Wait A Minute..... Martian Wind Autocorrelations
R. D. Lorenz, Space Exploration Sector, Johns Hopkins Applied Physics Laboratory, Laurel, Md
20723, Usa (Ralph.Lorenz@Jhuapl.Edu)
Introduction:
A Number Of Operations On The Surface Of
Mars Benefit From Knowledge Of The Wind : Regolith Manipulation For Sampling Or Solar Array Cleaning May Have More Favorable Results Under Certain
Wind Conditions, And Flight Of E.G. A Helicopter
May Be Risky In Strong Gusts. While It Is Impossible To Reliably Predict The Instantaneous Wind During The Turbulent Early Afternoon Period Purely As
A Function Of Time, A Useful Predictive Degree Of
Skill Can Be Brought Via Time Series Analysis. Specifically, The Turbulent Afternoon Is Characterized
By An Alternation Between Stronger Winds And
Weaker Ones, Presumably Associated With The Updraft Walls And Downwelling Cores Of Boundary
Layer Convection Cells. The Scale Of These Circulations Introduces A Characteristic Timescale Of The
Order Of 5~20 Minutes Which Defines Correlations
In The Wind Speed Time Series. The Autocorrelation
Function (Acf) Is Above 0.5 For Timescales Less
Than About A Minute , Whereas The Acf Is Actually
Negative For 200-500s. These Statistical Features
Can Be Reproduced With Simple Markov Models,
And Can Be Exploited To Improve The Odds Of Operational Success Via Logic Of The Form “Attempt 2