1-*-text-*- 2 32021-01-10 4 5 Imported NOS data from snapshot 2020-12-23. This includes a large number 6 of new currents because harmonic constants for currents are now available 7 through MDAPI. 8 9 The currents are a clean break from previous years. No data or metadata 10 were carried over. Coverage of the Salish Sea is mostly consistent with 11 what was imported 2019-06; a few stations and depths were dropped, but 12 the rest are equivalent. 13 14 Cleaned up more typographical style issues in station names. 15 16 Dropped a few more stations that appear to be in Canadian waters. 17 18 Made a serious effort to harmonize the states of all tide and current 19 stations with what Google Maps showed for the coordinates. The resulting 20 assignments may be surprising when the state line runs between the named 21 landmark and the location of data collection. 22 23 The following waters are especially problematic for assigning states: 24 - St. Marys River 25 - Savannah River 26 - Pocomoke Sound and River 27 - Delaware Bay and River 28 - Everything around Long Island 29 - Piscataqua River 30 - Columbia River 31 322019-12-29 33 34 Imported NOS data from snapshot 2019-12-18. 35 36 Acquired 32 new or previously dropped current subs that refer to Salish 37 Sea / Puget Sound stations that were imported over the summer. 3 of them 38 collide with a harmonic current (Waldron Island). 39 40 Added geographic areas to the names of stations imported 2019-06-20. 41 42 Fixed inconsistent capitalization of "entrance" and 43 "[north/south/east/west] jetty." 44 452019-06-20 46 47 Imported new Salish Sea / Puget Sound currents that were obtained from 48 NOAA by Charles Douglass (2019-06-11). 49 50 Expired the superseded reference station 51 PCT1956_1 Deception Pass (narrows), Washington Current 52 and its three subordinates. 53 54 All other data are untouched from 2018-12-27. 55 562018-12-27 57 58 Imported NOS data from snapshot 2018-12-24 using MDAPI again. There were 59 no new subordinate stations, but some harmonic stations were added. 60 61 Two more of the old current reference stations have expired. AFAICT, 62 harmonic constants for currents still have not been published on the NOAA 63 web site. 64 PCT2186_1 San Juan Channel (south entrance), Washington Current 65 PCT1996_1 Rosario Strait, Washington Current 66 67 The "wrong day" anomaly noted last year appears to have been fixed; 68 however, there still are plenty of time zones or meridians mismatched by 1 69 or 2 hours. 70 71 In the SQL dump, table data_sets no longer provides oids. 72 732018-01-01 74 75 Imported NOS data from snapshot 2017-12-17. Most data this year were 76 sourced from the CO-OPS Metadata API (MDAPI). 77 78 The perennial issues with time zones and meridians in Alaska and around 79 the Port St. Joe region of Florida have gotten worse all of a sudden. The 80 number of reference stations with local meridians in the wrong time zone 81 has increased from 8 to 21. Additionally, when local time predictions are 82 obtained from the NOS web service, Alaskan stations that are expected to 83 be 2 hours earlier than XTide's results (on UTC-11 instead of UTC-9) 84 instead are 23 hours *later*, on the wrong day. Predictions requested in 85 GMT match as expected. 86 87 Two more of the old current reference stations have expired. AFAICT, 88 harmonic constants for currents still have not been published on the NOAA 89 web site. 90 PCT1341 Strait of Juan de Fuca Entrance, Washington Current 91 PCT1541 Admiralty Inlet (off Bush Point), Washington Current 92 93 All remaining current stations now use "sidplus" station IDs, which is the 94 station id followed by an underscore and the "bin number" that is used to 95 separate depths. 96 97 Abandoned the practice of including the periods in U.S.A., F.S.M., D.C., 98 and the like. 99 100 Normalized the assignment of countries so that territories and 101 commonwealths of the US are called USA. Marshall Islands is now called 102 RMI (Republic of the Marshall Islands). Pending the conclusion of 103 long-running territorial claims, Wake Island has been assigned the RMI 104 country code, but its name is still "Wake Island, Pacific Ocean." 105 106 Discontinued the last remaining meridian "erratum," for 9466153 Helmick 107 Point. Predictions are still not available for comparison, but there is a 108 nearby station, 9466057 Popokamute (Kokokamute), which is consistent with 109 the unadjusted data. 110 111 Dropped the tables data_sets_2010, drops, and footnotes, which are no 112 longer used by import, and all tables associated with the discontinued 113 meridian errata check. 114 115 Added 7 new constituent name aliases to support revised constants for 116 Anchorage and constituent corrections as described below. 117 118 The investigation into 3 questioned constituents (3KM5, RP1, and KJ2) that 119 are used only by 9455920 Anchorage, Knik Arm, Cook Inlet, Alaska concluded 120 the following: 121 122 - Using this year's constants, which have amplitude for all 3 of the 123 questioned constituents, RMS error for predicted heights versus the NOAA 124 web site is indeed minimized when all 3 of those constituents are flipped 125 180 degrees from their definitions in congen_input.txt 4154 2012-01-05 126 (which is the same as congen_input.txt,v 1.3 2004/08/16). 127 128 - Reaffirmed the decision made last year regarding 3KM5. Although the 129 superseded definition was consistent with IHO (2017), the new definition 130 is the one that was used in the paper that introduced the use of many 131 constituents for Anchorage (Bernard D. Zetler and Robert A. Cummings, A 132 harmonic method for predicting shallow-water tides, J. Marine Res. 25(1), 133 pp. 103-114, 1967) and is also the one used by IOS (2006). The node 134 factors are different for the two different formulations. 135 136 - The definitions of RP1 and PSI1 (which are the same thing but flipped 137 180 degrees) in congen_input.txt are consistent with IHO, with the SP98 138 definition of PSI1, and with the IOS definition of PSI1. Therefore, to 139 reduce error for Anchorage, the RP1 constituent is just mapped to PSI1. 140 141 - The definition of KJ2 in congen_input.txt is consistent with SP98 but 142 inconsistent with IHO. KJ2 and ETA2 in congen_input.txt are two different 143 formulations of what IHO and IOS call ETA2, and the one apparently needed 144 by Anchorage is not present. Complicating matters, KJ2 is one of the 145 constituents that is inferred by libtcd using an SP98 rule-of-thumb which 146 assumes a consistent treatment of the constituents' phases; flipping KJ2 147 from its SP98 definition would be more likely to break this inference than 148 to fix it. Therefore, to reduce error for Anchorage, KJ2 is mapped to a 149 new constituent, KJ2-IHO, which is flipped from the SP98 definition. 150 151 The new constants for Anchorage also refer to a mysterious constituent 152 OO2, which has been mapped to OQ2-HORN based on its speed. IHO defines 153 OQ2 as both this constituent and its 180 degree reversal; however, error 154 is minimized by sticking with the OQ2-HORN definition. 155 1562016-12-31 157 158 Imported NOS data from snapshot 2016-12-18. 159 160 Changed the definition of constituent 3KM5, which is used only by 161 Anchorage (9455920), from 3*K1+M2 to K1+M2+K2. 162 - When calculated by Congen, K1+M2+K2 is close to but not exactly the same 163 as a phase reversal of 3*K1+M2. 164 - 3*K1+M2 was consistent with the 2006 IHO list. 165 - Both IOS and the unidentified YEARDATA.dat application instead used 166 K1+M2+K2. 167 - The K1+M2+K2 definition decreases the differences between XTide's 168 predictions and those of NOAA's web service. 169 Details on the investigation of 3KM5 and the other constituents that were 170 called into question last year are temporarily available at 171 flaterco.com/xtide/news.html under To do / Congen. 172 173 The Narrows, north end (midstream), Washington Current no longer matches 174 NOAA predictions and has been expired along with all dependent subordinate 175 stations. PCT1766 was superseded by PUG1524 (3 different depths). 176 AFAICT, harmonic constants for currents still have not been published on 177 the NOAA web site. 178 179 The erratum for Texaco Dock was removed because it matched predictions 180 retrievable from the NOAA web site without adjustment. The erratum for 181 Helmick Point was retained by default as no predictions were retrievable. 182 183 Fixed typo in Pillar Point Harbor, Half Moon Bay. 184 1852015-12-27 186 187 Imported NOS data from snapshot 2015-12-15. 188 189 Note: All comparisons with NOAA predictions now are using dynamically 190 generated "online" predictions rather than "tables" that used to be posted 191 annually. Differences of 5 minutes are now common. 192 193 *Tides* 194 195 Harmonic constants are now being retrieved from 196 opendap.co-ops.nos.noaa.gov/axis. 197 198 Datums are now being retrieved from tidesandcurrents.noaa.gov/api. 199 Benchmark Data Sheets are no longer used. In the 37 cases where the API 200 failed to return a usable value, the Benchmark Data Sheet either didn't 201 exist or didn't help. The same was true of online predictions. Missing 202 datums are still being set to an estimated MLLW that most often turns out 203 to be lower than the value eventually adopted by NOAA. 204 205 Datums for stations on the Columbia River have been corrected. 206 Previously, import mishandled stations that were using the Columbia River 207 Datum. Bug report credit: Mark Hayden. 208 209 The time zone of Savoonga has been harmonized with the rest of 210 St. Lawrence Island (HAST). Wikipedia sources are now claiming that 211 St. Lawrence Island is on AKST (which is where NOAA puts it), but see 212 http://alaska.gov/kids/learn/timezones.htm: "The far reaches of the 213 Aleutian Islands and St. Lawrence Island are in the next zone, 214 Hawaii-Aleutian Standard Time." The 2003 CFR do not clearly address 215 St. Lawrence Island at all, though by default, it appears that it should 216 be on Alaska time. 217 218 The errata for Texaco Dock and Helmick Point are unchanged. 219 220 *Currents* 221 222 Harmonic constants for currents still are not available for download. The 223 following reference current stations no longer match NOS predictions and 224 have been expired along with all dependent subordinate stations: 225 Old Tampa Bay Entrance (Port Tampa), Florida Current (15d) 226 Tampa Bay (Sunshine Skyway Bridge), Florida Current (15d) 227 228 The import of subordinate current stations has been migrated from the old 229 Table 2-based pages, which still have not been posted for 2016, to the new 230 "NOAA Current Predictions *Beta*" site. Names now include "Depth Xft" in 231 the middle instead of "(Xd)" at the end to indicate depths. Legacy 232 current refs were not renamed. 233 234 The footnotes that used to be in Table 2 have been dropped. 235 236 The harmonic constants for Wrangell Narrows obtained in 2011 were labelled 237 as depth 6 ft. They appear to match with the online predictions for depth 238 4 ft and are being used for all subordinate stations that request the 4 ft 239 reference. 240 241 *Coordinates* 242 243 The coordinates for all imported stations were taken preferably from the 244 regional station lists. Imported reference stations not included in the 245 regional lists got their coordinates from the metadata of the harmonic 246 constants. The coordinates of legacy current refs were left alone. 247 248 Coordinates retrieved from different places usually disagree with one 249 another. There is no general pattern such as rounding to the nearest 250 minute to show that one or the other is better. However, for a small 251 sample of reference stations where the disagreement was large (9455606, 252 9457527, 9465831), the station list coordinates were more plausible. 253 254 Coordinates for American Samoa are now in the correct hemisphere. 255 256 *Constituent definitions* 257 258 I received untraceable evidence this year that NOAA may be using 259 definitions of 3KM5, RP1, and KJ2 that are phase-reversed from what is in 260 the harmonics file. At present the only impacted NOAA station is 261 Anchorage, where 3KM5 has amplitude of 0.04 ft and the other two are null. 262 Comparison of all high/low tide predictions for Anchorage for year 2015 263 with NOAA tides online showed on average a small improvement after 264 flipping the phase of 3KM5: 265 266 Time RMSE (s) Tide RMSE (cm) 267 Default 63.7 2.1 268 Phase-reversed 44.1 1.7 269 270 Congen formulates 3KM5 as a compound constituent, which does not offer the 271 opportunity to accidentally reverse the phase with a data entry error. 272 More investigation is needed. For now I am holding off on upheaving the 273 constituent definitions, which would be a breaking change for anyone using 274 harmonic constants from non-NOAA sources, and instead am merely flipping 275 the phase of 3KM5 for Anchorage as an erratum. 276 277 *Other notes* 278 279 The anomaly with St. Michael, Norton Sound, Alaska is unchanged. 280 281 Some stations show dramatically different names in the regional station 282 list than on their prediction pages. It is hopeless to try to identify 283 all of these and figure out where they really are. 284 285 "D.C.", "Washington, D.C." and "District of Columbia" have been 286 standardized to just "D.C." 287 288 Inconsistent capitalization in the names of subordinate current stations 289 is not worth fixing. XTide's name matching is case-insensitive. 290 2912014-12-24 292 293 Imported NOS data from snapshot 2014-12-16. 294 295 Coordinates for reference stations had to be taken from a different page 296 this year. Many stations have moved slightly. 297 298 The erratum for College Pt was removed because the meridian changed back. 299 The erratum for Fortescue Creek was removed because the tide table now is 300 consistent with the data. 301 302 The harmonics for St. Michael, Norton Sound, Alaska are in disagreement 303 with the subordinate station that is presently used for tide tables. 304 Higher high tide differs by approximately 1.5 hours. The correct fix is 305 unclear; issue noted but no action. 306 307 The 2013 footnotes table was reused again without further checking. 308 309 Fixed time zone of Port Saint Joe again. 310 311 Fixed spelling of McCready's Creek. 312 3132013-12-28 314 315 Imported NOS data from snapshot 2013-12-10. 316 317 The following reference current stations no longer match NOS predictions 318 and have been expired along with all dependent subordinate stations: 319 Golden Gate Bridge, California Current (22d) 320 San Francisco Bay Entrance (outside), California Current 321 Key West, 0.3 mi. W of Ft. Taylor, Florida Current 322 Cape Cod Canal (railroad bridge), Massachusetts Current 323 324 Helmick Point added to errata for wrong meridian (thanks AED). 325 326 The 2014 currents web site no longer provides footnotes, but the code 327 still references them. The 2013 footnotes table (from 2012-12 web scrape) 328 was reused. A sampling of stations that referenced footnotes showed no 329 disagreement with the 2012 database. 330 3312012-12-24 332 333 Imported NOS data from snapshot 2012-12-22. 334 Expired: Mobile Bay Entrance (off Mobile Point), Alabama Current. 335 Renamed several stations. 336 3372012-03-02 338 339 Imported up-to-date NOS harmonic constants for Golden Gate Bridge Current 340 contributed by August Hahn, plus the 78 dependent subordinate stations 341 from the web snapshot taken 2011-12-11. 342 343 Note: Change history prior to 2012-03-02 continues in 344 http://www.flaterco.com/xtide/harmonics_boilerplate.txt. 345