An overview of sea state conditions and air-sea fluxes during RaDyO

Refining radiative-transfer modeling capabilities for light transmission through the sea surface requires a more detailed prescription of the sea surface roughness beyond the probability density function of the sea surface slope field. To meet this need, exciting new measurement methodologies now provide the opportunity to enhance present knowledge of sea surface roughness, especially at the microscale. In this context, two intensive field experiments using R/P Floating Instrument Platform were staged within the Office of Naval Research's Radiance in a Dynamic Ocean (RaDyO) field program in the Santa Barbara Channel and in the central Pacific Ocean south of Hawaii. As part of this program, our team gathered and analyzed a comprehensive suite of sea surface roughness measurements designed to provide optimal coverage of fundamental optical distortion processes associated with the air-sea interface. This contribution describes the ensemble of instrumentation deployed. It provides a detailed documentation of the ambient environmental conditions that prevailed during the RaDyO field experiments. It also highlights exciting new sea surface roughness measurement capabilities that underpin a number of the scientific advances resulting from the RaDyO program. For instance, a new polarimetric imaging camera highlights the complex interplay of wind and surface currents in shaping the roughness of the sea surface that suggests the traditional Cox-Munk framework is not sufficient. In addition, the breaking crest length spectral density derived from visible and infrared imagery is shown to be modulated by the development of the wavefield (wave age) and alignment of wind and surface currents at the intermediate (dominant) scale of wave breaking

Changes in the CFC inventories and formation rates of upper Labrador Sea Water, 1997-2001

Chlorofluorocarbon (component CFC-11) and hydrographic data from 1997, 1999, and 2001 are presented to track the large-scale spreading of the Upper Labrador Sea Water (ULSW) in the subpolar gyre of the North Atlantic Ocean. ULSW is CFC rich and comparatively low in salinity. It is located on top of the denser “classical” Labrador Sea Water (LSW), defined in the density range σΘ = 27.68–27.74 kg m−3. It follows spreading pathways similar to LSW and has entered the eastern North Atlantic. Despite data gaps, the CFC-11 inventories of ULSW in the subpolar North Atlantic (40°–65°N) could be estimated within 11%. The inventory increased from 6.0 ± 0.6 million moles in 1997 to 8.1 ± 0.6 million moles in 1999 and to 9.5 ± 0.6 million moles in 2001. CFC-11 inventory estimates were used to determine ULSW formation rates for different periods. For 1970–97, the mean formation rate resulted in 3.2–3.3 Sv (Sv ≡ 106 m3 s−1). To obtain this estimate, 5.0 million moles of CFC-11 located in 1997 in the ULSW in the subtropical/tropical Atlantic were added to the inventory of the subpolar North Atlantic. An estimate of the mean combined ULSW/LSW formation rate for the same period gave 7.6–8.9 Sv. For the years 1998–99, the ULSW formation rate solely based on the subpolar North Atlantic CFC-11 inventories yielded 6.9–9.2 Sv. At this time, the lack of classical LSW formation was almost compensated for by the strongly pronounced ULSW formation. Indications are presented that the convection area needed in 1998–99 to form this amount of ULSW exceeded the available area in the Labrador Sea. The Irminger Sea might be considered as an additional region favoring ULSW formation. In 2000–01, ULSW formation weakened to 3.3–4.7 Sv. Time series of layer thickness based on historical data indicate that there exists considerable variability of ULSW and classical LSW formation on decadal scales

Changes in the pool of Labrador Sea Water in the subpolar North Atlantic

Measurements of chlorofluorocarbon inventories during 1997–2003 allow the detection and quantification of significant changes in the formation rates of two modes of Labrador Sea Water (LSW): Upper (ULSW) and deep LSW, both here defined in fixed density intervals. Both modes contribute to the cold limb of the Meridional Overturning Circulation. Results reveal that the lighter ULSW formed since the mid-1990s has started to replace the large pool of the deep LSW stored in the western North Atlantic. Formation of deep LSW was absent in 1997–2003. Formation of ULSW compensated for this absence during 1998/99 (7.9 Sv), but afterwards significantly declined to 2.5 Sv. The decrease of the overall LSW formation throughout 1997–2003 correlates with a declining eastward baroclinic mass transport between the centers of the subpolar and subtropical gyres since 1997, a warming of LSW, and a gradually decreasing North Atlantic Oscillation index after 1999

Brain white matter structure and language ability in preschool-aged children

Brain alterations are associated with reading and language difficulties in older children, but little research has investigated relationships between early language skills and brain white matter structure during the preschool period. We studied 68 children aged 3.0-5.6 years who underwent diffusion tensor imaging and participated in assessments of Phonological Processing and Speeded Naming. Tract-based spatial statistics and tractography revealed relationships between Phonological Processing and diffusion parameters in bilateral ventral white matter pathways and the corpus callosum. Phonological Processing was positively correlated with fractional anisotropy and negatively correlated with mean diffusivity. The relationships observed in left ventral pathways are consistent with studies in older children, and demonstrate that structural markers for language performance are apparent as young as 3 years of age. Our findings in right hemisphere areas that are not as commonly found in adult studies suggest that young children rely on a widespread network for language processing that becomes more specialized with age

Young children in different linguistic environments: A multimodal neuroimaging study of the inferior frontal gyrus

This work was supported by the Canadian Institutes of Health Research (CIHR), funding reference numbers IHD-134090 and MOP-136797, and a grant from the Alberta Children’s Hospital Research Institute. Salary support provided by the University of Calgary’s NSERC CREATE I3T program (XL) and CIHR (CL).Magnetic resonance imaging (MRI) studies show that bilingual adults display structural and functional brain alterations, especially in the inferior frontal gyrus (IFG), dependent on when they learned their second language. However, it is unclear whether these differences are due to early exposure to another language, or to lifelong adaptation. We studied 22 children aged 3-5 years growing up in a multilingual environment and 22 age- and sex-matched controls exposed to an English-only environment. Resting-state functional MRI and T1-weighted MRI were used to assess functional connectivity and structure of the IFG. Children in a multilingual environment had higher functional connectivity between the left IFG and dorsal language and attention areas compared to children from a monolingual environment. Children in a multilingual environment also displayed decreased functional connectivity to temporal, anterior cingulate, and prefrontal areas. No significant group differences in IFG structure were observed. Our results suggest a more integrated functional language network, which is more segregated from other networks, in children who grow up in a multilingual environment. These findings suggest that functional alterations to the IFG due to second language learning occur early, while structural changes may not be apparent until later.Canadian Institutes of Health Research - Foundation Schem

Age-related functional brain changes in young children

Brain function and structure change significantly during the toddler and preschool years. However, most studies focus on older or younger children, so the specific nature of these changes is unclear. In the present study, we analyzed 77 functional magnetic resonance imaging datasets from 44 children aged 2-6 years. We extracted measures of both local (amplitude of low frequency fluctuation and regional homogeneity) and global (eigenvector centrality mapping) activity and connectivity, and examined their relationships with age using robust linear correlation analysis and strict control for head motion. Brain areas within the default mode network and the frontoparietal network, such as the middle frontal gyrus, the inferior parietal lobule and the posterior cingulate cortex, showed increases in local and global functional features with age. Several brain areas such as the superior parietal lobule and superior temporal gyrus presented opposite development trajectories of local and global functional features, suggesting a shifting connectivity framework in early childhood. This development of functional connectivity in early childhood likely underlies major advances in cognitive abilities, including language and development of theory of mind. These findings provide important insight into the development patterns of brain function during the preschool years, and lay the foundation for future studies of altered brain development in young children with brain disorders or injury.Canadian Institutes of Health Research - Project Schem

Salinity response to atmospheric forcing of the Terra Nova Bay polynya, Antarctica

The density and salinity of High Salinity Shelf Water, a key component of Antarctic Bottom Water emanating from the Ross Sea, are intensified by brine rejection induced by ice formation within the Terra Nova Bay (TNB) polynya. Ocean mooring data from 2007, meteorological observations from automatic weather stations and a satellite-derived history of the opening of TNB polynya delineate variability in water column salinity linked to atmospheric forcing, with a period on the order of 10 days. Lagged correlation analysis indicates that on average salinity response lags the polynya opening by 2 days and the wind forcing by 5 days. We find stronger correlations of salinity with the wind during March through May and with the polynya open-water fraction during June through October, with decreasing lags in the latter period. A one-dimensional mixed-layer model incorporating thermodynamic ice formation captures the oscillations in salinity. A process study shows that the variability in the polynya open-water fraction governs the final salinity attained by the model as well as the salinity cycling. Variability in surface heat fluxes modulates that effect. Our work suggests that there is a more complex relationship between salinity, the polynya open-water fraction, and atmospheric forcing than previously suggested

Data for: Spectral characteristics of gravity-capillary waves, with connections to wave growth and microbreaking

In order to improve our understanding of physical air-sea interaction, it is essential to better describe the short-scale ocean wave response to wind forcing. This is particularly true for waves which are small enough to evade observation by traditional buoy and point-based gauge measurements but large enough to appreciably alter the transfer of momentum between atmosphere and ocean. Such waves are restored to equilibrium both by the earth’s gravity and air-sea surface tension, hence the classification as “gravity-capillary”. Radar remote sensing techniques depend greatly upon these waves in order to extract useful physical parameters from afar. Despite this importance, field observations of gravity-capillary wave characteristics are uncommon and vary from study to study. Furthermore, leading-edge model wavenumber spectra generally do not match each other in shape or important spectral parameters. Here we present an extended analysis of short wave data collected via a polarimetric camera aboard Research Platform (R/P) FLoating Instrument Platform (FLIP) in the Santa Barbara Channel. Our wavenumber saturation spectra show the emergence of a peak in the gravity-capillary subrange at low wind forcing magnitude (u*~0.045 m/s), consistent with critical wave growth in air-side stability theory. This is accompanied by a sharp increase in gravity-capillary-scale wave slope variance, a phenomenon that was previously only observed in the laboratory. Finally, the effects of microbreaking on wave spectral characteristics are discussed