Climatological and radiative properties of midlatitude cirrus clouds derived by  automatic evaluation of lidar measurements

Kienast-Sjögren, Erika; Rolf, Christian; Seifert, Patric; Krieger, Ulrich K.; Luo, Bei P.; Krämer, Martina; Peter, Thomas

doi:https://doi.org/10.5194/acp-16-7605-2016

Articles | Volume 16, issue 12

https://doi.org/10.5194/acp-16-7605-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-16-7605-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 12

Research article

|

22 Jun 2016

Research article |

| 22 Jun 2016

Climatological and radiative properties of midlatitude cirrus clouds derived by automatic evaluation of lidar measurements

Erika Kienast-Sjögren, Christian Rolf, Patric Seifert, Ulrich K. Krieger, Bei P. Luo, Martina Krämer, and Thomas Peter

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Final revised paper (published on 22 Jun 2016)
Preprint (discussion started on 02 Feb 2016)

Interactive discussion

Status: closed

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

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- Supplement

SC1: 'How much contrail cirrus was in your cirrus?', Ulrich Schumann, 06 Feb 2016
- AC1: 'Reply to Ulich Schumann', Erika Kienast-Sjögren, 18 May 2016
RC1: 'Radiative properties of mid-latitude cirrus clouds derived by automatic evaluation of lidar measurements', Anonymous Referee #2, 08 Feb 2016
- AC2: 'Reply to Anonymous Referee 2', Erika Kienast-Sjögren, 18 May 2016
RC2: 'Referee comments on "Radiative properties of mid-latitude cirrus clouds derived by automatic evaluation of lidar measurements" by Erika Kienast-Sjögren et al.', Lamont Poole, 25 Feb 2016
- AC3: 'Reply to Lamont Poole', Erika Kienast-Sjögren, 18 May 2016

Peer-review completion

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

AR by Lorena Grabowski on behalf of the Authors (20 May 2016) Author's response

ED: Referee Nomination & Report Request started (20 May 2016) by Matthias Tesche

RR by Ulrich Schumann (21 May 2016)

Suggestions for revision or reasons for rejection

Dear editor,

I thank you for inviting me to comment on the revised manuscript.

As said before: This is a nice study of mid-latitude cirrus.

The authors made use of my comments, and added related references in the text, without changing the substance of the investigation. That is o.k.

The authors added a new sentence: “Clear indications for the occurrence of contrails were found on at least one day, given the optically and geometrically very thin cirrus.“
This needs a bit more explanation: Which indication is meant? (Indications derived from the Lidar data, or from other observations?)

I agree with the other reviewers and the authors, that the data set calls for follow-on studies, relating the lidar data to other cirrus and contrail data, e.g. from ground based observations (Lidar, Radar, cameras), satellite data (CERES, Meteosat SEVIRI, etc.), airborne measurements (see, e.g., Voigt et al., ML-CIRRUS, BAMS, doi: 10.1175/BAMS-D-15-00213.1), and model studies (radiation transfer, numerical weather prediction results , cirrus and contrail cirrus models). I am sure, much more can be learned. I would not be surprised if the outcome would be that much of the observed thin cirrus at these stations originates from aviation-induced cloudiness. In fact, I myself would be interested in participating in such studies.

Therefore, I ask that the authors provide information on the availability of the data for further research (internet library?).

I feel that the response to comment no. 5 of the reviewer 2 could be improved. The albedo taken (0.3) is the global mean albedo of the Earth system (including clouds). For clear sky, the albedo of the Earth varies with aerosol properties, humidity, snow-cover, vegetation type, orography, solar zenith angle (see, e.g., Yang, F., Mitchell, K., Hou, Y.-T., Dai, Y., Zeng, X., Wang, Z., and Liang, X.-Z.: Dependence of land surface albedo on solar zenith angle: Observations and model parameterization J. Appl. Meteor. Clim., 47, 2963-2982, DOI: 10.1175/2008JAMC1843.1, 2008) , and values far lower than 0.3 (as also noted by the reviewer #2) may apply often (in particular during summer and at noon time).

I have one more comments on the basic content of the paper, apparently not mentioned in the previous reviews, which the authors may consider to account for in the text, in particular in view of the more ambitious extended title (Climatological ...):

The absolute number of hours (13000) is impressive, but a percentage would be informative and would give a more realistic picture of the climatological value of the data set. The observation time given is the total from three stations. If one relates to the number of hours for the observing period (years 2010-2014, this may imply 5 years*365*24= 43800), the JFJ observations cover about 11 % of the total time. This fraction is important to note.

I assume that during part of the remaining time cirrus was not observable by ground lidar, e.g., because of lower-level clouds. The question arises whether cirrus have the same properties when observable from ground compared to cirrus not observable from ground. Perhaps part of the differences to satellite observations could be explained with differences of cirrus under weather conditions with low level clouds.

So, these comments may trigger a few minor changes. Otherwise, the paper appears to be acceptable.

Ulrich Schumann

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RR by Anonymous Referee #2 (23 May 2016)

ED: Publish subject to technical corrections (23 May 2016) by Matthias Tesche

Short summary

We present a climatology of mid-latitude cirrus cloud properties based on 13 000 hours of automatically analyzed lidar measurements at three different sites. Jungfraujoch, situated at 3580 m a.s.l., is found to be ideal to measure high and optically thin cirrus. We use our retrieved optical properties together with a radiation model and estimate the radiative forcing by mid-latitude cirrus. All cirrus clouds detected here have a positive net radiative effect.