Solar radiation tidal forcing of radon signals in

Solar radiation tidal forcing of radon signals in subsurface air Steinitz, G. , Piatibratova, O. , Kotlarsky, P. Geological Survey of Israel, Jerusalem steinitz@gsi. gov. il The reasoning Geophysical background Signal types, periodicity, Solar tide components Period 24 -, 12 -hours 1. Daily signals Temporal phenomena encountered differ among sites, but have similar fundamental characteristics. Tidal component S 1, S 2 2. Multi-Day 365. 2 days 182. 6 days 121. 7 days 6. Multi-Year Radon monitoring arrays along the Dead Sea Rift (DSR) (non-periodic) 3. Annual radon 4. Semi-annual radon 5. Ternary annual radon Rn Acronym DR (non-periodic? ) MD SA STA AR SAR TAR • Array of stations, along a 20 km sector • 1. 5 m deep in unconsolidated gravel 1999 NW Gulf Elat, Rn in seawater Shore gravel; 2 m deep, 130 days Granite; Elat; 54 m Main components Cycles Name Period (hr) O 1 25. 82 S 1 24. 00 (17 W, Gamma detector) M 2 12. 42 Principal solar S 2 12. 00 demonstrated. They are attributed to the solar tidal constituents Sa, SSa and STa. Day 2011 2008 2. 5 e+5 Gamma 2009 2010 2500 3000 3500 4000 4500 5000 Elat Granite: 5500 2002 2004 2006 2008 2010 1999 200 Gamma (counts) 1200 2. 3 e+5 1100 Alpha-H Alpha-L 1000 5600 5800 6000 6200 6400 6600 5600 6800 2003 2005 2007 5800 6000 6200 6400 6600 6800 Day since 1. 1. 1992 2002 2009 150 2003 2004 10000 400 500 MS MD AR DR S 1 8000 0 50 0 100 6000 Year 2005 100 12000 2. 2 e+5 2001 Amram 1300 (Rn source) • Measured pattern • Smoothed time series - AR signal and SAR signal as an asymmetry • Modulation of the residual time series - AR and SAR signal Roded: Annual variation of amplitude of the diurnal periodicities S 1, S 2 14000 2. 4 e+5 3 e+5 2011 Alpha 1400 2 e+5 Measured Long-term bias Annual Radon (AR) Long-term (MY) 5. 0 e+4 2. 0000 2010 the experiment. In addition to the annual periodicity clear semiannual and ternary annual signals are 5000 Counts 1 e+5 1. 9324 2009 Further insight is derived from the long term variations in time series from the geological environment and from Bias 1. 0000 2008 the amplitude and phase of the diurnal constituents S 1, S 2 and S 3. Historgram of values 0 Principal lunar Counts/15 -min external geophysical influence is further indicated by compounded relations that occur as annual modulation of 2007 0. 9295 Solar diurnal (air) 2005 and S 3. Periodicities indicative for diurnal gravity tide (O 1, M 2; Lunar influence) are clearly lacking. Profound 1. 0 e+5 (Day-1) Principal lunar declinational Metal tank, tight 2003 1. 5 e+5 Granite; Elat; 54 m Experimental replication 2001 17 W Gravel; NW Dead Sea; 1. 5 m are dominated by periodicities of 24 -, 12 -, and 8 -hours which are attributed to the Solar tidal constituents S 1, S 2, Amplitude Elat Granite gamma radiation emitted from radon in the tank air varies spatially and temporally. A 4 -year time series shows Counts Roded radon, the latter diffusing into the upper air volume from U bearing ground phosphorite (376 Kg). Alpha and 10000 S 2 • Array of stations, 20 km sector • In Precambrian basement rocks • Depth 2 to +100 meter recording radon within a confined volume of Air. The setup consisted of an isolated volume (640 L) of air with The multi-year rising trend observed at Experiment, 17 W and Amram sites. The temporal pattern is measured by alpha and gamma detectors in Amram and in the Experiment. S 1 Southern Arava phenomena at depth. multi-year and multi-day signals and especially periodic signals of annual and daily scale. The diurnal variations S 2 Amram meter. A component of solar irradiation tide was suggested (References) as the driver of these periodic Gravity tide - rare Solar irradiance related components - S 1, S 2 dominate = solar tide S 1 in the arid desert of southern Israel demonstrated that the periodic variations, are observed to a depth of >100 • Periodicity is forced by solar tide • A component of solar radiation? Intraplate GAV – multi-year, annual to daily and sub-daily duration. Analysis of extensive data sets from key sites 200 km apart IMPLIES Periodograms of the diurnal components of radon signals in subsurface air • Depth: 1. 2 m & 90 meter • Massive syenite temporal variations composed of periodic and non-periodic signals spanning several orders of magnitude in time Alpha (counts) 21 W by alpha and gamma activity during the decay of radon and its progeny. Radon in geogas exhibits systematic The issue of external forcing of radon signals was tested experimentally using alpha and gamma detectors MY NW Dead Sea 17 W Radon (Rn-222) occurs at highly varying levels as a trace component in subsurface air (geogas). It is measured S 2 400 200 300 200 0 100 Counts/15 -minute High temporal resolution monitoring of radon, using alpha & gamma detectors, is carried out at several arrays located in arid southern Israel. Monitoring, at a resolution of 15 -minutes, is conducted at depths ranging from 1. 5 to 120 meter. • Dominance of solar tidal frequencies of annual, and daily scale • Annual modulation of the amplitude and phase of daily and sub daily tidal frequencies • Systematic multi-year variation of signal and periodic characteristics • Occurrence different locations, at depth to >100 meter • Similar phenomena in laboratory experiments of radon in confined air And • Negation of climatic influences • [Lack of gravity tidal frequencies] Counts/15 -minute Monitoring sites 0 50 -200 5660 5670 5680 5690 26. 0 1335 2. 400 e+5 1330 6020 6030 6040 6050 6060 26. 6 6070 Day since 1. 1. 1992 1400 27. 4 2. 428 e+5 o 2009 26. 2 2010 2. 425 e+5 1390 1300 1200 2. 3 e+5 Gamma-C Alpha-H Alpha-L Temperature 27. 2 Alpha Gamma 2. 435 e+5 1400 Gamma Alpha C 2. 4 e+5 C 1385 27. 0 2. 423 e+5 5750 6000 6250 6500 o C 10 Spectral analysis: SA. SSA, STA periodicities 6390 6400 6410 Day since 1. 1. 1992 6420 6430 1375 6750 6760 6770 6780 6790 Day since 1. 1. 1992 6800 6810 26. 8 CWT analysis: Annual modulation of the amplitude of DR signal (S 1 and S 2) occurs as a compounded feature 80 2009 2010 2008 Alpha H 2001 2003 2005 2007 2009 2010 75 5 4 40 2 20 2500 0. 01 0. 02 0. 03 0. 04 0. 05 Cycle/day Mean of two alpha detectors 75 1 Gamma C 10 5 Alpha L 2006 2007 2008 2009 S 1 50 25 25 2 0. 04 0. 05 Cycle/day Spectra of alpha and gamma measurements (Experiment - 4 yrs) show clear peaks characteristic for annual and semiannual periodicity (365. 2 and 182. 6 cycle/day). 0 5500 S 1 0 5000 2004 2005 2006 S 2 2007 2008 500 0 GAV: Annual modulation of the amplitude of the diurnal 6 periodicities S 1 and S 2 150 S 2 3000 4000 5000 Days since 1. 1. 1992 6000 S 1 100 50 15 0 2003 10 2004 2005 2006 2007 2008 REFERENCES 0 2 4500 2 0. 03 4800 4 4 0. 02 4600 5 6 0 2 2 0 6 6 10 0. 01 4400 1000 4 8 0. 00 4200 0 12 50 2005 7 0 14 2003 2009 4 6 gamma-C 0 Amplitude 6380 2. 420 e+5 6740 Phase 60 Amplitude 26. 0 2008 5000 4000 GAV: Daily averages at 1. 2 meter 6 Amplitude 1380 2. 430 e+5 6370 1999 15 Day since 1. 1. 1992 3800 Days since 1. 1. 1992 diurnal periodicities S 1, S 2 Amplitude and phase are extracted by applying FFT windowing, where each point represents a (consecutive) 21 -day time interval. 6750 3600 Days since 1. 1. 1992 7000 Roded: Multi-year variation of phase of the 20 1100 o 3400 6000 Daily mean (counts) 5650 2008 Smoothed pattern of • AR & SAR signals • (maxima of T – lags) 25 6000 5000 amplitude 1340 26. 1 1330 5700 C 1345 1335 2. 430 e+5 5640 o 26. 8 2. 405 e+5 30 5000 4000 Spectra for alpha and gamma measurements (9 yrs) show clear peaks characteristic for annual and semi-annual periodicity (365. 2 and 182. 6 cycle/day). 2011 1400 4000 phase (rad) 26. 2 1355 2010 Day Amplitude (x 1000) 26. 3 2. 410 e+5 2009 3000 Amplitude (x 1000) C Gamma 2. 435 e+5 1350 Alpha Gamma 2007 26. 4 o Alpha 2. 440 e+5 1355 2008 27. 0 Counts/15 -min (gamma-C) 1360 2. 415 e+5 26. 5 0 Phase (rad) 30 days Semi-annual radon signals are superimposed on the annual signal recorded by alpha-L and gamma-C. A similar semi-annual pattern is absent in the ambient temperature. Amplitude (counts x 103) Gamma-C Alpha-H Alpha-L Temperature Counts/15 -min (alpha) Nuclear radiation - summer peak times of annual signal -100 4000 6500 Days since 1. 1. 1992 5500 S 1 S 2 S 3 5500 6000 6500 Days since 1. 1. 1992 0 6000 5000 6500 Days since 1. 1. 1992 Annual modulation of the periodic components (amplitude & phase) of the DR signal in Experiment. • Annual variation of the amplitudes of the daily components is dissimilar for gamma and alpha time series - showing opposite temporal patterns! 21 W: Annual and semi-annual modulation of the amplitude of the diurnal periodicities S 1 and S 2 1. Steinitz, G. , O. Piatibratova, and S. M. Barbosa, 2007. Radon daily signals in the Elat Granite, southern Arava, Israel, J. Geophys. Res. , 112, B 10211, doi: 10. 1029/2006 JB 004817. 2. Steinitz, G. , Piatibratova, O. , 2010 a. Radon signals in the Gavnunim intrusion, Makhtesh Ramon, Israel. Geophys. J. Int. 180, 651– 665. 3. Steinitz, G. and Piatibratova, O. , 2010. Radon signals at the Roded site, Southern Israel, Solid Earth, 1, 99 -109, doi: 10. 5194/se-1 -99 -2010.