Geomagnetic indices are convenient quantities that distill the complicated physics of some region or aspect of near-Earth space into a single parameter. Most of the best-known indices are calculated from ground-based magnetometer data sets, such as Dst, SYM-H, Kp, AE, AL, and PC. Many models have been created that predict the values of these indices, often using solar wind measurements upstream from Earth as the input variables to the calculation. This document reviews the current state of models that predict geomagnetic indices and the methods used to assess their ability to reproduce the target index time series. These existing methods are synthesized into a baseline collection of metrics for benchmarking a new or updated geomagnetic index prediction model. These methods fall into two categories: (1) fit performance metrics such as root-mean-square error and mean absolute error that are applied to a time series comparison of model output and observations and (2) event detection performance metrics such as Heidke Skill Score and probability of detection that are derived from a contingency table that compares model and observation values exceeding (or not) a threshold value. A few examples of codes being used with this set of metrics are presented, and other aspects of metrics assessment best practices, limitations, and uncertainties are discussed, including several caveats to consider when using geomagnetic indices. Plain Language Summary One aspect of space weather is a magnetic signature across the surface of the Earth. The creation of this signal involves nonlinear interactions of electromagnetic forces on charged particles and can therefore be difficult to predict. The perturbations that space storms and other activity causes in some observation sets, however, are fairly regular in their pattern. Some of these measurements have been compiled together into a single value, a geomagnetic index. Several such indices exist, providing a global estimate of the activity in different parts of geospace. Models have been developed to predict the time series of these indices, and various statistical methods are used to assess their performance at reproducing the original index. Existing studies of geomagnetic indices, however, use different approaches to quantify the performance of the model. This document defines a standardized set of statistical analyses as a baseline set of comparison tools that are recommended to assess geomagnetic index prediction models. It also discusses best practices, limitations, uncertainties, and caveats to consider when conducting a model assessment.
Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Griffis, T. J.; Chaliyakunnel, S.; Dlugokencky, E. J.; Saikawa, E.; Xiang, G.; Prinn, R. G.; O'Doherty, S.; Young, D.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R.; Steele, L. P.;
Published Date:
2018
Source:
Atmospheric Chemistry and Physics, 18(2), 735-756.
Description:
We present top-down constraints on global monthly N2O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well curr...
Raczka, B.; Biraud, S. C.; Ehleringer, J. R.; Lai, C. T.; Miller, J. B.; Pataki, D. E.; Saleska, S. R.; Torn, M. S.; Vaughn, B. H.; Wehr, R.; Bowling, D. R.;
Published Date:
2017
Source:
Journal of Geophysical Research-Biogeosciences, 122(8), 1969-1987.
Description:
The seasonal pattern of the carbon isotope content (delta C-13) of atmospheric CO2 depends on local and nonlocal land-atmosphere exchange and atmospheric transport. Previous studies suggested that the delta C-13 of the net land-atmosphere CO2 flux (d...
Journal of Geophysical Research-Atmospheres, 123(15), 7950-7973.
Description:
In this study, we analyze a set of agroclimatological indices across West Africa and assess their projected changes for the future. We apply the regional climate model CCLM (COnsortium for Small-scale MOdelling in CLimate Mode) with a high spatial re...
Kenagy, H. S.; Sparks, T. L.; Ebben, C. J.; Wooldrige, P. J.; Lopez-Hilfiker, F. D.; Lee, B. H.; Thornton, J. A.; McDuffie, E. E.; Fibiger, D. L.; Brown, S. S.; Montzka, D. D.; Weinheimer, A. J.; Schroder, J. C.; Campuzano-Jost, P.; Day, D. A.; Jimenez, J. L.; Dibb, J. E.; Campos, T.; Shah, V.; Jaegle, L.; Cohen, R. C.;
Published Date:
2018
Source:
Journal of Geophysical Research-Atmospheres, 123(17), 9813-9827.
Description:
Although urban NOx lifetimes have been examined extensively during summertime conditions, wintertime NOx chemistry has been comparatively less studied. We use measurements of NOx and its oxidation products from the aircraft-based WINTER (Wintertime I...
Jarvinen, E.; Ignatius, K.; Nichman, L.; Kristensen, T. B.; Fuchs, C.; Hoyle, C. R.; Hoppel, N.; Corbin, J. C.; Craven, J.; Duplissy, J.; Ehrhart, S.; El Haddad, I.; Frege, C.; Gordon, H.; Jokinen, T.; Kallinger, P.; Kirkby, J.; Kiselev, A.; Naumann, K. H.; Petaja, T.; Pinterich, T.; Prevot, A. S. H.; Saathoff, H.; Schiebel, T.; Sengupta, K.; Simon, M.; Slowik, J. G.; Trostl, J.; Virtanen, A.; Vochezer, P.; Vogt, S.; Wagner, A. C.; Wagner, R.; Williamson, C.; Winkler, P. M.; Yan, C.; Baltensperger, U.; Donahue, N. M.; Flagan, R. C.; Gallagher, M.; Hansel, A.; Kulmala, M.; Stratmann, F.; Worsnop, D. R.; Mohler, O.; Leisner, T.; Schnaiter, M.;
Published Date:
2016
Source:
Atmospheric Chemistry and Physics, 16(7), 4423-4438.
Description:
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requir...
Butler, R.; Palmer, P. I.; Feng, L.; Andrews, S. J.; Atlas, E. L.; Carpenter, L. J.; Donets, V.; Harris, N. R. P.; Montzka, S. A.; Pan, L. L.; Salawitch, R. J.; Schauffler, S. M.;
Published Date:
2018
Source:
Atmospheric Chemistry and Physics, 18(17), 13135-13153.
Description:
We use the GEOS-Chem global 3-D atmospheric chemistry transport model to interpret atmospheric observations of bromoform (CHBr3) and dibromomethane (CH2Br2) collected during the CAST and CONTRAST aircraft measurement campaigns over the western Pacifi...
Fried, A.; Barth, M. C.; Bela, M.; Weibring, P.; Richter, D.; Walega, J.; Li, Y.; Pickering, K.; Apel, E.; Hornbrook, R.; Hills, A.; Riemer, D. D.; Blake, N.; Blake, D. R.; Schroeder, J. R.; Luo, Z. J.; Crawford, J. H.; Olson, J.; Rutledge, S.; Betten, D.; Biggerstaff, M. I.; Diskin, G. S.; Sachse, G.; Campos, T.; Flocke, F.; Weinheimer, A.; Cantrell, C.; Pollack, I.; Peischl, J.; Froyd, K.; Wisthaler, A.; Mikoviny, T.; Woods, S.;
Published Date:
2016
Source:
Journal of Geophysical Research-Atmospheres, 121(12), 7430-7460.
Description:
We have developed semi-independent methods for determining CH2O scavenging efficiencies (SEs) during strong midlatitude convection over the western, south-central Great Plains, and southeastern regions of the United States during the 2012 Deep Convec...
Janssens-Maenhout, G.; Crippa, M.; Guizzardi, D.; Dentener, F.; Muntean, M.; Pouliot, G.; Keating, T.; Zhang, Q.; Kurokawa, J.; Wankmuller, R.; van der Gon, H. D.; Kuenen, J. J. P.; Klimont, Z.; Frost, G.; Darras, S.; Koffi, B.; Li, M.;
Published Date:
2015
Source:
Atmospheric Chemistry and Physics, 15(19), 11411-11432.
Description:
The mandate of the Task Force Hemispheric Transport of Air Pollution (TF HTAP) under the Convention on Long-Range Transboundary Air Pollution (CLRTAP) is to improve the scientific understanding of the intercontinental air pollution transport, to quan...
Brown, S. S.; Dube, W. P.; Tham, Y. J.; Zha, Q. Z.; Xue, L. K.; Poon, S.; Wang, Z.; Blake, D. R.; Tsui, W.; Parrish, D. D.; Wang, T.;
Published Date:
2016
Source:
Journal of Geophysical Research-Atmospheres, 121(5), 2457-2475.
Description:
Nighttime reactions of nitrogen oxides influence ozone, volatile organic compounds, and aerosol and are thus important to the understanding of regional air quality. Despite large emissions and rapid recent growth of nitrogen oxide concentrations, the...
Kim, J.; Johnson, L. E.; Cifelli, R.; Choi, J.; Chandrasekar, V.;
Published Date:
2018
Source:
Water, 10(7), 21.
Description:
Soil moisture retention (SMR) capacity plays a key role in estimating the direct runoff when a multi-pulse storm event occurs. It is very important to know how much SMR will be recovered during the intervals of no rain of a multi-pulse storm. This st...
Fairall, C. W.; Matrosov, S. Y.; Williams, C. R.; Walsh, E. J.;
Published Date:
2018
Source:
Journal of Atmospheric and Oceanic Technology, 35(3), 593-608.
Description:
The NOAA W-band radar was deployed on a P-3 aircraft during a study of storm fronts off the U.S. West Coast in 2015 in the second CalWater (CalWater-2) field program. This paper presents an analysis of measured equivalent radar reflectivity factor Z(...
A 4-year record of aerosol size and hygroscopic growth factor distributions measured at the Department of Energy's Southern Great Plains (SGP) site in Oklahoma, U.S. were used to estimate supersaturation (S)-dependent cloud condensation nuclei concen...
Mahoney, K.; Swales, D.; Mueller, M. J.; Alexander, M.; Hughes, M.; Malloy, K.;
Published Date:
2018
Source:
Journal of Climate, 31(16), 6281-6297.
Description:
Atmospheric rivers (ARs) are well-known producers of precipitation along the U.S. West Coast. Depending on their intensity, orientation, and location of landfall, some ARs penetrate inland and cause heavy rainfall and flooding hundreds of miles from ...
Dimdore-Miles, O. B.; Palmer, P. I.; Bruhwiler, L. P.;
Published Date:
2018
Source:
Atmospheric Chemistry and Physics, 18(24), 17895-17907.
Description:
We consider the utility of the annual inter-polar difference (IPD) as a metric for changes in Arctic emissions of methane (CH4). The IPD has been previously defined as the difference between weighted annual means of CH4 mole fraction data collected a...
Sea surface temperature anomalies (SSTA) in portions of the extratropics are known to recur from one winter to the next without persisting through the intervening summer. Previous studies identified only a limited number of midlatitude regions where ...
Richardson, K.; Asmutis-Silvia, R.; Drinkwin, J.; Gilardi, K. V. K.; Giskes, I.; Jones, G.; O'Brien, K.; Pragnell-Raasch, H.; Ludwig, L.; Antonelis, K.; Barco, S.; Henry, A.; Knowlton, A.; Landry, S.; Mattila, D.; MacDonald, K.; Moore, M.; Morgan, J.; Robbins, J.; van der Hoop, J.; Hogan, E.;
Published Date:
2019
Source:
Marine Pollution Bulletin, 138, 222-229.
Description:
Abandoned, lost or discarded fishing gear (ALDFG) comprises a significant amount of global marine debris, with diverse impacts to marine environments, wildlife, and the fishing industry. Building evidence on ALDFG is critical to holistically understa...
Smith, M.; Stammerjohn, S.; Persson, O.; Rainville, L.; Liu, G. Q.; Perrie, W.; Robertson, R.; Jackson, J.; Thomson, J.;
Published Date:
2018
Source:
Journal of Geophysical Research-Oceans, 123(5), 3164-3185.
Description:
High-resolution measurements of the air-ice-ocean system during an October 2015 event in the Beaufort Sea demonstrate how stored ocean heat can be released to temporarily reverse seasonal ice advance. Strong on-ice winds over a vast fetch caused mixi...
Chakraborty, A.; Ervens, B.; Gupta, T.; Tripathi, S. N.;
Published Date:
2016
Source:
Journal of Geophysical Research-Atmospheres, 121(8), 4317-4332.
Description:
Size-resolved fog water samples were collected in two consecutive winters at Kanpur, a heavily polluted urban area of India. Samples were analyzed by an aerosol mass spectrometer after drying and directly in other instruments. Residues of fine fog dr...
Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.;
Heiblum, R. H.; Altaratz, O.; Koren, I.; Feingold, G.; Kostinski, A. B.; Khain, A. P.; Ovchinnikov, M.; Fredj, E.; Dagan, G.; Pinto, L.; Yaish, R.; Chen, Q.;
Published Date:
2016
Source:
Journal of Geophysical Research-Atmospheres, 121(11), 6336-6355.
Description:
We study the evolution of warm convective cloud fields using large eddy simulations of continental and trade cumulus. Individual clouds are tracked a posteriori from formation to dissipation using a 3-D cloud-tracking algorithm, and results are prese...
An existing empirical model of the electron fluxes at geosynchronous orbit is extended radially outward in the equatorial plane to ~6–20 Earth radii (RE) using observations from the Research with Adaptive Particle Imaging Detectors (RAPID) instrume...
The numerous recent breakthroughs in machine learning make imperative to carefully ponder how the scientific community can benefit from a technology that, although not necessarily new, is today living its golden age. This Grand Challenge review paper...