Mixing of the upper ocean by the wind field associated with tropical cyclones (TCs) creates observable cold wakes in sea surface temperature and may potentially influence ocean heat uptake. The relationship between cold wake size and storm size, however, has yet to be explored. Here we apply two objective methods to observed daily sea surface temperature data to quantify the size of TC‐induced cold wakes. The obtained cold wake sizes agree well with the TC sizes estimated from the QuikSCAT‐R wind field database with a correlation coefficient of 0.51 and 0.59, respectively. Furthermore, our new estimate of the total cooling that incorporates the variations in the cold wake size provides improved estimates of TC power dissipation and TC‐induced ocean heat uptake. This study thus highlights the importance of cold wake size in evaluating the climatological effects of TCs.

A recent study noted reduced rainfall and cloud fraction over cold wakes induced by tropical cyclones, but a quantification of top‐of‐atmosphere (TOA) radiation change due to these cold wakes has not been attempted. Based on global TOA radiative flux observations, we show that TOA shortwave and longwave radiations increase by 0.76 W m−2 (0.2%) and 0.74 W m−2 (0.3%) over the cold wake area relative to local climatology, respectively. Due to the cancelation between the shortwave and longwave components, daily average TOA net radiation is only marginally modulated by cold wakes, but stands out in the day and night time average. In addition, the seasonal basin‐wide regulation of TOA net radiation by cold wakes can be up to 1.0 W m−2, locally comparable to the magnitude of radiative forcing due to man‐made aerosols. The regional impact of cold wakes on TOA radiations is therefore highly relevant and potentially important.

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Among the basic characteristics of tropical cyclone (TC), size is by far the most difficult one to understand and predict although it is crucial for TC hazard and risk analysis. Probably due to the lack of a basic theory, even the relationship between TC equilibrium size and environmental factors remains unclear. For example, we can hardly understand the strong dependence of TC size on sea surface temperature (SST) even in the simple idealized simulations (Zhou et al., 2014). Observational studies have indicated a positive correlation between TC size and relative SST (Chavas et al., 2016;Lin et al., 2015). In tentative works of theoretical research, idealized rotating radiative-convective equilibrium (RRCE) f-plane simulations have been used in recent years to investigate the potential scalings for TC size as it is convenient to isolate large-scale forcing (