Spring Transition Dates and Fall Transition Dates

Graph of Spring Transition Dates and Fall Transition Dates various methods

OSCURS Method

Method & Data Reference

Ingraham, W.J., Jr. and R. K. Miyihara. 1988. Ocean surface current simulations in the North Pacific Ocean and Bering Sea (OSCURS-Numerical Model). NOAA Tech. Mem., NMFS F/ NWC-130, 155 p.

Summary

Each year, along the Pacific Coast of North American between San Francisco (38 North Latitude) and the Queen Charlotte Islands (52 North Latitude), the coastal winds switch from the southerly winds of winter to the northerly winds of summer producing a transition in wind called the spring transition. Conversely, the yearly switch back from the northerly winds of summer to the southerly winds of winter produce a fall transition. The summer winds, which occur after the spring transition and prior to the fall transition, are known to be favorable for upwelling -- a process that transports the nutrients to the ocean surface, feeding the near-shore food chain. Estimates of the transition dates were derived from smoothed synthetic winds computed by the ocean surface currents model OSCURS (Ingraham and Miyihara 1988), which used daily sea level atmospheric pressure fields for years 1946 to 1994 as input. The spring and fall transition dates were calculated for the latitude of the Columbia's mouth (46 deg 12' North Latitude).

Disclaimer

The dates of the spring and fall transitions contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The estimates depend on the degree and type of smoothing used on the synthetic winds derived from OSCURS. Neither NOAA nor the University of Washington is responsible for any misuse of these data.

Logerwell et al. Method

Method Reference

Logerwell, E.A., N. Mantua, P. Lawson, R.C. Francis, V. Agostini. 2003. Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival. Fisheries Oceanography 12:554-568.

Data Reference

E. Logerwell (pers. com. 2007)

Summary

The date of spring transition can be indexed in several ways; the Logerwell et al. (2003) method indexes the spring transition date based on the first day when the value of the 10-day running average for upwelling is positive and the 10-day running average for sea level is negative.

Disclaimer

Transitions dates contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. Neither NOAA nor the University of Washington is responsible for any misuse of these data.

Biological Spring and Fall Transition Method

Primary Source

Please refer to Local Biological Indicators, NOAA Fisheries for the official documentation and dataset. Data last accessed: 25 August 2022.

Method Reference

Hooff, Rian C. and William T. Peterson. 2006. Copepod biodiversity as an indicator of changes in ocean and climate conditions of the northern California current ecosystem. Limnol. Oceanogr. 51:2607-2620. https://doi.org/10.4319/lo.2006.51.6.2607

Summary

The date of the biological spring transition each year is defined as the day when the copepod community has changed from a winter (southern, warm-water) community to a summer (northern, cold-water) community.

It is suggested that the timing of the summer copepod community may be a more useful indicator of the spring transition from downwelling to upwelling. The onset of the summer copepod community indicates the first appearance of the food most favorable for salmon, sardines, and sablefish. Large, lipid-rich copepods, euphausiids, and juvenile forage fish dominate this community and help fuel a productive, lipid-rich food web.

Alternatively, the arrival of the winter copepod community marks the fall transition and the end of the upwelling season.

Pierce and Barth Method

Method Reference

Barth, J. A., B. A. Menge, J. Lubchenco, F. Chan, J. M. Bane, A. R. Kirincich, M. A. McManus, K. J. Nielsen, S. D. Pierce, and L. Washburn (2007) Delayed upwelling alters nearshore coastal ocean ecosystems in the northern California current, Proceedings of the National Academy of Sciences, 104, 3719-3724.

Gustafsson, F. (2000) Adaptive filtering and change detection, John Wiley.

Hinkley, D. and E. Schechtman (1987) Conditional bootstrap methods in the mean-shift model. Biometrika, 74, 85-93.

Huyer, A., E. J. C. Sobey, and R. L. Smith (1979) The spring transition in currents over the Oregon continental shelf. J. Geophys. Res., 84, 6995-7011.

Large, W. G. and S. Pond (1981) Open ocean momentum flux measurements in moderate-to-strong winds. J. Phys. Oc., 11, 324-336.

Page, E. S. (1954) Continuous inspection schemes. Biometrika, 41, 100-115.

Pierce, S. D., J. A. Barth, R. E. Thomas, and G. W. Fleischer (2006) Anomalously warm July 2005 in the northern California Current: historical context and the significance of cumulative wind stress, Geophys. Res. Letters, 33, L22S04, doi:10.1029/2006GL027149.

Summary from "Wind stress, cumulative wind stress, and spring transition dates: data products for Oregon upwelling-related research "

Alongshore wind stress cumulative from the spring transition represents energy input into the upwelling system over the course of each season. This has been found to be strongly correlated with a number of different upwelling metrics (Pierce et al., 2006), eg. NH-line surface-layer temperature (0-30m).

Wind stress here is derived from observed winds at Newport, Oregon, using the method of Large and Pond (1981). The hourly data are low-pass filtered to remove diurnal variations. The spring and fall transitions (Huyer et al., 1979) are estimated for each year from the alongshore wind stress record, using a CUSUM algorithm for change-point detection (Page, 1954; Gustafsson, 2000). The significance (95%) of these two mean-shift change-points within each year's time series is confirmed using bootstrapping, as suggested by Hinkley and Schechtman (1987).

We hope that researchers will find it useful to compare their own upwelling-related data to the general development of upwelling represented by this cumulative wind stress product. Plots and data are available: damp.coas.oregonstate.edu/windstress/.

S. D. Pierce and J. A. Barth, College of Earth, Ocean, & Atmospheric Sciences

Logerwell based CBR Method

Method Reference

Logerwell, E.A., N. Mantua, P. Lawson, R.C. Francis, V. Agostini. 2003. Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival. Fisheries Oceanography 12:554-568.

Bilbao, P. 1999. Interannual and Interdecadal Variability in the Timing and Strength of the Spring Transitions along the United States West Coast. M.S. Thesis. Oregon State University, Oceanography.

Summary

The method is the same as that used in Logerwell (2003) to estimate spring transition dates.

Two time series were inspected for seasonal transitions: (1) area averaged daily upwelling indices for 42º to 48ºN, 125ºW (http://www.pfeg.noaa.gov), and (2) daily sea level residuals (corrected for the inverse barometer effect) measured at Neah Bay, WA, 48º22.1'N,124º37.0'W (University of Hawaii Sea Level Center, http://uhslc.soest.hawaii.edu/). High frequency variation was filtered out by applying a low pass filter with a stop frequency of 1/(10 days) (S-PLUS, MathSoft, Inc., Seattle, WA, USA). To extract the seasonal pattern, a low pass filter with a stop frequency of 1/(90 days) was constructed. The date of fall transition was chosen as the date when the 1/(10 days) low pass filtered lines crossed zero.  The 1/(90 days) low pass filter line confirmed that the selected date marked the beginning of a new seasonal state.

In most years the time series agree and the date is easy to pick. In other years the signals do not point to a single transition and some judgment must be made. Thus, although the model allows selection of the date, it does not form a completely objective and automated system for choosing that date.

Update

13 April 2007. Estimates for 1997, 2000, and 2004 were updated.

Disclaimer

Transitions dates contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The University of Washington is not responsible for any misuse of these data.

CBR Mean Method

Method & Data Reference

Mean Spring and Fall Upwelling Transition Dates off the Oregon and Washington Coasts. 2007. Van Holmes, Chris. white paper.

Summary

Pacific Fisheries Environmental Laboratory publishes indices of the intensity of large-scale, wind-induced coastal upwelling and alongshore transport at standard locations on a monthly basis. The CBR Mean method uses data from 1967 to the present for three locations along the Pacific Northwest coast:

  1. 42N125W West of OR/CA border,
  2. 45N125W West of Siletz Bay Lincoln, OR,
  3. 48N125W West of La Push, WA.

For all years, the CBR Mean method takes each day's upwelling deviations from the site-specific mean offshore transport. The upwelling deviation was used to account for long term trends at each site. Then the daily deviations were averaged from the three sites. The average upwelling deviation indices are then smoothed using a 15 day central mean calculation. The use of a central mean avoids the trailing nature of a running mean. The smoothed cumulative upwelling deviation indices are then examined for spring minima and fall maxima through the entire series. The julian day of these extremes are listed as the CBR Mean Spring and Fall Transition Dates.

Disclaimer

The dates of the spring and fall transitions contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The University of Washington is not responsible for any misuse of these data.

Further Investigation

DART Pacific Ocean Coastal Upwelling Index Graphics & Text queries, data courtesy of NMFS Pacific Fisheries Environmental Laboratory

Northwest Fisheries Science Center, NOAA

Data

Year Spring Transition Dates Fall Transition Dates
OSCURS Spring Logerwell et al. Spring Biological Spring Transition Pierce Barth Spring CBR Mean Spring OSCURS Fall Logerwell based CBR Fall Biological Fall Transition Pierce Barth Fall CBR Mean Fall
Year Spring Transition Dates Fall Transition Dates
OSCURS Spring Logerwell et al. Spring Biological Spring Transition Pierce Barth Spring CBR Mean Spring OSCURS Fall Logerwell based CBR Fall Biological Fall Transition Pierce Barth Fall CBR Mean Fall
2021 106 79 304 264
2020 97 34 274 258
2019 156 107 102 263 327
2018 149 105 105 340 295 292
2017 187 116 115 299 260 288
2016 NaN 87 81 NaN 273 278
2015 92 NaN 101 46 NaN 278 293
2014 101 91 130 94 273 263 281
2013 100 91 97 96 277 234 261
2012 121 125 125 114 318 281 284
2011 100 82 106 90 288 254 260
2010 100 169 161 99 NaN 257 286
2009 85 83 134 67 357 284 279
2008 89 64 120 36 324 259 297
2007 74 81 117 71 270 296 271 308
2006 112 150 110 108 304 333 304 304
2005 145 230 142 106 272 294 272 284
2004 110 146 112 89 311 302 234 338
2003 112 156 110 105 288 296 269 278
2002 80 120 107 81 310 319 308 302
2001 61 79 121 64 316 321 280 296
2000 72 97 164 78 294 312 285 288
1999 91 134 89 88 310 354 292 294
1998 105 209 83 71 310 226 258 277
1997 146 135 126 78 256 263 228 255
1996 120 193 117 116 321 305 275 311
1995 95 NaN 110 100 311 264 309
199493.23119 87 NaN 115 82 286.9727 298 286 294
1993130.7614 161 NaN 162 116 298.7134 325 278 327
199269.20528 123 NaN 121 64 281.1374 292 289 289
199171.92012 99 NaN 128 62 297.9998 309 294 304
199083.04251 81 NaN 81 76 281.5938 294 275 289
198999.03588 97 NaN 96 94 284.9838 293 266 288
198888.55508 68 NaN 155 85 289.755 305 268 301
1987101.2242 81 NaN 106 72 297.4697 312 309 309
198694.79562 89 NaN 85 86 280.8877 280 255 292
198570.7562 48 NaN 158 45 279.6091 292 283 290
1984107.5674 112 NaN 109 272.4462 277 276
198395.21371 126 202 91 289.6044 285 288
198283.30457 109 NaN 104 272.6492 261 276
198194.60262 88 NaN 83 268.9149 263 262
1980109.4162 78 NaN 76 275.2528 291 295
197974.41698 73 NaN 65 272.4335 286 289
197885.18182 97 NaN 66 302.4553 280 317
197771.79939 74 NaN 70 274.1748 295 292
197684.66428 103 NaN 100 293.4859 292 296
197573.96655 83 NaN 80 273.5765 276 273
1974102.7074 102 NaN 98 297.0226 309 306
197374.19205 80 NaN 64 285.4921 292 287
1972103.103 107 NaN 102 300.853 306 304
1971102.2719 106 79 103 292.8313 312 290
197068.57823 78 79 74 270.8927 290 287
196978.03237 117 116 268.9529 260 258
196890.6561 84 272.0233 282
196759.49914 82 268.3312 271
196688.50795 281.4956
196544.54589 277.2084
196441.98558 275.7526
196371.96294 256.3281
196251.33193 272.6711
196191.95937 307.0709
1960141.8394 285.5177
195984.73013 292.2119
195899.23275 268.9639
195790.8761 279.7934
195682.69133 282.0516
195564.76729 283.2569
195464.54433 265.5847
195351.18787 269.0659
195269.06229 278.7719
195164.79611 271.8619
1950109.9127 269.7495
1949115.0458 291.0623
1948139.7 256.3207
1947102.9139 270.5
1946106.5074 259.1