Observed variations in turbulent mixing efficiency in the deep ocean

Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 48 (2018): 1815-1830, doi:10.1175/JPO-D-17-0275.1.Recent progress in direct numerical simulations (DNSs) of stratified turbulent flows has led to increasing attention to the validity of the constancy of the dissipation flux coefficient Γ in the Osborn’s eddy diffusivity model. Motivated by lack of observational estimates of Γ, particularly under weakly stratified deep-ocean conditions, this study estimates Γ using deep microstructure profiles collected in various regions of the North Pacific and Southern Oceans. It is shown that Γ is not constant but varies significantly with the Ozmidov/Thorpe scale ratio ROT in a fashion similar to that obtained by previous DNS studies. Efficient mixing events with Γ ~ O(1) and ROT ~ O(0.1) tend to be frequently observed in the deep ocean (i.e., weak stratification), while moderate mixing events with Γ ~ O(0.1) and ROT ~ O(1) tend to be observed in the upper ocean (i.e., strong stratification). The observed negative relationship between Γ and ROT is consistent with a simple scaling that can be derived from classical turbulence theories. In contrast, the observed results exhibit no definite relationships between Γ and the buoyancy Reynolds number Reb, although Reb has long been thought to be another key parameter that controls Γ.This study was supported by MEXT KAKENHI Grant JP15H05824 and JSPS KAKENHI Grant JP15H02131.2019-02-1

The association between infrared thermal imagery of core eye temperature, personality, age and housing in cats

Understanding individual responses to stress is a key aspect of maintaining optimal animal welfare. This is especially important where animals are being kept in sub-optimal environments or where the species may not clearly demonstrate stress. Therefore, the aim of this study was to investigate how stress varies in cats in a cattery environment in association with personality, age and housing. Stress was measured using Infrared Thermal Imaging (IRT) of core eye temperature and compared with scores from the Feline Temperament Profile (FTP), age and single or group housing (n=34). It was predicted that higher eye temperature would be inversely correlated with acceptable scores and directly correlated with questionable scores calculated from the FTP as these are suggested to indicate a stress sensitive cat. As predicted, eye temperature correlated significantly with acceptable FTP scores (rs = -0.377, p = 0.028). Eye temperature was also higher in older cats (rs = 0.417, p = 0.014) and those singly-housed compared with group housed (U = 37, N1 = 12, N2 = 22, P = 0.001). This provides preliminary evidence that personality may predict stress sensitivity in cats and that older and singly housed cats may find the cattery environment more aversive. These findings may improve adoption rates as unresolved stress can cause avoidance and aggressive behaviour, both of which are undesirable in companion animals. Further, they may increase adoption success rates if owners have more knowledge of the personality and likely stress sensitivity of the cat before adopting. In addition, educating owners that the cat they have adopted is stress sensitive will encourage greater vigilance and awareness of subtle indicators of stress, thus improving welfare