Year: 2020
Type: article
Abstract: A new model validation and performance assessment tool is introduced, the sliding threshold of observation for numeric evaluation (STONE) curve. It is based on the relative operating characteristic (ROC) curve technique, but instead of sorting all observations in a categorical classification, the STONE tool uses the continuous nature of the observations. Rather than defining events in the observations and then sliding the threshold only in the classifier/model data set, the threshold is changed simultaneously for both the observational and model values, with the same threshold value for both data and model. This is only possible if the observations are continuous and the model output is in the same units and scale as the observations; the model is trying to exactly reproduce the data. The STONE curve has several similarities with the ROC curve – plotting probability of detection against probability of false detection, ranging from the (1,1) corner for low thresholds to the (0,0) corner for high thresholds, and values above the unity line indicating better than random predictive ability. The main difference is that the STONE curve can be nonmonotonic, doubling back in both the x and y directions. These ripples reveal asymmetries in the data-model value pairs. This new technique is applied to modeling output of a common geomagnetic activity index as well as energetic electron fluxes in the Earth’s inner magnetosphere. It is not limited to space physics applications but can be used for any scientific or engineering field where numerical models are used to reproduce observations.
Source: Earth and Space Science
DOI: 10.1029/2020ea001106
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,800
Funders: National Science Foundation, National Aeronautics and Space Administration, University of Michigan, European Commission, Directorate for Geosciences, National Oceanic and Atmospheric Administration, Goddard Space Flight Center, College of Pharmacy, University of Michigan, Horizon 2020 Framework Programme, Horizon 2020
Awards: G1390947965, Synoptic Investigation of Extreme Events: Sun to the Upper Atmosphere, WE PROPOSE TO EXAMINE VAN ALLEN PROBES DATA TO ASSESS THE ROLE OF NONLINEAR FEEDBACK IN GOVERNING THE SPATIAL STRUCTURE OF HOT IONS IN THE INNER MAGN, UNDERSTANDING ION HEATING AND CONVECTION USING TWINS AND SWMF THE SOLAR WIND DRIVES CHANGES IN EARTH S PLASMA SHEET, SUCH AS INCREASES IN ION TEMPERA, G3373072735, WE PROPOSE TO EXAMINE VAN ALLEN PROBES AND THEMIS DATA TO ASSESS THE CONNECTIONS BETWEEN AND THE DRIVERS OF INNER MAGNETOSPHERIC CURRENT DENSITIES AN, G434337789, G4620776195, THE DISTRIBUTION OF LOW ENERGY ELECTRONS BELOW 200 KEV IS CRITICALLY IMPORTANT FOR RADIATION BELT DYNAMICS BEING SEED POPULATION ACCELERATED TO MEV ENERGIES. THE ELECTRON FLUX AT THESE ENERGIES VARIES SIGNIFICANTLY WITH GEOMAGNETIC ACTIVITY DRIVEN BY THE SOLAR WIND. IT IS NOW CLEAR THAT SUBSTORMS ARE ESPECIALLY IMPORTANT. AT THE SAME TIME THE EXACT PHYSICAL PROCESSES OF THESE VARIATIONS ARE STILL FAR FROM BEING COMPLETELY UNDERSTOOD. AN INTEGRATED APPROACH TOWARD QUANTITATIVE UNDERSTANDING IS REQUIRED THAT COMBINES THE DATA ANALYSIS OF KEV ELECTRON FLUXES DRIVEN BY THE SOLAR WIND WITH DETAILED TRAJECTORY SIMULATIONS OF THE ENERGETIC ELECTRONS. SCIENCE GOALS AND OBJECTIVES THE PROPOSED RESEARCH IS TARGETED TO STUDY THE SOLAR WIND DRIVING OF KEV ELECTRONS IN THE NEAR EARTH SPACE. THE PROJECT IS AT THE VERY EDGE OF THE ONGOING RESEARCH IN THE PHYSICS OF EARTHS RADIATION ENVIRONMENT. THREE QUESTIONS WILL BE ANSWERED: 1. HOW DOES KEV ELECTRON RADIATION RESPOND TO THE SOLAR WIND VARIATIONS FOR DIFFERENT ACTIVITY CONDITIONS? 2. WHAT ARE THE CHARACTERISTIC VARIATIONS OF THE SOURCE ELECTRONS IN THE NEAR EARTH PLASMA SHEET? AND 3. WHAT IS THE ROLE OF SUBSTORM ASSOCIATED INJECTIONS AND ELECTROMAGNETIC FIELDS IN THE TRANSPORT AND ACCELERATION OF KEV ELECTRON POPULATION IN THE INNER MAGNETOSPHERE? WE WILL INVESTIGATE THE CHAIN OF PHYSICAL PROCESSES STARTING WITH THE ANALYSIS OF SOLAR WIND DRIVING OF THE SOURCE POPULATION IN THE PLASMA SHEET TRANSPORT AND ACCELERATION OF LOW ENERGY ELECTRONS FROM THE PLASMA SHEET TO GEOSTATIONARY ORBIT AND FURTHER INSIDE INCLUDING THE ROLES OF LARGE SCALE AND SMALLER SCALE SUBSTORM ASSOCIATED ELECTROMAGNETIC FIELDS AND THEN FORMING THE LOW ENERGY ELECTRON POPULATION IN THE INNER MAGNETOSPHERE INSIDE GEOSTATIONARY ORBIT. METHODOLOGY THEMIS ESA AND SST DATA IN THE PLASMA SHEET IN THE VICINITY OF THE EQUATORIAL PLANE ON THE NIGHTSIDE AT THE DISTANCES FROM 6 TO 10 RE WILL BE USED FOR QUANTIFYING STATISTICALLY THE SOURCE OF THE ELECTRONS DRIVEN BY THE SOLAR WIND AND FOR THE DEVELOPMENT OF THE DETAILED MODEL FOR SUBSTORM ASSOCIATED ELECTROMAGNETIC FIELDS. VAN ALLEN PROBES ECT HOPE AND MAGEIS DATA WILL BE USED TO IDENTIFY STATISTICALLY THE DEPENDENCIES OF KEV ELECTRON FLUXES ON THE SOLAR WIND DRIVING PARAMETERS INSIDE THE INNER MAGNETOSPHERE. ALL TIME INTERVALS SELECTED FOR THE ANALYSIS WILL BE ATTRIBUTED WITH THE CORRESPONDING SOLAR WIND AND IMF MEASUREMENTS OBTAINED FROM ACE AND DSCOVER SPACECRAFT. WE WILL EMPLOY OUR COMPREHENSIVE INNER MAGNETOSPHERE PARTICLE TRANSPORT AND ACCELERATION MODEL IMPTAM FOR ELECTRONS. IMPTAM MODEL RESULTS WILL BE PRESENTED IN A SIMILAR WAY AS STATISTICAL PATTERNS OF THE DEPENDENCIES OF KEV ELECTRON FLUXES ON THE SOLAR WIND DRIVING PARAMETERS FOR THEMIS AND VAN ALLEN PROBES DATA. WE WILL FOCUS SPECIFICALLY ON THE PROPER INCORPORATION OF THE SUBSTORM ASSOCIATED ELECTROMAGNETIC FIELDS IMPORTANT FOR KEV ELECTRON TRANSPORT AND ACCELERATION. THE PROCESSES OF THE FORMATION OF THE LOW ENERGY ELECTRON SEED POPULATION WILL BE STUDIED AND THREE MAIN SCIENTIFIC QUESTIONS WILL BE ANSWERED. RELEVANCE OF THE PROPOSED INVESTIGATION TO DECADAL SURVEY GOALS THE PROPOSAL ATTACKS ONE OF THE KEY QUESTIONS FOR MAGNETOSPHERE PHYSICS SUCH AS DYNAMICS OF KEV ELECTRONS IN THE NEAR EARTH GEOSPACE. IT WILL FURTHER INCREASE THE SCIENTIFIC RETURN FROM NASA OPERATING MISSIONS SUCH AS ACE DSCOVR THEMIS AND VAN ALLEN PROBES AND WILL PROVIDE A CRITICAL LINK IN OUR ABILITY TO UNDERSTAND THE COUPLING BETWEEN ELECTRONS SEED POPULATION AND RADIATIONS BELTS PARTICLES IN THE INNER MAGNETOSPHERE AND FURTHER COUPLING TO THE IONOSPHERE AND ATMOSPHERE VIA INVESTIGATING ELECTRON LOSSES AND THEIR PRECIPITATION. THUS THE PROPOSED STUDY DIRECTLY ADDRESSES ONE OF THE HIGH LEVEL SCIENCE GOALS FROM THE MOST RECENT HELIOPHYSICS DECADAL SURVEY NAMELY 2. DETERMINE THE DYNAMICS AND COUPLING OF EARTH S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS., Graduate Research Fellowship Program (GRFP), G8340697803, Prediction of Geospace Radiation Environment and solar wind parameters, Prediction of Adverse effects of Geomagnetic Storms and Energetic Radiation, G8883008220
OpenAlex ID: W3043673180