Agricultural and Forest Meteorology 217 (2016) 457–458 Contents lists available at ScienceDirect Agricultural and Forest Meteorology j our na l ho me page: www.elsevier.com/locate/agrformet Peer Review Report Peer review report 2 on “The effects of probe misalignment on sap flux density measurements and in situ probe spacing correction methods” 1. Original Submission 1.1. Recommendation Minor Revision 2. Comments to Author: I have reviewed this manuscript and I have the following com- ments. Summary The manuscript describes the effects of probe misalignment in estimating the heat pulse velocity (Vh) using 3 different heat pulse velocity sap flow techniques namely the compensation heat pulse, heat ratio and the Tmax methods. The theoretical basis of each method is described and the errors arising from the misalign- ment of the sensors are quantified using laboratory experiments. The authors assert that errors in the heat pulse velocity signals (Vh) and thermal property measurements arising from probe mis- alignment cannot be ignored. For similar probe deflection angles the errors in the thermal properties of the heat ratio method were largest compared with those of the Tmax and compensation heat pulse velocity techniques. Evaluation and general comments This manuscript is very well written and it addresses an impor- tant issue which is often a cause of uncertainty in the heat pulse velocity sap flow measurements, i.e. the question of probe align- ment. The authors develop a new method of correcting for probe misalignment, although the testing has not been as robust as one would have wished for. A few minor comments:- a) The fact that the new method has been tested in a glass beads set up under laboratory conditions only is rather disappoint- ing. It would have been good to see this testing extending to actual wood material preferably under field conditions. This is particularly important given that the new method includes 3 temperature sensors installed at 3 different radial locations into the sapwood, about 15 mm apart. In practice we know that the sap velocity varies with radial distance in the sapwood (e.g. Wullschleger and King, 2000). How would the proposed method handle this very real situation? Perhaps the authors DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2016.08.009. could include a few lines to explain what would happen in this situation. b) Secondly the authors use a lot of jargon which they don’t bother to explain and a novice in this field would struggle to follow the manuscript. Examples include words/phrases like “inline” and non-inline deflection, in situ probe spacing etc. Please explain in a few lines what causes probe deflection and how this can be minimized if possible. I appreciate the need for the corrections explained here, but careful drilling of the holes is a good first step in minimizing misalignment issues. Many users of HPV systems will likely relate more with the phrase probe misalignment than “probe deflection”. The authors could consider sticking to the former in the title and in the rest of the text as deflection in my mind is often associated with something moving and whose path is changed by something else. c) In terms of the presentation style, it would help to have the list of symbols presented at the beginning of the manuscript given the large number of equations and symbols used. Wullschleger SD., King AW. 2000. Radial variation in sap velocity as a function of stem diameter and sapwood thickness in yellow-poplar trees. Tree Physiol. 20, 511–518. Specific comments - In the title and elsewhere, consider replacing the phrase “probe deflection” with “probe misalignment”. - Pg 4 line 73. This level of precision is not possible in practice. Please confirm that the deviation is 0.1 mm and not 0.1 cm. The later seems more likely. - The word “in situ” should be italicized throughout. - Pg 5 line 104: replace the word “liberated” with “released” - Equation 3:- define the symbol EiPg 7 line 147: It is not clear to me why this equation is an improvement. One or two lines explaining why this is an improvement will clarify things. - Figs. 1 and 2 are not labelled. - Pg 11 line 217: something is missing between the words “Fur- thermore” and “compared”. - Pg 11 line 230:- replace the phrase “per-determined” with “pre- determined”. - Pg 13 line 275: specify the thermocouple type for the 10K3MCD1 sensor; - Pg 14:- line 294: Analyzing the “dates” doesn’t make sense to me. Do you mean “data”? See also line 296. http://dx.doi.org/10.1016/j.agrformet.2016.11.204 0168-1923/