Jovian chromophore characteristics from multispectral HST images

The chromophores responsible for coloring the jovian atmosphere are embedded within Jupiter’s vertical aerosol structure. Sunlight propagates through this vertical distribution of aerosol particles, whose colors are defined by ?₀(λ), and we remotely observe the culmination of the radiative transfer as I/F(λ). In this study, we employed a radiative transfer code to retrieve ?₀(λ) for particles in Jupiter’s tropospheric haze at seven wavelengths in the near-UV and visible regimes. The data consisted of images of the 2008 passage of Oval BA to the south of the Great Red Spot obtained by the Wide Field Planetary Camera 2 on-board the Hubble Space Telescope. We present derived particle colors for locations that were selected from 14 weather regions, which spanned a large range of observed colors. All ?₀(λ) curves were absorbing in the blue, and ?₀(λ) increased monotonically to approximately unity as wavelength increased. We found accurate fits to all ?₀(λ) curves using an empirically derived functional form: ?₀(λ) = 1 − A exp(−Bλ). The best-fit parameters for the mean ?₀(λ) curve were A = 25.4 and B = 0.0149 for λ in units of nm. We performed a principal component analysis (PCA) on our ?₀(λ) results and found that one or two independent chromophores were sufficient to produce the variations in ?₀(λ). A PCA of I/F(λ) for the same jovian locations resulted in principal components (PCs) with roughly the same variances as the ?₀(λ) PCA, but they did not result in a one-to-one mapping of PC amplitudes between the ?₀(λ) PCA and I/F(λ) PCA. We suggest that statistical analyses performed on I/F(λ) image cubes have limited applicability to the characterization of chromophores in the jovian atmosphere due to the sensitivity of I/F(λ) to horizontal variations in the vertical aerosol distribution.     

A reconstruction of extratropical Indo-Pacific sea-level pressure patterns during the Medieval Climate Anomaly

Subtropical and extratropical proxy records of wind field, sea level pressure (SLP), temperature and hydrological anomalies from South Africa, Australia/New Zealand, Patagonian South America and Antarctica were used to reconstruct the Indo-Pacific extratropical southern hemisphere sea-level pressure anomaly (SLPa) fields for the Medieval Climate Anomaly (MCA ~700–1350 CE) and transition to the Little Ice Age (LIA 1350–1450 CE). The multivariate array of proxy data were simultaneously evaluated against global climate model output in order to identify climate state analogues that are most consistent with the majority of proxy data. The mean SLP and SLP anomaly patterns derived from these analogues illustrate the evolution of low frequency changes in the extratropics. The Indo-Pacific extratropical mean climate state was dominated by a strong tropical interaction with Antarctica emanating from: (1) the eastern Indian and south-west Pacific regions prior to 1100 CE, then, (2) the eastern Pacific evolving to the central Pacific La Niña-like pattern interacting with a +ve SAM to 1300 CE. A relatively abrupt shift to –ve SAM and the central Pacific El Niño-like pattern occurred at ~1300. A poleward (equatorward) shift in the subtropical ridge occurred during the MCA (MCA–LIA transition). The Hadley Cell expansion in the Australian and Southwest Pacific, region together with the poleward shift of the zonal westerlies is contemporaneous with previously reported Hadley Cell expansion in the North Pacific and Atlantic regions, and suggests that bipolar climate symmetry was a feature of the MCA.     

O/O2 emissions in the Venus nightglow

The oxygen green line is one of the most characteristic features in the terrestrial visible nightglow; it can be seen in the Venus nightglow, but with much greater intensity variation than in the terrestrial case. Here we synthesize our current understanding of the green line in the Venus nightglow and discuss what might be expected observationally in the rising phase of solar cycle 24.     

Spatio-Temporal Analysis of the Concentration and Composition of Planktonic Cyanobacteria Community in a Tropical Reservoir Chain

Water Resources - Cyanobacteria are very heterogeneous microorganisms that are important in both natural and artificial environments. Nevertheless, an uncontrolled growth of cyanobacteria, or...     

Induction of zona radiata and vitellogenin genes in estradiol and nonylphenol exposed male sheepshead minnows (Cyprinodon variegatus)

Several genes normally induced by estradiol (E₂) in female fish, those for vitellogenins (VTGs) and zona radiata proteins (ZRPs), are also inducible in males exposed to estrogenic chemicals. Male sheepshead minnows (SHM) were exposed to both E₂ and para-nonylphenol (NP), at several doses and times to determine a dose-response. Quantitative real time PCR was used to measure mRNA for VTG1, VTG2, ZRP2 and ZRP3. Both E₂ and NP elicited a dose-response increase in all of the mRNAs tested. Exposure to both chemicals resulted in VTG2 expression at about a 10-fold lower level than VTG1, and ZRP2 expression at a lower level than ZRP3.     

Stable isotope differences among morphotypes of Neogloboquadrina pachyderma (Ehrenberg): implications for high-latitude palaeoceanographic studies

The stable isotopic composition of planktonic foraminifera plays a paramount role in interpretations of past oceanographic and environmental conditions; thus an accurate understanding of the factors which influence their isotopic composition is essential. In order to increase the palaeoceanographic utility of the high-latitude planktonic foraminifera Neogloboquadrina pachyderma , its shape and oxygen and carbon isotopic variability are quantitatively described in this study. Over 8200 specimens of N. pachyderma from 36 gravity and piston core tops from surface sediments of the North Atlantic and southern Indian Oceans were digitized and analysed via Fourier series in closed form. The morphological results are presented in detail elsewhere and are utilized in this study to select specimens for isotopic analyses. Significant isotopic differences exist between morphological variants of this important high-latitude speaes. Specimens become depleted in both oxygen and carbon isotopes as the test shape becomes more pentagonal and less quadrate. The isotopic differences cannot be attributed to test thickening nor to size or coiling direction. This observation has important implications in the use of this speaes as a tracer in high-latitude palaeoceanographic investigations. In particular, future isotopic investigations utilizing this species should analyse single forms to allow for clear interpretation of palaeoceanographic signals.     

Comparing methods and sediment contaminant indicators for determining produced water fate in a Louisiana estuary

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge. The current field method used to determine its fate in estuarine systems involves extending a compass oriented transect (COT) from the point source discharge--a method designed for a uniformly dispersing effluent discharged into a uniform offshore environment that may be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Prior research established the viability of the salinity stratification transect (SST) method. Both COT and SST methods were used in a small open bay to determine which more accurately detected effluent dispersion. Determination was based on sediment contaminant indicators (SCIs), including interstitial salinity, hydrocarbons, metals, and radium concentrations. Additionally, SCIs were evaluated for their ability to serve as indicators of effluent dispersion. The data revealed that SST stations exhibited higher contaminant concentrations and that this approach was more accurate in tracking the produced water plume. The data also suggested that SCIs varied in their ability to serve as indicators. Good indicators included interstitial salinity, total targeted aromatic hydrocarbons substantiated with a modified fossil fuel pollution index value, certain metals, and radium-228.     

缓变型地球化学灾害:特征、模型和应用

“缓变型地球化学灾害”是通过长期积累而存在于土壤或沉积物中的包括重金属和有机污染物在内的环境污染物,因环境物理化学条件(例如温度、pH值、湿度、有机质含量等)的改变减小了环境容量,某种或某些形态的污染物大量地被重新活化和突然释放出来并造成严重生态和环境损害的灾害现象。这种灾害具有明显的特征,其定量数学模型可较完整地概括出环境系统从“干净”到“污染”再到“灾害”的整个过程,可以用于灾害的风险概率评估、预测、灾害爆发轨迹等方面的研究,为土壤污染防治和灾害预警提供了定量研究工具和可供实际采用的基本手段,对当前国土资源调查中的“生态环境地球化学评价”具有重要的借鉴意义。     

用人工神经网络进行空间不完备数据的插补

在地学研究中,特别是区域性资料处理过程中,常常遇到“不完备数据”的问题,即所谓的“数据不全”。在尽量减小估计误差的条件下对缺失数据进行预测或插补,对于充分利用历史资料和已知信息,提高预测质量具有重要意义。利用径向基人工神经网络(RBF)同时具有自组织神经网络和回归网络的优点,可以对缺失数据进行预测。实际区域地球化学数据处理的结果表明,RBF网络对空间不完备数据的建模和预测具有优异的效果。