Determine the temporal trend in spatial wet-bulb temperature contraction

Determine whether the temporal trend in the association between high regional-mean wet-bulb temperature and reduced spatial wet-bulb temperature contrast in eastern China is nonzero, particularly over the 1991–2025 evaluation period.

Background

The study estimates a descriptive temporal trend of −0.22 percentage points per year for the high-versus-middle regional-mean wet-bulb temperature contrast. However, the reported interval based on between-summer variation includes zero, so the data do not resolve whether the contraction has strengthened or weakened over time. The authors therefore leave the temporal evolution of the association uncertain rather than establishing a definitive long-run trend.

References

The fitted trend was −0.22 percentage points per year (95% descriptive OLS interval based on between-summer variation, [−0.48, 0.05], two-sided p = 0.10). The 2008–2025 mean was 2.95 points more negative than the 1991–2007 mean, with a descriptive Welch interval based on between-summer variation of [−8.43, 2.52] points. Both intervals include zero, leaving the temporal trend uncertain.

— Scale-dependent contraction of spatial wet-bulb temperature contrasts in eastern China  (2608.14294 - Hou et al., 14 Aug 2026) in Section 5.2, page 10