4.1 Temporal and zonal mean structure

In this subsection, we show the vertical profiles of radiative cooling rate and condensation heating rate at the equator and the latitudinal distributions of rainfall intensity obtained by the experiment with adjustment scheme.

Vertical profiles of radiative cooling and condensation heating

The temporal and zonal mean vertical profiles of radiative cooling and condensation heating at the equator of the experiment with adjustment scheme are shown in the left and the right panel of Fig.4.1, respectively. As in the results with Kuo scheme (Fig.3.1), When the smaller value of band absorption coefficient of the dry air is adopted, radiative cooling rate in the upper troposphere increases. However, compared to the experiment with Kuo scheme, the change of condensation heating profile responding to the change of radiative cooling profile is less significant.

We call the case adj-a (red lines in Fig.4.1), in which the condensation heating takes maximum in the lower troposphere, as "lower-level cooling experiment",, and the case adj-c (blue lines in Fig.4.1), in which the condensation heating takes maximum in the upper troposphere as "upper-level cooling experiment", and compare them in detail in the later subsections. In the case adj-d (light blue lines in Fig.4.1), the condensation heating is more enhanced in the upper levels than in adj-c. Howevere, we do not select this case adj-d to be compared with case adj-a, because of the similar reason as that for Kuo scheme cases (subsection.3.1); the zonal mean circulation structures for adj-d is different from those for the othere cases as is implied in the difference in the latitudinal distributions of zonal mean precipitation (Fig.4.3).

Fig.4.1: Temporal and zonal mean vertical profiles of radiative cooling rate (left panel) and condensation heating rate (right panel) at the equator, averaged from 1000 day to 1700 day of the experiment with adjustment scheme. Unit is [K s-1]. The band absorption coefficient of dry air is the largest for the case adj-a (red), is gradually decreased for cases adj-con (black), adj-b (yellowish green), adj-c (blue), and is the smallest for adj-d (light blue).

Zonal wind at the equator

The vertical profiles of the zonal and temporal mean zonal wind at the equator of the experiment with adjustment scheme are compared in Fig.4.2. In all cases, there is strong vertical shear in the lower troposphere and easterly wind has a maximum around the height of 2 [km] (σ=0.8) which is about the lower level of condensation layer of the atmosphere. Easterly wind speed is larger for the upper level cooling experiment than for the lower cooling case.

Fig.4.2: Temporal and zonal mean vertical profiles of zonal mean wind at the equator, averaged from 1000 day to 1700 day of the experiment with adjustment scheme. Unit is [m s-1]. Line colors indicate the same cases as Fig.4.1.

Precipitation

The latitudinal distributions of zonal and temporal mean precipitation of the experiment with adjustment scheme is shown in Fig.4.3. In contrast to the experiment with Kuo scheme, all cases are characterized by the "single ITCZ" structure; precipitation takes a single maximum at the equator.

As the band absorption coefficient of dry air is decreased, precipitation concentrates around the equator with compensating reduction in subtropics (around 20 degrees north and south). This tendency is also observed in cases with Kuo scheme (Fig.3.3).

Other aspects of general circulation for adj-a, e.g., low latitude meridional circulation, the distribution of zonal mean zonal wind, etc., also differ from those for the other cases (the details are not presented here). This is the reason that we do not select this case adj-d to be compared with case adj-a.

Fig.4.3: Temporally and zonal mean latitudinal distribution of precipitation, averaged from 1000 day to 1700 day of the experiment with adjustment scheme. Unit is [Kg m-2 s-1]. Line colors indicate the same cases as in Fig.4.1.