Identification

Title

Improved cirrus simulations in a general circulation model using CARMA sectional microphysics

Abstract

We have developed a new cirrus model incorporating sectional ice microphysics from the Community Aerosol and Radiation Model for Atmospheres (CARMA) in the latest version of NCAR's Community Atmosphere Model (CAM5). Comparisons with DARDAR and 2C-ICE show that CAM5/CARMA improves cloud fraction, ice water content, and ice water path compared to the standard CAM5. Prognostic snow in CAM5/CARMA increases overall ice mass and results in a melting layer at ~4 km in the tropics that is largely absent in CAM5. Subgrid scale supersaturation following Wilson and Ballard (1999) improves ice mass and relative humidity. Increased middle and upper tropospheric condensate in CAM5/CARMA requires a reduction in low-level cloud for energy balance, resulting in a 3.1 W m−2 improvement in shortwave cloud forcing and a 3.8 W m−2 improvement in downwelling shortwave flux at the surface compared to CAM5 and Clouds and Earth's Radiant Energy Systems (CERES). Total and clear-sky longwave upwelling flux at the top are improved in CAM5/CARMA by 1.0 and 2.6 W m−2, respectively. CAM has a 2–3 K cold bias at the tropical tropopause mostly from the prescribed ozone file. Correction of the prescribed ozone or nudging the CAM5/CARMA model to GEOS5-DAS meteorology yields tropical tropopause temperatures and water vapor that agree with the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and the Microwave Limb Sounder (MLS). CAM5 relative humidity appears to be too large resulting in a +1.5 ppmv water vapor bias at the tropical tropopause when using GEOS5-DAS meteorology. In CAM5/CARMA, 75% of the cloud ice mass originates from ice particles detrained from convection compared to 25% from in situ nucleation.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7cr5v8z

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2013-10-27T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact