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In this work we study how the input data cadence affects the photosphericenergy and helicity injection estimates in eruptive NOAA active region 11158.We sample the novel 2.25-minute vector magnetogram and Dopplergram data fromthe \emph{Helioseismic and Magnetic Imager} (HMI) instrument onboard the\emph{Solar Dynamics Observatory} (SDO) spacecraft to create input datasets ofvariable cadences ranging from 2.25 minutes to 24 hours. We employstate-of-the-art data processing, velocity and electric field inversion methodsfor deriving estimates of the energy and helicity injections from thesedatasets. We find that the electric field inversion methods that reproduce theobserved magnetic field evolution through the use of Faraday's law are morestable against variable cadence: the PDFI (PTD-Doppler-FLCT-Ideal) electricfield inversion method produces consistent injection estimates for cadencesfrom 2.25 minutes up to 2 hours, implying that the photospheric processesacting on time scales below 2 hours contribute little to the injections, orthat they are below the sensitivity of the input data and the PDFI method. Onother hand, the electric field estimate derived from the output of DAVE4VM(Differential Affine Velocity Estimator for Vector Magnetograms), which doesnot fulfil Faraday's law exactly, produces significant variations in the energyand helicity injection estimates in the 2.25-minute to 2-hour cadence range. Wepresent also a third, novel DAVE4VM-based electric field estimate, whichcorrects the poor inductivity of the raw DAVE4VM estimate. This method is lesssensitive to the changes of cadence, but still faces significant issues for thelowest of considered cadences ($\geq$2 hours). We find several potentialproblems in both PDFI- and DAVE4VM-based injection estimates and conclude thatthe quality of both should be surveyed further in controlled environments.

Probing the effect of cadence on the estimates of photospheric energy and helicity injections in eruptive active region NOAA AR 11158