Convective Self-Aggregation in Numerical Simulations: A Review     

Allison A. Wing  Kerry Emanuel  Christopher E. Holloway  Caroline Muller 《Surveys in Geophysics》2017,38(6):1173-1197

Organized convection in the tropics occurs across a range of spatial and temporal scales and strongly influences cloud cover and humidity. One mode of organization found is “self-aggregation,” in which moist convection spontaneously organizes into one or several isolated clusters despite spatially homogeneous boundary conditions and forcing. Self-aggregation is driven by interactions between clouds, moisture, radiation, surface fluxes, and circulation, and occurs in a wide variety of idealized simulations of radiative–convective equilibrium. Here we provide a review of convective self-aggregation in numerical simulations, including its character, causes, and effects. We describe the evolution of self-aggregation including its time and length scales and the physical mechanisms leading to its triggering and maintenance, and we also discuss possible links to climate and climate change.  相似文献   

EUREC<Superscript>4</Superscript>A: A Field Campaign to Elucidate the Couplings Between Clouds,Convection and Circulation     

Sandrine Bony  Bjorn Stevens  Felix Ament  Sebastien Bigorre  Patrick Chazette  Susanne Crewell  Julien Delanoë  Kerry Emanuel  David Farrell  Cyrille Flamant  Silke Gross  Lutz Hirsch  Johannes Karstensen  Bernhard Mayer  Louise Nuijens  James H. RuppertJr.  Irina Sandu  Pier Siebesma  Sabrina Speich  Frédéric Szczap  Julien Totems  Raphaela Vogel  Manfred Wendisch  Martin Wirth 《Surveys in Geophysics》2017,38(6):1529-1568

Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization.  相似文献   

African climate variability in the satellite era     

Mark R. Jury  Emanuel J. Mpeta 《Theoretical and Applied Climatology》2009,98(3-4):279-291

Interannual fluctuations in rainfall and ocean-atmosphere fields over and around Africa were studied in the satellite era of 1979–2007 using singular value decomposition. The leading modes of rainfall variability in GPCP satellite-gauge merged fields include a leading mode over central Africa, two modes of marine origin in the Gulf of Guinea and Eastern Africa, and two sub-tropical modes over the Sahel and Southern Africa. This differs from earlier gauge-based studies that tend to isolate three leading modes over western, eastern, and southern Africa. In the sea-surface temperature, sea-level pressure and upper wind fields, ENSO signals dominate the leading modes. However, for the low-level wind field, a trough circulation over the southeast Atlantic – Kalahari is the leading mode. It demonstrates predictive potential when cross-correlated with rainfall at 6- to 12-month lead time. Based on continuous filtered data, the value of various indices and the predictability of different zones are examined. The Sahel achieves the highest rank followed by the Congo and southern zones in the next tier. The Guinea and East African rains, which peak in the March-to-May season, appear least predictable. The seasonal rainfall is shown to modulate economic growth rate, and multi-variate predictive algorithms are tested at 6-month lead time.  相似文献   

Hydrology of a spring complex, studied by geochemical time-series data, Acquarossa, Switzerland     

Emanuel Mazor  Francois D. Vuataz 《Applied Geochemistry》1990,5(5-6)

A case study of three springs in Switzerland is used to demonstrate the value of geochemical time-series data as a powerful tool to study the dynamics of groundwater systems. Values of repeatedly measured parameters revealed intermixings of two water types: (a) a 29°C water, circulating to a depth of 1100 m and containing approximately 700 mg/l Ca, 2000 mg/l SO₄, 700 mg/l HCO₃, 20 mg/l of Na and Cl, 6 mg/l Fe, at least 47 mg/l SiO₂, and with an isotopic composition of δD = − 73.0‰ and δ¹⁸ O = −10.9‰, and (b) a 12°C or colder water, shallow, and of a post-1953 age, containing 420 mg/l TDI or less, very low in Na and Cl (4 mg/l or less), isotopic values of δD = −71.0‰ and δ¹⁸ O = −10.5‰ and tritium as in recent (post-bomb) precipitation.  相似文献   

Comments on “carbon dioxide and hurricanes: Implications of northern hemispheric warming for Atlantic/Caribbean storms”     

Prof. K. A. Emanuel 《Meteorology and Atmospheric Physics》1991,47(1):83-84

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Studies of ionospheric variations during geomagnetic activities at the low-latitude station, Ile-Ife, Nigeria     

Emmanuel A. Ariyibi  Emanuel O. Joshua  Babatunde A. Rabiu 《Acta Geophysica》2013,61(1):223-239

The dual frequency SCINDA NovAtel GSV 4004B GPS receiver installed at the Ile-Ife (low-latitude station) has been in operation since December 2009. Data records for the year 2010 were processed to obtain Total Electron Content (TEC) and S ₄ index. These were interpreted to analyze the ionospheric condition during low geomagnetic activity period (when Dst is from ?40 to 0 nT) and during geomagnetic storm events (with Dst about ?100 nT). Seasonal variations of the TEC and S ₄ index were also investigated. The occurrence of scintillations is closely linked to the peak value of TEC during the daytime; this is very evident during the equinox months when TEC ≥ 30 TECu. When the maximum TEC value is below 30 TECu, as shown by most of the days in the summer months, the scintillation phenomenon does not occur. During geomagnetic storms, the daytime segment of the TEC plot experiences fluctuations (even bifurcations) in values with the peak TEC value of about 40 TECu. From the interpreted data, the occurrence of geomagnetic storm does not necessarily suggest an increase in the level of scintillations at a low-latitude region. Also, there is a remarkable difference between the IRI 2007 model and the observed TEC values, as the daytime TEC peak differs in magnitude and time of occurrence from the observed TEC.  相似文献   

Foraging behaviour,swimming performance and malformations of early stages of commercially important fishes under ocean acidification and warming     

Marta S. Pimentel  Filipa Faleiro  Tiago Marques  Regina Bispo  Gisela Dionísio  Ana M. Faria  Jorge Machado  Myron A. Peck  Hans Pörtner  Pedro Pousão-Ferreira  Emanuel J. Gonçalves  Rui Rosa 《Climatic change》2016,136(3-4):495-505

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电子束CT三维重建技术与颅颌面外科     

归来  罗茂萍  滕利  张智勇  黄绿萍  戴汝平  何沙 《CT理论与应用研究》2000,9(Z1):124

目的 探讨电子束CT三维重建技术在颅颌面外科的适应症和应用价值。方法 采用美国Imatron公司的电子束CT(electron beam CT,以下简称EBCT)C-150,对76例严重颅颌面病人实行薄层CT容积扫描。将所获CT图象经数字接口传至加拿大ISG公司生产的Allegro工作站进行三维重建。结果EBCT成像技术能立体的、详尽和精确的显示机体组织三维解剖结构极其相互关系。其再现畸形或病体模型的程度可以达到近乎解剖学的精度,为准确了解和掌握病情并制定合理的手术治疗计划提供了极为重要的依据,提高了手术治疗效果。结论EBCT三维重建技术是现代颅颌面外科最主要的诊断方法之一并具有重要的临床应用价值。  相似文献   

Noble-gas evidence for geothermal activity in a karstic terrain: Rocky Mountains,Canada.     

Emanuel Mazor  Robert O. van Everdingen  H.Roy Krouse 《Geochimica et cosmochimica acta》1983,47(6):1111-1115

Geothermally heated fluids are identified as a component in warm (up to 54°C) springs in the southern Canadian Rocky Mountains. High concentrations of radiogenic He (10^?3 ccSTP/cc gas) and atmospheric Ne, Ar, Kr and Xe in the gases that vigorously bubble at the Fairmont Hot Spring, assign the latter to be a “drowned” fumarole, fed by geothermal steam. Up to 75% depletions in the atmospheric noble gases in several warm springs indicate contributions of residual geothermal water. On the other hand, in a few cases noble gases were found in excess (W) over the expected concentrations in airequilibrated recharge water. The observed “reversed” pattern of w_nc >W_Ar >W_kr >W_xe is interpreted as excess air, incorporated during recharge through karstic conduits. The mixing ratios of geothermal and karstic waters can be deduced.  相似文献   

Flow variability and hillslope hydrology     

D. D. Huff  R. V. O'Neill  W. R. Emanuel  J. W. Elwood  J. D. Newbold 《地球表面变化过程与地形》1982,7(1):91-94

Examination of spatial variability of streamflow in headwater areas can provide important insight about factors that influence hillslope hydrology. Detailed observations of variations in stream channel input, based on a tracer experiment, indicate that topography alone cannot explain flow variability. However, determination of changes in channel input on a small spatial scale can provide valuable clues to factors, such as structural geology that control subsurface flows.  相似文献