Fig. 4: Contributions to the July HW.
a Evolution of a set of variables related to HWs and surface processes, averaged for a regional box over the record-breaking area of the July HW (NE France/Belgium [48°–50.5° N, 2°–6° E]): Upper panel shows TX (°C) and 0–10 cm soil moisture (volumetric fraction), while lower panel shows latent/sensible heat fluxes and net radiative flux anomalies (W/m2). Dashed lines represent the climatological values and hatched areas correspond to positive (negative) anomalies for TX and sensible heat flux (soil moisture). Days with Bowen Ratio above 1 are also presented (red bars in lower panel), illustrating periods where upward fluxes of sensible heat exceed those of latent heat. b Sensible heat flux anomalies (shading, W/m2) averaged during the 7 days prior to the July HW, with vectors depicting the mean near-surface wind during the same period. Dots represent areas with soil moisture deficits (different sizes depict 10%, 20 and 30% deficit), averaged during the 15 days before the July HW onset (here using the C3S satellite derived product). Black box represents the area considered for the series presented in a).
