for stable nighttime VPD conditions, default is 2-hours), and V is diurnal variability of delta-T for a 7-day moving window centered on a given night where
V = mean (P(i) - L(i))
and
P(i) is the peak value of delta-T for day i, defined by the upper quartile of nightime values L(i) is the low value of delta-T for day i, defined by the lower quartile of daytime values.
This quartile approach is used rather than the absolute maximum or minimum to avoid influence of data spikes.
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New automatic delta-T-max point selection will pick the peak nighttime value where VPD and delta-T stability are below user-defined threshold values. Previous approach selected the final value (i.e., last point in time) meeting these conditions, rather than the peak.
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Some changes to plot symbol shapes and colors in the graphical user interface (stable nighttime delta-T and low nighttime VPD).
New updates to SapEditWindow.m script introduces two new "export" options: (1) for cleaned dT data and (2) for estimated dTmax baseline (version displayed at time of export--either edited or default). These options can be used for addtional analysis, including Clearwater-correction (Clearwater et al., 1999; Tree Physiology 19, 681--687) if sensors are partially in contact with heartwood. For Clearwater-correction:
dT_sw = [dT - (b * dT_max)]/a
where, dT_sw is dT in sapwood (i.e., adjusted dT) dT is original (cleaned) dT dT_max is dT under zero-flow conditions (i.e., estimated "baseline") a is proportion of probe in sapwood (ranging from 0.0 to 1.0) b is proportion of probe in heartwood (b = 1 - a; ranging from 0.0 to 1.0)
and thus, k-values are calculated manually (using user generated code or spreadsheets),
k = (dTmax - dT_sw) / dT_sw
Functionally identical to previous version, but now will correct for common time-step errors, including missing or duplicate time-steps and midnight time/day errors (if midnight is recorded as 00:00 it should be the first time step of a day, else if 24:00 it should be the last time-step of the day).
MATLAB application for processing tree sapflow measurements.
Chris Oishi, Dave Hawthorne USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory
Ram Oren Duke University, Nicholas School of the Environment
Requirements:
- MATLAB 2014 or higher
- Statistics and Machine Learning Toolbox
Top level:
- SapEditWindow
please contact Chris Oishi with questions or feedback: andrew.c.oishi@usda.gov
Please use the following reference when citing this software: Oishi, A.C., Hawthorne, D., and Oren, R. Baseliner: An open-source, interactive tool for processing sap flux data from thermal dissipation probes. Software-X. 5: 139-143. DOI: 10.1016/j.softx.2016.07.003.
standalone application for Windows available here: https://github.com/Coweeta/Baseliner4_exe