The Solar Mesosphere Explorer (SME) satellite observed thermospheric nitric oxide (NO) during the period September 17--20, 1984, using the resonance fluorescence technique. Altitude profiles from 100 to about 130 km were obtained for 1500 LT along two orbital tracks: one over the United States and one over Europe. An auroral storm occurred on September 19. A comparison of data from September 20 with data from September 18 revealed a factor of 3 increase in NO at mid-latitudes over the United States. Little NO enhancement was seen over Europe or at equatorial latitudes. A larger increase was seen for the higher altitudes (>120 km). The SME observations are compared with the calculations of a one-dimensional photochemical model of the lower thermosphere. The National Center for Atmospheric Research (NCAR) thermospheric general circulation model (TGCM) is used to calculate the response of the background neutral atmosphere to auroral forcings such as Joule and particle heating. The output of the TGCM is used as input to the photochemical model. Calculations of the mid-latitude NO response show that temperature increases which result from Joule and compressional heating can explain the observed NO enhancements. A larger response is initially seen for altitudes greater than 120 km. After several days, downward diffusion leads to NO increases at lower altitudes. Equatorial NO shows little response because the combined effects of temperature enhancements and atomic oxygen enhancements largely cancel. The best absolute fit of the model to the data is for an N(2D)+O quenching rate of 5¿10-13 cm3 s-1, although uncertainties in the neutral composition preclude an exact specification of the quenching rate. The success of the model in reproducing the observed NO altitude and latitude variations argues against the importance of horizontal transport of E region NO. ¿ American Geophysical Union 1989