Fig. 5: Time-mean composite daily atmospheric fields and wildfire weather parameter anomalies averaged during the blocking lifecycle of North American blocking events in summer under different combinations of negative PDO (PDO−) with the central Pacific (CP) and eastern Pacific (EP) types of El Niño during 1979–2023.
From: Atmospheric and oceanic drivers behind the 2023 Canadian wildfires
a–j Time-mean anomaly fields averaged from lag −10 to 10 days of composite daily (a, b) 500-hPa geopotential height (Z500, contour interval=10 gpm) and surface air temperature (SAT, color shading, unit: K), (c, d) vapor pressure deficit (VPD, color shading, unit: hPa), (e, f) precipitation (P, color shading, unit: mm/day), (g, h) soil moisture (SM, color shading, unit: m3 m−3) and (i, j) fire weather index (FWI, color shading, unit: non-dimensional) of summer North American blocking events for the combinations of the negative PDO (PDO−) with the (a, c, e, g, i) CP and (b, d, f, h, j) EP types of El Niño during 1979–2023, where lag 0 denotes the peak day of each blocking event. The color shading denotes the region being statistically significant at the 95% confidence level. k, l Time-longitude evolutions of composite daily Z500 anomalies of summer North American blocking events averaged over the high latitudes (50o-70oN) during the blocking process for the (k) PDO− & CP El Niño and (l) PDO− & EP El Niño during 1979–2023.
