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Diandong Ren
,
Rong Fu
,
Lance M. Leslie
, and
Robert E. Dickinson

Abstract

An overview of storm-triggered landslides is presented. Then a recently developed and extensively verified landslide modeling system is used to illustrate the importance of two important but presently overlooked mechanisms involved in landslides. The model's adaptive design makes the incorporation of new physical mechanisms convenient. For example, by implementing a land surface scheme that simulates macropore features of fractured sliding material in the draining of surface ponding, it explains why precipitation intensity is critical in triggering catastrophic landslides.

Based on this model, the authors made projections of landslide occurrence in the upcoming 10 years over a region of Southern California, using atmospheric parameters provided by a highresolution climate model under a viable emission future scenario. Current global coupled ocean–atmosphere climate model (CGCM) simulations of precipitation, properly interpreted, provide valuable information to guide studies of storm-triggered landslides. For the area of interest, the authors examine changes in recurrence frequency and spatial distribution of storm-triggered landslides. For some locations, the occurrences of severe landslides (i.e., those with a sliding mass greater than 104 m3) are expected to increase by ~5% by the end of the twenty-first century.

The authors also provide a perspective on the ecosystem consequences of an increase in storm-triggered mudslides. For single plants, the morphological features required for defense against extreme events and those required to maximize growth and reproduction are at odds. Natural selection has resulted in existing plants allocating just enough resources to cope with natural hazards under a naturally varying climate. Consequently, many plant species are not prepared for the expected large changes in extremes caused by anthropogenic climate changes in the present and future centuries.

A supplement to this article is available online:

DOI: 10.1175/2010BAMS3017.2

Full access
Diandong Ren
,
Rong Fu
,
Robert E. Dickinson
,
Lance M. Leslie
, and
Xingbao Wang
Full access
Diandong Ren
,
Rong Fu
,
Robert E. Dickinson
,
Lance M. Leslie
, and
Xingbao Wang

Abstract

Aircraft cruising near the tropopause currently benefit from the highest thermal efficiency and the least viscous (sticky) air, within the lowest 50 km of Earth’s atmosphere. Both advantages wane in a warming climate, because atmospheric dynamic viscosity increases with temperature, in synergy with the simultaneous engine efficiency reduction. Here, skin friction drag, the dominant term for extra aviation fuel consumption in a future warming climate, is quantified by 34 climate models under a strong emissions scenario. Since 1950, the viscosity increase at cruising altitudes (∼200 hPa) reaches ∼1.5% century‒1, corresponding to a total drag increment of ∼0.22% century‒1 for commercial aircraft. Meridional gradients and regional disparities exist, with low to midlatitudes experiencing greater increases in skin friction drag. The North Atlantic corridor (NAC) is moderately affected, but its high traffic volume generates additional fuel cost of ∼3.8 × 107 gallons annually by 2100, compared to 2010. Globally, a normal year after 2100 would consume an extra ∼4 × 106 barrels per year. Intermodel spread is <5% of the ensemble mean, due to high inter–climate model consensus for warming trends at cruising altitudes in the tropics and subtropics. Because temperature is a well-simulated parameter in the IPCC archive, with only a moderate intermodel spread, the conclusions drawn here are statistically robust. Notably, additional fuel costs are likely from the increased vertical shear and related turbulence at NAC cruising altitudes. Increased flight log availability is required to confirm this apparent increasing turbulence trend.

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Masashi Nagata
,
Lance Leslie
,
Yoshio Kurihara
,
Russell L. Elsberry
,
Masanori Yamasaki
,
Hirotaka Kamahori
,
Robert Abbey Jr.
,
Kotaro Bessho
,
Javier Calvo
,
Johnny C. L. Chan
,
Peter Clark
,
Michel Desgagne
,
Song-You Hong
,
Detlev Majewski
,
Piero Malguzzi
,
John McGregor
,
Hiroshi Mino
,
Akihiko Murata
,
Jason Nachamkin
,
Michel Roch
, and
Clive Wilson

The Third Comparison of Mesoscale Prediction and Research Experiment (COMPARE) workshop was held in Tokyo, Japan, on 13–15 December 1999, cosponsored by the Japan Meteorological Agency (JMA), Japan Science and Technology Agency, and the World Meteorological Organization. The third case of COMPARE focuses on an event of explosive tropical cyclone [Typhoon Flo (9019)] development that occurred during the cooperative three field experiments, the Tropical Cyclone Motion experiment 1990, Special Experiment Concerning Recurvature and Unusual Motion, and TYPHOON-90, conducted in the western North Pacific in August and September 1990. Fourteen models from nine countries have participated in at least a part of a set of experiments using a combination of four initial conditions provided and three horizontal resolutions. The resultant forecasts were collected, processed, and verified with analyses and observational data at JMA. Archived datasets have been prepared to be distributed to participating members for use in further evaluation studies.

In the workshop, preliminary conclusions from the evaluation study were presented and discussed in the light of initiatives of the experiment and from the viewpoints of tropical cyclone experts. Initial conditions, depending on both large-scale analyses and vortex bogusing, have a large impact on tropical cyclone intensity predictions. Some models succeeded in predicting the explosive deepening of the target typhoon at least qualitatively in terms of the time evolution of central pressure. Horizontal grid spacing has a very large impact on tropical cyclone intensity prediction, while the impact of vertical resolution is less clear, with some models being very sensitive and others less so. The structure of and processes in the eyewall clouds with subsidence inside as well as boundary layer and moist physical processes are considered important in the explosive development of tropical cyclones. Follow-up research activities in this case were proposed to examine possible working hypotheses related to the explosive development.

New strategies for selection of future COMPARE cases were worked out, including seven suitability requirements to be met by candidate cases. The VORTEX95 case was withdrawn as a candidate, and two other possible cases were presented and discussed.

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