Please see attached a pdf file.

Review of "Factors causing stratocumulus to deviate

from subtropical high variability on seasonal to

interannual timescales"

by H. Ding, B. Stevens, and H. Schmidt

[A] Overall recommendation

This study presents statistical analyses of observational

data for maritime stratocumulus cloud fraction and 

atmospheric conditions. The study discusses whether the 

cloud fraction is controlled by the atmospheric 

conditions, focusing on the strength of the subtropical 

high pressure system.

The issue addressed in the paper is important. 

Stratocumulus cloud plays a major role in the global 

energy budget, and therefore, its changes can lead to 

sizable impact on the global climate. This motivates 

research on the factors controlling the stratocumulus 

cloud.

This study forwards understanding of the issue by 

rejecting two hypothesized processes by which the 

subtropical highs may affect the stratocumulus cloud.

The authors also illustrate that correlation between

the stratocumulus regime temperatures and the 

subtropical high dynamics exhibit strong regional and 

temporal dependencies, which is a valuable piece of 

information for those interested in the stratocumulus 

cloud variation.

There are, however, some minor points to mention 

regarding the presentation or interpretation of the 

results as listed below. I would therefore recommend 

accepting the manuscript for publication after minor 

revision.

[B] Minor Comments

(1) P.3 L.65 "This paper uses the second version of

the ATSR-AATSR"

Readers may be interested in the characteristics of 

this data set when compared with other observations 

such as ISCCP or MODIS. If the authors could comment 

on this, that will be helpful.

(2) P.5 L.109 "... it is fixed to be 500m"

It would be helpful to readers if the authors 

explain why the LCL is fixed to be 500m, rather 

than being estimated.

(3) P.5 Figure 2 caption "low cloud fraction (kappa)

from 2003 to 2014"

This appears inconsistent with the statement in 

L.70, that low cloud fraction data for the period

from Jan 2003 to Dec 2011 is analyzed.

(4) P.6 L.143 "C_D=0.0015 the drag coefficient"

Readers might wonder why the drag coefficient is 

assumed to be a constant value of 0.0015.

Additional clarification would be helpful.

(5) P.7 Table 1 caption "The dominant contribution

to EIS is denoted by a bold font"

It would be helpful to readers if the authors explain

in more detail what the dominant contribution means.

Does it mean that magnitude of the correlation or the 

standard deviation at one pressure level is larger 

than the magnitude at the other level?

(6) P.7 L.158 "explain most of the variability in EIS"

Readers might wonder if this statement is supported by

Table 1, because magnitude of the correlation is 

smaller at 700hPa than at 1000hPa at NP and SI on 

interannual timescale.

Additional clarification would be helpful.

(7) P.7 L.171 "this correlation does not imply causation"

Here the authors argue that the correlation does not 

imply causation. Does this argument apply to both 

seasonal cycle and interannual variability, or does it 

apply to interannual variability only?

Additional clarification would be helpful.

(8) P.8 Figure 3

I suggest that the authors give definition of the primes 

for EIS, Q_c, LHF_c, and W_E.

(9) P.8 L.187 "a clear relationship between Q_c and 

omega_700,c"

It would be helpful if the authors write the pressure 

level at which the Q_c is evaluated. Is it 700hPa?

(10) P.10 L.204 "Upwelling areas are restricted to the

coastal regions where the wind-stress curl is large"

In Figure 7(b), there appears to be no upwelling along 

the equator in the Pacific and the Atlantic. Readers 

might wonder how the SST cold tongue is maintained.

Additional clarification would be helpful.

(11) P.10 L.207 "variations in near-surface geopotential

gradients are not the primary driver of changes in

theta_1000"

It may be a good idea to show scatter plots for 

variations in geopotential gradients and variations 

in theta_1000, for both seasonal and interannual 

timescales, so that readers can better follow the 

argument.

[C] Typos

(1) P.6 L.133 "geopolitical"

geopotential?

(2) P.7 L.164 "SP"

SI?

(3) P.8 L.187 "theta_700"

omega_700?

(4) P.9 Figure 4 caption "omega_700(left)"

omega_700(top)?

(5) P.9 Figure 4 caption "Q(right)"

Q(bottom)?

(6) P.9 Figure 4 caption "Stratocumulus regions"

Subtropical high areas?

(7) P.12 Figure 8 caption "omega_700(top)"

omega_700(left)?

(8) P.12 Figure 8 caption "d(phi)/dx(bottom)"

d(phi)/dx(right)?