Initial README.md

# bjerknes_feedback_symmetry

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#   A comparison of the atlantic and pacific bjerknes feedbacks:   #

#   seasonality, symmetry, and stationarity                        #

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#   T. DIPPE, J. F. LÜBBECKE, R. J. GREATBATCH                     #

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#   in                                                             #

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#   JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS                        #

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#   Readme for using the Matlab scripts                            #

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"A comparison of the atlantic and pacific bjerknes feedbacks: seasonality, symmetry, and stationarity" by T. DIPPE, J. F. LÜBBECKE, R. J. GREATBATCH in Journal of Geophysical Research: Oceans

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# TECHNICAL #

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Matlab version used for all analysis: Matlab 2018

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# GENERAL #

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Many scripts will be made up of a group of three to four scripts. These are:

- <name>.m: The main script that does the principal calculations

- <name>_settings.m: Prescribing all kinds of settings, including paths and

  various plotting options

- <name>_plots.m or similar: Plots

- <name>_wrapper.m: A wrapper around the main script that allows looping over,

  for example, feedback elements or basins

  For a given script <name>, I will refer to the bundle as <name>*.m

Note that I do not provide any functions related to correct plotting, such as

functions that create customized colorbars. If you run into trouble with the

plotting scripts, contact me at the address given below.

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# USED DATASETS #

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- AVISO-SSH:        https://www.aviso.altimetry.fr/en/home.html

- ERSST:            https://www.ncdc.noaa.gov/data-access/marineocean-data/

                    extended-reconstructed-sea-surface-temperature-ersst-v5

- ERA-Interim USTR: https://www.ecmwf.int/en/forecasts/datasets/archive-

                    datasets/reanalysis-datasets/era-interim

- ERA-40 USTR:      https://apps.ecmwf.int/datasets/data/era40-moda/

- ORAS4 data:       http://icdc.cen.uni-hamburg.de/projekte/easy-init/

                    easy-init-ocean.html

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# LIST OF SCRIPTS #

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# FUNCTIONS

# +++++++++

- bootstrapFeedbackStrength() and bootstrapFeedbackStrengthDiff(): Significance

               test for feedback strengths and their differences.

- calcAnomalies(): Calculates the anomalies, and allows for variable detrending

- calcIndexAveraged(): Calculates an index, requires a file that describes the

                       grids that the variables are given on, including the

                       spatial extent of each grid cell to apply the correct

                       spatial averaging. (The grid files are stored in my case

                       in the file modelGrids.mat, which contains a structure

                       for each grid, which in turn stores information such as

                       box_grid_area.)

- calculateFeedback(): Perform a robust regression to estimate the strength of a

                       given feedback element.

- diagnoseLag(): Diagnose the lag at which the feedback strength between two

                 variables is maximum.

- eventCharacteristics(): Identifies events in a time series and returns various

                          statistical measures about them. This function is the

                          backbone of the SST event analysis in the Discussion.

- testValue(): Given a distribution, a significance level and a test value,

               discern whether the test value sits on the "significant" tails of

               the distribution.

# PREPARING THE DATA

# ++++++++++++++++++

- zonal_analysis_region_definition.m: Define the equatorial area and zonal bins

  to analyse

- calculate_equatorial_indices*.m: Calculate indices for each zonal bin defined

  in zonal_analysis_region_definition.m. These datasets are the basis for most

  of the analysis.

# ANALYSIS

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Fig. 1: compare_oras4_ersst*.m

Fig. 2: diagnose_zonal_feedback_lags.*

Fig. 3: Created in MacOS's Keynote

Fig. 4-6: lagged_feedback_strength*.m to diagnose the strengths of the feedback

          elements, and diagnose_feedback_strength_difference_significance*.m to

          test the significance

Fig. 7: total_bjerknes_feedback_from_regression*.m

Fig. 8: compare_aviso_oras4_strengths_Atl3_Nino34*.m

Figs. 9-11: decadal_feedback_variations*.m

Fig. 12: zonal_enso_properties*.m

Fig. 13: decadal_sst_event_variations*.m

Figs. A1-A2: calculate_instantaneous_feedback*.m, and

             compare_lagged_instantaneous_feedback_strengths*.m

Figs. A3-A5: total_bjerknes_feedback_from_regression*.m

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# CONTACT #

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Contact me via tina (DOT) dippe (AT) gmail (DOT) com if you have questions.

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