The Pacific Northwest Index (PNI)

The Pacific Northwest Index (PNI), developed by Ebbesmeyer (1995), is a terrestrial climate index useful for studying climate effects on salmon productivity trends. It is a composite index that characterizes Pacific Northwest climate patterns in both coastal waters and freshwater habitats. In addition, it is a century-long record. A composite climate index is an effective measurement because many environmental parameters in the Northwest are statistically related to one another; consequently, they may be combined to furnish a broad-scale understanding of the state of the Pacific Northwest environment. The PNI uses three parameters: 1) air temperature at Olga in the San Juan Islands, averaged annually from daily data; 2) total precipitation at Cedar Lake in the Cascade Mountains; and 3) snowpack depth at Paradise on Mount Rainier on March 15 of each year. For each parameter, annual values were normalized by subtracting the average of all years and dividing by the standard deviation. Finally, the three variables are averaged yearly giving a relative indicator of the variations in climate. Years with positive values of the PNI are warmer and dryer than average and those with negative values are cooler and wetter than average. The PNI Index data set is provided courtesty of Curtis Ebbesmeyer. The PNI Index data set is featured at the University of Washington, School of Aquatic and Fisheries Sciences, Data Access Real Time (DART) Program. DART provides an interactive data resource designed for research and management purposes relating to the Columbia Basin salmon populations and river environment. Currently, daily data plus historic information dating back to 1910 is accessible online. DART focuses on the Columbia Basin dams and fish passage. Detailed information is brought in daily from federal, state and tribal databases to provide a comprehensive information tool. DART generates user-specified data files which can be saved to a user's personal directory in a variety of formats designed to be compatible with most spreadsheet programs. In addition, DART has graphing capabilities which allow for the visual comparison of multiple variables on one plot. These output formats are available for the following data resources related to fish passage, PIT tags and the river environment.

Data e Risorse

Campo Valore
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contact-email curt@evanshamilton.com
coupled-resource []
dataset-reference-date [{"type": "publication", "value": "1995-01-01"}]
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licence ["\nAlthough these data have been processed\nsuccessfully on a computer system at the\nUniversity of Washington, no warranty expressed or\nimplied is made regarding the accuracy or utility\nof the data on any other system or for general or\nscientific purposes, nor shall the act of\ndistribution constitute any such warranty. This\ndisclaimer applies both to individual use of the\ndata and aggregate use with other data. It is\nstrongly recommended that these data are directly\nacquired from a University of Washington server,\nand not indirectly through other sources which may\nhave changed the data in some way. It is also\nstrongly recommended that careful attention be\npaid to the contents of the metadata file\nassociated with these data. The University of\nWashington shall not be held liable for improper\nor incorrect use of the data described and/or\ncontained herein.\n"]
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resource-type dataset
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  • pacific-northwest
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  • salmon-productivity
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  • united-states
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metadata_created 2025-11-22T23:47:45.412922
metadata_modified 2025-11-22T23:47:45.412926
notes The Pacific Northwest Index (PNI), developed by Ebbesmeyer (1995), is a terrestrial climate index useful for studying climate effects on salmon productivity trends. It is a composite index that characterizes Pacific Northwest climate patterns in both coastal waters and freshwater habitats. In addition, it is a century-long record. A composite climate index is an effective measurement because many environmental parameters in the Northwest are statistically related to one another; consequently, they may be combined to furnish a broad-scale understanding of the state of the Pacific Northwest environment. The PNI uses three parameters: 1) air temperature at Olga in the San Juan Islands, averaged annually from daily data; 2) total precipitation at Cedar Lake in the Cascade Mountains; and 3) snowpack depth at Paradise on Mount Rainier on March 15 of each year. For each parameter, annual values were normalized by subtracting the average of all years and dividing by the standard deviation. Finally, the three variables are averaged yearly giving a relative indicator of the variations in climate. Years with positive values of the PNI are warmer and dryer than average and those with negative values are cooler and wetter than average. The PNI Index data set is provided courtesty of Curtis Ebbesmeyer. The PNI Index data set is featured at the University of Washington, School of Aquatic and Fisheries Sciences, Data Access Real Time (DART) Program. DART provides an interactive data resource designed for research and management purposes relating to the Columbia Basin salmon populations and river environment. Currently, daily data plus historic information dating back to 1910 is accessible online. DART focuses on the Columbia Basin dams and fish passage. Detailed information is brought in daily from federal, state and tribal databases to provide a comprehensive information tool. DART generates user-specified data files which can be saved to a user's personal directory in a variety of formats designed to be compatible with most spreadsheet programs. In addition, DART has graphing capabilities which allow for the visual comparison of multiple variables on one plot. These output formats are available for the following data resources related to fish passage, PIT tags and the river environment.
num_resources 2
num_tags 19
title The Pacific Northwest Index (PNI)