The equatorial lower ionosphere like indicator of solar activity and tropical cyclone action Liudmila Vanina-Dart Space Research Institute, Moscow, Russia This paper presents the results of rocket-borne measurements of the electron density in the equatorial ionospheric D layer at the rocket testing ground Tumba ( India ). Special attention will be paid for ionosphere during tropical cyclones. For example, was detected that possible large-scale response of ionospheric state can be the “fast” depletion (2-4 times) in electron density at heights of 50 – 80 km during the action of the active phase of a tropical cyclone. The author analyzed data including the space weather influence fact to equatorial ionosphere.

Thus, the catastrophic atmospheric vortex systems play an important (and possibly determining) role in the formation of the temperature regime of the Earth (the greenhouse effect), removing excess heat and preventing from strong overheating of the atmosphere (of its tropical part) and the surface ocean layer in the tropical zone It is known that the whole spectrum of powerful dynamical phenomena is originated in the tropical zone of the atmosphere. The most intense of these phenomena are TCs, which are possible potential sources of the influence from “below”. Catastrophic atmospheric vortices, which originate near the equator, and develop in the tropical zone of the Earth’s atmosphere, present a peculiar mechanism of effective heat effluence under such atmospheric conditions, when the action of ordinary mechanisms (the main mechanisms are turbulent convection and global circulation) becomes evidently insufficient. Thus, the catastrophic atmospheric vortex systems play an important (and possibly determining) role in the formation of the temperature regime of the Earth (the greenhouse effect), removing excess heat and preventing from strong overheating of the atmosphere (of its tropical part) and the surface ocean layer in the tropical zone.

Gherzi (1946) was the first to suggest that ionospheric soundings could be used as an aid for weather forecasting and for predicting the movement of typhoons. But much of this work was based on misconceptions and some of his claims on this subject have not stood up to scrutiny. Observations have shown that the passage of tropical storms can lead to perturbations in the plasma drift [Bishop et al., 2006]

Relationships between meteorological and ionospheric phenomena come about through vertical motions in the ionosphere induced by underlying large scale weather systems or from gravity waves which originate from the surface or upper troposphere. The amplitude of gravity waves (Gws) of certain frequencies increases exponentially a with height because of the decreasing density. The growth factor is given, if by the square root of the ratio of the atmospheric density at source and at the height of interest. A displacement at the earth's surface of a few centimetres can originate an atmospheric GW which will grow in amplitude to several kilometres at ionospheric levels. Growth factors of 10 4 to 10 5 are typical. The layers of constant electron density move up and down with oscillatory motions similar to the acoustic pressure wave itself. Normal ocean waves do not generate acoustic waves which grow exponentially with height because their periods are well below the Brunt-Vaisala period of the atmosphere (about 300s) and their speeds are much less than the speed of sound (330 m/s); a combination which gives rise to atmospheric waves which quickly fade with height weakly ionised layers.

One of the first papers presented the special processing results of rocket-borne measurements of the electron density in the equatorial ionospheric D layer over the troposphere catastrophes ( tropical cyclones ) area at the rocket testing ground Tumba ( India ). Remote sensing observations for tropical cyclones were performed over the North Indian Ocean, the West North Pacific and the South Indian Ocean. It was detected that possible large-scale response of ionospheric state can be the “fast” depletion (2-4 times) in electron density at heights of 50 – 80 km during the action of the active phase of a tropical cyclone. It is the first observated finding of the “high-rate” action on ionosphere layer by troposphere intensive vortical systems. We suppose that the wide-spead influence of tropical cyclone is carried in the wide latitude zone. We proposed, that the lower ionosphere in the Tumba region (8 0 N, 77 0 E) has a more than only “local” influence of tropical cyclones in the North Indian Ocean the lower ionosphere of this region has global influence from the West North Pacific to the South Indian Ocean. ISSN , Geomagnetism and Aeronomy, 2008, Vol. 48, No. 2, pp. 245–250. © Pleiades Publishing, Ltd., 2008.

ISSN , Geomagnetism and Aeronomy, 2008, Vol. 48, No. 2, pp. 245–250. © Pleiades Publishing, Ltd., Table 1. Solar and geophysical information accompanying rocket flights in May–June 1985 Flight Flight Flight Zenith, deg F 10.7 Kp Ap Dst, N data time (UT) angle χ nT Based on a synchronous analysis of the series of rocket measurements of the electron concentration and thermodynamic parameters of the lower ionosphere in the equatorial region and on the remote sensing data on tropical cyclogenesis in the northern Indian Ocean, we for the first time experimentally registered a decrease in [e] in the D region at the distance of about 1000 km (in the horizontal projection) from the nucleus of a tropical cyclone in the active phase. A decrease in electron concentration is maximal (on average, a factor of 3–4) at altitudes of 71 ―/+ 3 km. In this case the lower boundary of the D region ascends by a few kilometers (not more than 5 km). During the action of TC, the temperature also slightly increased (by about 3°) at the stratopause altitude.

Rtc([e],F) — the correlation coefficient between the electron concentration and the 10.7-cm Solar radio flux in days with TC, Rq([e],F) — the correlation coefficient between the electron concentration and the 10.7-cm Solar radio flux in days without TC.

MONTHLY MEAN SUNSPOT NUMBERS ======================================================================= Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ftp://ftp.ngdc.noaa.gov/STP/space-weather/solar-data/solar-indices/sunspot-numbers/international/tables

Height, км Rq([e],F),% (1985,1988 yy.) Rtc([e],F),% (1985,1988 yy.) Rq([e],F),% ( yy.) Rtc([e],F),% ( yy.)

D ate: 28 MAY-1 JUN 1985 Tropical Storm #2 ADV LAT LON TIME WIND PR STAT /28/06Z 30 - TROPICAL DEPRESSION /28/12Z 35 - TROPICAL STORM /28/18Z 40 - TROPICAL STORM /29/00Z 45 - TROPICAL STORM /29/06Z 45 - TROPICAL STORM /29/12Z 50 - TROPICAL STORM /29/18Z 50 - TROPICAL STORM /30/00Z 50 - TROPICAL STORM /30/06Z 45 - TROPICAL STORM /30/12Z 45 - TROPICAL STORM /30/18Z 40 - TROPICAL STORM /31/00Z 40 - TROPICAL STORM /31/06Z 35 - TROPICAL STORM /31/12Z 30 - TROPICAL DEPRESSION /31/18Z 25 - TROPICAL DEPRESSION /01/00Z 20 - TROPICAL DEPRESSION

Tumba region (8 0 N, 77 0 E) Tiruchirapalli (TI311) N E

D ate: MAY 1985 Tropical Storm #1 ADV LAT LON TIME WIND PR STAT /22/18Z 30 - TROPICAL DEPRESSION /23/00Z 30 - TROPICAL DEPRESSION /23/06Z 35 - TROPICAL STORM /23/12Z 40 - TROPICAL STORM /23/18Z 45 - TROPICAL STORM /24/00Z 45 - TROPICAL STORM /24/06Z 50 - TROPICAL STORM /24/12Z 55 - TROPICAL STORM /24/18Z 60 - TROPICAL STORM /25/00Z 60 - TROPICAL STORM /25/06Z 30 - TROPICAL DEPRESSION

Date: 25 OCT-2 NOV 1981 Tropical Storm #1 ADV LAT LON TIME WIND PR STAT /25/06Z 20 - TROPICAL DEPRESSION /25/12Z 25 - TROPICAL DEPRESSION /25/18Z 25 - TROPICAL DEPRESSION /26/00Z 25 - TROPICAL DEPRESSION /26/06Z 25 - TROPICAL DEPRESSION /26/12Z 30 - TROPICAL DEPRESSION /26/18Z 30 - TROPICAL DEPRESSION /27/00Z 35 - TROPICAL STORM /27/06Z 40 - TROPICAL STORM /27/12Z 45 - TROPICAL STORM /27/18Z 50 - TROPICAL STORM /28/00Z 55 - TROPICAL STORM /28/06Z 60 - TROPICAL STORM /28/12Z 60 - TROPICAL STORM /28/18Z 60 - TROPICAL STORM /29/00Z 60 - TROPICAL STORM /29/06Z 60 - TROPICAL STORM /29/12Z 50 - TROPICAL STORM /29/18Z 45 - TROPICAL STORM /30/00Z 40 - TROPICAL STORM /30/06Z 40 - TROPICAL STORM /30/12Z 45 - TROPICAL STORM /30/18Z 50 - TROPICAL STORM /31/00Z 55 - TROPICAL STORM /31/06Z 60 - TROPICAL STORM /31/12Z 60 - TROPICAL STORM /31/18Z 60 - TROPICAL STORM /01/00Z 60 - TROPICAL STORM /01/06Z 55 - TROPICAL STORM /01/12Z 50 - TROPICAL STORM /01/18Z 45 - TROPICAL STORM /02/00Z 35 - TROPICAL STORM Kodaikanal (KO310) N E

Date: OCT 1980 Tropical Storm #1 ADV LAT LON TIME WIND PR STAT /10/06Z 25 - TROPICAL DEPRESSION /10/12Z 25 - TROPICAL DEPRESSION /10/18Z 25 - TROPICAL DEPRESSION /11/00Z 20 - TROPICAL DEPRESSION /11/06Z 20 - TROPICAL DEPRESSION /11/12Z 25 - TROPICAL DEPRESSION /11/18Z 25 - TROPICAL DEPRESSION /12/00Z 25 - TROPICAL DEPRESSION /12/06Z 25 - TROPICAL DEPRESSION /12/12Z 25 - TROPICAL DEPRESSION /12/18Z 25 - TROPICAL DEPRESSION /13/00Z 25 - TROPICAL DEPRESSION /13/06Z 25 - TROPICAL DEPRESSION /13/12Z 25 - TROPICAL DEPRESSION /13/18Z 25 - TROPICAL DEPRESSION /14/00Z 25 - TROPICAL DEPRESSION /14/06Z 25 - TROPICAL DEPRESSION /14/12Z 25 - TROPICAL DEPRESSION /14/18Z 25 - TROPICAL DEPRESSION /15/00Z 25 - TROPICAL DEPRESSION /15/06Z 25 - TROPICAL DEPRESSION /15/12Z 25 - TROPICAL DEPRESSION /15/18Z 25 - TROPICAL DEPRESSION /16/00Z 30 - TROPICAL DEPRESSION /16/06Z 30 - TROPICAL DEPRESSION /16/12Z 35 - TROPICAL STORM /16/18Z 35 - TROPICAL STORM /17/00Z 35 - TROPICAL STORM /17/06Z 30 - TROPICAL DEPRESSION /17/12Z 25 - TROPICAL DEPRESSION /17/18Z 25 - TROPICAL DEPRESSION /18/00Z 25 - TROPICAL DEPRESSION /18/06Z 25 - TROPICAL DEPRESSION /18/12Z 25 - TROPICAL DEPRESSION /18/18Z 25 - TROPICAL DEPRESSION /19/00Z 25 - TROPICAL DEPRESSION /19/06Z 25 - TROPICAL DEPRESSION /19/12Z 25 - TROPICAL DEPRESSION /19/18Z 25 - TROPICAL DEPRESSION /20/00Z 25 - TROPICAL DEPRESSION Kodaikanal (KO310) N E

Date: NOV 1980 Tropical Storm #3 ADV LAT LON TIME WIND PR STAT /12/06Z 20 - TROPICAL DEP /12/12Z 25 - TROPICAL DEP /12/18Z 25 - TROPICAL DEP /13/00Z 25 - TROPICAL DEP /13/06Z 25 - TROPICAL DEP /13/12Z 25 - TROPICAL DEP /13/18Z 25 - TROPICAL DEP /14/00Z 25 - TROPICAL DEP /14/06Z 25 - TROPICAL DEP /14/12Z 25 - TROPICAL DEP /14/18Z 25 - TROPICAL DEP /15/00Z 30 - TROPICAL DEP /15/06Z 30 - TROPICAL DEP /15/12Z 30 - TROPICAL DEP /15/18Z 30 - TROPICAL DEP /16/00Z 30 - TROPICAL DEP /16/06Z 30 - TROPICAL DEP /16/12Z 30 - TROPICAL DEP /16/18Z 30 - TROPICAL DEP /17/00Z 35 - TROPICAL STO /17/06Z 35 - TROPICAL STO /17/12Z 35 - TROPICAL STO /17/18Z 35 - TROPICAL STO /18/00Z 35 - TROPICAL STO /18/06Z 35 - TROPICAL STO /18/12Z 30 - TROPICAL DEP /18/18Z 25 - TROPICAL DEP /19/00Z 20 - TROPICAL DEP /19/06Z 20 - TROPICAL DEP Bombay (BM219) N E