Background paper on the international seafood trade and poverty

(121 p.

Solar wind and geomagnetism: toward a standard classification of geomagnetic activity from 1868 to 2009

We examined solar activity with a large series of geomagnetic data from 1868 to 2009. We have revisited the geomagnetic activity classification scheme of Legrand and Simon (1989) and improve their scheme by lowering the minimum Aa index value for shock and recurrent activity from 40 to 20 nT. This improved scheme allows us to clearly classify about 80% of the geomagnetic activity in this time period instead of only 60% for the previous Legrand and Simon classification

A nighttime temperature maximum in the thermosphere above Saint Santin in winter

International audienceThe Saint Santin (45 N) incoherent scatter radar data base shows a local enhancement in nighttime ion temperature that occurs in winter only. Its amplitude can exceed 100 K and averages 40 K on the basis of a conservative computation. The enhancement peaks near 4 LT and has a duration of about 4 hours. We discuss two possible explanations for this feature: (1) it is caused by the convergence of global winds at the global pressure minimum, under which Saint Santin rotates at winter solstice, and (2) it is an extension or propagation of the well-known low-latitude midnight temperature maximum to midlatitudes, perhaps to that pressure minimum

Hot O and nighttime ionospheric temperatures

International audienceBy analysing a large set of St. Santin F region Incoherent Scatter (IS) data for low solar activity we find nighttime ion temperature (T*) on average to be apparentlys lightlyh ighert han electront emperature( Te). We show that this difference is a bias incurred by the IS spectral analysisp rocedureo wingt o the neglecto f H + ionsi n the 300-500 km altitude region. Further, we show Te and T* to depart from the neutral temperature T* with increasing altitude. We perform a simulation of ion and electron temperatures and show that the difference between T*, T* and T* can be caused by the presence of a small amount of hot oxygen. Using our simulation we estimate the ratio of hot oxygen to cold oxygen density to be 0.13% on average at 400-kin altitude for low solar activity

Solar wind fluctuations and solar wind activity long-term swing 1963-2012

International audienc

Radar studies of mid-latitude ionospheric plasma drifts

We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the evolution of the disturbance drifts driven by the combined effects of prompt penetration and longer lasting perturbation electric fields. The meridional electrodynamic disturbance drifts have largest amplitudes in the midnight-noon sector. The zonal drifts are predominantly westward, with largest amplitudes in the dusk-midnight sector and, following a decrease in the high-latitude convection, they decay more slowly than the meridional drifts. The prompt penetration and steady state zonal disturbance drifts derived from radar measurements are in good agreement with results obtained from both the ion drift meter data on board the Dynamics Explorer 2 (DE 2) satellite and from the Rice Convection Model

Some results of GPS observations in the Southeast Asian Region

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