Search

Your search keyword '"Mannucci, A.J"' showing total 69 results
Start Over Author "Mannucci, A.J"
69 results on '"Mannucci, A.J"'

8. The goals, achievements, and tools of modern geodesy

Author

Plag, H.-P., Altamimi, Z., Bettadpur, S., Beutler, G., Beyerle, G., Cazenave, A., Crossley, D., Donnellan, A., Forsberg, R., Gross, R., Hinderer, J., Komjathy, A., Ma, C., Mannucci, A.J., Noll, C., Nothnagel, A., Pavlis, E.C., Pearlman, M., Poli, P., Schreiber, U., Senior, K., Woodworth, P.L., Zerbini, S., Zuffada, C., Plag, Hans-Peter, editor, and Pearlman, Michael, editor

Published
2009
Full Text
View/download PDF

42. On the comparisons of tropical relative humidity in the lower and middle troposphere among COSMIC radio occultations and MERRA and ECMWF data sets

Author

Vergados, P., Mannucci, A.J., Ao, C.O., Jiang, J.H., Su, Hui, Vergados, P., Mannucci, A.J., Ao, C.O., Jiang, J.H., and Su, Hui

Abstract

The spatial variability of the tropical tropospheric relative humidity (RH) throughout the vertical extent of the troposphere is examined using Global Positioning System Radio Occultation (GPSRO) observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission. These high vertical resolution observations capture the detailed structure and moisture budget of the Hadley Cell circulation. We compare the COSMIC observations with the European Center for Medium-range Weather Forecast (ECMWF) Reanalysis Interim (ERA-Interim) and the Modern-Era Retrospective analysis for Research and Applications (MERRA) climatologies. Qualitatively, the spatial pattern of RH in all data sets matches up remarkably well, capturing distinct features of the general circulation. However, RH discrepancies exist between ERA-Interim and COSMIC data sets that are noticeable across the tropical boundary layer. Specifically, ERA-Interim shows a drier Intertropical Convergence Zone (ITCZ) by 15-20% compared to both COSMIC and MERRA data sets, but this difference decreases with altitude. Unlike ECMWF, MERRA shows an excellent agreement with the COSMIC observations except above 400 hPa, where GPSRO observations capture drier air by 5-10%. RH climatologies were also used to evaluate intraseasonal variability. The results indicate that the tropical middle troposphere at ±5-25° is most sensitive to seasonal variations. COSMIC and MERRA data sets capture the same magnitude of the seasonal variability, but ERA-Interim shows a weaker seasonal fluctuation up to 10% in the middle troposphere inside the dry air subsidence regions of the Hadley Cell. Over the ITCZ, RH varies by maximum 9% between winter and summer.

Published
2015

47. Interplanetary magnetic field B y control of prompt total electron content increases during superstorms.

Author

Mannucci, A.J., Crowley, G., Tsurutani, B.T., Verkhoglyadova, O.P., Komjathy, A., and Stephens, P.

Subjects
*INTERPLANETARY magnetic fields, *TOTAL electron content (Atmosphere), *HALLOWEEN Nor'easter, 1991, *PLANETARY ionospheres, *SOLAR cycle, *ASTRONOMICAL observations
Abstract

Large magnitude increases in ionospheric total electron content (TEC) that occur over 1–3h on the dayside are a significant manifestation of the main phases of superstorms. For the largest superstorms of solar cycle 23 (based on the Dst index), ground networks of GPS receivers measured peak total electron content increases greater than a factor of 2 relative to quiet time TEC averaged over the broad latitude band ±40° for local times 1200–1600LT. Near 30° latitude, the Halloween storms of October 29–30, 2003 appeared to produce storm-time TEC exceeding quiet time values by a factor of 5 within 2–3h of storm onset, at 1300LT. The physical cause of these large positive phase ionospheric storms is usually attributed to prompt penetration electric fields (PPEFs) initiated by Region 1 current closure through the ionosphere (Nopper and Carovillano, 1978 mechanism). An unresolved question is what determines variation of the TEC response for different superstorms. It has been suggested that the cross polar cap potential and Region 1 currents are significant factors in determining PPEF in the equatorial ionosphere, which are related to the solar wind reconnection electric field estimated by Kan–Lee and others. In this paper, we show evidence that suggests B y may be a significant factor controlling the TEC response during the main phase of superstorms. We analyzed the interplanetary conditions during the period that TEC was increasing for eight superstorms. We find that increasing daytime TEC during superstorms only occurs for large reconnection electric fields when B y magnitude is less than B z . The data suggest that B z is a far more important factor in the TEC response than the reconnection electric field. We also find that TEC decreases following its peak storm-time value for two superstorms, even though B z remains large and B y magnitudes are less than B z . Such decreases during the geomagnetic disturbance may indicate the role of magnetospheric shielding currents, or of changes in the thermosphere that have developed over the prolonged period of large solar wind electric field. Further analysis is warranted covering a wider range of storm intensities on the role of B y in affecting the daytime TEC response for a range of storm intensities. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results