DOI: 10.5061/dryad.cnp5hqccr
title: Data from: Supersaturation and critical size of cloud condensation nuclei in marine stratus clouds

description: Observations of marine stratus clouds in clean air off the Californian
 coast reveal a functional relationship between the number of cloud
 condensation nuclei (CCN) and supersaturation. Satellite-derived liquid
 droplet density estimates the number density of CCN. Combining the
 estimated supersaturation using Kohler theory, global maps of
 supersaturation and the critical activation size of CCN are estimated.
 Here, we show that high supersaturation &gt;0.5% persists over the
 oceans with a critical CCN size of 25-30 nm, which is smaller than the
 conventional wisdom of 60 nm. Independent support for such high
 supersaturation in the marine cloud is obtained from CCN measurements
 provided by the "Atmospheric Tomography Mission". Higher
 supersaturation implies smaller activation size for CCN making cloud
 formation more sensitive to changes in aerosol nucleation.
description: The present data set is the critical size of cloud condensation
 nuclei of low clouds over the oceans and the corresponding
 supersaturations. <br>Satellite retrieval of Liquid Water Path,
 Optical Thickness, and cloud fraction makes it possible to estimate the
 average number density of warm cloud droplets over the oceans. An
 empirical relationship between effective supersaturation and cloud number
 density allows for determining the effective supersaturation in a 1x1 deg
 pixel. Finally, Kohler's theory and the obtained supersaturation give
 a critical CCN size. <br><br> 
description: # Data from: Supersaturation and critical size of cloud condensation
 nuclei in marine stratus clouds
 [https://doi.org/10.5061/dryad.cnp5hqccr](https://doi.org/10.5061/dryad.cnp5hqccr) The data set consists of four netCDF files, one with a critical mean diameter of Cloud Condensation Nuclei and a file of the corresponding supersaturation, in a 1x1 deg grid covering the oceans. In addition, two files where the supersaturation and critical diameter of Cloud Condensation Nuclei are within a 90% confidence interval. i.e., there is a  90% probability that the supersaturation is higher than the given values and the critical diameter of Cloud Condensation Nuclei is smaller.  The data files are the data used to produce the four panels of Fig. 3 of the GRL paper. ## Description of the data and file structure The files are: Critical_d.nc contains 360 points of longitude (-179.5 to 179.5) and 180 points of latitude (-89.5 to 89.5), and a critical diameter in a (360,180) grid. Land pixel values are set to -99 Supersaturation.nc contains 360 points of longitude (-179.5 to 179.5) and 180 points of latitude (-89.5 to 89.5), and an effective supersaturation in a (360,180) grid. Land pixel values are set to -99 Critical_d90%.nc contains 360 points of longitude (-179.5 to 179.5) and 180 points of latitude (-89.5 to 89.5) and a critical diameter in a (360,180) grid. Land pixel values are set to -99. The critical diameter is 90% likely to be smaller than the given value. Supersaturation90%.nc contains 360 points of longitude (-179.5 to 179.5) and 180 points of latitude (-89.5 to 89.5), and an effective supersaturation in a (360,180) grid. Land pixel values are set to -99. The supersaturation is 90% likely to be larger than the given value.