From May to September 2017 measurements of gas and heat emissions were made at Solfatara Plateau Thermal Area, an acid-sulfate, vapor-dominated area in Yellowstone National Park, Wyoming. An eddy covariance system measured half-hourly CO2, H2O and sensible and latent heat fluxes, air temperature and pressure, wind speed and direction and soil moisture. A Multi-GAS instrument measured (0.5 Hz frequency) atmospheric H2O, CO2, SO2 and H2S volumetric mixing ratios, air pressure, temperature and relative humidity and wind speed and direction. Soil temperature at 30 cm depth and CO2 flux were also measured on a grid across a 0.11 km2 area using thermocouple probes and the accumulation chamber method, respectively. The eddy covariance, Multi-GAS and soil CO2 flux and temperature data sets are saved in spreadsheets in the *.csv format.

From 14 May to 6 October 2016 measurements of gas and heat emissions were made at Bison Flat, an acid-sulfate, vapor-dominated area (0.04-km2) of Norris Geyser Basin, Yellowstone National Park, WY. An eddy covariance system measured half-hourly CO2, H2O and sensible and latent heat fluxes, air temperature and pressure, wind speed and direction, soil moisture and rainfall. A Multi-GAS instrument measured (1 Hz frequency) atmospheric H2O, CO2 and H2S volumetric mixing ratios, air pressure, temperature and relative humidity and wind speed and direction. Soil CO2 fluxes and temperature profiles were also measured on a grid using the accumulation chamber method and thermocouple probes, respectively. These data were used to derive hydrothermal CO2 and heat emission rates and characterize the chemical compositions of fumarole and soil-gas emissions. The eddy covariance, Multi-GAS and soil CO2 flux and temperature data sets are saved in spreadsheets in the *.csv format.

From 14 May to 6 October 2016 measurements of gas and heat emissions were made at Bison Flat, an acid-sulfate, vapor-dominated area (0.04-km2) of Norris Geyser Basin, Yellowstone National Park, WY. An eddy covariance system measured half-hourly CO2, H2O and sensible and latent heat fluxes, air temperature and pressure, wind speed and direction, soil moisture and rainfall. A Multi-GAS instrument measured (1 Hz frequency) atmospheric H2O, CO2 and H2S volumetric mixing ratios, air pressure, temperature and relative humidity and wind speed and direction. Soil CO2 fluxes and temperature profiles were also measured on a grid using the accumulation chamber method and thermocouple probes, respectively. These data were used to derive hydrothermal CO2 and heat emission rates and characterize the chemical compositions of fumarole and soil-gas emissions. The eddy covariance, Multi-GAS and soil CO2 flux and temperature data sets are saved in spreadsheets in the *.csv format.

We installed an eddy covariance station on July 10, 2018 at Bison Flat, an acid-sulfate, vapor-dominated area (0.04-km2) in Norris Geyser Basin, Yellowstone National Park, WY to monitor variations in hydrothermal gas and heat emissions. Since then, this station has measured CO2, H2O and sensible and latent heat fluxes, air temperature and pressure, and wind speed and direction on a half-hourly basis. We also measured soil CO2 fluxes and temperatures on a grid using the accumulation chamber method and thermocouple probes, respectively, on July 11-12, 2018 and soil CO2 fluxes only on June 25, 2019. On July 10, 2018 and June 24, 2019, we collected fumarole gas samples for analysis of bulk chemical and carbon (d13C-CO2) and helium (Rc/Ra) isotope compositions. The eddy covariance, soil CO2 flux and temperature, and gas geochemical data sets were used to characterize baseline temporal and spatial variations in hydrothermal CO2 and heat emissions and gas sources for the study area and their relationships to meteorological variations.

We installed an eddy covariance station on July 10, 2018 at Bison Flat, an acid-sulfate, vapor-dominated area (0.04-km2) in Norris Geyser Basin, Yellowstone National Park, WY to monitor variations in hydrothermal gas and heat emissions. Since then, this station has measured CO2, H2O and sensible and latent heat fluxes, air temperature and pressure, and wind speed and direction on a half-hourly basis. We also measured soil CO2 fluxes and temperatures on a grid using the accumulation chamber method and thermocouple probes, respectively, on July 11-12, 2018 and soil CO2 fluxes only on June 25, 2019. On July 10, 2018 and June 24, 2019, we collected fumarole gas samples for analysis of bulk chemical and carbon (d13C-CO2) and helium (Rc/Ra) isotope compositions. The eddy covariance, soil CO2 flux and temperature, and gas geochemical data sets were used to characterize baseline temporal and spatial variations in hydrothermal CO2 and heat emissions and gas sources for the study area and their relationships to meteorological variations.

This release presents provisional volcanic gas monitoring data from multi-GAS (multiple Gas Analyzer System) station "YELL_MUD", installed in July 2021 in the Obsidian Pool thermal area, Yellowstone National Park, USA. The multi-GAS station includes gas sensors to measure water vapor, carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S) in gas plumes, as well as meteorologic parameters (wind speed and direction, ambient temperature and relative humidity, ambient pressure), and the temperature of a nearby geothermal feature. The station is duty cycled to conserve power and collects data for 30 minutes every 6 hours beginning at 00:00, 06:00, 12:00, and 18:00 UTC. Before each measurement cycle the gas sensors' baseline responses are checked by recirculating trapped air through chemical scrubbers (soda lime and anhydrite) to remove acid gases and water vapor. On-site CO2, SO2, and H2S standard gases are sampled every 28.25 days to verify the sensor responses. High-rate data are logged onsite and half-hourly averaged values from each sample cycle, along with baseline ('zero') and verification ('span') results, are telemetered every 6 hours by a BGAN satellite system. The half-hourly averages and diagnostic data obtained via telemetry are presented herein. Real-time values from the station can be viewed on the USGS Yellowstone monitoring webpage by clicking on the small 'gas cloud' icon (https://www.usgs.gov/volcanoes/yellowstone). Please note that the data presented herein are provisional, as described below. For a more detailed technical description of the multi-GAS instrument please see Lewicki et al., 2017. PROVISIONAL DATA DISCLAIMER: These data are preliminary or provisional and are subject to revision. They are being provided to meet the need for timely best science. The data have not received final approval by the U.S. Geological Survey (USGS) and are provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the data. While every effort is made to obtain accurate measurements, volcanic environments can be extremely harsh and provisional data and results generated by automated processing routines have not been analyst-reviewed and may be inaccurate due to instrument malfunctions, sensor drift, or other problems. Any such problems may take some time to address due to the remote location of the site. Users are cautioned to carefully consider the provisional nature of the data before using it. Information concerning the accuracy and appropriate uses of these data may be obtained from the USGS. Reference Lewicki, J.L., Kelly, P.J., Bergfeld, D., Vaughan, R.G., Lowenstern, J.B., 2017. Monitoring gas and heat emissions at Norris Geyser Basin, Yellowstone National Park, USA based on a combined eddy covariance and Multi-GAS approach. J. Volcanol. Geotherm. Res. 347, 312–326. https://doi.org/10.1016/J.JVOLGEORES.2017.10.001

This release presents provisional volcanic gas monitoring data from multi-GAS (multiple Gas Analyzer System) station "YELL_MUD", installed in July 2021 in the Obsidian Pool thermal area, Yellowstone National Park, USA. The multi-GAS station includes gas sensors to measure water vapor, carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S) in gas plumes, as well as meteorologic parameters (wind speed and direction, ambient temperature and relative humidity, ambient pressure), and the temperature of a nearby geothermal feature. The station is duty cycled to conserve power and collects data for 30 minutes every 6 hours beginning at 00:00, 06:00, 12:00, and 18:00 UTC. Before each measurement cycle the gas sensors' baseline responses are checked by recirculating trapped air through chemical scrubbers (soda lime and anhydrite) to remove acid gases and water vapor. On-site CO2, SO2, and H2S standard gases are sampled every 28.25 days to verify the sensor responses. High-rate data are logged onsite and half-hourly averaged values from each sample cycle, along with baseline ('zero') and verification ('span') results, are telemetered every 6 hours by a BGAN satellite system. The half-hourly averages and diagnostic data obtained via telemetry are presented herein. Real-time values from the station can be viewed on the USGS Yellowstone monitoring webpage by clicking on the small 'gas cloud' icon (https://www.usgs.gov/volcanoes/yellowstone). Please note that the data presented herein are provisional, as described below. For a more detailed technical description of the multi-GAS instrument please see Lewicki et al., 2017. PROVISIONAL DATA DISCLAIMER: These data are preliminary or provisional and are subject to revision. They are being provided to meet the need for timely best science. The data have not received final approval by the U.S. Geological Survey (USGS) and are provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the data. While every effort is made to obtain accurate measurements, volcanic environments can be extremely harsh and provisional data and results generated by automated processing routines have not been analyst-reviewed and may be inaccurate due to instrument malfunctions, sensor drift, or other problems. Any such problems may take some time to address due to the remote location of the site. Users are cautioned to carefully consider the provisional nature of the data before using it. Information concerning the accuracy and appropriate uses of these data may be obtained from the USGS. Reference Lewicki, J.L., Kelly, P.J., Bergfeld, D., Vaughan, R.G., Lowenstern, J.B., 2017. Monitoring gas and heat emissions at Norris Geyser Basin, Yellowstone National Park, USA based on a combined eddy covariance and Multi-GAS approach. J. Volcanol. Geotherm. Res. 347, 312–326. https://doi.org/10.1016/J.JVOLGEORES.2017.10.001

Degassing thermal features at Yellowstone National Park include spectacular geysers, roiling hot springs, bubbling mud pots, fumaroles, frying pans, and areas of passive degassing characterized by steaming ground. Most of these features are readily identified by visible clouds of steam that are occasionally accompanied by a strong “rotten egg” odor from emissions of hydrogen sulfide gas. Gas compositions typically are greater than 90% carbon dioxide with lesser amounts of helium, hydrogen, hydrogen sulfide, methane, nitrogen and other trace components. The composition of the gas and relative amounts of gas and steam relate both to the type of feature as well as the geographic location within the park. In 2003 we began a long-term field study of Yellowstone gases with a goal of obtaining complete chemical analyses from a variety of features from all areas of the park. Results from samples collected through 2012 are published in numerous journal articles and reports (Bergfeld et al., 2012, 2014; Chiodini et al., 2012; Evans et al., 2010; Lowenstern et al., 2012, 2014, 2015; and Werner et al., 2008). Synthesis of these data allow us to delineate areas within Yellowstone that are dominated by magmatic versus crustal gas sources and to tease out additional information regarding sedimentary and metamorphic sources for crustal gas. This report compiles our published gas and water data with new gas data from samples collected through September, 2018 and includes some previously unpublished carbon isotope data from waters collected during 2011. Some of the analyses represent replicate samples collected in different bottles on the same day, others are samples collected from the same location in different years, and some sites were only sampled once. A companion data release focused on water chemistry and discharge for 2017-18 waters is planned be published in a separate report. The data herein are organized by sample type: Tables 1 and 2 include bulk chemistry and isotope data for 199 gas samples collected in evacuated bottles containing sodium hydroxide and 41 gas samples collected in dry evacuated bottles, respectively; Table 3 presents chemical and isotope data for 62 water samples from thermal and non-thermal features; Table 4 contains helium and carbon isotope data for 10 water samples and 1 gas sample. Each sample is assigned a group number linked to a particular area within the park (figure 1). Samples in groups 2 through 10 and 12 through 22 tend to be in close proximity. Group 11 includes samples from general locations across Eastern Yellowstone. Samples keyed to group 1 (miscellaneous) are not co-located. The analytical results include major and trace element chemistry for the gases and waters, and isotope values for carbon dioxide (d13C-CO2), dissolved inorganic carbon (d13C-DIC), helium (3He/4He), steam (d18O, dD), neon (20Ne/22Ne and 21Ne/22Ne), and argon (38Ar/36Ar and 40Ar/36Ar). All data in this report supersede previously published analyses. The reader is directed to early publications for details on sampling and analytical methods and for in depth discussions regarding interpretations of the gas data.

Degassing thermal features at Yellowstone National Park include spectacular geysers, roiling hot springs, bubbling mud pots, fumaroles, frying pans, and areas of passive degassing characterized by steaming ground. Most of these features are readily identified by visible clouds of steam that are occasionally accompanied by a strong “rotten egg” odor from emissions of hydrogen sulfide gas. Gas compositions typically are greater than 90% carbon dioxide with lesser amounts of helium, hydrogen, hydrogen sulfide, methane, nitrogen and other trace components. The composition of the gas and relative amounts of gas and steam relate both to the type of feature as well as the geographic location within the park. In 2003 we began a long-term field study of Yellowstone gases with a goal of obtaining complete chemical analyses from a variety of features from all areas of the park. Results from samples collected through 2012 are published in numerous journal articles and reports (Bergfeld et al., 2012, 2014; Chiodini et al., 2012; Evans et al., 2010; Lowenstern et al., 2012, 2014, 2015; and Werner et al., 2008). Synthesis of these data allow us to delineate areas within Yellowstone that are dominated by magmatic versus crustal gas sources and to tease out additional information regarding sedimentary and metamorphic sources for crustal gas. This report compiles our published gas and water data with new gas data from samples collected through September, 2018 and includes some previously unpublished carbon isotope data from waters collected during 2011. Some of the analyses represent replicate samples collected in different bottles on the same day, others are samples collected from the same location in different years, and some sites were only sampled once. A companion data release focused on water chemistry and discharge for 2017-18 waters is planned be published in a separate report. The data herein are organized by sample type: Tables 1 and 2 include bulk chemistry and isotope data for 199 gas samples collected in evacuated bottles containing sodium hydroxide and 41 gas samples collected in dry evacuated bottles, respectively; Table 3 presents chemical and isotope data for 62 water samples from thermal and non-thermal features; Table 4 contains helium and carbon isotope data for 10 water samples and 1 gas sample. Each sample is assigned a group number linked to a particular area within the park (figure 1). Samples in groups 2 through 10 and 12 through 22 tend to be in close proximity. Group 11 includes samples from general locations across Eastern Yellowstone. Samples keyed to group 1 (miscellaneous) are not co-located. The analytical results include major and trace element chemistry for the gases and waters, and isotope values for carbon dioxide (d13C-CO2), dissolved inorganic carbon (d13C-DIC), helium (3He/4He), steam (d18O, dD), neon (20Ne/22Ne and 21Ne/22Ne), and argon (38Ar/36Ar and 40Ar/36Ar). All data in this report supersede previously published analyses. The reader is directed to early publications for details on sampling and analytical methods and for in depth discussions regarding interpretations of the gas data.

The data in the csv and text files provided in this release are an update to the data tables originally published in USGS Open-File Report (OFR) 83-250 (https://doi.org/10.3133/cir892). Those data were published as paper tables and have until now only been available as pdf image documents that were not machine readable. USGS OFR 83-250 presented data for 2071 geothermal sites which are representative of 1168 low-temperature geothermal systems identified in 26 states. The low-temperature geothermal systems consist of 978 isolated hydrothermal-convection systems, 148 delineated-area hydrothermal-convection systems, and 42 delineated-area conduction-dominated systems. The basic data and estimates of reservoir conditions are presented for each geothermal system, and energy estimates are given for the accessible resource base, resource, and beneficial heat for each isolated system. This electronic version of USGS OFR 83-250 tables includes several changes. Typographical errors were corrected. The location accuracy of many wells and springs was improved by comparing the original locations with other databases and with USGS topographic maps. Charge balance and additional geothermometer calculations made by the original authors that have become available since the original publication were also included.