tokens: data. Section 3 shows an example of SIR and presents the identification criteria for SIRs and shocks. Section 4 presents the statistical distributions of the properties of SIRs and their associated shocks, and compares the results with those at 1 au. The last section concludes with a summary of the contributions. 2. <italic>MAVEN</italic> Data The MAVEN spacecraft carries nine sensors that measure the solar wind and the plasma and neutral environment at Mars. In this work, we use data from the following three instruments: Solar Wind Ion Analyzer (SWIA; Halekas et al. 2015 ), Magnetometer (MAG; Connerney et al. 2015 ), and Solar Wind Electron Analyzer (SWEA; Mitchell et al. 2016 ). SWIA is an electrostatic analyzer that measures 3D distributions of ions from 25 eV to 25 keV. When MAVEN is in the solar wind, SWIA provides the solar wind parameters with a cadence of 4 s. MAG measures the three components of magnetic field with 32 Hz cadence. We use 4 s resolution MAG data that are extracted from the full resolution measurements and are in one-to-one correspondence with SWIA data. SWEA provides the energy and angular distributions of 3–4600 eV electrons with 2 s time resolution. We utilize the MAVEN data in Mars Solar Orbital (MSO) coordinates, in which X points from Mars toward the Sun, Y points in the opposite direction of the Mars orbital velocity component perpendicular to X, and Z completes the right-handed system. 3. Observations of an SIR during 2016 August 2–3 Figure 1 shows solar wind plasma and magnetic field data from MAVEN during 2016 August 2–3 encompassing a typical SIR event. The SIR is clearly identified by the signatures including a compression of IMF ∣ B ∣, an increase of proton speed V p , an increase of proton number density N p , an enhancement of proton temperature T p , and a significant enhancement of total perpendicular pressure P t (e.g., Guo et al. 2015 , 2016 ; Wang et al. 2018 ). P t is defined as the sum of the magnetic pressure and plasma thermal pressure perpendicular to the magnetic field (Gosling et al. 1987 ). Note that SWIA does not have the capability to discriminate ions based on mass, and thus the plasma parameters are calculated assuming that all ions are protons. SWEA does not provide direct measurements of solar wind electron temperature and density. In the calculation of P t , the electron contributions are not included and the proton temperature is assumed to be isotropic. An SI in the SIR, characterized by a decrease in proton density and a simultaneous increase in proton temperature, can be discerned at about 13:25 UT on August 2. A pair of forward–reverse shocks bounding the SIR are observed at about 03:44 UT on August 2 and at about 07:37 UT on August 3 respectively. Figure 1. MAVEN observations of an SIR at 1.52 au during 2016 August 2–3. From top to bottom: the MAVEN spacecraft altitude, pitch angle distributions of electron (∼282 eV), electron energy spectra, ion energy spectra, proton speed ( V p
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