Climatologies
Global Climatologies
Version 2.4 of SCENGEN contains global fields at a 5° lat/long resolution for mean monthly surface air temperature (deg C), mean monthly precipitation (mm/day) and mean monthly cloud cover (tenths). These global fields in SCENGEN have been extracted from the following global climatology, which represents mean 1961-90 climate:
New,M., Hulme,M. and Jones,P.D. (1999) Representing twentieth-century space-time climate variability. Part I: development of a 1961-90 mean monthly terrestrial climatology J.Climate, 12, 829-856.
The SCENGEN fields have been degraded from the original 0.5° lat/long resolution and exist for land areas only. No values are provided for precipitation and cloud cover over Antarctica owing to insufficient observations.
Regional Climatologies
The regional climatologies used in SCENGEN are all new 1961-90 climatologies gridded from station data to 0.5° lat/long resolution. Funding support for this work has come from a variety of sources. The interpolation procedure which has been used is based on the thin-plate splines approach developed by Mike Hutchinson from the Australian National University. With the exception of South Asia, the following variables have been calculated and are used in SCENGEN:
CLD mean monthly cloud cover (10ths)
DIU diurnal temperature range (°C)
PRE mean monthly precipitation total (mm/day)
TMN mean monthly minimum surface air temperature (°C)
TMX mean monthly maximum surface air temperature (°C)
TMP mean monthly surface air temperature (°C), the average of TMX and TMN
VAP mean monthly vapour pressure (approx. 24-hour mean; hPa)
WND mean monthly wind speed (approx. 10m height; m/sec)
Europe
This region is defined by 35° to 68°N and 15°W to 45°E. This climatology was constructed by Declan Conway in 1994/95 and followed on the work originally done by Tao Jiang during 1993. The raw station data used in the interpolation were obtained by the Climatic Research Unit (CRU) directly from National Met. Services in the region.
South Asia
This region is defined by 5° to 38°N and 50° to 110°E. This climatology was constructed by Shekhar Mohile from the Indian Institute of Tropical Meteorology in Pune, India, during his four month secondment to the Climatic Research Unit funded by the British Council during 1994. At present, fields exist only for TMP,TMX,TMN,DIU and PRE. The raw station data used in the interpolation were a combination of 1961-90 data already held by CRU for non-Indian countries and station normals for India constructed by Mohile from original time series data supplied by the IITM. The reliability of the climatology should, in principle, be greatest over India itself.
Southern Africa
This region is defined by 0° to 35°S and 5°W to 55°E. This climatology was constructed by Henry Mulenga (assisted by Declan Conway) from the Zambian Meteorological Department during his four month secondment to the Climatic Research Unit during 1995. The raw station data used in the interpolation were a combination of 1961-90 data already held by CRU and station normals obtained by Mulenga from some of the SADC National Met. Services in the region.
USA
This region is defined by 22.5° to 52.5°N and 125° to 65°E. This climatology was constructed by Olga Brown during 1994. The raw USA 1961-90 station data (some 600 stations) used in the interpolation were obtained from NCDC at Asheville, NC. Some Canadian and Mexican station data were also used.