HYDROGRAPHY OF THE NAVO CENCAL REGION FOR DEC01                         LT Kitch Kennedy OC3570

What is hydrography Historically, the term hydrography has meant the scientific study of the physical conditions of systems of water. Within the field of physical oceanography, hydrography is the branch of our field which looks to understand the movements of the ocean through its measurable physical properties, including: temperature, salinity, and oxygen, and chemical constituents. http://www.oce.orst.edu/po/hydro.html

Project Domain

Dynamic Topography General circulation through the entire layer of the CCS. California Current (CC) California Undercurrent (CUC) Davidson Current (CC) Dynamic through driving flow. Contour - 0.02 dyn-m

Dynamic Topography Surface signature Meandering CC Weak Davidson current present. Strong onshore flow into Monterey Bay Contour - 0.005 dyn-m

Dynamic Topography Heart of the CUC CC weakening Product of large scale gradients Relatively strong poleward flow CC weakening Max depth ~500m Contour – 0.003 dyn-m

Dynamic Topography Both CC and CUC still apparent Breakdown of dynamic trough Overall weakening currents Topography influencing CUC Contour – 0.003 dyn-m

Pressure fields on Sigma level Pressure btwn 50-80 dbar Dome of low pressure corresponds to dynamic trough CC and DC Contour – 4 dbar

Pressure fields on Sigma level Pressure btwn 90-150 dbar Stronger gradients = stronger currents CUC influencing poleward flow along the coast Onshore flow building pressure max in Monterey Bay Contour – 5 dbar

Pressure fields on Sigma level Pressure 280-335 dbar More variability in the flow Core of the CUC Meander in CC not present at upper levels Contour – 5 dbar

Density vs. Salinity Curve Equatorial Pacific water Pacific Sub-artic Water -26.7 -26.2 -25.8

Surface Salinity Weak salinity gradient in the heart of the data region Fresh water signatures Mouth of San Francisco bay Pacific Sub-artic water Larger salinity gradient correlates well with 0/200 dynamic height contours

Salinity Analysis Fresh water run-off near SF Bay not evident Salinity max near coast Equatorial water advected north by DC and CUC Mixing of Sub-artic and Equatorial waters Strong gradient may represent the boundary of the CC Equatorial Pacific water Pacific Sub-artic Water -26.7 -26.2 -25.8 Contour – 0.03

Salinity Analysis CUC advection high salinity along the coast Relatively fresh pool created by subduction of surrounding waters CTD cast plots Equatorial Pacific water Pacific Sub-artic Water -26.7 -26.2 -25.8 Contour – 0.02

Salinity Analysis Distinct boundary btwn water masses Stronger currents allowing less mixing Equatorial Pacific water Pacific Sub-artic Water -26.7 -26.2 -25.8 Contour – 0.01

Sea Surface Temperature Poor indicator of current dynamics Warm water in region of dynamic trough Highly influenced by air-sea interactions Cooler water in vicinity of Monterey and San Francisco Bays Cold water intrusion from SW Contour – 0.2 degC

ADCP Data Qualitative comparison Strong correlation with 0/200 and 25.8 Sigma-lvl pressure contours

QUESTIONS?