Land-atmosphere coupling amplifies hot extremes over China

Zhang, Jingyong; Wu, Lingyun

doi:10.1007/s11434-011-4628-3

Cited by 60 publications

(50 citation statements)

References 34 publications

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“…This result is consistent with the conclusions in previous climate studies (e.g. Fischer et al, 2007;Zhang and Wu, 2011), i.e. because low soil moisture strongly reduces latent cooling, the surface temperature anomalies or heat waves are amplified.…”

Section: Spatial Distributionsupporting

confidence: 93%

“…For example, the coupling of soil moisture and temperature is mainly determined by the ability of the soil moisture to affect surface fluxes (e.g. Fischer et al, 2007;Zhang et al, 2011). It also shows that, similarly to long-term (e.g.…”

Section: Sensible and Latent Heat Fluxesmentioning

confidence: 99%

“…Using an atmospheric general circulation model, Fennessy and Kinter (2011) emphasised the important roles of both the warm local sea surface temperature and the dry local soil in intensifying the 2003 European heatwave. Using two long-term Weather Research and Forecasting model (WRF) simulations with and without soil moisture-atmosphere interactions to evaluate the influence of the land-atmosphere coupling on a summer heatwave in China, Zhang and Wu (2011) found that the land-atmosphere coupling amplifies hot extremes over China, especially in most areas of eastern and southeastern China; the increase was statistically significant. Regarding the summer 2010 Russian heatwave, Lau and Kim (2012) demonstrated that there was positive feedback between the extratropical atmospheric blocking pattern and an underlying extensive land region with below-normal soil moisture, which amplified the heatwave.…”

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confidence: 99%

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Sensitivity of high-temperature weather to initial soil moisture: a case study using the WRF model

et al. 2014

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Abstract. Using a succession of 24 h Weather Research andForecasting model (WRF) simulations, we investigate the sensitivity to initial soil moisture of a short-range hightemperature weather event that occurred in late July 2003 in East China. The initial soil moisture (SMOIS) in the Noah land surface scheme is adjusted (relative to the control run, CTL) for four groups of simulations: DRY25 (−25 %), DRY50 (−50 %), WET25 (+25 %) and WET50 (+50 %). Ten 24 h integrations are performed in each group.We focus on 2 m surface air temperature (SAT) greater than 35 • C (the threshold of "high-temperature" events in China) at 06:00 UTC (roughly 14:00 LT in the study domain) to analyse the occurrence of the high-temperature event. The 10-day mean results show that the 06:00 UTC SAT (SAT06) is sensitive to the SMOIS change; specifically, SAT06 exhibits an apparent increase with the SMOIS decrease (e.g. compared with CTL, DRY25 generally results in a 1 • C SAT06 increase over the land surface of East China), areas with 35 • C or higher SAT06 are the most affected, and the simulations are more sensitive to the SMOIS decrease than to the SMOIS increase, which suggests that hot weather can be amplified under low soil moisture conditions. Regarding the mechanism underlying the extremely high SAT06, sensible heat flux has been shown to directly heat the lower atmosphere, and latent heat flux has been found to be more sensitive to the SMOIS change, resulting in an overall increase in surface net radiation due to the increased greenhouse effect (e.g. with the SMOIS increase from DRY25 to CTL, the 10-day mean net radiation increases by 5 W m −2 ). Additionally, due to the unique and dynamic nature of the western Pacific subtropical high, negative feedback occurs between the regional atmospheric circulation and the air temperature in the lower atmosphere while positive feedback occurs in the midtroposphere.Using a method based on an analogous temperature relationship, a detailed analysis of the physical processes shows that for the SAT change, the SMOIS change affects diabatic processes (e.g. surface fluxes) more strongly than the adiabatic process of subsidence in the western Pacific subtropical high in the five groups of simulations. Interestingly, although diabatic processes dominate subsidence during the daytime and night-time separately, they do not necessarily dominate during the 24 h periods (e.g. they are dominant in the WET and CTL simulations only). Further, as the SMOIS decreases, the SAT06 increases, which is largely due to the reduced cooling effect of the diabatic processes, rather than the warming effect of subsidence.Unlike previous studies on heatwave events at climate timescales, this paper presents the sensitivity of simulated short-term hot weather to initial soil moisture and emphasises the importance of appropriate soil moisture initialization when simulating hot weather.

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Section: Spatial Distributionsupporting

confidence: 93%

Section: Sensible and Latent Heat Fluxesmentioning

confidence: 99%

mentioning

confidence: 99%

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Sensitivity of high-temperature weather to initial soil moisture: a case study using the WRF model

et al. 2014

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“…The persistence of droughts and heat waves has also been linked to land processes, mostly through the soil moisture limitation of evapotranspiration (Fischer et al 2007;Lorenz et al 2010;Jaeger and Seneviratne 2011;Zhang and Wu 2011;Mueller and Seneviratne 2012;Roundy et al 2014). LUC modifies the biophysical characteristics of the land surface, the surface energy balance (Boisier et al 2012), and how the land connects to the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Modulation of Land-Use Change Impacts on Temperature Extremes via Land–Atmosphere Coupling over Australia

et al. 2015

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The role of land-atmosphere coupling in modulating the impact of land-use change (LUC) on regional climate extremes remains uncertain. Using the Weather and Research Forecasting Model, this study combines the Global Land-Atmosphere Coupling Experiment with regional LUC to assess the combined impact of land-atmosphere coupling and LUC on simulated temperature extremes. The experiment is applied to an ensemble of planetary boundary layer (PBL) and cumulus parameterizations to determine the sensitivity of the results to model physics. Results show a consistent weakening in the soil moisture-maximum temperature coupling strength with LUC irrespective of the model physics. In contrast, temperature extremes show an asymmetric response to LUC dependent on the choice of PBL scheme, which is linked to differences in the parameterization of vertical transport. This influences convective precipitation, contributing a positive feedback on soil moisture and consequently on the partitioning of the surface turbulent fluxes. The results suggest that the impact of LUC on temperature extremes depends on the land-atmosphere coupling that in turn depends on the choice of PBL. Indeed, the sign of the temperature change in hot extremes resulting from LUC can be changed simply by altering the choice of PBL. The authors also note concerns over the metrics used to measure coupling strength that reflect changes in variance but may not respond to LUC-type perturbations.

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“…The IPCC AR4 (IPCC 2007) has pointed out that in middle-and high-latitude continental areas, the observed decadal trends of extreme temperatures can probably be attributed to human activities. China has experienced rapid urbanization since the 1970s, and some previous studies have focused on the impact of land use and urbanization on extreme hot events (Hu et al 2010;Jones et al 2008;Ren et al 2008;Zhang and Wu 2011).…”

Section: Conclusion and Discussionmentioning

confidence: 99%