ES658; tools for the Earth Sciences

1. ES658; tools for the Earth Sciences What you really, really need to know to do science that we don’t teach you in any of the other classes because we would rather teach you more Earth Science! We would rather you take another statistics course, a course in differential equations, and some computer science course (and we still want you to!). This is not a substitute for any of those; but it will be enough so you will know what you need to learn further, and to help you learn more on your own or in more classes.

2. Where has all the geophysics/geodynamics gone? • See Dr. Boettcher’s courses • All slides for this class will be on http://oxbow.sr.unh.edu/class.html • However, I will update some of these just before class

3. What will I cover: • Basic statistics & (not the same thing) data analysis. • Chosen to be useful for the Earth Sciences • Includes many of the wrinkles that are not taught in basic stats courses. • Intro to programming in MATLAB • Again, including many of the real world details not covered in programming courses • Introduction to modeling of simple systems • Calculus based! • So that you see why we had you take the math! • Not a substitute for Math/Stats/CS course!

4. Required materiel • The train wreck book (Taylor’s Intro to error analysis; the book covers much more than just that.) • A Matlab book (Pratap’s Getting started with Matlab) or equivalent. • Why not R or Python; discuss. • Site licenses as a gateway drug… • Access to Matlab • Will discuss later today

5. Structure of the class: • WF lectures on non-computer materiel • M lecture on matlab • M lab (with 1/2 hour lunch break) to do Matlab based homework. • Lab due following Monday, as described in syllabus. • One takehome exam. • One lab that you must do on your own, totally. • Required reading given in the syllabus!

6. What you are and are not allowed to do together: Except when specified: • All code must be your own work, and must be well commented as described in class. You are allowed to ask your fellow students (and me!) for help, but the code must be your own. I will use plagiarism detection software to discover incidences of copying. • However (!) you may look for helpful routines on the web; this is an integral part of programming. However, you must be careful that they are correct; this is also an integral part of programming! “I found it on the web” is not a valid excuse. You must cite what code you found elsewhere in the main program as a comment, and provide a URL pointing to the code.http://www.mathworks.com/matlabcentral/ is a good place to look.

7. How to get Matlab: • On cluster computers • On your own computer, follow instructions at • http://at.unh.edu/acs/services/software/matlab_win.html • http://at.unh.edu/acs/services/software/matlab_mac.html • http://at.unh.edu/acs/services/software/matlab_unix.html • Will run off campus if you have an internet connection • If you are going to try to install it from off campus, copy over entire install directory to local directory. (Ask me how, or bring in your computer) • Code must be written so it runs on PC’s, Macs & Linux boxes unchanged. • If you know Matlab, and want to do the course in R or Python, go for it.

8. Why error analysis? • Confirmation of theory of General Relativity; 1.8 or 0.9 milli-arcseconds? These are small changes. • Skeptics (& cranks!) have always picked on the error analysis: • But as McCausland reveals, the 1919 eclipse observations were flimsy, indeed, and were in no sense a validation of General Relativity. But from that point on, it was impossible to stop the Einstein juggernaut, even in the face of alternative theories to relativity and experimental observations which contradicted it. Today, some physicists seem to believe that Special Relativity has been elevated to the level of fact, not theory— criticism of it is neither allowed nor respected. By implication, those who do criticize it are foolish incompetents.

9. Current thinking • Error analysis was mostly right; • Further, error analysis with more “accurate” instruments get same answer. But this argument depends entirely on estimate of accuracy! • GPS • Hipparchos • Observed lensing; pictures on next page!

11. Data analysis (what is error?) • Is the Atlantic Overturning circulation changing? • Who cares? • A statistical question rarely taught in Stats classes, but common in the Earth Sciences • Involves Auto-correlations (explain) and non-error based fluctuations! • Bryden et al. 2005 Claim 30% slowing in circulation from 1957 to 2004 based on two observations (why only two?)

12. Was it slowing? • Similar issues in Global temp! • We don’t know (and knowing what we don’t know is important!) • “From now, the RAPID system should allow researchers to detect circulation changes from one year to the next, provided the average circulation volume changes by 20% or more. But because the unknown variability from year to year may also be large, it will take at least ten more years of continuous measurements until a possible downward trend will become recognizable in the data noise.” Nature 2005

13. Are two time series related? How do we quantify that?

14. How do we identify periodic signals in a data set?

15. How do we make maps from spatially discrete data sets?

16. Why do we have flash floods, and other dynamics… • Tidal bore in China.

17. So lets learn a few things today! • Quantization error: • Ubiquitous! • Instrument error/noise! • S=36.1, 35.9,36.2,36.1…., all from the same sample! What do we really know?

18. What is difference between bias and random error? • Easy in theory, hard to tell in practice!