Planetary Wave Propagation off California and Its Effect on Zooplankton

2008 ◽  
Vol 38 (3) ◽  
pp. 702-714 ◽  
Author(s):  
Allan J. Clarke ◽  
Marcelo Dottori
Keyword(s):  
Wave Propagation ◽  
Sea Level ◽  
Rossby Wave ◽  
Nutrient Concentration ◽  
Large Scale ◽  
Time Derivative ◽  
Sea Level Anomalies ◽  
Zooplankton Population ◽  
Coastal Sea ◽  
Rossby Wave Propagation

Abstract Lagged correlation of dynamic height from the gappy California Cooperative Oceanic Fisheries Investigation (CalCOFI) with monthly San Diego sea level for the period 1949–2001 shows that the dynamic height propagates westward at 4.10 cm s−1, about double the speed of the large-scale low-frequency Rossby wave (2.2 cm s−1). Ocean Topography Experiment (TOPEX)/Poseidon/Jason-1’s along-track sea level height estimates since January 1993, filtered interannually, propagate westward at 4.3 cm s−1, verifying that observed westward propagation is about double that expected. Including the effect of the mean California Current on the Rossby wave propagation does not explain the discrepancy but rather slightly increases it. If variations in the ocean depth in the CalCOFI region are also taken into account, the westward propagation is still only about one-half that observed. Standard theory therefore does not explain the observations. Because of the westward propagation, interannual variations in alongshore geostrophic surface current are proportional to the time derivative of sea level. This means that such large-scale interannual current variability can be monitored with appropriate lag by the time derivative of coastal sea level. The anomalous alongshore flow advects particles, the anomalous alongshore particle displacement being proportional to sea level. Since nutrient concentration is lower in the south, the anomalous alongshore displacement results in a lower nutrient concentration when sea level is anomalously high and a higher nutrient concentration when the sea level is anomalously low. Vertical displacement also results in a similar relationship between nutrients and sea level, so it is not surprising that sea level anomalies are strongly related to fluctuations in zooplankton population. In fact, consistent with the westward Rossby wave propagation, the logarithm of the zooplankton population averaged over the CalCOFI region is well correlated with coastal sea level anomalies and lags it by about 2 months. By this result monthly anomalous San Diego sea level can be used to monitor and predict interannual changes in the zooplankton population.

scholarly journals Rossby Waves and the Interannual and Interdecadal Variability of Temperature and Salinity off California

2009 ◽  
Vol 39 (10) ◽  
pp. 2543-2561 ◽  
Author(s):  
Marcelo Dottori ◽  
Allan J. Clarke
Keyword(s):  
Sea Level ◽  
Rossby Wave ◽  
Large Scale ◽  
Southern California ◽  
Rossby Waves ◽  
Salinity Gradient ◽  
Time Derivative ◽  
Temperature Fluctuations ◽  
Dynamic Height ◽  
The Mean

Abstract Previous work has shown that large-scale interannual Rossby waves, largely remotely generated by equatorial winds, propagate westward from the coast off southern California. These waves have a large-scale anomalous alongshore velocity field that is proportional to the time derivative of the interannual sea level anomaly. Using these results, a theory is developed for interannual perturbations to a mean density field that varies both vertically and alongshore, like that for the California Current region off southern California. Because both the anomalous vertical and alongshore currents are proportional to the time derivative of the interannual sea level, the theory suggests that the anomalous currents associated with the Rossby waves, acting on the mean temperature field, should induce temperature fluctuations proportional to the anomalous dynamic height. The alongshore and vertical advections contribute to the temperature fluctuations in the same sense, a higher-than-normal sea level, for example, resulting in downward and poleward displacement of warmer water and a local higher-than-normal temperature. Near the surface, alongshore advection dominates vertical advection but both contribute comparably near the thermocline and below. The correlation of observed temperature and dynamic height anomalies from the California Cooperative Oceanic Fisheries Investigation (CalCOFI) data is positive, which is consistent with the theory. The correlation is highest (r ≈ 0.8) near 100-m depth in the thermocline. Although the correlation falls toward the surface, it is still between 0.5 and 0.6, suggesting that the advection mechanism is a major contributor to the temperature anomalies there. The anomalous Rossby wave currents, acting on the mean background salinity gradient, also induce salinity anomalies. At halocline depths of 100–200 m, consistent with the theory, the correlation of observed CalCOFI salinity and dynamic height anomalies is negative and large in magnitude (r ≈ −0.8). However, the surface salinity anomaly is not due to Rossby wave dynamics; instead, much of it is driven by the alongshore wind stress, which it lags by 4 months.

scholarly journals Atmospheric circulation changes and their impact on extreme sea levels around Australia

2019 ◽  
Vol 19 (5) ◽  
pp. 1067-1086 ◽  
Author(s):  
Frank Colberg ◽  
Kathleen L. McInnes ◽  
Julian O'Grady ◽  
Ron Hoeke
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Climate Models ◽  
Tide Gauge ◽  
Austral Summer ◽  
Sea Level Changes ◽  
Sea Level Variability ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Coastal Sea

Abstract. Projections of sea level rise (SLR) will lead to increasing coastal impacts during extreme sea level events globally; however, there is significant uncertainty around short-term coastal sea level variability and the attendant frequency and severity of extreme sea level events. In this study, we investigate drivers of coastal sea level variability (including extremes) around Australia by means of historical conditions as well as future changes under a high greenhouse gas emissions scenario (RCP 8.5). To do this, a multi-decade hindcast simulation is validated against tide gauge data. The role of tide–surge interaction is assessed and found to have negligible effects on storm surge characteristic heights over most of the coastline. For future projections, 20-year-long simulations are carried out over the time periods 1981–1999 and 2081–2099 using atmospheric forcing from four CMIP5 climate models. Changes in extreme sea levels are apparent, but there are large inter-model differences. On the southern mainland coast all models simulated a southward movement of the subtropical ridge which led to a small reduction in sea level extremes in the hydrodynamic simulations. Sea level changes over the Gulf of Carpentaria in the north are largest and positive during austral summer in two out of the four models. In these models, changes to the northwest monsoon appear to be the cause of the sea level response. These simulations highlight a sensitivity of this semi-enclosed gulf to changes in large-scale dynamics in this region and indicate that further assessment of the potential changes to the northwest monsoon in a larger multi-model ensemble should be investigated, together with the northwest monsoon's effect on extreme sea levels.

scholarly journals Rossby Wave Propagation from the Arctic into the Midlatitudes: Does It Arise from In Situ Latent Heating or a Trans-Arctic Wave Train?

2020 ◽  
Vol 33 (9) ◽  
pp. 3619-3633 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Sukyoung Lee
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Wave Train ◽  
The Arctic ◽  
Latent Heating ◽  
Latent Heat Release ◽  
Rossby Wave Propagation ◽  
Rossby Wave Train ◽  
In Situ Generation

AbstractThe relationship between latent heating over the Greenland, Barents, and Kara Seas (GBKS hereafter) and Rossby wave propagation between the Arctic and midlatitudes is investigated using global reanalysis data. Latent heating is the focus because it is the most likely source of Rossby wave activity over the Arctic Ocean. Given that the Rossby wave time scale is on the order of several days, the analysis is carried out using a daily latent heating index that resembles the interdecadal latent heating trend during the winter season. The results from regression calculations find a trans-Arctic Rossby wave train that propagates from the subtropics, through the midlatitudes, into the Arctic, and then back into midlatitudes over a period of about 10 days. Upon entering the GBKS, this wave train transports moisture into the region, resulting in anomalous latent heat release. At high latitudes, the overlapping of a negative latent heating anomaly with an anomalous high is consistent with anomalous latent heat release fueling the Rossby wave train before it propagates back into the midlatitudes. This implies that the Rossby wave propagation from the Arctic into the midlatitudes arises from trans-Arctic wave propagation rather than from in situ generation. The method used indicates the variance of the trans-Arctic wave train, but not in situ generation, and implies that the variance of the former is greater than that of latter. Furthermore, GBKS sea ice concentration regression against the latent heating index shows the largest negative value six days afterward, indicating that sea ice loss contributes little to the latent heating.

scholarly journals Rossby Wave Ray Tracing in a Barotropic Divergent Atmosphere

2008 ◽  
Vol 65 (5) ◽  
pp. 1679-1691 ◽  
Author(s):  
Chungu Lu ◽  
John P. Boyd
Keyword(s):  
Wave Propagation ◽  
Ray Tracing ◽  
Rossby Wave ◽  
Level Structure ◽  
Low Frequency ◽  
Present Theory ◽  
Wave Ray ◽  
Divergent Wind ◽  
Rossby Wave Propagation ◽  
Upper Level

Abstract The effects of divergence on low-frequency Rossby wave propagation are examined by using the two-dimensional Wentzel–Kramers–Brillouin (WKB) method and ray tracing in the framework of a linear barotropic dynamic system. The WKB analysis shows that the divergent wind decreases Rossby wave frequency (for wave propagation northward in the Northern Hemisphere). Ray tracing shows that the divergent wind increases the zonal group velocity and thus accelerates the zonal propagation of Rossby waves. It also appears that divergence tends to feed energy into relatively high wavenumber waves, so that these waves can propagate farther downstream. The present theory also provides an estimate of a phase angle between the vorticity and divergence centers. In a fully developed Rossby wave, vorticity and divergence display a π/2 phase difference, which is consistent with the observed upper-level structure of a mature extratropical cyclone. It is shown that these theoretical results compare well with observations.

scholarly journals Data-Driven Interpolation of Sea Level Anomalies Using Analog Data Assimilation

2019 ◽  
Vol 11 (7) ◽  
pp. 858 ◽  
Author(s):  
Redouane Lguensat ◽  
Phi Huynh Viet ◽  
Miao Sun ◽  
Ge Chen ◽  
Tian Fenglin ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Sea Level ◽  
Large Scale ◽  
Empirical Orthogonal Functions ◽  
Data Driven ◽  
Optimal Interpolation ◽  
Observation System ◽  
Orthogonal Functions ◽  
Sea Level Anomalies ◽  
Recent Developments

From the recent developments of data-driven methods as a means to better exploit large-scale observation, simulation and reanalysis datasets for solving inverse problems, this study addresses the improvement of the reconstruction of higher-resolution Sea Level Anomaly (SLA) fields using analog strategies. This reconstruction is stated as an analog data assimilation issue, where the analog models rely on patch-based and Empirical Orthogonal Functions (EOF)-based representations to circumvent the curse of dimensionality. We implement an Observation System Simulation Experiment (OSSE) in the South China Sea. The reported results show the relevance of the proposed framework with a significant gain in terms of Root Mean Square Error (RMSE) for scales below 100 km. We further discuss the usefulness of the proposed analog model as a means to exploit high-resolution model simulations for the processing and analysis of current and future satellite-derived altimetric data with regard to conventional interpolation schemes, especially optimal interpolation.

scholarly journals Rossby Wave Propagation in Idealized and Realistic Zonally Varying Flows

1997 ◽  
Vol 75 (3) ◽  
pp. 687-700 ◽  
Author(s):  
Hiroaki Naoe ◽  
Yoshihisa Matsuda ◽  
Hisashi Nakamura
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Rossby Wave Propagation

Teleconnections from Tropics to Northern Extratropics through a Southerly Conveyor

2005 ◽  
Vol 62 (11) ◽  
pp. 4057-4070 ◽  
Author(s):  
Zhuo Wang ◽  
C-P. Chang ◽  
Bin Wang ◽  
Fei-Fei Jin
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Rossby Waves ◽  
Propagation Theory ◽  
Wave Source ◽  
Tropical Forcing ◽  
Rossby Wave Source ◽  
Rossby Wave Response ◽  
Rossby Wave Propagation ◽  
The Tropics

Abstract Rossby wave propagation theory predicts that Rossby waves in a tropical easterly flow cannot escape from the Tropics to the extratropics. Here the authors show that a southerly flow component in the basic state (a southerly conveyor) may transfer a Rossby wave source northward; thus, a forcing embedded in the deep tropical easterlies may excite a Rossby wave response in the extratropical westerlies. It is shown that the southerly conveyor determines the location of the effective Rossby wave source and that the extratropical response is relatively insensitive to the location of the tropical forcing, provided that the tropical response can reach the southerly conveyor. A stronger southerly flow favors a stronger extratropical response, and the spatial structure of the extratropical response is determined by the extratropical westerly basic flows.

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