Global representation of tropical cyclone-induced short-term ocean thermal changes using Argo data

Abstract

Abstract. Argo floats are used to examine tropical cyclone (TC) induced ocean thermal changes on the global scale by comparing temperature profiles before and after TC passage. We present a footprint method that analyzes cross-track thermal responses along all storm tracks during the period 2004-2012. We combine the results into composite representations of the vertical structure of the average thermal response for two different categories: tropical storms/tropical depressions (TS/TD) and hurricanes. The two footprint composites are functions of three variables: cross-track distance, water depth and time relative to TC passage. We find that this footprint strategy captures the major features of the upperocean thermal response to TCs on timescales up to 20 days when compared against previous case study results using in situ measurements. On the global scale, TCs are responsible for 1.87 PW (11.05 W m −2 ) of heat transfer annually from the global ocean to the atmosphere during storm passage (0-3 days). Of this total, 1.05 ± 0.20 PW (4.80 ± 0.85 W m −2 ) is caused by TS/TD and 0.82 ± 0.21 PW (6.25 ± 1.5 W m −2 ) is caused by hurricanes. Our findings indicate that ocean heat loss by TCs may be a substantial missing piece of the global ocean heat budget. Changes in ocean heat content (OHC) after storm passage are estimated by analyzing the temperature anomalies during wake recovery following storm events (4-20 days after storm passage) relative to pre-storm conditions. Results indicate the global ocean experiences a 0.75 ± 0.25 PW (5.98 ± 2.1 W m −2 ) heat gain annually for hurricanes. In contrast, under TS/TD conditions, the ocean experiences 0.41 ± 0.21 PW (1.90 ± 0.96 W m −2 ) ocean heat loss, suggesting the overall oceanic thermal response is particularly sensitive to the intensity of the event. The ocean heat uptake caused by all storms during the restorative stage is 0.34 PW.

The responses of cyclonic and anticyclonic eddies to typhoon forcing: The vertical temperature‐salinity structure changes associated with the horizontal convergence/divergence

“…Although the air‐sea flux can be as large as 260 MJ/m 2 at certain small location for a category 5 typhoon [ Shay et al ., ], the typical value of air‐sea flux was quite smaller, e.g., area average value of the whole forcing region is only about 20–30 MJ/m 2 [ Shay et al ., ] and 40 MJ/m 2 for a category 2 typhoon [ Sun et al ., ]. The annual mean of air‐sea flux due to typhoon forcing on the global scale is 34 MJ/m 2 (11.05 w/m 2 ) [ Cheng et al ., ]. It implies that such huge subsurface heat content loss in the AEs cannot be simply due to the local air‐sea interaction.…”

“…The only difference is that the maximum cooling occurred at 350 m in the CEs, whereas the maximum cooling occurred at subsurface of 100 m depth in the AEs. Previous study also identified the cooling center at 100 and 350 m depth [ Cheng et al ., ]. In this study, only two different cooling centers are detected in the CEs and AEs.…”

Effects of ocean grid resolution on tropical cyclone‐induced upper ocean responses using a global ocean general circulation model

“…We analyze SST responses for storm days with weak intensity (Categories 1 and 2) and medium to high intensity (Categories 3–5). The temporal evolution of the SST cooling is consistent among all three models, and the magnitude of cooling is within the range of observation‐based estimates [ D'Asaro et al ., , ; Cheng et al ., ] and other modeling studies [ Vincent et al ., ; Li et al ., ; Jullien et al ., ]. The anomalous cooling before the storm arrival (Day 0 in Figure ) is likely due to the cold wakes left by the earlier storms.…”

“…The figure reveals that a persistent cooling below the thermocline warming that acts to compensate the OHU. This deep cooling is also found in other observation‐based and modeling studies [ Cheng et al ., ; Jullien et al ., ]. The cooling occurs mainly in the Southern Indian ocean near the Seychelles‐Chagos thermocline ridge (5°S–15°S) (see supporting information animations and Figures S4 and S5), where the shallow thermocline permits efficient vertical mixing and strong upwelling of cold water by TC‐induced Ekman pumping.…”

Tropical Cyclone Activity in the High‐Resolution Community Earth System Model and the Impact of Ocean Coupling

“…Ocean‐atmosphere coupling is also important for analyzing TC‐induced feedbacks that can influence climate variability. An increasing number of studies have found TC‐induced ocean vertical mixing can lead to ocean heat uptake and transport (Bueti et al, ; Cheng et al, ; Emanuel, ; Jansen et al, ; Jullien et al, ; Li & Sriver, ; Sriver & Huber, ), potentially influencing global SST patterns and affecting large‐scale circulations in the ocean and the atmosphere (Fedorov et al, ; Sriver & Huber, ). These potential feedbacks can affect climate mean‐state and variability on seasonal to interannual time scales.…”