the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
JAXA Level2 algorithms for EarthCARE mission from single to four sensors: new perspective of cloud, aerosol, radiation and dynamics
Abstract. This article gives the overview of the Japan Aerospace Exploration Agency (JAXA) level 2 (L2) Standard and Research algorithms and products by Japanese science teams for EarthCARE Clouds, Aerosols and Radiation Explorer (EarthCARE), which is a JAXA and the European Space Agency (ESA) joint satellite mission. First three single sensor algorithms for 94GHz cloud profiling radar (CPR)-only, 355nm-atmospheric lidar with high spectral resolution function (ATLID)-only, and multi-spectral imager (MSI)-only retrievals, and their products were briefly reviewed. CPR-echo algorithms provide radar reflectivity factor, Doppler velocity, normalized radar cross section and path integral attenuation. CPR-only, CPR-ATLID synergy and CPR-ALTID-MSI synergy algorithms for standard cloud products provide cloud detection, cloud particle type and cloud microphysics, and the research products further provide Doppler velocity, terminal velocity and vertical air motion inside clouds. ATLID standalone algorithms produce aerosol, cloud and clear sky classification products as well as total aerosol extinction and extinction and number concentration of each aerosol types. ATLID-MSI synergy algorithms are developed to retrieve effective radius for each aerosol species in addition to the ATLID-only products. MSI algorithms retrieve cloud effective radius, ice and water content and cloud top pressure. Four sensor algorithms are prepared to produce shortwave and longwave radiative fluxes at the top of atmosphere, those at the surface and also heating rate profiles by using the outputs from CPR, ATLID and their synergy algorithms. The shortwave and longwave fluxes from the four sensor algorithms will then be compared with broad band radiation (BBR) to examine the consistency of the JAXA L2 retrievals.
The algorithms are developed and evaluated by using observational data from satellites and ground-based instruments, and simulation data from the Japanese global cloud-resolving model, the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) with Joint simulator. As for space-borne data, existing space-borne satellites data such as CloudSat, CALIPSO, MODIS and CERES datasets are intensively used. For ground-based observations, High-sensitivity Ground-based Super Polarimetric Ice-crystal Detection and Explication Radar (HG-SPIDER) with a minimum sensitivity of -40 dBZ at 15 km and over -60 dBZ at 1 km, Electronic Scanning SPIDER (ES-SPIDER), 355 nm high spectral resolution lidar, multiple-field-of-view multiple scattering lidar and Doppler lidars are installed at EarthCARE super-site in Koganei, Tokyo and offers unique opportunities to evaluate and analyse EarthCARE data.
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RC1: 'Comment on amt-2024-101', Anonymous Referee #1, 22 Jul 2024
This is a tricky paper to review. On the one hand, the EarthCARE mission offers new and exciting data, and it is important to understand the algorithms that will be used to process the data. On the other hand, this paper does not offer enough detail to evaluate the methodologies of the individual algorithms, and there is no science question or hypothesis being tested. There are also other "overview" papers about EarthCare published in AMT that contain similar information to this one (for example, https://doi.org/10.5194/amt-17-839-2024 ). When considering the "review criteria" that AMT specifies, I must answer "no" to several of the questions listed:
1.) Does the paper address relevant scientific questions within the scope of AMT?
While the topic is relevant, there is no specific scientific question.
3.) Are substantial conclusions reached?
The only real conclusions are that "smile effects in MSI measurements are ... small" and that "the four sensor radiative flux products were demonstrated to have good correspondence with CERES observations" (for one day, using simulated data). These hardly feel substantial.
4.) Are the scientific methods and assumptions valid and clearly outlined?
No, there is not nearly enough detail to fully understand the methods and assumptions of each algorithm. However, given that there are dozen of algorithms mentioned (side note: a diagram or a table showing how these each relate to each other would be very helpful), it seems impossible to do this in a reasonable length paper. In my view, each of these algorithms should be explained in separate papers. And some of them already have, but that makes me question the need for this specific paper.
6.) Is the description of experiments and calculations sufficiently complete and precise to allow their reproduction by fellow scientists (traceability of results)?
No. Even though the EarthCARE synthetic data is publicly available, there is not enough information about what is going on "under the hood" of each algorithm to be able to reproduce the figures in this paper.
11.) Is the language fluent and precise?
No, there are many grammatical errors (missing articles, improper tenses, subject/verb agreement, etc.) throughout the paper; too many to list in a review.
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For these reasons, I am forced to recommend a rejection of this paper as a stand-alone article. I do realize that this was submitted to a special issue, "EarthCARE Level 2 algorithms and data products." In this context, perhaps my concerns are unfounded - I leave that decision up to the Editor. I do think this paper presents useful overview information about the JAXA Level 2 EarthCARE algorithms that belongs somewhere in the public domain; I'm just not sure AMT is the appropriate place for it. At the minimum, there should be a very thorough English language proofreading performed before this paper is ready for publication.
Citation: https://doi.org/10.5194/amt-2024-101-RC1 -
RC2: 'Comment on amt-2024-101', Anonymous Referee #2, 02 Aug 2024
General Comments:
I see two basic problems with this paper:
(1) It is too ambitious. Each of the various sections could be its own paper. As it is written, most sections do not include sufficient detail and are just a list of references to other papers. There are only two reasonable options: (a) spin this one paper into five separate papers or (b) add significant detail to the existing paper, in which case detail should be added in most sections.
(2) The ordering of the sections makes it very boring and difficult to read. I would recommend restructuring the paper so that some of the figures and results from section 3 are included in section 2. This would make the paper much easier to read. For example, 3-1 can be merged with section 2-3 easily. Likewise 3-2 and 2-4 can be combined and so on with the other sections. Section 2-8 should be moved before any of the algorithm sections. I think this structure would be much easier for the reader.
Furthermore, it is clear that insufficient effort was put into this paper. There are a large number of grammatical problems with the paper. Figures 2 and 3 aren’t referenced anywhere in the text. As I’ve stated above the detail describing these algorithms is very thin. I’ve included some recommendations below for the radar-only algorithms, but similar comments could clearly be added for other subsections and the authors should put renewed effort into adding sufficient detail to each subsection.
Finally, because this paper is covering so many algorithms, you need a figure to orient the reader. Some sort of flow chart showing how all of the various products relate to each other should be included in the beginning of the paper.
I recommend major revisions for this paper.
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Specific comments:
Line 86: fix ‘20204’
Section 2-1: Show an example of the data products or at the very least of a simulation.
Section 2-1-1: This section is missing important detail. It seems like the radar equation should be included here. How is the radar calibration factor determined? how is the noise power estimated?
Section 2-1-2: Are other Doppler moments included such as spectrum width?
Section 2-1-3: Equation for NRCS should be here.
Section 2-2: Every subsection here should have more detail.
Line 401: Figures 4, 5 and 6 are not pointing to the correct figures. It should be 3, 4, 5
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Citation: https://doi.org/10.5194/amt-2024-101-RC2 -
RC3: 'Comment on amt-2024-101', Anonymous Referee #3, 15 Aug 2024
The authors provide an overview of the planned products for the EarthCARE mission. Although I understand the need for overview papers such as this for new missions, after review I don't believe that AMT is the correct publication for an article like this. As an overview paper, few details are provided about the nature of the retrieval methods and algorithms. Instead, the reader is most frequently referred to other papers. In the section describing the "synergy" products, in several cases even references to other works are lacking. Very little quantitative assessment of the retrievals is provided. I can't say that the manuscript provides "substantial new concepts, ideas, methods or data" (scientific significance) or results that are "valid" (scientific quality).  I think that a descriptive, summary paper like this is probably more appropriate for a different journal (possibly BAMS), but I've recommended "reconsider after major revisions" rather than "reject". I've provided detailed comments in the attached PDF.
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