Remote effects of Tibetan Plateau spring land temperature on global subseasonal to seasonal precipitation prediction and comparison with effects of sea surface temperature: the GEWEX/LS4P Phase I experiment

Abstract

The prediction skill for precipitation anomalies in late spring and summer months—a significant component of extreme climate events—has remained stubbornly low for years. This paper presents a new idea that utilizes information on boreal spring land surface temperature/subsurface temperature (LST/SUBT) anomalies over the Tibetan Plateau (TP) to improve prediction of subsequent summer droughts/floods over several regions over the world, East Asia and North America in particular. The work was performed in the framework of the GEWEX/LS4P Phase I (LS4P-I) experiment, which focused on whether the TP LST/SUBT provides an additional source for subseasonal-to-seasonal (S2S) predictability. The summer 2003, when there were severe drought/flood over the southern/northern part of the Yangtze River basin, respectively, has been selected as the focus case. With the newly developed LST/SUBT initialization method, the observed surface temperature anomaly over the TP has been partially produced by the LS4P-I model ensemble mean, and 8 hotspot regions in the world were identified where June precipitation is significantly associated with anomalies of May TP land temperature. Consideration of the TP LST/SUBT effect has produced about 25–50% of observed precipitation anomalies in most hotspot regions. The multiple models have shown more consistency in the hotspot regions along the Tibetan Plateau-Rocky Mountain Circumglobal (TRC) wave train. The mechanisms for the LST/SUBT effect on the 2003 drought over the southern part of the Yangtze River Basin are discussed. For comparison, the global SST effect has also been tested and 6 regions with significant SST effects were identified in the 2003 case, explaining about 25–50% of precipitation anomalies over most of these regions. This study suggests that the TP LST/SUBT effect is a first-order source of S2S precipitation predictability, and hence it is comparable to that of the SST effect. With the completion of the LS4P-I, the LS4P-II has been launched and the LS4P-II protocol is briefly presented.

Sources of MJO teleconnection errors in the ECMWF extended‐range forecasts

“…Table 3 shows an increase in NAO index and amplitudes, but not in spatial correlations when comparing TMP1 to CONTROL48R1. These results are consistent with Xue et al (2023) who showed that changes to Tibetan Plateau land temperature initialization had remote impacts on subseasonal to seasonal prediction, although they focussed on the spring season instead of winter as in the present article.…”

Precursory signals of summer precipitation over southern Central Asia: Combined effect of April soil moisture and sea surface temperature

“…Apart from the SSTAs in several key ocean areas, land conditions (e.g., soil temperature, soil moisture [SM], snow cover, surface sensible, and latent heat fluxes) and associated land-air interaction play a crucial role in modulating precipitation over some regions (Ardilouze et al, 2022;Xue et al, 2022Xue et al, , 2023. Of these land conditions, SM has persistence ranging from several weeks to months (Entin et al, 2000;Orth & Seneviratne, 2012;Seneviratne et al, 2006;Song et al, 2019) and is an important slowly varying component of the Earth system (Dirmeyer, 2011;Koster et al, 2004;Materia et al, 2022).…”

Subseasonal-to-seasonal predictability of extreme precipitation and land forcing

“…The spring and summer 2003 have been selected for the case study, when the TP had a very cold spring and the southern Yangtze River basin had a severe drought, which cause had never been identified. Xue et al (2023) summarizes the major results from the LS4P-I ESM ensemble mean regarding the S2S predictability. In addition to the southern Yangtze River basin, another 7 hotspot regions over Northern Hemisphere have been identified where the TP spring LST/SUBT had significant impact on the dry or wet conditions, which are also It is well-known that the root cause of extreme hydroclimate events, i.e., heatwave, droughts, and floods, under climate change is in the variability of precipitation at subseasonalto-seasonal(S2S) time scales.…”

“…Among 8 hotspots regions, 5 are along the TRC and one is in its extension. Zhang et al (2024) and Xue et al (2023) in this special issue analyzed the possible mechanisms for TP's influence in global circulation and East Asian monsoon, respectively. The TRC's role in the TP's remote effect has been further confirmed by Ardilouze and Boone (2023) and Qin et al (2023).…”