We present a joint study of substorm growth phase flow enhancements observed by Super Dual Auroral Radar Network HF radars and auroral optical intensifications observed by Canadian Auroral Network for the OPEN Program Unified Study meridian-scanning photometers (MSPs). During the event time, 0426--0500 UT on 26 December 1998, a flow enhancement structure was observed by HF radar from just equatorward of the polar cap boundary, whose location is estimated from the MSP observation of the poleward edge of 630 nm emissions, down to 68.5¿ ¿ 0.4¿ magnetic latitude, which is the boundary between the boundary plasma sheet and the central plasma sheet (CPS) inferred from the analysis of radar Doppler spectral widths. We suggest that the flow enhancements were associated with the tail reconnection process in response to the solar wind activation. The auroral optical intensifications were located inside the CPS. A zonal flow shear region characteristic of the Harang discontinuity was also inferred from the radar observation and was found to be closely associated with the auroral intensification structure. The flow enhancement and auroral intensifications were well correlated and occurred almost simultaneously. We found that existing models associating the tail reconnection process and near-geosynchronous onset of substorms do not explain this temporal relationship very well, and thus we propose a new model.