We would like to acknowledge the support and successful cooperation of NASA and CNES in the development and operation of CALIPSO and the advocacy of Gérard Mégie for the mission. We thank Bill Hunt and the team at Ball Aerospace for CALIOP and payload integration; the teams at SODERN and Thales Alenia Space for the IIR and platform integration, respectively; the operations teams at NASA and CNES; and the support of the ASDC and ICARE data centers, who all made essential contributions to the success of the CALIPSO mission. The work described in "The occurrence of marine stratus and stratocumulus" was carried out by T. Kubar in collaboration with D. E.

[1] We perform an observationally based evaluation of the cloud ice water content (CIWC) and path (CIWP) of present-day GCMs, notably 20th century CMIP5 simulations, and compare these results to CMIP3 and two recent reanalyses. We use three different CloudSat + CALIPSO ice water products and two methods to remove the contribution from the convective core ice mass and/or precipitating cloud hydrometeors with variable sizes and falling speeds so that a robust observational estimate can be obtained for model evaluations. The results show that for annual mean CIWP, there are factors of 2-10 in the differences between observations and models for a majority of the GCMs and for a number of regions. However, there are a number of CMIP5 models, including CNRM-CM5, MRI, CCSM4 and CanESM2, as well as the UCLA CGCM, that perform well compared to our past evaluations. Systematic biases in CIWC vertical structure occur below the mid-troposphere where the models overestimate CIWC, with this bias arising mostly from the extratropics. The tropics are marked by model differences in the level of maximum CIWC ($250-550 hPa). Based on a number of metrics, the ensemble behavior of CMIP5 has improved considerably relative to CMIP3, although neither the CMIP5 ensemble mean nor any individual model performs particularly well, and there are still a number of models that exhibit very large biases despite the availability of relevant observations. The implications of these results on model representations of the Earth radiation balance are discussed, along with caveats and uncertainties associated with the observational estimates, model and observation representations of the precipitating and cloudy ice components, relevant physical processes and parameterizations. F., et al. (2012), An observationally based evaluation of cloud ice water in CMIP3 and CMIP5 GCMs and contemporary reanalyses using contemporary satellite data,

Two simple heuristic model formulations for warm rain formation are introduced and their behavior explored. The first, which is primarily aimed at representing warm rain formation in shallow convective clouds, is a continuous collection model that uses an assumed cloud droplet size distribution consistent with observations as the source of embryonic drizzle drops that are then allowed to fall through the (assumed constant) cloud accreting cloud droplets. The second, which is applicable to steady-state precipitation formation in stratocumulus, is a simple two-moment autoconversion and accretion model in which cloud liquid water is removed by drizzle formation and replenished on a externally-specified timescale that reflects the efficacy of turbulent overturning that characterizes stratocumulus.The models' behavior is shown to be broadly consistent with observations from the ATrain constellation of satellites, allowing us to explore reasons for changing model sensitivity to microphysical and macrophysical cloud properties. The models are consistent with one another, and with the observations, in that they demonstrate that the sensitivity of rain rate to cloud droplet concentration N d (which here represents microphysical influence) is greatest for weakly precipitating clouds, i.e. for low cloud liquid water path and/or high N d ). For the steady-state model, microphysical sensitivity is shown to strongly decrease with the ratio of replenishment to drizzle timescales. Thus, rain from strongly drizzling and/or weakly replenished clouds shows low sensitivity to microphysics. This is essentially because most precipitation in these clouds is forming via accretion rather than autoconversion. For the continuous-collection model, as cloud liquid water content increases, the precipitation rate becomes more strongly controlled by the availability of cloud liquid water than by the initial embryo size or by the cloud droplet size. The models help to explain why warm rain in marine stratocumulus clouds is sensitive to N d but why precipitation from thicker cumulus clouds appears to be less so.

The importance of macrophysical variables [cloud thickness, liquid water path (LWP)] and microphysical variables (effective radius r e , effective droplet concentration N eff ) on warm drizzle intensity and frequency across the tropics and subtropics is studied. In this first part of a two-part study, Moderate Resolution Imaging Spectroradiometer (MODIS) optical and CloudSat cloud radar data are used to understand warm rain in marine clouds. Part II uses simple heuristic models. Cloud-top height and LWP substantially increase as drizzle intensity increases. Droplet radius estimated from MODIS also increases with cloud radar reflectivity (dBZ) but levels off as dBZ . 0, except where the influence of continental pollution is present, in which case a monotonic increase of r e with drizzle intensity occurs. Off the Asian coast and over the Gulf of Mexico, r e values are smaller (by several mm) and N eff values are larger compared to more remote marine regions. For heavy drizzle intensity, both r e and N eff values off the Asian coast and over the Gulf of Mexico approach r e and N eff values in more remote marine regions.Drizzle frequency, defined as profiles in which maximum dBZ . 215, increases dramatically and nearly uniformly when cloud tops grow from 1 to 2 km. Drizzle frequencies exceed 90% in all regions when LWPs exceed 250 g m 22 and N eff values are below 50 cm 23 , even in regions where drizzle occurs infrequently on the whole. The fact that the relationship among drizzle frequency, LWP, and N eff is essentially the same for all regions suggests a near universality among tropical and subtropical regions.

Using satellite cloud data from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and collocated precipitation rates from the Advanced Microwave Scanning Radiometer (AMSR), it is shown that rain rate is closely related to the amount of very thick high cloud, which is a better proxy for precipitation than outgoing longwave radiation (OLR). It is also shown that thin high cloud, which has a positive net radiative effect on the top-of-atmosphere (TOA) energy balance, is nearly twice as abundant in the west Pacific compared to the east Pacific. For a given rain rate, anvil cloud is also more abundant in the west Pacific. The ensemble of all high clouds in the east Pacific induces considerably more TOA radiative cooling compared to the west Pacific, primarily because of more high, thin cloud in the west Pacific. High clouds are also systematically colder in the west Pacific by about 5 K.The authors examine whether the anvil cloud temperature is better predicted by low-level equivalent potential temperature (⌰ E ), or by the peak in upper-level convergence associated with radiative cooling in clear skies. The temperature in the upper troposphere where ⌰ E is the same as that at the lifting condensation level (LCL) seems to influence the temperatures of the coldest, thickest clouds, but has no simple relation to anvil cloud. It is shown instead that a linear relationship exists between the median anvil cloud-top temperature and the temperature at the peak in clear-sky convergence. The radiatively driven clear-sky convergence profiles are thus consistent with the warmer anvil clouds in the EP versus the WP.