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191.
Elaine?R.?MilesEmail author Claire?M.?Spillman John?A.?Church Peter?C.?McIntosh 《Climate Dynamics》2014,43(7-8):2131-2145
Advanced warning of extreme sea level events is an invaluable tool for coastal communities, allowing the implementation of management policies and strategies to minimise loss of life and infrastructure damage. This study is an initial attempt to apply a dynamical coupled ocean–atmosphere model to the prediction of seasonal sea level anomalies (SLA) globally for up to 7 months in advance. We assess the ability of the Australian Bureau of Meteorology’s operational seasonal dynamical forecast system, the Predictive Ocean Atmosphere Model for Australia (POAMA), to predict seasonal SLA, using gridded satellite altimeter observation-based analyses over the period 1993–2010 and model reanalysis over 1981–2010. Hindcasts from POAMA are based on a 33-member ensemble of seasonal forecasts that are initialised once per month for the period 1981–2010. Our results show POAMA demonstrates high skill in the equatorial Pacific basin and consistently exhibits more skill globally than a forecast based on persistence. Model predictability estimates indicate there is scope for improvement in the higher latitudes and in the Atlantic and Southern Oceans. Most characteristics of the asymmetric SLA fields generated by El-Nino/La Nina events are well represented by POAMA, although the forecast amplitude weakens with increasing lead-time. 相似文献
192.
Silva Vinicius Oliveira de Mello Carlos Rogério Chou Sin Chan 《Theoretical and Applied Climatology》2022,148(3-4):1289-1302
Theoretical and Applied Climatology - South of Minas Gerais state, in Southeast Brazil, is known for the coffee crop production (more than 30% of country’s production) and hydroelectricity... 相似文献
193.
European floods during the winter 1783/1784: scenarios of an extreme event during the ‘Little Ice Age’ 总被引:1,自引:0,他引:1
Rudolf Brázdil Gaston R. Demarée Mathias Deutsch Emmanuel Garnier Andrea Kiss Jürg Luterbacher Neil Macdonald Christian Rohr Petr Dobrovolný Petr Kolář Kateřina Chromá 《Theoretical and Applied Climatology》2010,100(1-2):163-189
The Lakagígar eruption in Iceland during 1783 was followed by the severe winter of 1783/1784, which was characterised by low temperatures, frozen soils, ice-bound watercourses and high rates of snow accumulation across much of Europe. Sudden warming coupled with rainfall led to rapid snowmelt, resulting in a series of flooding phases across much of Europe. The first phase of flooding occurred in late December 1783–early January 1784 in England, France, the Low Countries and historical Hungary. The second phase at the turn of February–March 1784 was of greater extent, generated by the melting of an unusually large accumulation of snow and river ice, affecting catchments across France and Central Europe (where it is still considered as one of the most disastrous known floods), throughout the Danube catchment and in southeast Central Europe. The third and final phase of flooding occurred mainly in historical Hungary during late March and early April 1784. The different impacts and consequences of the above floods on both local and regional scales were reflected in the economic and societal responses, material damage and human losses. The winter of 1783/1784 can be considered as typical, if severe, for the Little Ice Age period across much of Europe. 相似文献
194.
S. H. Franchito V. Brahmananda Rao R. Ramos da Silva 《Meteorology and Atmospheric Physics》1998,69(1-2):23-38
Summary A parameterization of shortwave and longwave radiation fluxes derived from detailed radiative transfer models is included in a global primitive equation statistical-dynamical model (SDM) with two bulk atmospheric layers. The model is validated comparing the model simulations with the observed mean annual and seasonal zonally averaged climate. The results show that the simulation of the shortwave and longwave radiation fluxes matches well with the observations. The SDM variables such as surface and 500 hPa temperatures, zonal winds at 250 hPa and 750 hPa, vertical velocity at 500 hPa and precipitation are also in good agreement with the observations. A comparison between the results obtained with the present SDM and those with the previous version of the model indicates that the model results improved when the parameterization of the radiative fluxes based on detailed radiative transfer models are included into the SDM.The SDM is used to investigate its response to the greenhouse effect. Sensitivity experiments regarding the doubling of CO2 and the changing of the cloud amount and height are performed. In the case 2×CO2 the model results are consistent with those obtained from GCMs, showing a warming of the climate system. An enhancement of the greenhouse effect is also noted when the cloud layer is higher. However, an increase of the cloud amount in all the latitude belts provokes an increase of the surface temperature near poles and a decrease in all the other regions. This suggests that the greenhouse effect overcomes the albedo effect in the polar latitudes and the opposite occurs in other regions. In all the experiments the changes in the surface temperature are larger near poles, mainly in the Southern Hemisphere.With 8 Figures 相似文献
195.
196.
197.
Particle composition and size distributions in and around a deep-pit swine operation,Ames, IA 总被引:1,自引:0,他引:1
Randal S. Martin Philip J. Silva Kori Moore Mark Erupe Vishal S. Doshi 《Journal of Atmospheric Chemistry》2008,59(2):135-150
The contribution of emissions from agricultural facilities is rapidly becoming a major concern for local and regional air
quality. Characterization of particle properties such as physical size distribution and chemical composition can be valuable
in understanding the processes contributing to emissions and ultimate fate of particulate matter from agricultural facilities.
A measurement campaign was conducted at an Iowa, deep-pit, three-barn swine finishing facility to characterize near-source
ambient particulate matter. Size-specific mass concentrations were determined using minivol samplers, with additional size
distribution information obtain using optical particle counters. Particulate composition was determined via ion chromatographic
analysis of the collected filters. A thermal-CO2 elemental/organic carbon analyzer measured particulate carbon. The chemical composition and size distribution of sub-micron
particles were determined via real-time aerosol mass spectrometry. Primary particulate was not found to be a major emission
from the examined facility, with filter-based impactor samples showing average near-source increases (~15–50 m) in ambient
PM10 of 5.8 ± 2.9 μg m−3 above background levels. PM2.5 also showed contribution attributable to the facility (1.7 ± 1.1 μg m−3). Optical particle counter analysis of the numerical size distributions showed bimodal distributions for both the upwind
and downwind conditions, with maximums around 2.5 μm and below the minimum quantified diameter of 0.3 μm. The distributions
showed increased numbers of coarse particles (PM10) during periods when wind transport came from the barns, but the differences were not statistically significant at the 95%
confidence level. The PM10 aerosols showed statistically increased concentrations of sulfate, nitrate, ammonium, calcium, organic carbon, and elemental
carbon when the samplers were downwind from the pig barns. Organic carbon was the major constituent of the barn-impacted particulate
matter in both sub-micron (54%) and coarse size (20%) ranges. The AMS PM1 chemical speciation showed similar species increases, with the exception of and Ca+2, the latter not quantified by the AMS. 相似文献
198.
M. N. Khaliq P. Gachon A. St-Hilaire T. B. M. J. Ouarda B. Bobée 《Theoretical and Applied Climatology》2007,88(1-2):83-101
Summary Summer-season (May–September) daily maximum temperature (T
max) and daily minimum temperature (T
min) observations and three types of heat spells obtained from these temperature observations at seven weather stations located
in southern Quebec (Canada) for the 60-year period from 1941 to 2000 are studied to assess temporal changes in their characteristics
(i.e. frequency of occurrence, seasonal hot days and extremal durations of heat spells). Type-A and Type-B heat spells are
obtained respectively from T
max and T
min observations and Type-C heat spells from simultaneous joint observations of T
max and T
min using suitable thresholds and spells of duration ≥1-day and ≥3-day. The results of this investigation show that the majority
of the selected percentiles (i.e. 5P, 10P, 25P, 50P, 75P, 80P, 90P, 92P, 95P, and 98P) of T
max observations show a negative time-trend with statistically significant decreases (at 10% level) in some of the higher percentiles
and in the maximal values at four out of seven stations. Almost all of the selected percentiles (same as for the T
max) and the maximal and minimal values of T
min observations show a positive trend, with statistically significant increases for all seven stations. Examination of frequencies
of occurrence of heat spells, seasonal hot days and annual extremes of heat spell durations indicate that many of these characteristics
of heat spells have undergone statistically significant changes over time at some of the stations for Type-A and Type-B heat
spells as compared to Type-C heat spells. The Type-C heat spells are generally small in number and are found to be relatively
temporally stable. More severe Type-C heat spells, i.e. the ones having T
max and T
min values simultaneously above very high thresholds and with duration ≥3-day have been rarely observed in southern Quebec. 相似文献
199.
Large-eddy simulations of the neutrally stratified flow over the Askervein Hill were performed, to improve the knowledge of
the flow obtained from field measurements and numerical simulations with Reynolds averaged Navier-Stokes (RANS) methods. A
Lagrangian dynamic subgrid model was used but, to avoid the underdissipative character near the ground, it was merged with
a damped Smagorinsky model. Simulations of a flat boundary-layer flow with this subgrid model showed that the turbulent vertical
motions and shear stress were better resolved using grids with a stream to spanwise aspect ratio Δx / Δy = 2 than with an aspect ratio Δx / Δy = 1. Regarding the flow over the Askervein Hill, it was found that large-eddy simulations provide an acceptable solution
for the mean-velocity field and better predictions of the turbulent kinetic energy in the upstream side of the hill than the
model. However, as with the model, grid convergence was not achieved in the lee side and the size of the zone with reversed flow increased with the grid
refinement. Nevertheless, the existence of the intermittent separation predicted with unsteady RANS in part one of this work
seems unquestionable, due to the deceleration of the flow. In our opinion, a better modelling of the decelerating boundary
layer in the lee side is required to improve the results obtained using equilibrium assumptions and achieve grid convergence. 相似文献
200.
Filip Lefebre Xavier Fettweis Hubert Gallée Jean-Pascal Van Ypersele Philippe Marbaix Wouter Greuell Pierluigi Calanca 《Climate Dynamics》2005,25(1):99-116
A simulation of the 1991 summer has been performed over south Greenland with a coupled atmosphere–snow regional climate model
(RCM) forced by the ECMWF re-analysis. The simulation is evaluated with in-situ coastal and ice-sheet atmospheric and glaciological
observations. Modelled air temperature, specific humidity, wind speed and radiative fluxes are in good agreement with the
available observations, although uncertainties in the radiative transfer scheme need further investigation to improve the
model’s performance. In the sub-surface snow-ice model, surface albedo is calculated from the simulated snow grain shape and
size, snow depth, meltwater accumulation, cloudiness and ice albedo. The use of snow metamorphism processes allows a realistic
modelling of the temporal variations in the surface albedo during both melting periods and accumulation events. Concerning
the surface albedo, the main finding is that an accurate albedo simulation during the melting season strongly depends on a
proper initialization of the surface conditions which mainly result from winter accumulation processes. Furthermore, in a
sensitivity experiment with a constant 0.8 albedo over the whole ice sheet, the average amount of melt decreased by more than
60%, which highlights the importance of a correctly simulated surface albedo. The use of this coupled atmosphere–snow RCM
offers new perspectives in the study of the Greenland surface mass balance due to the represented feedback between the surface
climate and the surface albedo, which is the most sensitive parameter in energy-balance-based ablation calculations. 相似文献