deletions | additions       diff --git a/Three_spacecraft_landed_on_Mars__.tex b/Three_spacecraft_landed_on_Mars__.tex  index ce1d266..7e5960d 100644  --- a/Three_spacecraft_landed_on_Mars__.tex  +++ b/Three_spacecraft_landed_on_Mars__.tex 
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Three spacecraft landed on Mars carried meteorological instrumentation that allows investigators to conduct such surveys, providing a wealth of data on Martian dust devils and other meteorological phenomena, but such surveys suffer from important biases when it comes to studying dust devils. Foremost among these biases is the fact that a pressure dip does not necessarily correspond to a dust-lofting vortex. Indeed, recent studies \citep{2014DPS....4630006S} suggest pressure dips are often unaccompanied by lofted dust, likely because the attendant wind velocities are insufficient to lift dust. The problem of identifying dustless vortices can be mitigated if barometers are deployed alongside solar cells, which can register obscuration by dust, and such sensor pairs have recently been deployed in terrestrial studies \cite{Lorenz_2015}. However, such an arrangement is not fool-proof since a dusty devil can easily pass by the sensors on the anti-sunward side and not register an obscuration signature.  Another key biasconfronted by single-barometer surveys  arises from the miss distance effect: a fixed barometric sensor is more likely to have a more distant than closer encounter with a dust devil. Since the pressure perturbation associated with a devil falls off with distance from the devil's center, the deepest point in the observed pressure profile will almost always be less than the actual pressure well at the devil's center. The observed shape of the profile will be distorted as well. These miss distance biases are intrinsic to the detection methods, and additional biases can influence the inferred statistical properties. For instance, noise in the pressure time series from a barometer may make more difficult detection of a dust devils with smaller pressure perturbations, depending on the exact detection scheme. Although it is inherent in single-barometer surveys for dust devils, simple geometric considerations can mitigate the influence of the miss distance effect, allowing single-barometer surveys to be corrected. In particular, the physical parameters for dust devils estimated from the pressure time-series can be corrected for the miss distance effect, at least in a statistical sense. In this study, we consider the geometry of encounters between dust devils and barometers and present a statistical model for correcting the miss distance effect. This study is similar to and motivated by \citet{Lorenz_2014}, but, where that study used a numerical simulation to investigate biases in the recovered population of dust devil properties, we employ an analytic framework that allows wider applicability and provides more insight into the problem. As we discuss, though, our model involves some important assumptions and simplifications.