English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Remote sensing of cloud effective particle size with passive sensors likethe Moderate Resolution Imaging Spectroradiometer (MODIS) is an importanttool for cloud microphysical studies. As a measure of the radiativelyrelevant droplet size, effective radius can be retrieved with differentcombinations of visible through shortwave and midwave infrared channels. Inpractice, retrieved effective radii from these combinations can be quitedifferent. This difference is perhaps indicative of different penetrationdepths and path lengths for the spectral reflectances used. In addition,operational liquid water cloud retrievals are based on the assumption of arelatively narrow distribution of droplet sizes; the role of largerprecipitation particles in these distributions is neglected. Therefore,possible explanations for the discrepancy in some MODIS spectral sizeretrievals could include 3-D radiative transport effects, including sub-pixelcloud inhomogeneity, and/or the impact of drizzle formation.  For three cloud cases the possible factors of influence are isolated andinvestigated in detail by the use of simulated cloud scenes and syntheticsatellite data: marine boundary layer cloud scenes from large eddysimulations (LES) with detailed microphysics are combined with Monte Carloradiative transfer calculations that explicitly account for the detaileddroplet size distributions as well as 3-D radiative transfer to simulateMODIS observations. The operational MODIS optical thickness and effectiveradius retrieval algorithm is applied to these and the results are comparedto the given LES microphysics.  We investigate two types of marine cloud situations each with and withoutdrizzle from LES simulations: (1) a typical daytime stratocumulus deck attwo times in the diurnal cycle and (2) one scene with scattered cumulus.Only small impact of drizzle formation on the retrieved domain average andon the differences between the three effective radius retrievals is noticedfor both cloud scene types for different reasons. For our, presumablytypical, overcast stratocumulus scenes with an optical thickness of 8 to 9and rain rates at cloud bottom up to 0.05 mm/h clear drizzle impact on theretrievals can be excluded. The cumulus scene does not show much drizzlesensitivity either despite extended drizzle areas being directly visiblefrom above (locally >1 mm/h), which is mainly due to technicalcharacteristics of the standard retrieval approach. 3-D effects, on the otherhand, produce large discrepancies between the 1.6 and 2.1 μm channelobservations compared to 3.7 μm retrievals in the latter case. A generalsensitivity of MODIS particle size data to drizzle formation is notcorroborated by our case studies

Testing remote sensing on artificial observations: impact of drizzle and 3-D cloud structure on effective radius retrievals