Mesoscale analysis and cloud climatologies with SCANDIA

The results from the SCANDIA cloud classification model has been used for objective mesoscal analysis.

The SCANDIA cloud classification results on the large domain is imported in the operational objective mesoscale analysis scheme (MESAN) which blends remote sensing data, surface observations and NWP first guess fields. SCANDIA results add important information in the analysis of total cloud cover, amount of low-level clouds, cloud top height and cloud base height. The influence of SCANDIA results in MESAN is high over sea areas (the Baltic sea) where conventional observations are scarse. In cases when SCANDIA products are not available, the three hourly analysis is made from a simple utilisation of Meteosat IR data (of course still in combination with the other data sources).

Archived results from the SCANDIA model have been used to estimate the cloud climatology in the Nordic region (Karlsson, 1994, 1995, 1996a). The aim is to establish a 10-year cloud climatology over Sweden based on SCANDIA results from 1991 till 2000.

The compiled cloud climatologies are only based on those NOAA passages having optimal observation conditions (i.e., with low satellite zenith viewing angles) over the Scandinavian region. In practice, this means that four NOAA observations per day is used (valid at night, morning, afternoon and evening) when creating climatologies. Below are shown three different kind of cloud climatologies for the month of July based on SCANDIA results for a total period of eight years (1991-1998).

Mean of total cloud cover.
Mean of total cloud cover (%) in July 1991-1998 over the Scandinavian region. The horizontal resolution is 4 km. Enlarge Image
Thin cirrus clouds, SCANDIA
The contribution to the mean cloud cover (%) in July 1991-1998 from thin cirrus clouds. Enlarge Image
Low cloud climatologies from SCANDIA model.
The contribution to the mean cloud cover (%) in July 1991-1998 from from low-level clouds. Enlarge Image

Cloud climatology data from the enlarged area has also been used in NWP model validation studies (Karlsson, 1996b). Similar applications are also planned within the ongoing BALTEX research programme studying the water and energy cycle of the Baltic Sea (Karlsson, 1999).


Karlsson, K.-G., 1994: Satellite-estimated cloudiness from NOAA AVHRR data in the Nordic area during 1993. Reports Meteorology and Climatology, SMHI, 51 pp.

Karlsson, K.-G., 1995: Estimation of cloudiness at high latitudes from multispectral satellite measurements. AMBIO, 24, 33-40.

Karlsson, K.-G., 1996a: Cloud classifications with the SCANDIA model, Reports Meteorology and Climatology, SMHI, 36 pp.

Karlsson, K.-G., 1996b: Validation of modelled cloudiness using satellite-estimated cloud climatologies, Tellus, 48A, No. 5, containing papers from the First Study Conference on BALTEX, Visby, Sweden, 28 Aug.-1 Sep. 1995, 767-785.

Karlsson, K.-G., 1999: Satellite Sensing techniques and applications for the purposes of BALTEX, Contr. Atm. Phys., in press.