Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1&thinsp;min synchronous measurements

Cuevas, Emilio; Romero-Campos, Pedro Miguel; Kouremeti, Natalia; Kazadzis, Stelios; Räisänen, Petri; García, Rosa Delia; Barreto, Africa; Guirado-Fuentes, Carmen; Ramos, Ramón; Toledano, Carlos; Almansa, Fernando; Gröbner, Julian

doi:https://doi.org/10.5194/amt-12-4309-2019

Articles | Volume 12, issue 8

https://doi.org/10.5194/amt-12-4309-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-12-4309-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 8

Research article

|

09 Aug 2019

Research article |

| 09 Aug 2019

Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements

Emilio Cuevas, Pedro Miguel Romero-Campos, Natalia Kouremeti, Stelios Kazadzis, Petri Räisänen, Rosa Delia García, Africa Barreto, Carmen Guirado-Fuentes, Ramón Ramos, Carlos Toledano, Fernando Almansa, and Julian Gröbner

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Final revised paper (published on 09 Aug 2019)
Supplement to the final revised paper
Preprint (discussion started on 17 Dec 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review Cuevas E. et al.', Anonymous Referee #1, 08 Jan 2019
- AC1: 'Reply to Referee 1 amt-2018-438', García Cabrera Rosa Delia, 07 Apr 2019
RC2: 'Review of “Aerosol optical Depth comparison between GAW-PFR and AERONET-Cimel radiometers from long term ( 2005-2015) 1-minute synchronous measurements”', Anonymous Referee #2, 10 Jan 2019
- AC2: 'Reply to Referee#2 amt-2018-438', García Cabrera Rosa Delia, 07 Apr 2019
RC3: 'Review', Anonymous Referee #3, 11 Jan 2019
- AC3: 'Reply to Referee#3 amt-2018-438', García Cabrera Rosa Delia, 07 Apr 2019
RC4: 'Review', Anonymous Referee #4, 11 Jan 2019
- AC4: 'Reply to Referee#4 amt-2018-438', García Cabrera Rosa Delia, 07 Apr 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Emilio Cuevas on behalf of the Authors (23 Apr 2019) Author's response

ED: Referee Nomination & Report Request started (25 Apr 2019) by Thomas Eck

RR by Anonymous Referee #4 (27 May 2019)

RR by Anonymous Referee #3 (30 May 2019)

Suggestions for revision or reasons for rejection

I appreciate the authors’ responses and revision, especially regarding the FOV. Unfortunately, two of the three major data interpretation issues remain.

First, as the authors confirm, the duration of each measurement is less than 1s for PFR and a little over one minute for the Cimel triplets. The 59s differences make it more likely for Cimel to capture the atmospheric changes than for PFR. Thus, the wider diurnal ranges of Cimel AOD shown in Figure 3 and S7 may be attributable to the natural variability rather than calibration inaccuracies and other instrument- and algorithm-related causes.

The author response G.3 does not refute this hypothesis. It points out that the natural variability over one minute exceeds 0.005 for 0.8% of the records, taking the year 2013 as an example. The authors seem to dismiss this fraction as negligible. But the data highlighted in Figure 3 and S7 – presented in the discussion of instrument and algorithm artifacts in Page 19 – may well overlap with that small and special subset of data. These evaluations are centered on the daily max AOD–the most extreme measurement of each day (see also the review S.26). That single measurement represents only a small fraction of the entire records. It is 3.3% if 30 data points are available on average for the days shown in Figure 3. Of these, approximately a third (i.e, quite possibly around 1% of the entire records) has the max-min difference exceeding 0.005 (shown in the original Figure 3). That is comparable to the 0.8% identified as the high natural variability cases.

Second, Figure 7 of the original discussion paper shows that PFR AOD is significantly higher than Cimel in many cases with PFR AOD just above 0.03. It is misleading to be quiet about these cases while discussing the high Cimel cases in relation to the artifacts. The author response G.4 is not adequate, as it does not present the PFR-Cimel differences. Just as lamentably, the new Figure 7 hides the negative outliers by starting its abscissa from 0.1. It does not adequately respond to the review S.32 either.

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ED: Reconsider after major revisions (30 May 2019) by Thomas Eck

AR by Emilio Cuevas on behalf of the Authors (28 Jun 2019) Author's response Manuscript

ED: Publish as is (10 Jul 2019) by Thomas Eck

AR by Emilio Cuevas on behalf of the Authors (16 Jul 2019) Manuscript

Short summary

A comprehensive comparison of more than 70 000 synchronous 1 min aerosol optical depth (AOD) data from 3 Global Atmosphere Watch precision filter radiometers (GAW-PFR) and 15 Aerosol Robotic Network Cimel radiometers (AERONET-Cimel) was performed for the four near wavelengths (380, 440, 500 and 870 nm) in the period 2005–2015. The goal of this study is to assess whether their long term AOD data are comparable and consistent.