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Tropical cyclone rainfall area controlled by relative sea surface temperature.

Lin Y, Zhao M, Zhang M - Nat Commun (2015)

Bottom Line: Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST.Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity.Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084, China.

ABSTRACT
Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates.

No MeSH data available.


Frequency distributions of rainfall radius and rainfall rate from HIRAM simulations.(a) Frequency distributions of TC rainfall radius from the four HIRAM simulations (CTL=the control simulation; AMIP=the AMIP simulation; P2K=the P2K simulation and P4K=the P4K simulation; see text for details). (b) Frequency distributions of TC rainfall rate within a 100-km radius of the TC centre. (c) Same as (b) but for TC rainfall rate within the objectively determined rainfall radius. Mean values of rainfall radius (in km) and rainfall rate (in mm h−1) are labelled in each panel.
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f4: Frequency distributions of rainfall radius and rainfall rate from HIRAM simulations.(a) Frequency distributions of TC rainfall radius from the four HIRAM simulations (CTL=the control simulation; AMIP=the AMIP simulation; P2K=the P2K simulation and P4K=the P4K simulation; see text for details). (b) Frequency distributions of TC rainfall rate within a 100-km radius of the TC centre. (c) Same as (b) but for TC rainfall rate within the objectively determined rainfall radius. Mean values of rainfall radius (in km) and rainfall rate (in mm h−1) are labelled in each panel.

Mentions: The frequency distributions of TC rainfall radius based on all of these simulations are very similar (Fig. 4a). The overall increase in rainfall radius is only around 3 km for the P2K simulation (relative to the control simulation) and around 10 km for the P4K simulation (relative to the AMIP simulation). These small increases in rainfall radius are mainly due to increases in rainfall rate with increasing absolute SST (the rainfall rate threshold used in the method is fixed at 0.5 mm h−1 (see Fig. 5 and Methods). The negligible change in TC rainfall area under global warming scenarios is in sharp contrast to the strong dependence of TC size on absolute SST, and is consistent with the hypothesis that rainfall area depends primarily on relative SST. This suggests that, to the first order, TC rainfall area is primarily controlled by relative SST instead of absolute SST. Relative SST has also been identified as better than absolute SST for explaining variations in Atlantic TC frequency52526 and tropical convection27.


Tropical cyclone rainfall area controlled by relative sea surface temperature.

Lin Y, Zhao M, Zhang M - Nat Commun (2015)

Frequency distributions of rainfall radius and rainfall rate from HIRAM simulations.(a) Frequency distributions of TC rainfall radius from the four HIRAM simulations (CTL=the control simulation; AMIP=the AMIP simulation; P2K=the P2K simulation and P4K=the P4K simulation; see text for details). (b) Frequency distributions of TC rainfall rate within a 100-km radius of the TC centre. (c) Same as (b) but for TC rainfall rate within the objectively determined rainfall radius. Mean values of rainfall radius (in km) and rainfall rate (in mm h−1) are labelled in each panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4382685&req=5

f4: Frequency distributions of rainfall radius and rainfall rate from HIRAM simulations.(a) Frequency distributions of TC rainfall radius from the four HIRAM simulations (CTL=the control simulation; AMIP=the AMIP simulation; P2K=the P2K simulation and P4K=the P4K simulation; see text for details). (b) Frequency distributions of TC rainfall rate within a 100-km radius of the TC centre. (c) Same as (b) but for TC rainfall rate within the objectively determined rainfall radius. Mean values of rainfall radius (in km) and rainfall rate (in mm h−1) are labelled in each panel.
Mentions: The frequency distributions of TC rainfall radius based on all of these simulations are very similar (Fig. 4a). The overall increase in rainfall radius is only around 3 km for the P2K simulation (relative to the control simulation) and around 10 km for the P4K simulation (relative to the AMIP simulation). These small increases in rainfall radius are mainly due to increases in rainfall rate with increasing absolute SST (the rainfall rate threshold used in the method is fixed at 0.5 mm h−1 (see Fig. 5 and Methods). The negligible change in TC rainfall area under global warming scenarios is in sharp contrast to the strong dependence of TC size on absolute SST, and is consistent with the hypothesis that rainfall area depends primarily on relative SST. This suggests that, to the first order, TC rainfall area is primarily controlled by relative SST instead of absolute SST. Relative SST has also been identified as better than absolute SST for explaining variations in Atlantic TC frequency52526 and tropical convection27.

Bottom Line: Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST.Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity.Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University, Beijing 100084, China.

ABSTRACT
Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates.

No MeSH data available.