<|begin_of_text|><|start_header_id|>system<|end_header_id|>

You are an expert at identifying data availability statements in scientific text. A data availability statement describes where research data can be found or how it can be accessed.<|eot_id|><|start_header_id|>user<|end_header_id|>

Determine if the following text contains a data availability statement. Answer with 'yes' or 'no'.

Text: the monthly temperature and precipitation data covering the study period were obtained from the climatic research unit (cru) ts 3.1 datasets at the resolution of 0.5á (http://www.cru.uea.ac.uk/cru/data/hrg/). the atmospheric co2 concentrations at point barrow (brw), alaska was obtained from the noaa/esrl network for the period of 1979_2009 (ftp://aftp.cmdl.noaa.gov/data/trace_gases/). the normalized difference vegetation index (ndvi) generated from noaaís advanced very high resolution radiometer (avhrr) data can be accessed at http://sites.bu.edu/cliveg/datacodes/.<|eot_id|><|start_header_id|>assistant<|end_header_id|>

yes<|eot_id|>