Asher William E.

No Thumbnail Available
Last Name
Asher
First Name
William E.
ORCID

Filters

2015 - 2019 3
3
3
Reset filters

Settings

Search Results

Now showing 1 - 3 of 3
  • Article
    Satellite and in situ salinity : understanding near-surface stratification and subfootprint variability
    (American Meteorological Society, 2016-08-31) Boutin, Jacqueline ; Chao, Yi ; Asher, William E. ; Delcroix, Thierry ; Drucker, Robert S. ; Drushka, Kyla ; Kolodziejczyk, Nicolas ; Lee, Tong ; Reul, Nicolas ; Reverdin, Gilles ; Schanze, Julian J. ; Soloviev, Alexander ; Yu, Lisan ; Anderson, Jessica ; Brucker, Ludovic ; Dinnat, Emmanuel ; Santos-Garcia, Andrea ; Jones, W. Linwood ; Maes, Christophe ; Meissner, Thomas ; Tang, Wenqing ; Vinogradova, Nadya ; Ward, Brian
    Remote sensing of salinity using satellite-mounted microwave radiometers provides new perspectives for studying ocean dynamics and the global hydrological cycle. Calibration and validation of these measurements is challenging because satellite and in situ methods measure salinity differently. Microwave radiometers measure the salinity in the top few centimeters of the ocean, whereas most in situ observations are reported below a depth of a few meters. Additionally, satellites measure salinity as a spatial average over an area of about 100 × 100 km2. In contrast, in situ sensors provide pointwise measurements at the location of the sensor. Thus, the presence of vertical gradients in, and horizontal variability of, sea surface salinity complicates comparison of satellite and in situ measurements. This paper synthesizes present knowledge of the magnitude and the processes that contribute to the formation and evolution of vertical and horizontal variability in near-surface salinity. Rainfall, freshwater plumes, and evaporation can generate vertical gradients of salinity, and in some cases these gradients can be large enough to affect validation of satellite measurements. Similarly, mesoscale to submesoscale processes can lead to horizontal variability that can also affect comparisons of satellite data to in situ data. Comparisons between satellite and in situ salinity measurements must take into account both vertical stratification and horizontal variability.
  • Article
    Novel and flexible approach to access the open ocean: Uses of sailing research vessel Lady Amber during SPURS-2.
    (Oceanography Society, 2019-06-14) Rainville, Luc ; Centurioni, Luca R. ; Asher, William E. ; Clayson, Carol A. ; Drushka, Kyla ; Edson, James B. ; Hodges, Benjamin A. ; Hormann, Verena ; Farrar, J. Thomas ; Schanze, Julian J. ; Shcherbina, Andrey Y.
    SPURS-2 (Salinity Processes in the Upper-ocean Regional Study 2) used the schooner Lady Amber, a small sailing research vessel, to deploy, service, maintain, and recover a variety of oceanographic and meteorological instruments in the eastern Pacific Ocean. Low operational costs allowed us to frequently deploy floats and drifters to collect data necessary for resolving the regional circulation of the eastern tropical Pacific. The small charter gave us the opportunity to deploy drifters in locations chosen according to current conditions, to recover and deploy various autonomous instruments in a targeted and adaptive manner, and to collect additional near-surface and atmospheric measurements in the remote SPURS-2 region.
  • Article
    From salty to fresh—salinity processes in the Upper-ocean Regional Study-2 (SPURS-2) : diagnosing the physics of a rainfall-dominated salinity minimum
    (The Oceanography Society, 2015-03) Schmitt, Raymond W. ; Asher, William E. ; Bingham, Frederick ; Carton, James A. ; Centurioni, Luca R. ; Farrar, J. Thomas ; Gordon, Arnold L. ; Hodges, Benjamin A. ; Jessup, Andrew T. ; Kessler, William S. ; Rainville, Luc ; Shcherbina, Andrey Y.
    One of the notable features of the global ocean is that the salinity of the North Atlantic is about 1 psu higher than that of the North Pacific. This contrast is thought to be due to one of the large asymmetries in the global water cycle: the transport of water vapor by the trade winds across Central America and the lack of any comparable transport into the Atlantic from the Sahara Desert. Net evaporation serves to maintain high Atlantic salinities, and net precipitation lowers those in the Pacific. Because the effects on upper-ocean physics are markedly different in the evaporating and precipitating regimes, the next phase of research in the Salinity Processes in the Upper-ocean Regional Study (SPURS) must address a high rainfall region. It seemed especially appropriate to focus on the eastern tropical Pacific that is freshened by the water vapor carried from the Atlantic. In a sense, the SPURS-2 Pacific region will be looking at the downstream fate of the freshwater carried out of the SPURS-1 North Atlantic region. Rainfall tends to lower surface density and thus inhibit vertical mixing, leading to quite different physical structure and dynamics in the upper ocean. Here, we discuss the motivations for the location of SPURS-2 and the scientific questions we hope to address.