/pdf/statistical-analysis-in-climate-research-51ik9f04rx.pdf

Statistical Analysis in Climate Research

羟氨苄青霉素引起大疱性类天疱疮样疹

This study focuses on the improved estimation of mesoscale surface ocean circulation obtained by merging TOPEX/Poseidon (T/P) and ERS-1 and -2 altimeter measurements between October 1992 and May 1998. Once carefully intercalibrated and homogenized, these data are merged through an advanced global objective analysis method that allows us to correct for residual long wavelength errors and uses realistic correlation scales of ocean dynamics. The high-resolution (0.25°×0.25°) merged T/P+ERS-1 and -2 sea level anomaly maps provide more homogeneous and reduced mapping errors than either individual data set and more realistic sea level and geostrophic velocity statistics than T/P data alone. Furthermore, the merged T/P+ERS-1 and -2 maps yield eddy kinetic energy (EKE) levels 30% higher than maps of T/P alone. They also permit realistic global estimates of east and north components of EKE and their seasonal variations, to study EKE sources better. A comparison of velocity statistics with World Ocean Circulation Experiment surface drifters in the North Atlantic shows very good agreement. Comparison with contemporary current meter data in various oceanic regimes also produces comparable levels of energy and similar ratios of northward and eastward energy, showing that the maps are suitable to studying anisotropy. The T/P + ERS zonal and meridional components of the mapped currents usually present comparable rms variability, even though the variability in the Atlantic is more isotropic than that in the Pacific, which exhibits strong zonal changes. The EKE map presents a very detailed description, presumably never before achieved at a global scale. Pronounced seasonal changes of the EKE are found in many regions, notably the northeastern Pacific, the northeastern and northwestern Atlantic, the tropical oceans, and the zonally extended bands centered near 20°S in the Indian and western Pacific Oceans and at 20°N in the northwestern Pacific.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2000JC900063

Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2

The monsoon circulation of the Indian Ocean

We show that inferences of competence based solely on facial appearance predicted the outcomes of U.S. congressional elections better than chance (e.g., 68.8% of the Senate races in 2004) and also were linearly related to the margin of victory. These inferences were specific to competence and occurred within a 1-second exposure to the faces of the candidates. The findings suggest that rapid, unreflective trait inferences can contribute to voting choices, which are widely assumed to be based primarily on rational and deliberative considerations.

https://science.sciencemag.org/content/sci/308/5728/1623.full.pdf

Inferences of Competence from Faces Predict Election Outcomes

Cross-shelf exchange dominates the pathways and rates by which nutrients, biota, and materials on the continental shelf are delivered and removed. This follows because cross-shelf gradients of most properties are usually far greater than those in the alongshore direction. The resulting transports are limited by Earth's rotation, which inhibits flow from crossing isobaths. Thus, cross-shelf flows are generally weak compared with alongshore flows, and this leads to interesting observational issues. Cross-shelf flows are enabled by turbulent mixing processes, nonlinear processes (such as momentum advection), and time dependence. Thus, there is a wide range of possible effects that can allow these critical transports, and different natural settings are often governed by different combinations of processes. This review discusses examples of representative transport mechanisms and explores possible observational and theoretical paths to future progress.

Cross-Shelf Exchange

An intensive, yearlong deployment of current meter moorings was made over and around Fieberling Guyot (32.5°N, 127.75°W) in the North Pacific. The measurements are used to investigate tidal currents, the mean flow, and subinertial current fluctuations. The K1 and O1 diurnal tides were greatly amplified over the seamount, apparently through dynamics resembling nonlinear seamount-trapped waves. The diurnal tides interacted nonlinearly to induce constituents at the sum frequency (M2) and difference frequency (fortnightly) above the summit. Diurnal amplification was strongest at about 450 m, and it extended from the seamount center out over the flanks. The S2 semidiurnal tide was not substantially amplified over the seamount. The mean flow was primarily along isobaths and was strongest about 50 m above the seamount rim. It was driven by tidal rectification, so that mean along-isobath velocity at a given location correlated well with the amplitude of the local fortnightly tide at that location. Accompanying the mean flow was a “cold dome” over the seamount that was presumably maintained by a balance of mean downward advection and eddy (tidal) radial heat transport. Lower frequency current fluctuations were enhanced near the seamount and were apparently driven by fluctuations in the ambient flow.

Tidal and lower frequency currents above Fieberling Guyot

Estimation of the terms in the upper-ocean heat budget from a moored array in the central Arabian Sea shows periods when a rough balance between the temperature trend and the horizontal advection of heat exists. Altimetry and sea-surface temperature imagery are used to demonstrate that these episodes of strong horizontal advection are associated with mesoscale features. During the wintertime Northeast (NE) Monsoon these are capped-off mesoscale eddy features generated during the previous summertime Southwest (SW) Monsoon and have little horizontal transport of heat within the mixed layer. During the SW Monsoon the major contribution is strong offshore export of coastally upwelled water in a filament with a strong surface presence. Temperature and salinity properties from the moored array and a SeaSoar survey during the formation of the coastal filament confirm the offshore transport of the upwelled water mass to the site of the moored array, more than 600 km offshore. Estimates of the filament section heat flux are several percent of the total estimated heat flux due to upwelling along the Arabian Peninsula, and remote sensing data show that similar mesoscale variability along the coast is enhanced during the SW Monsoon. This points to the importance of mesoscale-modulated transports in not only the observed heat budget at the moored array, but in the overall upper-ocean heat budget in the Arabian Sea.

Mesoscale eddies, coastal upwelling, and the upper-ocean heat budget in the Arabian Sea

A stochastic model for current, pressure, and density fluctuations over the continental shelf and slope is solved for coherence, phase, and gain between the oceanographic variables arid wind stress. Comparison of wind stress spectra and transfer functions show that free coastal-trapped wave physics tends to exist in a frequency band bounded at the low end because of frictional predominance and at the high end because of the absence of wind energy at appropriate alongshore length scales. The transfer functions for density and especially cross-shelf velocity show that these variables are sensitive to short length scales in the forcing and are thus difficult to predict in general. Model results are compared to observations of bottom pressure and alongshore velocity from the 1982 Coastal Ocean Dynamics Experiment off northern California. The results agree with observations, at least qualitatively, with regard to spatial and frequency patterns in coherence and gain. The poorest point of agreement is in the amplitude of wind stress-current gains, which the model systematically underpredicts. The comparisons do demonstrate the importance of including accurate representations of bottom friction and of both cross-shelf and alongshore gradients of wind stress amplitude.

A stochastic model for wind-driven currents over the continental shelf

Observations of the velocity fields over the continental shelf and slope off Oregon and off Peru have shown that there is a phase difference in the onshore-offshore direction, with the velocity fluctuations nearshore leading those offshore in time It is shown here that the effects of bottom Ekman layer friction and cross-shelf depth variation combine to result in such a phase lag in a model for forced or free long barotropic continental shelf waves The model also shows that bottom friction results in a smaller phase lag between the alongshore components of velocity and wind stress than that predicted by a frictionless model, a feature found in the observations off Oregon

https://ir.library.oregonstate.edu/downloads/7h149r24m

Kenneth H. Brink

Papers

Cross-Shelf Exchange

Tidal and lower frequency currents above Fieberling Guyot

Mesoscale eddies, coastal upwelling, and the upper-ocean heat budget in the Arabian Sea

A stochastic model for wind-driven currents over the continental shelf

On the Effect of Bottom Friction on Barotropic Motion Over the Continental Shelf