Meetings: Documents

Quantification of Precipitation Minus Evaporation During SPURS-2
[12-Feb-2018] Edson, J.B., Clayson, C.A., Farrar, J.T., Paget, A., and Graham, R.
Presented at the 2018 Ocean Sciences Meeting
A comprehensive set of atmospheric and oceanic data was collected on the R/V Revelle and 3-m discus buoy during the SPURS-2 experiment in the tropical Eastern Pacific Ocean. These measurements are being used to quantify the amount of precipitation versus evaporation (P-E) that drives a freshwater flux into or out of the upper ocean, respectively. The salinity variability of the upper ocean is profoundly influenced by the freshwater flux at the surface, in combination with the effects of mixing and advection within the upper ocean. The mixing in the upper ocean is itself affected by the surface fluxes of freshwater, momentum, and heat. To quantify these fluxes, our measurements include direct estimates of the heat, moisture, and momentum using Direct Covariance Flux Systems (DCFS) on the ship and buoy, as well as their related mean variables and radiative fluxes to estimate bulk fluxes.
The related means include four time daily launches of rawinsondes to provide atmospheric soundings of temperature, humidity, wind speed, and wind direction. These sounds provide the precipitable water available in the overlying atmosphere. These observations are being combined with remotely sensed data from satellites and model reanalysis (MERRA-2) to investigate the relative importance of local evaporation, moisture storage, and moisture convergence using the vertically integrated moisture budget in the region under the Inter-Tropical Convergence Zone.
This talk will describe some of our efforts to quantify the surface fluxes and the sources/sinks of precipitable water over the SPURS-2 region. The principle hypothesis of this research is that the surface fluxes are a key factor in the evolution of salinity variability in this region, and that measurements of these parameters will greatly enhance our ability to simulate and predict the upper ocean salinity budget and resulting salinity structure in this region.

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