An observationally based evaluation of cloud ice water in CMIP3 and CMIP5 GCMs and contemporary reanalyses using contemporary satellite data

Abstract

[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,

Effects of pre-existing ice crystals on cirrus clouds and comparison between different ice nucleation parameterizations with the Community Atmosphere Model (CAM5)

“…Global annual mean results from present-day simulations and observations. Shown are total cloud fraction (CLDTOT, %) and high cloud fraction (CLDHGH, %) compared to ISCCP data (Rossow and Schiffer, 1999), MODIS data (Platnick et al, 2003) and HIRS data (Wylie et al, 2005); shortwave cloud forcing (SWCF, W m −2 ), long-wave cloud forcing (LWCF, W m −2 ), whole-sky shortwave (FSNT, W m −2 ) and long-wave (FLNT, W m −2 ) net radiative fluxes at the top of the atmosphere, clear-sky shortwave (FSNTC, W m −2 ) and longwave (FLNTC, W m −2 ) radiative fluxes at the top of the atmosphere compared to ERBE data (Kiehl and Trenberth, 1997) and CERES data (Loeb et al 2009); liquid water path (LWP; g m −2 ) compared to SSM/I oceans data (Greenwald et al, 1993;Weng and Grody, 1994) and ISCCP data (Han et al, 1994); ice water path (IWP, g m −2 ) compared to CloudSat data (Li et al, 2012); column-integrated grid-mean cloud droplet number concentration (CDNUMC, 10 10 m −2 ) compared to MODIS data (Table 4 in Barahona et al, 2014); column-integrated grid-mean ice crystal number concentration (CDNUMI, 10 6 m −2 ), convective (PRECC, mm d −1 ) and large-scale (PRECL, mm d −1 ) and total precipitation rate (PRECT, mm d −1 ) compared to Global Precipitation Climatology Project data set (Adler et al, 2003 (Wielicki et al, 1996). Units are shown in the upper right corner.…”

Development of two-moment cloud microphysics for liquid and ice within the NASA Goddard Earth Observing System Model (GEOS-5)

“…Satellite data sets included level 3 products from the NASA MODIS (http://modis.gsfc.nasa.gov/) combined TERRA and AQUA data product , and the International Satellite Cloud Climatology Project (ISCCP) (Rossow and Schiffer, 1999) and CloudSat (Li et al, 2012(Li et al, , 2014 (Rossow and Schiffer, 1999). When possible, the Cloud Feedback Model Intercomparison Project Observation Simulator Package, COSP (Bodas-Salcedo et al, 2011), was used to compare model output against satellite retrievals.…”

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

“…Cloud ice water amount is one of the largest sources of uncertainty in quantifying cloud-climate feedbacks and sensitivities. For example, the mean cloud ice water path (IWP) ranges from 10 to 120 g m −2 in the tropics among a variety of global climate models (GCMs) in the most recent 20th century Coupled Model Intercomparison Project Phase 5 (CMIP5) runs (Li et al, 2012). Accurate cloud IWP measurements are critically needed to guide model developments and reduce model uncertainties.…”

“…Until cross-instrument consistency is achieved, current cloud ice observations will allow too much variation in cloud properties and become insufficient for constraining the model physics Li et al, 2012). Difficulties for accurate IWP and microphysical measurements arise mainly from remote sensing in the presence of cloud inhomogeneity and sensitivity limitations associated with each technique.…”