Eastern WP

Gap winds

April 2013

Dec 2013

SST

warmest

coldest

Local gap wind effect

Regional conditions, comments by Gordon and Sprintall

SST 6 April 2014

Aquarius SatelliteFebruary 2014

water vapor

Spurs 1

Spurs 2

Gap winds water vapor flux ~0.3 Sv, a bit larger than the Amazon!

Amazon

limited water vapor flux

limited water vapor flux

x

1

2

ERA-40ERA Interim

Satellite measurements of surface winds (Quickscat 10-m) and sea surface temperature (from a satellite microwave radiometer, TMI) averaged for January 2000.

Satellite measurements of surface winds (Quickscat 10-m) and sea surface temperature (from a satellite microwave radiometer, TMI) averaged for January 2000.

Vertical integral of eastward (red) and northward (blue) water vapor flux from ECMWF ERA-40 and ERA-Interim. Color lines represent the 12-month running mean and the thinner line the annual averages.

Vertical integral of eastward (red) and northward (blue) water vapor flux from ECMWF ERA-40 and ERA-Interim. Color lines represent the 12-month running mean and the thinner line the annual averages.

3

3

zonal

meridional

Gap 2 is largest, interannual variability

Local gap wind effect

Total ~0.3 Sv water vapor flux

Climatological annual SSS (upper 20 m), 1°x1° lat/long World Ocean Atlas. Ekman transport vectors in Sv, within 2.5°x2.5° cells using long term mean wind stresses based on ECMWF ERA-40 monthly data). Contours of mean ocean dynamic topography (MDOTMaximenko (IPRC) and Niiler (SIO).

1958-2001 average of the divergence of water vapor flux (color; kg m-2s-1 x 103) monthly ECMWF ERA-40. E-P (contours; m yr-1) estimated from ERA-40

2013, Aquarius SSS + OSCAR

Winter freshness in Panama Gulf; ITCZ freshness in summer

2013, Aquarius SSS + OSCAR

Winter freshness in Panama Gulf; ITCZ freshness in summer

Where to site SPURS-2? What m

onths?

Specific Objectives; experim

ent components

and design

Regional Scale Variability in Eastern Pacific: Relevance to SPURS-2 Campaign

Janet Sprintall, Scripps Institution of Oceanography

MoorSPICE Cruise, Solomon Sea

SIO La Jolla

Westpac Vietnam

Sorry I can’t join you today but I am on travel!

Wind Forcing

Kessler, W. The circulation of the eastern tropical Pacific: A review, PiO, 2006.

Positive Curl: Upwelling in NH

Note significantmeridional component

• Surface layer variability in the eastern Pacific is influenced by the seasonal migration of the ITCZ (most northerly in ~November).

• In the far eastern Pacific, the ITCZ interacts with wind jets that blow through gaps that produce strong wind stress curl dipoles (+ve on left flank; -ve curl on right) .

• Gap winds are strongest in winter; vary on short (weekly) time scales and generate coastal eddies

Precipitation

Fiedler and Talley. Hydrography of the eastern tropical Pacific: A review, PiO, 2006.

• ITCZ: P>> E with a maximum slightly west of Gulf of Panama

• Also, high river runoff off western slope of Andes

• Also, MJO intraseasonal variability high in winter drives heavy rainfall

• Also, “temporales”, week-long periods of continuous rain but weak winds maybe related to interaction of ITCZ and Caribbean systems.

Questions of InterestFocus is on understanding the role of the regional scale forcing and circulation in driving the seasonal patterns of salinity in SPURS-2 area.•How does the regional ocean circulation (i.e. NECC; SEC) impact the local coastal circulation including eddy variability?•What interplay between regional currents, local upwelling driven by gap wind and/or regional wind forcing, eddy variability and precipitation causes the distinctive SSS “bumps” in the far eastern Pacific?•What mix of local (wind-driven upwelling, precipitation, background stratification etc.) and remote (Kelvin waves, regional advection etc.) forcing drives the seasonal variability in barrier layer formation?

Approach• Addressing these links of the regional/large-scale circulation to the

local circulation will consist of analysis of existing remotely sensed (winds, SSS, SST, precip etc.) and in situ (Argo, XBT/CTD etc) data sets to map the climatological local and regional fields

• Field work (CTD, TSG, hull-mounted ADCP and side-mounted high-freq. ADCP to resolve near-surface currents) required to examine the T-S-V characteristics of the upper ocean stratification (incl. MLD, barrier layer etc.) and circulation (incl. the very near-surface wind-driven Ekman transport)

• I look forward to future discussion and interaction• Contact me at jsprintall@ucsd.edu

• me too: agordon@ldeo.columbia.edu