Luo and Han “Impacts of the Saharan air layer on the physical properties of the Atlantic tropical cyclone cloud systems: 2003-2019”

This study investigates the impacts of the Saharan air layer (SAL) on the physical properties of the Atlantic tropical cyclone cloud systems (TCCS) for the summer of 17 years. It divided the 70 TC samples into three categories, tropical depression (TD), tropical storm (TS), and hurricane (HU). It found that the SAL makes crucial impacts on the generation and evolution of Tropical cyclones (TCs). The authors have attempted to identify whether and how the effects of the SAL play a positive or negative role on the TCCS, and to draw a qualitative conclusion of how SAL affects the various intensities of the TCs. The conclusions are beneficial to better understanding of the physical processes and evolutions of TCs in the Atlantic region. In addition, the manuscript is well written. I would recommend its acceptance for publication after necessary revisions.

Considering that this article involves lots of satellite and ground-based data, such as AOD, CTT, CERi, and CIWP, Atlantic TC track data and meteorological data etc., I would suggest that the authors add more information about the data matching in part 2.

A schematic diagram in Part 3 to reflect the relationship between 3.1-3.3 might be helpful to the readers.

Line 33, I am not sure if this descrption is accurate or not. The North Atlantic is one of the areas with the most frequent TCs in the world, along with the west pacific. However, I am not sure if the North Atlantic is an area with the most frequent TCs in the world. Actually, in my understanding the west Pacific have more and stonger TC activities than the North Atlantic. Anyway, please provide a reference to support your claim here.

Line 35-37, regarding these three kinds of aerosol radiative effects, three more references are recommended here, Albrecht (1989, doi: 10.1126/science.245.4923.1227), Garrett and Zhao (2006, doi: 10.1038/nature04636) and Zhao and Garrett (2015, doi: 10.1002/2014GL062015).

Line 40-45: In my understanding, mineral dust particles have weak absorption and strong scattering, therefore, it is suggested that the author to examine the statement of this sentence “As absorbing aerosols, mineral dust particles absorb solar radiation and heat the atmosphere through the semi-direct effect, further enhancing cloud evaporation”.

Line 50-58, The recent study by Sun and Zhao (2020) have done a comprehensive analysis about the dust aerosol effects on the meteorological environment, including the vorticity, temperature, wind shear, and humidity, which suggested a negative effect to TC formation. This recent study is worthy to read and mention here.

Line 62-64: Add a word “all” before the factors.

Line 94-95: Add a word “etc.” at the end of this sentence.

Figure 1, it should be noted that the aerosol property (AOD) is generally averaged for time when there are no clouds (so no TC activities).

Line 113-116, The question is how accurate the meteorological variables from FNL reanalysis data are.

Line 155: Add “respectively” at the end of this sentence.

Line 168-170: Rephrase this sentence.

Line 200-201, Similar findings have also been found by a recent study of Zhao et al. (2018, doi: 10.1029/2018GL079427), which showed that aerosols can cause broader precipitation area (horizontal range of TC) and weaker maximum precipitation intensity (lower cloud thickness at the band near TC eye).

Figure 9, using “μm” might be better for the cloud effective radius unit.

Line 220-225: Adding the peak perpendicular line of the probability density function to FIG. 9, clarifying the moving value of the peak, the specific situation can be clearly marked on FIG. 9.

Line 267-269: Add “respectively” at the end of this sentence.

Review of “Impacts of the Saharan air layer on the physical properties of the Atlantic tropical cyclone cloud systems: 2003-2019” by Luo and Han.

General comments:

This is an interesting study that examines the impacts of the Saharan air layer (SAL) on the physical features of the Atlantic tropical cyclone (TC) cloud systems (TCCS) by using co-located satellite-based cloud and aerosol observations. The authors attempt to distinguish the various effects of SAL on different intensities of TCs, and further find out the probable causes of the varied feedback mechanisms. Based on the 70 TC samples during the summertime of 2003-2019, the varying impacts of SAL on different intensities of TCCS are well analyzed and concluded. They find that the various responses of TCCS to SAL are determined by the combined factors of dry air masses, the dust aerosols as ice nuclei, as well as the thermodynamic and moisture conditions. These conclusions may contribute to a better understanding of the physical mechanisms between the SAL and TCs over the Atlantic region. Overall, the manuscript is well written and the data are well analyzed and presented. Therefore, I would recommend its acceptance for publication in ACP after minor revisions.

Specific comments:

Line 22: Please rephrase this sentence. “but the PDF curve becomes flatten for HU” should be “whereas the PDF curve becomes flatter for HU”.

Line 60: Please specify what is meant by TCCS macro and micro properties. After reviewing all of the figures and the remainder of the paper, it seems that the macro properties include the cloud top temperature and the cloud ice water path, while the micro properties refer to the ice cloud effective radius. Since “cloud macro or micro properties” is a rather broad term that could be interpreted in many different ways, please state this clearly at least once.

Line 76: “characteristics” should be “variation characteristics”.

Line 224: Related to Line 22.

Figure 9: The units of cloud effective radius should be “μm” to match the units shown in Figure 11.

Line 258: “flatten” should be “flat”.

Line 276: The “TC nephsystems” should be “TCCS” to be consistent with the context.

Line 277: Add a comma before “respectively”.

Line 282: Related to Line 22.

Line 287: “various feedbacks” should be “various feedback mechanisms”. Please modify it throughout the context.

Line 310: Please provide relevant search terms for the public data retrieval in the data availability statement.