Remotely sensed winds for episodic forcing of ocean models

Morey, Steven L.; Bourassa, Mark A.; Davis, Xujing Jia; O’Brien, James J.; Zavala‐Hidalgo, Jorge

doi:10.1029/2004jc002338

Cited by 18 publications

(18 citation statements)

References 26 publications

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“…This is crucial for heat budget studies such as this one where the role of the oceanic processes and the thermodynamic response of the lowest layer of the atmosphere to SST changes need to be represented accurately. The model is forced here with the weekly mean scatterometer winds [Morey et al, 2005] along with climatological radiation from Earth Radiation Budget Experiment (ERBE), cloudiness from International Satellite Cloud Climatology Project, and precipitation from CPC Merged Analysis of Precipitation (CMAP) as by Murtugudde et al [1996].…”

Section: Model Description and Forcingsmentioning

confidence: 99%

Arabian Sea response to monsoon variations

2007

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[1] This study aims to quantify the impact of strong monsoons on the mixed layer heat budget in the Arabian Sea by contrasting forced ocean general circulation model simulations with composite strong and weak monsoon winds. Strong (weak) monsoons are defined as years with zonal component of the Somali Jet being greater (smaller) by more than a standard deviation of the long-term mean of the National Centers for Environmental Prediction reanalysis winds. Coastal upwelling is shown to be demonstrably stronger for strong monsoons leading to significant surface cooling, shallower thermoclines, and deeper mixed layers. A coupled ecosystem model shows that surface chlorophyll, primary, and export production are indeed higher for strong monsoons compared to weak monsoons driven by the supply of colder, nutrient-rich waters from greater than 100 m depths. The surprising result is that a strong monsoon results in stronger negative wind stress curl away from the coasts and drives Ekman pumping that results in a deeper thermocline. The weaker stratification and larger turbulent kinetic energy from the winds drive deeper mixed layers leading entrainment cooling with some contribution from the advection of colder upwelled waters from the coastal upwelling regions. Thus the strong monsoons, in fact, enhance oceanic heat uptake indicating that ocean dynamics are cooling the surface and driving the lower atmosphere which has implications for the interpretation of monsoon variability from paleorecords.

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Section: Model Description and Forcingsmentioning

confidence: 99%

Arabian Sea response to monsoon variations

2007

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“…The wind fields used in the model are objectively gridded with dynamical constraints to blend NCEPR 2 and H*Wind fields (see Morey et al (2005) for more details on the objective gridding technique). In simplified terms, the gridded wind product largely matches the high-resolution observationally derived H*Wind fields within several hundred kilometers of the center of the hurricane, and farther away, the coarser-resolution (2.5°) NCEPR 2 data are mostly used to complete the fields.…”

Section: Estimates Of Maximum Storm Tidementioning

confidence: 99%

“…Wind fields are constructed for the time period 00:00 UTC 8 July-23:00 10 July UTC 2005, by applying an objective gridding method (Morey et al 2005) to combine data from the NOAA AOML Hurricane Research Division Wind Analyses (H*Wind fields, Powell et al 1998) and the National Centers for Environmental Prediction Reanalysis II (NCEPR2) winds. Stress is calculated on the basis of bulk aerodynamic formulae with a Large et al (1994) drag coefficient as in Morey et al (2005). The H*Wind fields provide 1-min maximum sustained winds over a region centered about the hurricane on a 6-km grid roughly 960 km by 960 km.…”

Section: Introductionmentioning

confidence: 99%

Simulation of the Hurricane Dennis storm surge and considerations for vertical resolution

Dukhovskoy

Morey

2010

Nat Hazards

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A high-resolution storm surge model of Apalachee Bay in the northeastern Gulf of Mexico is developed using an unstructured grid finite-volume coastal ocean model (FVCOM). The model is applied to the case of Hurricane Dennis (July 2005). This storm caused underpredicted severe flooding of the Apalachee Bay coastal area and upriver inland communities. Accurate resolution of complicated geometry of the coastal region and waterways in the model reveals processes responsible for the unanticipated high storm tide in the area. Model results are validated with available observations of the storm tide. Model experiments suggest that during Dennis, excessive flooding in the coastal zone and the town of St. Marks, located up the St. Marks River, was caused by additive effects of coincident high tides (*10-15% of the total sea-level rise) and a propagating shelf wave (*30%) that added to the locally wind-generated surge. Wave setup, the biggest uncertainty, is estimated on the basis of empirical and analytical relations. The Dennis case is then used to test the sensitivity of the model solution to vertical discretization. A suite of model experiments is performed with varying numbers of vertical sigma (r) levels, with different distribution of r-levels within the water column and a varying bottom drag coefficient. The major finding is that the storm surge solution is more sensitive to resolution within the velocity shear zone at mid-depths compared to resolution of the upper and bottom layer or values of the bottom drag coefficient.

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“…Here, we again use a C DA of 0.002, which is perhaps a bit high for fast winds (see, e.g., Morey et al, 2005), but is adequate for a slightly unstable atmosphere such as the one above the warm Agulhas Current. The above choice of stress is supported by several other studies.…”

Section: A Present Day Observationsmentioning

confidence: 99%

The arrested Agulhas retroflection

Nof¹,

Zharkov²,

Ortiz³

et al. 2011

j mar res

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Paleoceanographic proxy data indicate that the Agulhas leakage into the South Atlantic was dramatically reduced during glacial times. In our former papers, we suggested that this was due to a northward shift of the zero wind stress curl that, in turn, forced the retroflection to occur farther north, where the slant of the coastline relative to the north is steep. In the present paper, we propose that strong westerlies (0.4 Pa, implying a wind speed of ∼12 m s −1 at zero degrees centigrade), which were supposedly common during glaciations, can also arrest the leakage. This arrest occurred because the wind stress opposed the momentum flux associated with the retroflection; such an arrest did not require the retroflection to shift in latitude.We use a simple, nonlinear, "reduced gravity" model to show analytically and numerically that, under the above conditions, the eastward wind stress compensates for the zonal westward flow-force associated with the retroflection, thus avoiding the development and shedding of rings. For a nearly zonal wall, westerly winds, and small upper layer thickness along the wall, the arresting wind stress is found, theoretically, to be, τ x = 0.042α 3/2 ρf 0 [(2f 0 Q) 3 /g ] 1/4 , where α is twice the retroflection eddy vorticity, ρ is the water density, Q is the Agulhas Current volume flux, and the remaining notation is conventional. A few words on Stern's contribution to the field of eddiesEddies, the oceanic analogs of tornadoes and hurricanes, were one of Melvin's specialties. In an elegant paper that most people originally referred to as "esoteric" (1974, JMR), Melvin showed that much can be learned about eddies by looking at groups of two adjacent vortices, each spinning in a different direction. For reasons known only to him, he coined this counter-spinning vortex a "Modon". (A modon actually means a collection of cities in Arabic.) Despite the initial skepticism by some (evidently, one editor of a respectable 1.

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Remotely sensed winds for episodic forcing of ocean models

Cited by 18 publications

References 26 publications

Arabian Sea response to monsoon variations

Arabian Sea response to monsoon variations

Simulation of the Hurricane Dennis storm surge and considerations for vertical resolution

The arrested Agulhas retroflection

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