Examination of Folland and Parker's Bucket Correction to Historical SST Data Using Long-term Coastal SST Data
Kimio Hanawa and Sayaka Yasunaka(Tohoku University)
Teruko Manabe(Japan Meteorological Agency)
Naoto lwasaka(Tokyo University of Mercantile Marine)
Abstract:
Folland and Parker(1995)proposed the correction(so-called bucket correction)to historical sea surface temperature(SST)data from ship reports such as the Comprehensive Ocean-Atmosphere Data Set(COADS).In order to examine the validation of this correction,comparison between SST data and long-term coastal SST(CSST)data taken at 9 stations around Japan is made.For this purpose,we extract SST data in the adjacent areas surrounding 9 CSST stations,from the files of COADS and the Kobe Collection data which have been recently released by the Japan Meteorological Agency and the Japan Weather Association.As a result,it is found that the data of 5 CSST stations among 9 stations are suitable for comparison.When Folland and Parker's correction is adopted to the historical SST data,the systematic biases in monthly mean SST anomalies have been corrected almost perfectly at three stations,and the biases at the other two stations have been reduced by 40-50%.
1. Introduction -Background of the present study-
In order to precisely detect the climate variation,climate jump or so-called regime shift and global warming,to accumulate the historically long-term data as much as possible is very important and essential.However,since the measuring instruments and methods have been changed sometimes,we have to pay careful attention on the data quality,i.e.,existence of instrumental and methodological biases.For instance,before World War II,sea surface temperatures(SST)have been measured mainly by the bucket(wooden or canvas buckets)method on board, but after then the bucket method has been replaced by the intake method.For this methodological change,many researchers have already pointed out the existence of systematic biases between the two(e.g.,Barnett,1984;Folland et al.,1984;Wright,1986).Therefore,based on this situation in historical SST data,correction for the historical SST data taken by the bucket method has been investigated and proposed(e.g.,Folland and Parker,1995).
Recently,the Japan Meteorological Agency(JMA)and the Japan Weather Association(JWA)have released the historical marine meteorological data of approximately I million by CD-ROM(Manabe,1999).Since these data have been archived mainly by the former Kobe Marine Observatory/JMA,these data are called the ‘Kobe Collection’.
