//h----------------------------------------------------------------------------- //h .root/data_access/MEM_2dspectra.cdip //h //h Creates a 2D (dir/freq) energy spectra from a standard CDIP spectral //h file using the Maximum Entropy Method (MEM). //h //h NOTE: This is ONE WAY to estimate a 2d spectrum from the buoy data. //h CDIP uses it because it makes narrow directional spectra for swell in the //h Pacific. //h //h //h For information on the MEM estimator and its limitations, please see: //h Kuik et al, //h A Method for the Routine Analysis of Pitch-and-Roll Buoy Wave Data //h http://journals.ametsoc.org/doi/abs/10.1175/1520-0485(1988)018%3C1020:AMFTRA%3E2.0.CO;2 //h //h Lygre & Krogstad, //h Maximum Entropy Estimation of the Directional Distribution in Ocean Wave Spectra //h http://journals.ametsoc.org/doi/abs/10.1175/1520-0485(1986)016%3C2052%3AMEEOTD%3E2.0.CO%3B2 //h //h Ochoa & Delgado-Gonzalez, //h Pitfalls in the estimation of wind wave directional spectra by variational principles //h http://www.sciencedirect.com/science/article/pii/S014111870580025 //h //h //h By default the directions are grouped in 5-degree bins, and the //h frequencies bands are the same as in the sp file. Values are given //h in units of m*m/Hz/deg. //h //h Data is output as a matrix: +------Direction bands------> //h - First column is centered at 5 degrees; | 72 columns //h - Last column is centered at 360 degrees; | //h - First row is the lowest freq (.025 Hz | //h for directional buoys); Frequency bands //h - Last row is the highest freq (.58 Hz | 64 rows for Mk3 buoys or //h for Mk3 buoys, 1.0 Hz for DWR4s); | 100 rows for DWR4s //h | //h v //h //h Arguments: 1 - either a 3-digit station ID for the latest data, or a //h 19-character sp filename. //h 2 - optional; set to 'even' to get evenly spaced freq bands, //h all with a bandwidth of 0.01Hz (0.03Hz-0.58Hz) //h //h NOTE: This script is intended for single-file access and is limited to //h data from the past 7 days. Due to resource constraints, historic and bulk //h requests must be directed to www@cdip.ucsd.edu. //h //h Usage: //h http://cdip.ucsd.edu/data_access/MEM_2dspectra.cdip?{args} //h where {args} examples are: //h 1. h -> returns this help //h 2. 029 -> MEM spectra for most recent 029 sp //h 3. sp21501YYYYMMDDHHMM -> MEM spectra for Stn 215 spectral file; //h YYYYMMDDHHMM must fall in last 7 days //h 4. 106+even -> Latest 106 spectra, 0.01Hz bands //h-----------------------------------------------------------------------------