A non-modeler experience with models: adventures in OSSEs and experiment planning

A non-modeler experience with models: adventures in OSSEs and experiment planning Developing Heliophysics Standards and Cross-science Collaborations Workshop Rafael Mesquita ([email protected]) Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 2 Full disclosure… I’m not a modeler and have very little experience with models, but I experience models Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 3 Observing System Simulation Experiment (OSSE) What is an OSSE? •An OSSE is an exercise to simulate what an instrument would realistically measure if it sampled a modeled atmosphere. It is not just to sample the model, but simulate the instrument and its measurement capabilities with noise and errors. •For a satellite, we simulate the instrument measurement as if it was flying through a realistic modeled environment to optimize mission design and operations, establish system requirements, test and ready retrieval algorithms, demonstrate measurement capabilities, ensure science closure, and plan for experiments beyond launch, etc. EZIE measurement forward model using WACCM-X atmosphere Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 4 OSSE – GAMERA Global MHD Model Magnetosphere from global MHD GAMERA model Auroral electrojet currents calculated with GAMERA model output magnetic fields. We can then fly the satellite through the model at any configuration (different MLT rotations). 0 MLT 18 6 0.1 µA/m2 RE 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 JHALL (µA/m2 RE) Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 5 OSSE – Basic Steps Simulated Tυ, Beam 3 Tυ sensitivity to 1 nT change in Bz Simulated Retrievals of Vector B One simulated observation every 2.0 seconds using GAMERA, 98 kHz per channel, and 128 channels in the simulation. Sensitivity plot that relates brightness temperature to magnetic fields of the simulated measurements. Retrieved magnetic fields (scatter plot) with radiance noises of 1.45 K in comparison with GAMERA at 80 km. (K/nT) Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 6 OSSE – Radiance Simulator Top Level Diagram Populates the points along the line-of-sight from the ground to a hard-coded altitude. The atmospheric parameters can be populated either from file (WACCM-X or TIEGCM) or calculated using MSIS and dBs come from either GAMERA (high-latitude) or WACCM-X (low-latitude). Read atmosphere state Populate the line-of-sight atmos Read mag. perturbation (dB) Populate the line-of-sight dBs Populate the line-of-sight with IGRF Unit conversions are done post spectra calculation. Calculate O2 Zeeman spectra Calculate O2 Zeeman emission propagation matrix Populate line-of-sight effect of spacecraft motion and Earth rotation Read simulated orbit from file, adjust orbit based on configuration files, and output a LOS Read configuration files Establish spacecraft path Establish sub-limb geometry Read HITRAN and est. frequency domain *Within blocks, tasks run in series from top to bottom and each block from left to right. **All quantities are delivered in geomagnetic and geographic coordinates ***The above diagram is repeated with and without dB In the case of EZIE Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 7 EZIE Science Questions and Closure Assessment Targeted Science Question 2: To what extent is the auroral electrojet modulated by localized (hundreds of km) current segments? Targeted Science Question 1: What is the structure and evolution of the auroral electrojet segment of the substorm current wedge? SCALE SIZE OF INDIVIDUAL FEATURES LARGER AEJ MORPHOLOGY As an example on how an OSSE can be used we have the EZIE OSSE. We gather GAMERA configurations with different configurations corresponding to the different hypotheses. Here are four of them: Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 8 OSSE Results •Different examples of OSSES: -“Laminar” current configuration Developing Heliophysics Standards and Cross-science Collaborations WorkshopAdvantures in OSSEs & Experiment Planning | Rafael Mesquita | [email protected] 9 OSSE Results •Different examples of OSSES: -Disconnected postand pre-midnight current wedges