A Framework for Quantitative Assessment of Impacts Related to Energy and Mineral Resource Development

Natural resource planning at all scales demands methods for assessing the impacts of resource development and use, and in particular it requires standardized methods that yield robust and unbiased results. Building from existing probabilistic methods for assessing the volumes of energy and mineral resources, we provide an algorithm for consistent, reproducible, quantitative assessment of resource development impacts. The approach combines probabilistic input data with Monte Carlo statistical methods to determine probabilistic outputs that convey the uncertainties inherent in the data. For example, one can utilize our algorithm to combine data from a natural gas resource assessment with maps of sage grouse leks and piñon-juniper woodlands in the same area to estimate possible future habitat impacts due to possible future gas development. As another example: one could combine geochemical data and maps of lynx habitat with data from a mineral deposit assessment in the same area to determine possible future mining impacts on water resources and lynx habitat. The approach can be applied to a broad range of positive and negative resource development impacts, such as water quantity or quality, economic benefits, or air quality, limited only by the availability of necessary input data and quantified relationships among geologic resources, development alternatives, and impacts. The framework enables quantitative evaluation of the trade-offs inherent in resource management decision-making, including cumulative impacts, to address societal concerns and policy aspects of resource development.     

Sudden stratospheric warmings and tropospheric blockings in a multi-century simulation of the IPSL-CM5A coupled climate model

The relation between sudden stratospheric warmings (SSWs) and blocking events is analyzed in a multi-centennial pre-industrial simulation of the Institut Pierre Simon Laplace coupled model (IPSL-CM5A), prepared for the fifth phase of the coupled model intercomparison project. The IPSL model captures a fairly realistic distribution of both SSWs and tropospheric blocking events, albeit with a tendency to overestimate the frequency of blocking in the western Pacific and underestimate it in the Euro-Atlantic sector. The 1000-year long simulation reveals statistically significant differences in blocking frequency and duration over the 40-day periods preceding and following the onset of SSWs. More specifically, there is an enhanced blocking frequency over Eurasia before SSWs, followed by an westward displacement of blocking anomalies over the Atlantic region as SSWs evolve and then decline. The frequency of blocking is reduced over the western Pacific sector during the life-cycle of SSWs, while the model simulates no significant relationship with eastern Pacific blocks. Finally, these changes in blocking frequency tend to be associated with a shift in the distribution of blocking lifetime toward longer-lasting blocking events before the onset of SSWs and shorter-lived blocks after the warmings. This study systematically verifies that the results are consistent with the two pictures that (1) blockings produce planetary scale anomalies that can force vertically propagating Rossby waves and then SSWs when the waves break and (2) SSWs affect blockings in return, for instance via the effect they have on the North Atlantic Oscillation.     

Impacts of large-scale climatic disturbances on the terrestrial carbon cycle

Background

The amount of carbon dioxide in the atmosphere steadily increases as a consequence of anthropogenic emissions but with large interannual variability caused by the terrestrial biosphere. These variations in the CO₂ growth rate are caused by large-scale climate anomalies but the relative contributions of vegetation growth and soil decomposition is uncertain. We use a biogeochemical model of the terrestrial biosphere to differentiate the effects of temperature and precipitation on net primary production (NPP) and heterotrophic respiration (Rh) during the two largest anomalies in atmospheric CO₂ increase during the last 25 years. One of these, the smallest atmospheric year-to-year increase (largest land carbon uptake) in that period, was caused by global cooling in 1992/93 after the Pinatubo volcanic eruption. The other, the largest atmospheric increase on record (largest land carbon release), was caused by the strong El Niño event of 1997/98.

Results

We find that the LPJ model correctly simulates the magnitude of terrestrial modulation of atmospheric carbon anomalies for these two extreme disturbances. The response of soil respiration to changes in temperature and precipitation explains most of the modelled anomalous CO₂ flux.

Conclusion

Observed and modelled NEE anomalies are in good agreement, therefore we suggest that the temporal variability of heterotrophic respiration produced by our model is reasonably realistic. We therefore conclude that during the last 25 years the two largest disturbances of the global carbon cycle were strongly controlled by soil processes rather then the response of vegetation to these large-scale climatic events.     

Influence of road network and population demand assumptions in evacuation modeling for distant tsunamis

Tsunami evacuation planning in coastal communities is typically focused on local events where at-risk individuals must move on foot in a matter of minutes to safety. Less attention has been placed on distant tsunamis, where evacuations unfold over several hours, are often dominated by vehicle use and are managed by public safety officials. Traditional traffic simulation models focus on estimating clearance times but often overlook the influence of varying population demand, alternative modes, background traffic, shadow evacuation, and traffic management alternatives. These factors are especially important for island communities with limited egress options to safety. We use the coastal community of Balboa Island, California (USA), as a case study to explore the range of potential clearance times prior to wave arrival for a distant tsunami scenario. We use a first-in–first-out queuing simulation environment to estimate variations in clearance times, given varying assumptions of the evacuating population (demand) and the road network over which they evacuate (supply). Results suggest clearance times are less than wave arrival times for a distant tsunami, except when we assume maximum vehicle usage for residents, employees, and tourists for a weekend scenario. A two-lane bridge to the mainland was the primary traffic bottleneck, thereby minimizing the effect of departure times, shadow evacuations, background traffic, boat-based evacuations, and traffic light timing on overall community clearance time. Reducing vehicular demand generally reduced clearance time, whereas improvements to road capacity had mixed results. Finally, failure to recognize non-residential employee and tourist populations in the vehicle demand substantially underestimated clearance time.     

Causes of the Intraseasonal SST Variability in the Tropical Indian Ocean

Satellite observations reveal a much stronger intraseasonal sea surface temperature (SST) variability in the southern Indian Ocean along 5-10oS in boreal winter than in boreal summer. The cause of this seasonal dependence is studied using a 2?-layer ocean model forced by ERA-40 reanalysis products during 1987-2001. The simulated winter-summer asymmetry of the SST variability is consistent with the observed. A mixed-layer heat budget is analyzed. Mean surface westerlies along the ITCZ (5-10oS) in December-January-February (DJF) leads to an increased (decreased) evaporation in the westerly (easterly) phase of the intraseasonal oscillation (ISO), during which convection is also enhanced (suppressed). Thus the anomalous shortwave radiation, latent heat flux and entrainment effects are all in phase and produce strong SST signals. During June-July-August (JJA), mean easterlies prevail south of the equator. Anomalies of the shortwave radiation tend to be out of phase to those of the latent heat flux and ocean entrainment. This mutual cancellation leads to a weak SST response in boreal summer. The resultant SST tendency is further diminished by a deeper mixed layer in JJA compared to that in DJF. The strong intraseasonal SST response in boreal winter may exert a delayed feedback to the subsequent opposite phase of ISO, implying a two-way air-sea interaction scenario on the intraseasonal timescale. Citation: Li, T., F. Tam, X. Fu, et al., 2008: Causes of the intraseasonal SST variability in the tropical Indian ocean, Atmos. Oceanic Sci. Lett., 1, 18-23     

The intraseasonal oscillations of precipitation and circulations from January to March in 2010 in East Asia

The rainfall from January to March in 2010 in East Asia is positive anomaly and the temporal evolution characteristics present the cycle of 20–40 days. In the present paper, the low-frequency circulations and its formation mechanism are analyzed. The results show that during the peak rainfall phase, the upstream of the rainfall regions is controlled by low-frequency cyclone, and the downstream is controlled by low-frequency anticyclone in the middle and low troposphere. In the upper troposphere, the westerly jet presents the oscillation characteristics between the north and the south. Both the integrated (from the surface to 100 hPa) diabatic heating and the horizontal vorticity advection contribute to the vertical velocity. In addition, the vorticity vertical advection has effects on the vertical speed, which is a self-feedback process. The latent heating in the precipitation has influences on the westerly jet in the upper troposphere. The interactions between the precipitation and the westerly jet are mainly manifested as the intraseasonal oscillations.     

Evaluation of forecast strategies for seasonal and decadal forecasts in presence of systematic model errors

This study discusses and compares three different strategies used to deal with model error in seasonal and decadal forecasts. The strategies discussed are the so-called full initialisation, anomaly initialisation and flux correction. In the full initialisation the coupled model is initialised to a state close to the real-world attractor and after initialisation the model drifts towards its own attractor, giving rise to model bias. The anomaly initialisation aims to initialise the model close to its own attractor, by initialising only the anomalies. The flux correction strategy aims to keep the model trajectory close to the real-world attractor by adding empirical corrections. These three strategies have been implemented in the ECMWF coupled model, and are evaluated at seasonal and decadal time-scales. The practical implications of the different strategies are also discussed. Results show that full initialisation results in a clear model drift towards a colder climate. The anomaly initialisation is able to reduce the drift, by initialising around the model mean state. However, the erroneous model mean state results in degraded seasonal forecast skill. The best results on the seasonal time-scale are obtained using momentum-flux correction, mainly because it avoids the positive feedback responsible for a strong cold bias in the tropical Pacific. It is likely that these results are model dependent: the coupled model used here shows a strong cold bias in the Central Pacific, resulting from a positive coupled feedback between winds and SST. At decadal time-scales it is difficult to determine whether any of the strategies is superior to the others.     

耦合模式FGOALS_s 模拟的亚澳季风年际变率及ENSO

本文评估了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 (LASG/IAP) 新一代耦合气候模式FGOALS_s对亚澳季风和ENSO的模拟。结果表明, FGOALS_s可以模拟出亚澳季风的主要气候态特征。FGOALS_s模拟的ENSO事件振幅为观测值的70%, 同时它合理再现了ENSO周期的非规则性。FGOALS_s可以定性模拟出ENSO的主要空间特征。当赤道东太平洋SST升高时, 印度洋和西太平洋海表面气压升高, 而东太平洋海表面气压降低。FGOALS_s的主要缺陷在于模拟的ENSO峰值多出现在春季和夏季。与ENSO振幅偏小相反, FGOALS_s模拟的亚澳季风年际变率振幅大于观测。但是观测中亚澳季风年际变率与ENSO暖位相的显著负相关关系, 在模式中没有得到合理再现, 原因部分可归之于耦合模式在ENSO锁相模拟上的缺陷。由于模式模拟的ENSO峰值出现在北半球春季和夏季, Walker环流异常下沉支移动到西北太平洋, 其激发出的异常反气旋位置较之观测要偏东, 导致印度季风降水和El Niño的负相关关系不显著; 在北半球冬季, 由于模式中的赤道东太平洋SST暖异常较弱, 亚澳季风响应也偏弱。此外, 由于赤道东太平洋SST异常向西伸展, 观测中位于澳洲季风区的辐散中心向西偏移, 最终导致模式中澳洲季风降水与ENSO的负相关同样不显著。     

What controls early or late onset of tropical North Atlantic hurricane season?

The occurrence of first hurricane in early summer signifies the onset of an active Atlantic hurricane season. The interannual variation of this hurricane onset date is examined for the period 1979-2013. It is found that the onset date has a marked interannual variation. The standard deviation of the interannual variation of the onset day is 17.5 days, with the climatological mean onset happening on July 23.A diagnosis of tropical cyclone (TC) genesis potential index (GPI) indicates that the major difference between an early and a late onset group lies in the maximum potential intensity (MPI). A further diagnosis of the MPI shows that it is primarily controlled by the local SST anomaly (SSTA). Besides the SSTA, vertical shear and mid-tropospheric relative humidity anomalies also contribute significantly to the GPI difference between the early and late onset groups.It is found that the anomalous warm (cold) SST over the tropical Atlantic, while uncorrelated with the Niño3 index, persists from the preceding winter to concurrent summer in the early (late) onset group. The net surface heat flux anomaly always tends to damp the SSTA, which suggests that ocean dynamics may play a role in maintaining the SSTA in the tropical Atlantic. The SSTA pattern with a maximum center in northeastern tropical Atlantic appears responsible for generating the observed wind and moisture anomalies over the main TC development region. A further study is needed to understand the initiation mechanism of the SSTA in the Atlantic.