(top) Scatterplot of AHT_{EQ} vs the mass overturning streamfunction at 500 hPa over the equator over the seasonal cycle in the observations. Each asterisk is a monthly average and the dashed line is the linear best fit. (bottom) Scatterplot of the location of the 0 mass overturning streamfunction ?_{?=0} at 500 hPa vs AHT_{EQ} (red asterisk and linear best fit dashed line) and P_{Penny} vs AHT_{EQ} (blue asterisk and linear best fit dashed line). The expected relationship between ?_{?=0} and AHT_{EQ} from Eq. (9) is shown by the dashed black line.

## 1) Design runs put and you may methodology

I fool around with design returns regarding phase 3 of the Paired Design Intercomparison Venture (CMIP3) multimodel database (Meehl mais aussi al. 2007): a clothes out-of standard combined climate simulations out-of twenty-five different environment models that have been included in the brand new Intergovernmental Committee towards the Climate Change’s Fourth Testing Report. We analyze the fresh new preindustrial (PI) simulations here. In those simulations, greenhouse gas density, aerosols, and you may solar power pressuring was repaired within preindustrial profile additionally the habits are run for 400 age. The final twenty years of PI simulations are used to calculate climatological industries. This new 16 activities utilized in this research is listed in Dining table step one.

Models included in this study and their quality. The newest lateral resolution is the latitudinal and you may longitudinal grid spacing and/or spectral truncation. The brand new straight resolution ‘s the quantity of vertical membership.

The turbulent and radiative energy fluxes at the surface and TOA are provided as model output fields. This allows ?SWABS? and ?SHF? to be directly calculated from Eqs. (6) and (7). The ?OLR? is directly calculated and ?STOR_{ATMOS}? is calculated from finite difference of the monthly averaged vertically integrated temperature and specific humidity fields; AHT_{EQ} is then calculated from the residual of the other terms in Eq. (5).

## 2) Performance

We show the seasonal amplitude (given by half the length of the line) and the regression coefficient (given by the slope of the line) between P_{Penny} and AHT_{EQ} for each CMIP3 ensemble member in the upper panel of Fig. 6. We define the seasonal amplitude of P_{Cent} and AHT_{EQ} as the amplitude of the annual harmonic of each variable. The CMIP3 ensemble sex hookup ios apps mean regression coefficient between P_{Penny} and AHT_{EQ} is ?2.4° ± 0.4° PW ?1 (the slope of the thick black line) and is slightly smaller but statistically indistinguishable from the value of ?2.7° ± 0.6° PW ?1 found in the observations (the thick purple line). Table 2 lists the seasonal statistics of P_{Penny} and AHT_{EQ} in observations and the models. Seasonal variations in P_{Penny} and AHT_{EQ} are significantly correlated with each other in all models with an ensemble average correlation coefficient of ?0.89. On average, the linear best fits in the models come closer to the origin than do the observations (thick black line in Fig. 6), conforming to our idealized expectation that when the precipitation is centered on the equator, the ascending branch of the Hadley cell will also be on the equator, resulting in zero cross-equatorial heat transport in the atmosphere. The relationship between P_{Penny} and AHT_{EQ} over the seasonal cycle is fairly consistent from one model to the next (all the slopes in Fig. 6 are similar) and is similar to the relationship found in the observations. _{Cent} and AHT_{EQ}, mainly the mutual relationship among the tropical precipitation maximum, AHT_{EQ}, and the location of the Hadley cell. The precipitation centroid lags the cross-equatorial atmospheric heat transport in the models by 29 days in the ensemble average (with a standard deviation of 6 days). This is in contrast to the observations where there is virtually no (<2 days) phase shift between P_{Cent} and AHT_{EQ}. We further discuss this result later in this section.

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