Changes between Version 1 and Version 2 of DataAssimilationDiagnostics
 Timestamp:
 Dec 20, 2016, 1:41:51 PM (4 years ago)
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DataAssimilationDiagnostics
v1 v2 19 19 Rank histograms are frequently used to assess the distribution of an ensemble around an observation or, in twin experiments, the true state. The histograms use bins computed form the ensemble distribution and count how frequent e.g. the observation falls into which bin. A flat histogram typically indicates a good ensemble. A concave (Ushaped) histogram indicates too little ensemble spread, while a convex histogram is obtained when the ensemble spread is too large. Further, a sloped histogram indicates bias. (A discussion on the interpretation of rank histograms can be found in Hamill, Monthly Weather Review, 129 (2001) 550560) 20 20 21 For a documention on `PDAF_diag_histogram` see the [wiki:PDAF_diag_histogram detail page on PDAF_diag_histogram]. The routine is used in the L Orenz96example in `testsuite/src/lorenz96/compute_truerms.F90`.21 For a documention on `PDAF_diag_histogram` see the [wiki:PDAF_diag_histogram detail page on PDAF_diag_histogram]. The routine is used in the Lorenz96 model example in `testsuite/src/lorenz96/compute_truerms.F90`. 22 22 23 23 … … 26 26 Ensemble Kalman filters assume that the ensemble is Gaussian distributed. In this case the distribution is symmetric and only the first and second moments of the distribution (the mean and standard deviation) are nonzero. The routine `PDAF_diag_ensstats` allows a data assimilation program to check the values of the third (skewness) and fourth (kurtosis) moment of the distribution. As there are different definition of the kurtosis, please note that PDAF uses the definition used by Lawson and Hansen, Mon. Wea. Rev. 132 (2004) 1966. 27 27 28 For a documention on `PDAF_diag_ensstats` see the [wiki:PDAF_diag_ensstats detail page on PDAF_diag_ensstats]. The routine is used in the L Orenz96example in `testsuite/src/lorenz96/compute_truerms.F90`.28 For a documention on `PDAF_diag_ensstats` see the [wiki:PDAF_diag_ensstats detail page on PDAF_diag_ensstats]. The routine is used in the Lorenz96 model example in `testsuite/src/lorenz96/compute_truerms.F90`.