the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Cloud liquid water path detectability and retrieval accuracy from airborne passive microwave observations over Arctic sea ice
Abstract. Clouds are critical in the Arctic’s water balance and energy budget. Especially, the cloud liquid water path (CLWP) modifies the cloud radiative properties and affects the surface energy balance. Spaceborne microwave radiometers provide a high sensitivity to CLWP at pan-Arctic scales, but extracting this information over sea ice requires separation of surface and cloud emission. Here, we assess CLWP detectability and retrieval accuracy over sea ice from a physical optimal estimation retrieval applied to airborne passive microwave observations during the HALO–(𝒜𝒞)3 campaign. Reference data on surface temperature, young ice fraction, hydrometeor occurrence, and cloud liquid layers are available from collocated airborne instruments. The retrieval estimates CLWP and five surface parameters by inverting a forward operator consisting of the Snow Microwave Radiative Transfer (SMRT) and Passive and Active Microwave radiative TRAnsfer (PAMTRA) models. We find a consistent representation of sea ice and snow emission from 22–183 GHz under clear-sky conditions in both observation and state space. The CLWP detectability, defined as the 95th percentile of retrieved CLWP under clear-sky conditions, is about 50 g m−2 in the Central Arctic and increases towards the marginal ice zone up to 350 g m−2. The CLWP retrieval accuracy increases with increasing CLWP, with a relative root mean squared error below 50 % for CLWP above 100 g m−2. Retrieval uncertainties occur due to ambiguities between cloud liquid water emission and scattering in the snowpack and emission by newly formed sea ice. We further analyze the impact of surface melt and a rain-on-snow event associated with the warm air intrusion on the surface parameters. Finally, we show CLWP distributions along the flight track for all HAMP observations in comparison to ERA5 for different cloud regimes. The retrieval algorithm enhances the understanding of Arctic clouds and allows for an improved use of passive microwave satellite data in polar regions.
- Preprint
(8286 KB) - Metadata XML
- BibTeX
- EndNote
Status: open (until 16 Oct 2025)
-
RC1: 'Comment on egusphere-2025-3311', Christian Mätzler, 26 Sep 2025
reply
Only some of my comments were taken into account.For the rest, I miss a response of the authors.ReplyCitation: https://doi.org/
10.5194/egusphere-2025-3311-RC1 -
EC1: 'Editor comment', Andreas Richter, 27 Sep 2025
reply
Dear Christian Mätzler,
Thank you for your comment. I think there is a misunderstanding about the publication process in AMT, which has two stages:
1) A quick review, which basically gives the go-ahead for publication of the preprint. At this point, authors are not expected to implement larger changes in the document.
2) The full review, which also allows for public comments and discussion. This is the current status of the manuscript. You are expected to provide your full review of the manuscript now, which should include those points you already made in the quick review and which have not yet been taken on by the authors.
After this public discussion phase, the authors can submit a revised version of their manuscript, which will then be considered for publication, further revisions, or rejection.
I hope this clarifies the procedure.
Best regards,
Andreas Richter
Citation: https://doi.org/10.5194/egusphere-2025-3311-EC1 -
RC2: 'Reply on EC1', Christian Mätzler, 27 Sep 2025
reply
Dear Editor,
Thank you for the explanations. I was not aware of this situation. Please let the authors know. I do not plan to do any further review of this rather complex work.
Best wishes, Christian Mätzler
Citation: https://doi.org/10.5194/egusphere-2025-3311-RC2
-
RC2: 'Reply on EC1', Christian Mätzler, 27 Sep 2025
reply
-
EC1: 'Editor comment', Andreas Richter, 27 Sep 2025
reply
Data sets
Data related to: Cloud liquid water path detectability and retrieval accuracy from airborne passive microwave observations over Arctic sea ice Nils Risse https://doi.org/10.5281/zenodo.15848709
Model code and software
nrisse/si-clouds: Code related to: Cloud liquid water path detectability and retrieval accuracy from airborne passive microwave observations over Arctic sea ice Nils Risse https://doi.org/10.5281/zenodo.17064296
Viewed
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
1,456 | 25 | 10 | 1,491 | 11 | 12 |
- HTML: 1,456
- PDF: 25
- XML: 10
- Total: 1,491
- BibTeX: 11
- EndNote: 12
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1