Joshua Hostler

SOM Analysis Tool

Enter a set of years to see how often each circulation pattern occurred in those summers, compared with the rest of the record (1959–2025). It is a lightweight version of the composite tools at NOAA/PSL, run against the self-organizing maps from my research. Any set of years works: fire seasons, ENSO phases, or an arbitrary selection.

Fill in the second field to compare two sets of years directly, an enhanced composite. Each value is then how many more days per season a pattern occurred in set A than in set B. Left blank, set A is compared with the full-record climatology.

The maps are 4×5 SOMs of daily 500-hPa Z and SLP over Alaska and the North Pacific, defined in Hostler et al. (2025). Cite that paper rather than this page. The training code is in synoptic-SOM (v1.0). Values are days per season: +2.5 means the pattern occurred 2.5 days more often than in an average summer.

The baseline period sets what “average” means. It defaults to the whole record; narrow it to match the period of another dataset. It also sets which years the significance test draws from.

The checkboxes above the download links select which panels appear in the figure.

Baseline period

Computing…

Selected years
Anomaly vs climatology

Node patterns

Figure panels
Publication figure: PNG PDF SVG rendered on the Pi, same numbers as above
Cite as
  • SOM patterns and labels ★ Hostler, J., U. S. Bhatt, P. Bieniek, T. Ballinger, C. Borries-Strigle, M. Burgard, J. Chriest, E. Fischer, R. Lader, E. Stevens, H. Strader, R. Thoman, C. Waigl, and Z. Parish, 2025: Daily SLP and 500-hPa Z SOM patterns explain lightning variability in Alaska. Artificial Intelligence for the Earth Systems, 4(4). doi:10.1175/AIES-D-24-0122.1

Figures and data from this tool are CC BY 4.0 — reuse them freely, including in papers and talks, and attribute with the citation marked ★. Patterns derive from ERA5, generated by the Copernicus Climate Change Service. CC BY 4.0

show entry
@article{Hostler2025,
  author  = {Hostler, Joshua and Bhatt, Uma S. and Bieniek, Peter and
             Ballinger, Thomas and Borries-Strigle, Cecilia and Burgard, Mitchell and
             Chriest, Jonathan and Fischer, Elizabeth and Lader, Rick and
             Stevens, Eric and Strader, Heidi and Thoman, Richard and
             Waigl, Christine and Parish, Zachary},
  title   = {Daily {SLP} and 500-hPa {Z} {SOM} Patterns Explain Lightning
             Variability in {A}laska},
  journal = {Artificial Intelligence for the Earth Systems},
  year    = {2025},
  volume  = {4},
  number  = {4},
  doi     = {10.1175/AIES-D-24-0122.1},
  url     = {https://doi.org/10.1175/AIES-D-24-0122.1}
}