A precipitation-dominated,mid-latitude glacier system: Mount Shasta,California

Temperature is often seen as the dominant control on inter-decadal glacier volume changes. However, despite regional warming over the past half-century, the glaciers of Mount Shasta have continued to expand following a contraction during a prolonged drought in the early twentieth century, indicating a greater sensitivity to precipitation than temperature. We use the 110 year record of fluctuations in Mount Shasta’s glaciers and climate to calibrate numerical glacier models of the two largest glaciers. The reconstructed balance and volume histories show a much greater correlation to precipitation than temperature and significant correlation to oscillatory modes of Pacific Ocean climate. An approximately 20% increase in precipitation is needed for every 1°C increase in temperature to maintain stability. Under continued historical trends, oscillations in climate modes and random variability will dominate inter-decadal variability in ice volume. Under the strong warming trend predicted by a regional climate model, the temperature trend will be the dominant forcing resulting in near total loss of Mount Shasta’s glaciers by the end of the twenty-first century.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Precipitation changes due to the introduction of eddy-resolved sea surface temperatures into simulations of the “Pasha Bulker” Australian east coast low of June 2007

Stratocumulus is often present offshore of Peru and northern Chile and exists at the top of a cool, moist and well-mixed marine boundary layer (MBL) under a marked temperature inversion maintained by large-scale subsidence. The subtropical MBL and stratocumulus has been the focus of many recent studies, but mid-latitude systems can exert a strong influence. However, this connection is not well established due to debatable model results and few in situ measurements south of 20°S. During a 2-week field campaign in August 2011 at Robinson Crusoe Island (~700 km offshore at 33.6°S), radiosondes were launched to observe the response of the MBL to mid-latitude synoptic forcing. During the observation period a broad, slow-moving cutoff low (COL) passed over the region. Other observations include COSMIC GPS, infrared satellite imagery, TRMM radar reflectivity, and operational radiosondes from the Chilean weather service. A numerical simulation is included to diagnose the synoptic features. The inversion prior to the COL was maintained and lifted above 5 km as the COL passed over the island. Soon after the COL center passed the island, the MBL top did not descend or reform near the surface and then deepen, but rather an inversion reformed at ~2.7 km. Using a variety of datasets, the height of the reformation of the inversion is related to the cloud top height of the scattered shallow cumulus convection under the COL, which coincides with the level of maximum convergence of the vertical velocity.     

The impact of weather and climate on tourist demand: the case of Chester Zoo

Warmer, drier summer weather brought by global climate change should encourage use of outdoor leisure facilities. Yet few studies assess the effect of current weather and climate conditions upon visits to leisure attractions. Statistical time series models are used to analyse the short-run impact of weather and the long-run impact of climate upon visits to Chester Zoo, England. Temperature has a non-linear effect on visit levels. Daily visits rise with temperature up to a threshold around 21 °C. Thereafter visitor numbers drop on hot days. Visits are redistributed over time in accordance with the weather. Visitors discouraged by rainy weather one day turn up later when the weather improves. Otherwise, visitor behaviour is mainly influenced by the annual rhythm of the year and the pattern of public and school holidays. Out-of-sample tests suggest almost 70 % of the variation in visit levels can be explained by the combination of weather and time of year. Climate change is likely to redistribute visitors across the year. But it does not follow that “summer” visitor behaviour will transfer to spring and autumn. Day length, existing patterns of human activity and availability of leisure time constrain visit levels regardless of better weather. The main implication of potential climate change is the need for physical adaptation of the tourist environment as temperatures rise and rainfall diminishes in summer.     

The vertical structure of the quasi‐biennial oscillation: Observations and theory

Abstract

Rocketsonde observations of the zonal wind over Ascension Island (8°S) were analysed to obtain the amplitude and phase of the quasi‐biennial oscillation (QBO) in the height range 25–58 km. It was found that the amplitude peaked at about 30km and decreased rapidly above 40km. In fact, above 45 km there is no clear evidence that a QBO actually exists.

A number of simulations using the Holton‐Lindzen model of the QBO were performed. It was found that when the waves in the model were damped with Dickinson's (1973) Newtonian cooling, the simulated QBO extended to higher levels than actually observed. However, when the wavelength‐dependent cooling rates of Fels(1981) were used, a fairly realistic vertical structure resulted.     

A Causality-guided Statistical Approach for Modeling Extreme Mei-yu Rainfall Based on Known Large-scale Modes——A Pilot Study

Extreme Mei-yu rainfall(MYR) can cause catastrophic impacts to the economic development and societal welfare in China. While significant improvements have been made in climate models, they often struggle to simulate local-to-regional extreme rainfall(e.g., MYR). Yet, large-scale climate modes(LSCMs) are relatively well represented in climate models.Since there exists a close relationship between MYR and various LSCMs, it might be possible to develop causality-guided statistical models for MYR pr...     

2018 Continues Record Global Ocean Warming

The increasing heat-trapping gases emitted by human activities into the atmosphere produce an energy imbalance between incoming solar radiation and outgoing longwave radiation that leads to global heating(Rhein et al.,2013;Trenberth et al.,2014;von Schuckmann et al.,2016).The vast majority of global warming heat ends up deposited in the world’s oceans,and ocean heat content(OHC)change is one of the best—if not the best—metric for climate change(Cheng et al.,2019).In 2018,continued record heat was measured in the Earth’s climate system.In fact,2018 has set a new record of ocean heating,surpassing 2017,which was the previous warmest year ever recorded(Cheng et al.,2018)(Fig.1).     

Experimental verification of torsional response control of asymmetric buildings using MR dampers

This paper proposes a semiactive control system to reduce the coupled lateral and torsional motions in asymmetric buildings subjected to horizontal seismic excitations. Magnetorheological (MR) dampers are applied as semiactive control devices and the control input determination is based on a clipped‐optimal control algorithm which uses absolute acceleration feedback. The performance of this method is studied experimentally using a 2‐story building model with an asymmetric stiffness distribution. An automated system identification methodology is implemented to develop a control‐oriented model which has the natural frequencies observed in the experimental system. The parameters for the MR damper model are identified using experimental data to develop an integrated model of the structure and MR dampers. To demonstrate the performance of this control system on the experimental structure, a shake table is used to reproduce an El Centro 1940 N–S earthquake as well as a random white noise excitation. The responses for the proposed control system are compared to those of passive control cases in which a constant voltage is applied to the MR damper. Copyright © 2003 John Wiley & Sons, Ltd.     

Mapping the geochemistry of the northern Rub' Al Khali using multispectral remote sensing techniques

Spatial variations in sand sea geochemistry relate to mixing of different sediment sources and to variations in weathering. Due to problems of accessibility, adequate spatial coverage cannot be achieved using field surveys alone. However, maps of geochemical composition produced from remotely sensed data can be calibrated against limited field data and the results extrapolated over large, inaccessible areas. This technique is applied to part of the Rub' Al Khali in the northern United Arab Emirates. Trend surface analysis of the results suggests that the sand sea at this location can be modelled as an east–west mixing zone of two spectral components: terrestrial reddened quartz sands and marine carbonate sands. Optical dating of these sediments suggests that dune emplacement occurred rapidly around 10 ka BP , when sea level was rising rapidly. The spatial distribution of mineralogical components suggests that this phase of dune emplacement resulted from coastal dune sands being driven inland during marine transgression, thereby becoming mixed with rubified terrestrial sands. Copyright © 2001 John Wiley & Sons, Ltd.     

Long-Term Ground Water Quality Impacts from the Use of Hexazinone for the Commercial Production of Lowbush Blueberries

Lowbush blueberries, native to eastern Canada and Maine, are an important economic crop in these areas. Herbicides containing the active ingredient hexazinone are commonly applied to blueberry fields, and there is a high frequency of detection of relatively low concentrations of hexazinone in domestic wells located close to areas of lowbush blueberry production. The objective of this study was to determine the long-term impacts from hexazinone-based herbicide use on ground water quality in the immediate growing areas.
Physical and chemical hydrogeologic data were collected for an outwash sand and gravel aquifer in southwestern New Brunswick, Canada. The majority of the land overlying the aquifer is devoted to lowbush blueberry production. Twenty-one nested monitoring wells were sampled for hexazinone and hexazinone metabolites over a four-year period. Hexazinone was consistently detected at values of 1 to 8 parts per billion (ppb) in all but two of these wells, one that is upgradient of herbicide applications, and one that is downgradient with anoxic conditions. Hexazinone metabolites B and A1 were also detected in all but two of the 21 wells at values ranging from 0.5 to 2.5 ppb. The hexazinone and metabolite data suggest both aerobic and anaerobic degradation of hexazinone. Complete degradation of hexazinone appears to occur only in the one downgradient well exhibiting anoxic ground water conditions. Concentrations of hexazinone and its metabolites in the ground water were essentially constant over the four-year period.