Cai & Jiang - second review
The authors have done a good job in answering most of my comments and those of the other rewiewer.
I still, however, think that additional explanations are needed to a couple of my initial concerns.
1. Derivation of A7 and A6 in the Appendix and double summation term in eq. A7:
Isn't the message in A7 self-evident? I.e. the rate of change of particle concentration in range k....u is
equal to condensational growth into range (I) minus condensation out of range (Ju) plus coagulation into
range minus coagulation out of range ?
and
In A6, the rate of change of particle concentration above size k is equal to condensational growth into
the range (I) minus collision rate in the range ?
In my view, the only slightly difficult part to formulate is the coagulation into range term in A7, and this
is not thoroughly explained here (and perhaps, slightly wrong?).
Let's say that we have a linear bin structure in volume so that v1 = 1, v2 = 2, ....., vk = k, ..... and we
are looking at the range from 7 to 10, i.e. dN(7,10)/dt.
According to the indexing in eq. A5, the following index-pairs contribute to the coagulation source-term
into the range: 1 and 5, 2 and 4, 3 and 3, 4 and 2, 5 and 1, 1 and 6, 2 and 5, 3 and 4, 4 and 3, 5 and 2,
4 and 3, 1 and 7, 2 and 6, 3 and 5, 4 and 4, 5 and 3, 6 and 2, 7 and 1.
The factor (1/2) takes care of the double counting and this is correct.
But what about the 5 first pairs in the list? They also produce particles into the range 6 to 7 which is not
in the range 7 to 10 ? Please explain!
Also, what if you have a different bin structure, say logarithmically spaced? Then, the conditions under
the summation term on the third term of the right hand side of equation A7, i.e. v(i) + v(j+1) = v(g) cannot
hold? If the equation in its current form is only applicable for a linearly spaced bin structure, it must be
clearly stated.
In my original review, I suggested removing most of the derivations in the Appendix. As they are located
in the Appendix, they might as well stay there, if the authors wish so. |