Olsson Short-term Climatic Characteristics And Re-analyze The Data Analysis In The Region Of Applicability

Based on hourly surface conventional meteorological and radiation observation data collected at Germany Koldwey Station during the period of 1994-2003, this paper conducted a statistical analysis on the short-term climate and surface radiation characteristics for Ny-Alesund. Then comparative study against our country's observation data at floatingice in the Arctic Ocean was carried out to find out the differences of the climate characters between tundra and ice underground. Last, we compared the observation data with NCEP/NCAR reanalysis data and ECMWF reanalysis d ata and discussed the reanalysis data's applicability in N y-Alesund. The main results include:1) Affected by the North Atlantic warming current, this area is one of the warmest areas in the Arctic region with the same latitude. Ny-Alesund had a humid temperate climate, and the air temperature could raise up to above 0℃ even during deep winter. The wind speed in this area was low and the mean wind speed was about 3.9 m/s. Wind direction was mainly southeast. We found that the air temperature at Ny-Alesund was raising at the faster speed(0.68℃/10a) than other places in the whole Arctic area.2) On average, Ny-Alesund's sunshine percent was only 29.2% due to its cloudy sky. The actual sunshine time was 72.4% of the total year, and was the main period of time to obtain solar radiation energy. In the summer, as a result of ice and snow's melting effect during warm season, Ny-Alesund's surface was tundra underground and its surface reflecting ratio was only about 15%. In other periods, the surface was ice-snow underground and its surface reflecting ratio was 79%. The total net radiation was positive during the whole year.3) Comparison between our observation data on floating ice in the Arctic Ocean and ground observation data at Koldwey Station in Ny-Alesund during the same period shows that there are significant climate differences between tundra and snow-ice underground in the Arctic. Ny-Alesund accepted weaker solar radiation due to its cloudy sky, but this area had stronger surface net radiation due to its smaller surface reflect ratio compared with floating ice area. Ny-Alesund had relatively better climate conditions than floating ice region at the same latitude (5-6℃ higher in air temperature, more humid air, lower wind speed) and is the appropriate site for our country to set up arctic science expedition station.4) Comparition between NCEP data and observation data at Koldwey Station shows that the c onsistency o f s ea 1 evel p ressure i s perfect. B ut for surface p ressureNCEP data was 20hPa smaller than actual observation data. The reason may be overhigh estimate height above sea level at the grid next to Koldwey station in the reanalysis model(the actual height above sea level at Koldwey station is only llm). So the terrain parameter in the model needs to be adjusted again.5) Compared with Koldwey Station observation data, NCEP/NCAR reanalysis data roughly shows the general characteristics of surface factors. For air temperature and Specific humidity the annual change curves of NCEP data and observation data were roughly consistent in the winter while were more divergent in the summer. Total radiation's actual observation data was 50 W m"2 lower than reanalysis model data in the summer. It may be due to too much low-cloud which affected solar radiation in summer. It means that the cloud parameterization scheme needs to be improved in the reanalysis model in the future.6) In the summer, as a result of increasing solar radiation and ice and snow's melting effect, Ny-Alesund's surface appeared tundra underground and its surface reflecting ratio decreased fast. Radiation factors' annual change curves appeared bias peaks because of the change of actual underground status in the summer While NCEP/NCAR reanalysis data failed to model these changes. In a word, NCEP data was not as accurate in the summer. The reason may be due to the radical changes of Ny-Alesund's underground character parameters in the summer and inappropriate parameter selection i...