Browsing by Author "Chau, J. L."
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Item Open Access Diurnal and semidiurnal tides in the Mesosphere and Lower Thermosphere over the central coast of Peru(Instituto Geofísico del Perú, 2021-06) Suclupe, J.; Milla, Marco; He, M.; Chau, J. L.It has been over a year since measurements of mesosphere and lower thermosphere (MLT) winds have been obtained with the SIMONe Peru radar. This modern multistatic specular meteor radar, placed on the central coast of Peru, has its transmitter located at the Jicamarca Radio Observatory (11.95° S, 76.87° W, dip angle 1°). This work will show some results of the climatology of diurnal and semidiurnal tides obtained from the analysis of zonal and meridional mean winds that have been estimated at heights between 80-100 km using one year of data (Nov 2019 - Oct 2020). The monthly and seasonal variation of tide amplitudes will be described. From the results we have seen that diurnal tides are more intense than semidiurnal tides, which is typical at low latitudes and that diurnal tide is more intense in August and September. These and others results will also be described in this work.Item Open Access Multistatic specular meteor radar network in Peru: system description and initial results(American Geophysical Union, 2021-01) Chau, J. L.; Urco, J. M.; Vierinen, J.; Harding, B. J.; Clahsen, M.; Pfeffer, N.; Kuyeng, Karim; Milla, Marco; Erickson, P. J.The mesosphere and lower thermosphere (MLT) region is dominated globally by dynamics at various scales: planetary waves, tides, gravity waves, and stratified turbulence. The latter two can coexist and be significant at horizontal scales less than 500 km, scales that are difficult to measure. This study presents a recently deployed multistatic specular meteor radar system, SIMONe Peru, which can be used to observe these scales. The radars are positioned at and around the Jicamarca Radio Observatory, which is located at the magnetic equator. Besides presenting preliminary results of typically reported large‐scale features, like the dominant diurnal tide at low latitudes, we show results on selected days of spatially and temporally resolved winds obtained with two methods based on: (a) estimation of mean wind and their gradients (gradient method), and (b) an inverse theory with Tikhonov regularization (regularized wind field inversion method). The gradient method allows improved MLT vertical velocities and, for the first time, low‐latitude wind field parameters such as horizontal divergence and relative vorticity. The regularized wind field inversion method allows the estimation of spatial structure within the observed area and has the potential to outperform the gradient method, in particular when more detections are available or when fine adaptive tuning of the regularization factor is done. SIMONe Peru adds important information at low latitudes to currently scarce MLT continuous observing capabilities. Results contribute to studies of the MLT dynamics at different scales inherently connected to lower atmospheric forcing and E‐region dynamo related ionospheric variability.Item Open Access The case for combining a large low-band very high frequency transmitter with multiple receiving arrays for geospace research: a geospace radar(American Geophysical Union, 2019-07-09) Hysell, D. L.; Chau, J. L.; Coles, W. A.; Milla, Marco; Obenberger, K.; Vierinen, J.We argue that combining a high-power, large-aperture radar transmitter with several large-aperture receiving arrays to make a geospace radar—a radar capable of probing near-Earth space from the upper troposphere through to the solar corona—would transform geospace research. We review the emergence of incoherent scatter radar in the 1960s as an agent that unified early, pioneering research in geospace in a common theoretical, experimental, and instrumental framework, and we suggest that a geospace radar would have a similar effect on future developments in space weather research. We then discuss recent developments in radio-array technology that could be exploited in the development of a geospace radar with new or substantially improved capabilities compared to the radars in use presently. A number of applications for a geospace radar with the new and improved capabilities are reviewed including studies of meteor echoes, mesospheric and stratospheric turbulence, ionospheric flows, plasmaspheric and ionospheric irregularities, and reflection from the solar corona and coronal mass ejections. We conclude with a summary of technical requirements.