(top) Scatterplot of AHTEQ 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 AHTEQ (red asterisk and linear best fit dashed line) and PPenny vs AHTEQ (blue asterisk and linear best fit dashed line). The expected relationship between ??=0 and AHTEQ from Eq. (9) is shown by the dashed black line.
1) Design operates made use of and you may methods
I play with model yields of phase 3 of Coupled Design Intercomparison Opportunity (CMIP3) multimodel databases (Meehl ainsi que al. 2007): an outfit away from standardized coupled climate simulations away from twenty-five more environment patterns which were found in new Intergovernmental Panel into the Climate Change’s Fourth Testing Statement. We get to know the preindustrial (PI) simulations here. In those simulations, greenhouse gasoline density, aerosols, and you will solar forcing try repaired during the preindustrial accounts together with habits are run having 400 years. The very last 2 decades of PI simulations are used to assess climatological fields. This new 16 designs included in this study is actually listed in Table 1.
Designs used in this research in addition to their solution. New horizontal solution is the latitudinal and you will longitudinal grid spacing or even the spectral truncation. The brand new vertical quality is the number of vertical account.
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 ?STORATMOS? is calculated from finite difference of the monthly averaged vertically integrated temperature and specific humidity fields; AHTEQ is then calculated from the residual of the other terms in Eq. (5).
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 PCent and AHTEQ for each CMIP3 ensemble member in the upper panel of Fig. 6. We best free asian hookup apps define the seasonal amplitude of PPenny and AHTEQ as the amplitude of the annual harmonic of each variable. The CMIP3 ensemble mean regression coefficient between PCent and AHTEQ 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 PPenny and AHTEQ in observations and the models. Seasonal variations in PPenny and AHTEQ 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 PCent and AHTEQ 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 AHTEQ, mainly the mutual relationship among the tropical precipitation maximum, AHTEQ, 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 PPenny and AHTEQ. We further discuss this result later in this section.