Satellite microwave SST observations of transequatorial tropical instability waves

Abstract

Abstract.Satellite

Influence of ocean‐atmosphere coupling on the properties of tropical instability waves

“…The phase propagation speed of the waves is around 30 cm s À1 , in the lowest part of the observed speed range [Chelton et al, 2000;Kennan and Flament, 2000]. The period of TIWs is around 30 days, in good agreement with estimates from observations [Qiao and Weisberg, 1995].…”

“…[13] The model simulates the gross features of the cold tongue, as shown in Figure 1 (upper panel), and also exhibits a well defined cusp-shaped wave pattern similar to the TIW patterns described in the literature [Chelton et al, 2000]. The phase propagation speed of the waves is around 30 cm s À1 , in the lowest part of the observed speed range [Chelton et al, 2000;Kennan and Flament, 2000].…”

“…[3] Two studies using satellite data Chelton et al, 2000] described the spatial patterns associated with the TIW signal: wind is accelerated over warm anomalies and decelerated over cold ones, producing centers of convergence and divergence collocated with maximum SST gradient regions. The convergence (divergence) centers in turn lead to increased (decreased) water vapor content in the lower layers of the atmosphere.…”

“…They have a longitudinal scale of 1000-2000 km and propagation speed of about 30 cm s À1 to 60 cm s À1 [Qiao and Weisberg, 1995;Chelton et al, 2000]. Although there is no consensus on the exact nature of these instabilities, lateral shear associated with the equatorial undercurrent (EUC), south equatorial current (SEC), north equatorial countercurrent (NECC) and density gradients between the equatorial cold tongue and warmer water north of it are thought to be the main structures conducive to the appearance of these instabilities [e.g., Cox, 1980;Philander, 1978].…”

The influence of salinity on tropical Atlantic instability waves

“…Thousand kilometer zonal scale propagating waves with typical periods of tens of days have been observed in the tropical Pacific and Atlantic Oceans, affecting the physical and biogeochemical properties of the ocean and its interaction with the atmosphere [e.g., Legeckis, 1977;Legeckis and Reverdin, 1983;McPhaden et al, 1984;Hayes et al, 1989;Luther and Johnson, 1990;Yoder et al, 1994;Qiao and Weisberg, 1995;McPhaden, 1996;Xie et al, 1998;Chelton et al, 2000;Liu et al, 2000;Polito et al, 2001;Lee et al, 2012]. These tropical instability waves (TIWs) are generated from barotropic and baroclinic instabilities associated with the horizontal and vertical shear of equatorial current systems and related density gradients [e.g., Philander, 1978;Weisberg and Weingartner, 1988;McCreary and Yu, 1992;Masina et al, 1999;Grodsky et al, 2005;Jochum et al, 2004;Lyman et al, 2007;von Schuckmann et al, 2008].…”