The spread-F Experiment (SpreadFEx): Program overview and first results

David C. Fritts, NorthWest Research Associates
M. A. Abdu, Instituto Nacional de Pesquisas Espaciais (INPE)
B. R. Batista, Instituto Nacional de Pesquisas Espaciais (INPE)
I. S. Batista, Instituto Nacional de Pesquisas Espaciais (INPE)
P. P. Batista, Instituto Nacional de Pesquisas Espaciais (INPE)
R. Buriti, Universidade Federal de Campina Grande (UFCG)
B. R. Clemesha, Instituto Nacional de Pesquisas Espaciais, INPE
T. Dautermann, Purdue Uniersity
E. de Paula, Instituto Nacional de Pesquisas Espaciais, INPE
B. J. Fechine, Instituto Nacional de Pesquisas Espaciais, INPE
Bela Fejer, Utah State University
D. Gobbi, Instituto Nacional de Pesquisas Espaciais, INPE
J. Haase, Purdue University
F. Kamalabadi, University of Illinois
B. Laughman, NorthWest Research Associates
L. M. Lima, Universidade Estadual da Paraíba
H. L. Liu, National Center for Atmospheric Research, Boulder
A. Medeiros, Universidade Federal de Campina Grand
Pierre-Dominique Pautet, Utah State University
D. M. Riggin, NorthWest Research Associates
F. São Sabbas, Instituto Nacional de Pesquisas Espaciais, INPE
J. H. A. Sobral, Instituto Nacional de Pesquisas Espaciais, INPE
P. Stamus, NorthWest Research Associates
H. Takahashi, Instituto Nacional de Pesquisas Espaciais, INPE
Michael J. Taylor, Utah University
Sharon L. Vadas, NorthWest Research Associates
C. M. Wrasse, Universidade do Vale do Paraíba—UNIVAP

Abstract

We performed an extensive experimental campaign (the spread F Experiment, or SpreadFEx) from September to November 2005 to attempt to define the role of neutral atmosphere dynamics, specifically wave motions propagating upward from the lower atmosphere, in seeding equatorial spread F and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12 and the GUVI instrument aboard the TIMED satellite. Initial results of our analyses of SpreadFEx and related data indicate 1) extensive gravity wave (GW) activity apparently linked to deep convection predominantly to the west of our measurement sites, 2) the presence of small-scale GWactivity confined to lower altitudes, 3) larger-scaleGWactivity apparently penetrating to much higher altitudes suggested by electron density and TEC fluctuations in the E and F regions, 4) substantial GW amplitudes implied by digisonde electron densities, and 5) apparent direct links of these perturbations in the lower F region to spread F and plasma bubbles extending to much higher altitudes. Related efforts with correlative data are defining 6) the occurrence and locations of deep convection, 7) the spatial and temporal evolutions of plasma bubbles, the 8) 2D (height-resolved) structures of plasma bubbles, and 9) the expected propagation of GWs and tides from the lower atmosphere into the thermosphere and ionosphere.