Multi‐satellite measurements of large diurnal warming events

Abstract

[1] Diurnal warming events between 5 and 7 K, spatially coherent over large areas ($1000 km), are observed in independent satellite measurements of ocean surface temperature. The majority of the large events occurred in the extra-tropics. Given sufficient heating (from solar radiation), the location and magnitude of these events appears to be primarily determined by large-scale wind patterns. The amplitude of the measured diurnal heating scales inversely with the spatial resolution of the different sensors used in this study. These results indicate that predictions of peak diurnal warming using wind speeds with a 25 km spatial resolution available from satellite sensors and those with 50-100 km resolution from Numerical Weather Prediction models may have underestimated warming. Thus, the use of these winds in modeling diurnal effects will be limited in accuracy by both the temporal and spatial resolution of the wind fields.

Physics of diurnal warm layers : turbulence, internal waves, and lateral mixing

“…While it is challenging to separate out potential effects of advection due to the dominance of the diurnal cycle of temperature in the upper ocean, DWL shear can enhance or suppress the signal of warming in the near-surface ocean, and may be an important source of lateral heat transport in the upper ocean. This possible enhancement may account for some of the large diurnal warming observed, such as Gentemann et al (2008).…”

“…Kudryavtsev and Soloviev (1990) observed this momentum trapping and found the velocities to be on the order of 0.1 m/s. During periods of low wind speed and high solar insolation the upper few meters of the ocean can warm and then cool several degrees over the course of a diurnal cycle (Gentemann et al, 2008), and the DWL shear can be trapped in the upper few meters of the ocean. Throughout this paper, the near-surface current caused by momentum trapped by the stable stratification of diurnal warming is referred to as DWL shear or the DWL current.…”

Global Daily High-Resolution Satellite-Based Foundation Sea Surface Temperature Dataset: Development and Validation against Two Definitions of Foundation SST

“…The diurnal SST variation strength is determined mainly by the amount of solar heating and the magnitude of sea surface wind (SSW). Although the average diurnal amplitude of SST is a few tenths of a degree [12], diurnal variations of several degrees in amplitude with spatially-coherent structures over large areas up to 1000 km are often observed [13,14]. The diurnal variations of upper surface temperature, however, increase during daytime usually within a top of several meters in oceans [15].…”

A Review of Ocean/Sea Subsurface Water Temperature Studies from Remote Sensing and Non-Remote Sensing Methods

“…The day-night difference between SST peaks may surpass 3 K [70,71] due to different locations and environmental conditions. Air-sea interactions may be temporarily affected by the changing heat and gas fluxes, atmospheric circulation, and the height of the atmospheric boundary layer [44].…”