A Climatology of Clouds and Radiative Forcing
| Liu, Yang | University of North Dakota |
A Climatology of Clouds and Radiative Forcing at at the University of North Dakota Liu, Y., Dong, X. University of North Dakota Point of Contact: Yang Liu, yliu@aero.und.edu, 701-777-4877 A record of cloud fraction has been generated using ceilometer data collected at the UND ground observational site from January 1998 to December.2004. The total and low cloud (cloud-base height < 3 km) fractions are estimated for this time period, and compared with 11 years (1971-1981) of surface observations reported by Warren et al. (1986) and 8 years (1983-1991) of D2 data from the International Satellite Cloud Climatology Project (ISCCP). The annual total cloud fraction in this study is 0.46, which is about 7% lower than the Warren et al. study and 13% lower than ISSCP result. On June 27, 2003, two standard Eppley Precision Spectral Pyranometers (PSPs) and two Precision Infrared Radiometers (PIRs) were set up at the UND ground site to acquire downward and upward shortwave and longwave flux measurements to study cloud radiative forcing (CRF). The hourly, monthly, and seasonal SW/LW/NET CRFs have been calculated under the conditions of all sky, total and low clouds. The annual averages of clear-sky net SW and LW fluxes are 183.7 W/m2 and -77.9 W/m2 respectively. The annual averages of SW/LW/NET CRFs are -57.1 W/m2, 33.8 W/m2 and -23.3 W/m2 for all sky, respectively; are -93.1 W/m2, 51.7 W/m2 and -41.4 W/m2 for total clouds; and are -99.7 W/m2, 63.8 W/m2 and -35.9 W/m2 for low clouds.
