NABOS 2003 Conductivity, Temperature, and Depth Data Project Description The Nansen and Amundsen Basins Observational System (NABOS) is a full-scale long-term program aimed to provide a quantitative observationally based assessment of circulation, water mass transformations, and transformation mechanisms along the principal pathways transporting water from the Nordic Seas into the central Arctic Basin. The 2003 NABOS cruise aboard I/B Kapitan Dranitsyn was the second expedition under the NABOS framework. The overarching goal is to characterize the thermohaline conditions within the continental slope of the Laptev Sea along with mooring deployments and recovering. The measurements described here were made with a Seabird SBE-19 Plus from the Russian conventional icebreaker Kapitan Dranitsyn. Data set title: NABOS 2003 CTD profiles PI and Data Contact: Igor Polyakov (igor@iarc.uaf.edu), International Arctic Research Center, University of Alaska Fairbanks NSF Grant: # 0327664 Data Set Descriptions Data coverage: Data were collected over a continental slope of the Laptev Sea and adjacent Arctic Ocean basin. Profiles were carried out on two transects across the continental slope in the central and eastern Laptev Sea and on another two transects approximately orientated along the continental slope. The survey within the Russian Exclusive Economical Zone was conducted in according to authorization from Russian Ministry for Industry and Science. Profile data were generally collected to a depth of 1000 m at 0.25 m intervals in the vertical. Data were obtained between September 1 and September 11, 2003. Data collection and processing: The profile data were collected using Seabird SBE-19 Plus. The winch site was situated at the helicopter deck of icebreaker in approximately 17 m from three icebreaker propellers. The draft of icebreaker at the position of CTD winch varies between 8.5 and 9.5 m. During CTD sounding the propellers were not switched off to keep the right ship position respectively ice floes. Data collection and processing software was SBE SEASOFT software package for Windows. Derived variables include pressure (in db), temperature (in ?C) and conductivity (S/m). The design accuracy of the probes is 0.005 degrees C in temperature, 0.0005 S/m in conductivity and 0.1% of full scale range in pressure. The original row data (pressure, temperature and salinity) from the downcasts are presented. Data collection problems: Portions of the data, which were considered poor quality from the upper water layer, were removed. Poor quality was mainly determined by higher than normal noise levels, spikes or jumps in the data due to the strong impact from rotating propellers of icebreaker in the upper water layer. Although in some cases the data were considered reliable one should take into account that the noise from propellers and ship draft can affects the data within the upper 20-m layer. Because of technical problems with winch in the most of cases the CTD casts were completed only up to 1000 m. The ocean depth was reliably measured only within the range of 2000 m. Otherwise the depth information was obtained from the navigation charts. Though the information from the upper 85 m layer at station nabos_015 has not been removed, it cannot be considered as reliable. Data Structure Profile Data: The data set consists of a single ASCII character file in columnar format, containing multiple profiles. Data are preceded by a fore lines file header, which identifies the data set, total number of casts in file, area of activity, missing value identification, year, CTD type, data source and comments. The following two lines after the blank describe the variables in the cast header - which are the cast number, latitude, and longitude of the cast, the year, Julian date, and station depth, number of points collected and total observed ice concentration. The next line describes the variables for the data columns - which are pressure (db), temperature (?C) and salinity (psu). The data columns are followed by the cast header. Supporting Information For more information or assistance, please contact International Arctic Research Center, University of Alaska Fairbanks at: 930 Koyukuk Drive P.O.Box 757335 Fairbanks, Alaska 99775-7335 USA (907) 474-2686 PHONE (907) 474-2643 FAX e-mail:nabos@iarc.uaf.edu Use of this data should be coordinated with the above PI and data contact and should reference the NABOS Program and PI as a data source.