Magnetic Power Spectra Derived from Ground and Space Measurements of the Solar Magnetic Fields

We study magnetic power spectra of active and quiet regions by using Big Bear Solar Observatory and SOHO/MDI measurements of longitudinal magnetic fields. The MDI power spectra were corrected with Gaussian Modulation Transfer Function. We obtained reliable magnetic power spectra in the high wave numbers range, up to k=4.6 Mm⁻¹, which corresponds to a spatial scale l=1.4 Mm. We find that the occurrence of the spectral discontinuity at high wave numbers, k≥3 Mm⁻¹, largely depends on the spatial resolution of the data and it appears at progressively higher wave numbers as the resolution of the data improves. The spectral discontinuity in the raw spectra is located at wave numbers about 3 times smaller than wave numbers, corresponding to the resolution of the data, and about 1.5–2.0 times smaller in the case of the noise- and-resolution corrected spectra. The magnetic power spectra for active and quiet regions are different: active-region power spectra are described as ∼k ^−1.7, while in a quiet region the spectrum behaves as ∼k ^−1.3. We suggest that the difference can be due to small-scale dynamo action in the quiet-Sun photosphere. Our estimations show that the dynamo can generate more than 6% of the observed magnetic power.     

High-Spatial-Resolution Imaging Combining High-Order Adaptive Optics,Frame Selection,and Speckle Masking Reconstruction

We present, for the first time, high-spatial-resolution observations combining high-order adaptive optics (AO), frame selection, and post-facto image correction via speckle masking. The data analysis is based on observations of solar active region NOAA 10486 taken with the Dunn Solar Telescope (DST) at the Sacramento Peak Observatory (SPO) of the National Solar Observatory (NSO) on 29 October 2003. The high Strehl ratio encountered in AO corrected short-exposure images provides highly improved signal-to-noise ratios leading to a superior recovery of the object’s Fourier phases. This allows reliable detection of small-scale solar features near the diffraction limit of the telescope. Speckle masking imaging provides access to high-order wavefront aberrations, which predominantly originate at high atmospheric layers and are only partially corrected by the AO system. In addition, the observations provided qualitative measures of the image correction away from the lock point of the AO system. We further present a brief inspection of the underlying imaging theory discussing the limitations and prospects of this multi-faceted image reconstruction approach in terms of the recovery of spatial information, photometric accuracy, and spectroscopic applications.The editors apologize to the authors: due to a misunderstanding during the editorial process, the publication of this paper has been delayed.     

High-Resolution Hα Observations of Proper Motion in NOAA 8668: Evidence for Filament Mass Injection by Chromospheric Reconnection

There have been two different kinds of explanations for the source of cool material in prominences or filaments: coronal condensations from above and cool plasma injections from below. In this paper, we present observational results which support filament mass injection by chromospheric reconnection. The observations of an active filament in the active region NOAA 8668 were performed on 17 August 1999 at a wavelength of H–0.6 Å using the 65 cm vacuum reflector, a Zeiss H birefringent filter, and a 12-bit SMD digital camera of Big Bear Solar Observatory. The best image was selected every 12 s for an hour based on a frame selection algorithm. All the images were then co-aligned and corrected for local distortion due to the seeing. The time-lapse movie of the data shows that the filament was undergoing ceaseless motion. The H flow field has been determined as a function of time using local correlation tracking. Time-averaged flow patterns usually trace local magnetic field lines, as inferred from H fibrils and line-of-sight magnetograms. An interesting finding is a transient flow field in a system of small H loops, some of which merge into the filament. The flow is associated with a cancelling magnetic feature which is located at one end of the loop system. Initially a diverging flow with speeds below 10 km s^–1 is visible at the flux cancellation site. The flow is soon directed along the loops and accelerated up to 40 km s^–1 in a few minutes. Some part of the plasma flow then merges into and moves along the filament. This kind of transient flow takes place several times during the observations. Our results clearly demonstrate that reconnection in the photosphere and chromosphere is a likely way to supply cool material to a filament, as well as re-organizing the magnetic field configuration, and, hence, is important in the formation of filaments.     

Assessment of site-effects using acceleration time series. Application to São Sebastião volcanic crater

The Azores archipelago is located at the North America, Eurasia and Africa triple junction and shows seismicity and volcanism typical of an active plate boundary. Terceira Island has been affected by several damaging earthquakes being the 1980 January 1st event (M=7.2) the strongest in Azores during the last century.     

An approach to handling non-Gaussianity of parameters and state variables in ensemble Kalman filtering

The ensemble Kalman filter (EnKF) is a commonly used real-time data assimilation algorithm in various disciplines. Here, the EnKF is applied, in a hydrogeological context, to condition log-conductivity realizations on log-conductivity and transient piezometric head data. In this case, the state vector is made up of log-conductivities and piezometric heads over a discretized aquifer domain, the forecast model is a groundwater flow numerical model, and the transient piezometric head data are sequentially assimilated to update the state vector. It is well known that all Kalman filters perform optimally for linear forecast models and a multiGaussian-distributed state vector. Of the different Kalman filters, the EnKF provides a robust solution to address non-linearities; however, it does not handle well non-Gaussian state-vector distributions. In the standard EnKF, as time passes and more state observations are assimilated, the distributions become closer to Gaussian, even if the initial ones are clearly non-Gaussian. A new method is proposed that transforms the original state vector into a new vector that is univariate Gaussian at all times. Back transforming the vector after the filtering ensures that the initial non-Gaussian univariate distributions of the state-vector components are preserved throughout. The proposed method is based in normal-score transforming each variable for all locations and all time steps. This new method, termed the normal-score ensemble Kalman filter (NS-EnKF), is demonstrated in a synthetic bimodal aquifer resembling a fluvial deposit, and it is compared to the standard EnKF. The proposed method performs better than the standard EnKF in all aspects analyzed (log-conductivity characterization and flow and transport predictions).     

Mathematical modeling of the aquatic macrophyte inputs of mid-chain n-alkyl lipids to lake sediments: Implications for interpreting compound specific hydrogen isotopic records

We present a systematic study of chain-length distributions and D/H ratios of n-alkyl lipids (both n-alkanes and n-alkanoic acids) in a wide range of terrestrial and aquatic plants around and in Blood Pond, Massachusetts, USA. The primary goal is to establish a model to quantitatively assess the aquatic plant inputs of the mid-chain length n-alkyl lipids to lake sediments and to determine the average hydrogen isotopic ratios of these lipids in different plants. Our results show that middle-chain n-alkyl lipids (C₂₁-C₂₃n-alkanes and C₂₀-C₂₄n-alkanoic acids) are exceptionally abundant in floating and submerged aquatic plants, in contrast to the dominance of long-chain n-alkyl lipids (C₂₇-C₃₁n-alkanes and C₂₆-C₃₂n-alkanoic acids) in other plant types, which are consistent with previously published data from Mountain Kenya and the Tibetan Plateau. Combining available data in different environmental settings allows us to establish statistically robust model distributions of n-alkyl lipids in floating/submerged macrophytes relative to other plant types. Based on the model distributions, we established a multi-source mixing model using a linear algebra approach, in order to quantify the aquatic inputs of mid-chain n-alkyl lipids in lake sediments. The results show that ∼97% of the mid-chain n-alkyl lipids (C₂₃n-alkane and C₂₂n-acid (behenic acid)) in Blood Pond sediments are derived from floating and submerged macrophytes. In addition, D/H ratios of C₂₂n-acid and C₂₃n-alkane in the floating and submerged plants from Blood Pond display relatively narrow ranges of variation (−161 ± 16‰ and −183 ± 18‰, respectively). Our study demonstrates that mid-chain n-alkyl lipids such as C₂₃n-alkane and C₂₂n-acid could be excellent recorders of past lake water isotopic ratios in lakes with abundant floating and submerged macrophyte inputs.     

Serphitid wasps in Early Cretaceous amber from Spain (Hymenoptera: Serphitidae)

The diversity of serphitid wasps (Proctotrupomorpha: Serphitoidea) in Early Cretaceous (Albian) amber from Spain is described. Four new species have been found representing the genera Serphites Brues 1937, Aposerphites Kozlov and Rasnitsyn 1979, and Microserphites Kozlov and Rasnitsyn 1979. From the Peñacerrada I (Moraza) outcrop two species are described as Aposerphites angustus Ortega-Blanco, Delclòs, Peñalver and Engel, new species and Serphites lamiak, new species. A single species was found at the San Just (Teruel) outcrop and is described as S. silban, new species. Another single specimen was found in El Soplao (Cantabria) outcrop, described as Microserphites soplaensis, new species. This last specimen is especially interesting in sharing typical serphitid and mymarommatoid characters, giving additional support to the apparent close relationship of both groups.     

Waves in the solar photosphere

Time-sequences of line profile data have been subjected to a unique analysis which produces an amplitude and phase of the velocity and intensity at several line depths for each time sample and spatial point on the Sun. The data have been filtered to pass only the frequencies and spatial wavenumbers of the 5-min band. Yet, a secondary oscillation emerges, the phase of which propagates downward. Empirical eigenfunctions for velocity and intensity are given, and the kinetic energy flux is computed.Operated by the Association of Universities for Research in Astronomy under contract with the National Science Foundation.