UV data of the “Universitetsky-Tatiana-1” satellite and plans for the Tatiana-2.

A.V. Dmitriev, G.K. Garipov, O.R. Grigoryan, B.A. Khrenov, P.A. Klimov, L.L Lazutin, I.N. Myagkova, A.N. Petrov, V.L. Petrov, M. I. Panasyuk, V.I. Tulupov,

V.M. Shahparonov, A.V. Shirokov, N.N. Vedenkin, I.V. YashinD.V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Russia.

J.A. Jeon, S.M. Jeong, A. Jung, J.E. Kim, W.S. Kim, J. Lee, H.Y. Lee, G.W.

Na, S.W. Nam, S.J. Oh, I.H. Park, J.H. ParkResearch Center of MEMS Space Telescope, Ewha Womans University,

Seoul, Korea J.Y. Jin, M. Kim, Y.K. Kim, B.W. YooDepartment of Electrical Engineering, Seoul National University, Seoul, Korea Y.-S. Park, H.J. YooDepartment of Astronomy, Seoul National University, Seoul, Korea C.H. LeeDepartment of Physics, Pusan National University, Pusan, KoreaH.I Salazar, O.B. Martinez, E.L. Ponce, J.P. Cotsomi University of Puebla (BUAP), Puebla, Mexico.

Corresponding author: B.A. Khrenov, bkhrenov@yandex.ru

UV detector on board the “Universitetsky-Tatiana” satellite has measured the atmosphere glow in near UV range (wavelengths 300-400 nm), [1-4]. Polar orbit, height-950 km. Measurements were done in period January 2005-March 2007.It is an educational satellite, see Web site http://cosmos.msu.ru

Important detector features [3]:1. Constant anode current, HV iscontrolled by UV intensity.2. Digital oscilloscopes for UV flashes.

FOV diameter in the atmosphere- 250 km

The “Universitetsky-Tatiana” detector measured UV intensity from minimal night values of 2 107 ph/cm2 s sr to maximal values of 1013 ph/cm2 s sr on the day side.At moonless nights it allowed to measure variable UV intensity on the night side from bright aurora oval to minimal glow in the equatorial region.

UV intensity on July 5, 2005, the satellite crosses the aurora oval in the Southern Hemisphere. Order of magnitude less intensity is detected at middle latitudes. Minimal intensity is near the equator.

UV intensity on December, 2005, the satellite crosses the aurora oval in the Northern Hemisphere. 10 times less intensity is detected near the equator. Moonless night.

In most other satellite circulations the aurora oval is out of sight butUV intensity at the middle latitudes and near equator was measured (seethe next Figure).

Winter in the NorthernHemisphere |

Winter inthe SouthernHemisphere

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The “Universitetsky- Tatiana” data indicate two regions of the UV intensity in the Earth atmosphere different by order of magnitude:

1. polar aurora zones (Iuv ~109 ph/cm2 s sr) and 2. equatorial- middle latitude zones (Iuv ~108 ph/cm2 s sr).

At moon nights the moon UV light back scattered from the atmosphereand clouds light is the brightest source. Variation of detected light due to cloud “albedo” effect prevails over other effects: at some regions UV intensity comes up to 2 109 photons/cm2 s sr.

The electron and proton intensity was measured at the Tatiana orbit [4].

The bright UV aurora zones (red points) evidently are correlated with the electron outer belt. Origin of the moderate UV intensity at middle and near equator latitudes (pink points) is not certain and has to be studied.

Electron threshold 70 KeV.

No correlation of UV radiation with electrons in South Atlantic Animaly (SAA) was observed by Tatiana.

Example of data for Tatiana’s orbit crossing SAA (time interval 4.8-4.9). Electron threshold energy is indicated in the figure. UV intensity is the thick black line.

UV intensity order of magnitude weaker than aurora in the equatorial-middle latitudes was observed in GUVI measurements but for the wavelength 135.6 nm (O- line) [5]. The Tatiana’s results are for 300-400 nm (N2

+- lines).

This phenomenon is day-night- and season variable and is not well understood. Equatorial Ionosphere Anomaly in the sunlight hemisphere and ring current charge-exchange losses at nighttime are under discussion.

UV flashes registered by the “Tatiana” detector [1,2].

We select the brightest event in one circulation.The noise event is rare (see the left event below)UV energy released in the atmosphere is in the range of10kJ -1MJ.

Oscilloscope trace 4 ms.

Oscilloscope trace- 64 ms. There are events with UV energy release in the atmosphere up to 1 MJ.

In 2 years of observation the UV events ( map in the upper panel) do not correlate with continents as it is the case for lightning (the bottompanel, [6]).

The “Tatiana” data on UV flashes indicate the correlation with the lunar phase, [7]. Bottom panels are:a- for all registered (362) events, b- for events with energy above the threshold:E=10KJ for 4 ms trace, and E=50KJ for 64 ms trace.

World map of UV events. a- at full moon, b- at new moon.Shaded areas are for water vapor column: a->5 g/cm2, b- >3 g/cm2

Preliminary interpretation of the moon effect ([7]).

The water vapor concentration in the equatorial region is expected to be higher at full and new moons due to lunar tidal effect on the atmosphere. As a consequence, the electric field in the equatorial region with larger water vapor amount is higher and the rate of UV transients is higher during full and new moon. The other effect is also of the same origin. The moon tidal force brings water vapor to higher altitudes where the atmospheric temperature is lower. For lower temperatures, the yield of UV fluorescence is higher due to the fact that radiation de-excitation prevails over collision de-excitation. The colder temperature also increases the contamination of ice crystals in the clouds- in favor of electric activity.

Both of these effects (larger electric field and higher UV radiation yield) may enlarge the rate and brightness of UV transient events at full moon.

Observation of correlation between Transient Luminous Events (TLE) and lunar phase is a difficult experiment. Only few TLE detectors are able to operate at full moon.Gigantic Jets (5 events) detected by theTaiwanese group were observed at full moon night, [8].

ISUAL group [9,10] does not consider the moon night pictures as good for statistical analysis. For full moon they could not fix the distance to TLE in many cases. Nevertheless some examples of ISUAL events were observed in the same region where the Tatiana event was registered(example in the Figure). Red points are ISUAL events, the blue one is the Tatianaevent.

ISUAL spectral/temporal signature of Elves

Comparison of Tatiana events with the ISUAL ones shows a common feature between Tatiana events and ISUAL ELVEs events.

More than half of the Tatiana and ELVEs events are detectedabove ocean in contrast tosprite events which are concentrated above continents.

An interesting question is: could TLEs be a source of near equatorialelectrons detected at the Tatiana orbit?In the “run away electrons” model of TLE development electrons are accelerated to energies of tens MeV so that some percentage of them (~10%, Lehtinen [11]) are capable to escape the atmosphere. They will be trapped at L~1-2 shells. Life time of such a “belt” is expected to be short (several bounces). At the conjugate point electrons are coming back to the atmosphere and produce an UV glow. Intensity of UV at the conjugate point will be much less than in the TLE origin point.

Disadvantages of the “Universitetsky-Tatiana” mission were:1. Shortages of data-transmittance system. Only data for 5 orbits (among 15 per day) were recorded and transmitted.2. In many days per year the satellite orientation was not as specified.3. There was no imager for transient events.4. Only near UV range was available for transients.

In the next Tatiana-2 mission the instrumentation for transient events will beimproved.

1. Data transmitter will allow to send 5 Mbit data per orbit.2. In transient detector the UV range (300-400 nm) will be added by red range (600-700 nm). Temporal profile in UV and Red will give the additional information on vertical profile of he event.

The new detectors on board of Tatiana-2 are:-MEMS “telescope” and spectrometer.-Electron flux detector of area 400 cm2 .

___________ electron detector,

_________ telescope and spectrometer

MTEL imager. The image is organized by micro mirror beamreflection of the object light to multi-anode photomultiplier.

MTEL Spectrometer. Spectrometer FOV covers the same area in the atmosphere as MTEL imager.

_____Multi anode PMT

Multi- band filters____

The expected transient event development in nadir observation andsignals in the new imager and in the spectrometer..

Artistic view ofthe transient eventin nadir observation(based on the calculations in [12,13[ .

Signal in the imager.

Signal in the spectrometer

Measurement of TLE radiation spectrum will help to interpret the nadirimages. At the atmosphere depths X<0.2 g/cm2 (altitudes H>57 km) the TLEred yield prevails over UV.

Dependence of UV and Red light yield from N+2 excitation on the depth in the atmosphere.

Detector of UV (300-400 nm) and red radiation (600-700 nm).

Electron flux detector. Area 400 cm2.

Scintillation plate

Photomultipliertube

Light guide- convertor

Temporal profiles of signal in UV-Red detector will be compared with the profiles in the electron detector.

Conclusion.1. The Universitetsky-Tatiana mission gave interesting results on origin of UV

glow at various latitudes in simultaneous monitoring of the atmosphere UV glow and charge particle flux at the orbit. Monitoring of UV and electron flux at equatorial- middle latitudes has to be continued in Tatiana-2 mission.

2. The detected transient UV events are concentrated in the equatorial region, frequent over ocean and affected by the Moon.

3. In the “Tatiana-2” experiment the data on transient events will be improved in the following directions:

- image observation in UV range (wavelengths 300-400 nm) with high resolution in space and time,

- simultaneous measurement of radiation spectrum in wide range of wavelengths 300-600 nm,

- simultaneous measurement of the electron flux at the satellite orbit by large area detector capable to measure a low electron density flux in sub-millisecond time samples,

- larger energy range of the detected events and much larger statistics due to improved data transmitting system.

4. New sets of data on radiation in the atmosphere in wide wavelength range, on electron flux at the orbit and on transient events could be interrelated due to a possible electron acceleration in the electrical atmosphere discharges.

References1. Garipov G.K., Khrenov B.A., Panasyuk M.I., Tulupov V.I., Salazar H., Shirokov A.V., Yashin I.V., UV flashes in the equatorial region of the Earth. JETP Letters, 82 (2005) 185-187. 2. Garipov G.K., Khrenov B.A., Panasyuk M.I., Tulupov V.I., Shirokov A.V., Yashin I.V. and Salazar H., UV radiation from the atmosphere: Results of the MSU “Tatiana” satellite measurements, Astroparticle Physics, 24 (2005) 400-408,.3. Garipov G.K., Khrenov B.A., Panasyuk M.I., Rubinshtein I.A., Tulupov V.I., Salazar H., Shirokov A.V., Yashin I.V., UV radiation detector of the MSU research educational micro satellite “Universitetsky-Tatyana”. Instruments and Experimental Techniques, 49 (2006) 126-131. 4. Sadovnichy V.A. et al, Cosmic Research, First results of investigating the space environment onboard the “Universitetsky-Tatiana” satellite. Cosmic Research, 45, 273-286, 2007.5. Christensen, A. B., L. J. Paxton, S. Avery, J. Craven, G. Crowley, D. C. Humm, H. Kil, R. R. Meier, C.-I Meng, D. Morrison, B. S. Ogorzalek, P. Straus, D. J. Strickland, R. M. Swenson, R. L. Walterscheid, B. Wolven, and Y. Zhang, Initial observations with the Global Ultraviolet Imager (GUVI) in the NASA TIMED satellite mission, J. Geophys. Res., 108 (A12), 1451, 2003.6. GHCC Lightning Research Overview,

www.ghcc.msfc.nasa.gov/overview/lightning.ht

7. Garipov G.K., Khrenov B.A. and Panasyuk M.I., Geophys. Research Lett., 35, L10807;doi: 10.1029/2007 GL032679, 2008.8. Su H.T., Hsu R.R, Chen A.B., Wang Y.C., Hsiao W.S., Lal W.C., Lee L.C., Sato M., Fukunishi H. Gigantic Jets between a thundercloud and the ionosphere, Nature, 423, 974- 976, 2003. 9. Chern, J.L., R.R. Hsu et al, Global survey of upper atmospheric transient luminous events on the ROCSAT-2 satellite. J. Atmos. Sol. Terr. Phys., 65, 647-659 (2003). 10. ISUAL data at WEB, http://proton.phys.ndu.edu.tw/spr.11. Lehtinen N.G., Relativistic runaway electrons above the thunderstorms. PhD dissertation, Stanford University, 2000. 12. Pasko V.P., Inan U.S. and Bell T.F., Mesosphere-troposphere coupling due to sprites. Geophys. Res. Letters, v.28, #19, p. 3821-3824 (2001). 13. Pasko V.P. Physical mechanisms of TLE between thunderstorm tops and lower ionosphere. Lorentz Center, Leiden University, 2005, May 9-13.