Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar

Parameswaran, K.; Sasi, M. N.; Ramkumar, Geetha; Nair, Prabha R.; Deepa, V.; Murthy, B. V. Krishna; Nayar, S. R. Prabhakaran; Revathy, K.; Mrudula, G; Satheesan, K.; Bhavanikumar, Y.; Sivakumar, Venkataraman; Raghunath, K.; Rajendraprasad, T; Krishnaiah, M.

doi:10.1016/s1364-6826(00)00124-3

Cited by 35 publications

(32 citation statements)

References 13 publications

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“…For 15% un cer tainty in the pres sure at the top of the height range, the tem per a ture un cer tainty would be < 2% at 15 km be low the top. Com plete de tails about the tem per ature re trieval and er rors in volved were given by Parameswaran et al (2000). The tem per a ture pro file can be ob tained with a ver ti cal res o lu tion of 300 m, how ever, we have in ter po lated the data to 100 m for com par i son with other in stru ments.…”

Section: Nd: Yag Rayliegh Lidar Datamentioning

confidence: 99%

Validation of the COSMIC Radio Occultation Data over Gadanki (13.48°N, 79.2°E): A Tropical Region

Rao¹,

Ratnam²,

Mehta³

et al. 2009

Terr. Atmos. Ocean. Sci.

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AB STRACTCon stel la tion Ob serv ing Sys tem for Me te o rol ogy Ion o sphere and Cli mate (COS MIC), con sist ing of six Low Earth Or bit (LEO) Global Po si tion Sys tem (GPS) re ceiv ers, on board the Formosat Sat el lite 3 (FORMOSAT-3) is pro vid ing dense ob ser va tions of den sity, refractivity, tem per a ture and wa ter va por pro files of the neu tral at mo sphere since mid dle of July 2006. Spe cial ra dio sonde (Väisälä) cam paign was con ducted at Gadanki (13.48°N, 79.18°E), a trop i cal site in In dia, dur ing July 2006 to March 2007 to val i date these me te o ro log i cal pa ram e ters. Co-lo cated Nd: YAG Ray leigh lidar was also op er ated dur ing the over pass of COS MIC and is uti lized to val i date the tem per a tures in the height range of 30 to 40 km. A to tal of 142 over passes oc curred dur ing the above men tioned pe riod within 300 km dis tance from Gadanki out of which 41 over passes oc curred within a time dif fer ence of ±4 hours of ra dio sonde launch. In ad di tion, 18 over passes oc curred within the time dif fer ence of ±4 hours of lidar op er a tion. A de tailed com par i son has been made with all these over passes for the refractivity, tem per a ture and wa ter va por ob tained from COS MIC. The wa ter va por com par i son has shown gen er ally a good agree ment with a mean dif fer ence of 5 -10% be low 6 -7 km. Al though there is a colder bias be tween COS MIC and ra dio sonde, a very good com par i son in tem per a ture is also found be tween 10 and 27 km with a mean dif fer ence of less than 1 K (RMS dif fer ence is only 0.64 K). There ex ists a large dif fer ence in tem per a ture of about 8 K be tween 30 and 40 km (be tween COS MIC and lidar). Pos si ble rea sons for these large dif fer ences are given. There was one event that oc curred just over Gadanki for which a de tailed com par i son has been made with spe cial em pha sis on wa ter va por re triev als. Sen si tiv ity test is also done on the frac tional dif fer ence in N for the event that occurred on 24 July 2006 between COSMIC (1D-var) and radiosonde and found that pressure plays a key role than temperature in determining the refractivity. Atmos. Ocean. Sci., 20, 59-70, doi: 10.3319/ TAO.2008.01.23.01(F3C) IN TRO DUC TIONRa dio occultation soundings of the sig nals from the Global Po si tion ing Sys tem Sat el lites (GPS) are be ing used to ob tain ver ti cal pro files of at mo spheric tem per a ture, pressure and wa ter va por for cli mate re search and weather predic tion (Kursinski et al. 1997). The GPS Ra dio occultation tech nique has emerged as a pow er ful tool for ex plor ing the earth's at mo sphere from ground to a height of around 40 km and also in the ion o sphere af ter the suc cess ful launch of GPS/MET which has pro vided a 'proof of con cept' of GPS Ra dio Occultation (RO) tech nique. Sev eral mis sions such as Oers ted and SAC-C (Hajj et al. 2004) fol lowed GPS/

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Section: Nd: Yag Rayliegh Lidar Datamentioning

confidence: 99%

Validation of the COSMIC Radio Occultation Data over Gadanki (13.48°N, 79.2°E): A Tropical Region

Rao¹,

Ratnam²,

Mehta³

et al. 2009

Terr. Atmos. Ocean. Sci.

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“…The standard error of these measurements is 0.7 K at 7 km and 1.6 K at 20 km (Revathy et al, 1998). The altitude profiles of temperature in the altitude region of 27 to 65 km over Gadanki are obtained from the Rayleigh Lidar observations (Parameswaran et al, 2000). Lidar employs an Nd:YAG laser, operated at its harmonic wavelength of 532 nm, as the transmitter.…”

Section: Datamentioning

confidence: 99%

“…The system provides backscattered signals, which are integrated over 5000 transmitted pulses, corresponding to a temporal averaging of 250 s and these form the basic raw data for further analysis. Estimation of temperature from lidar data and the sources of errors are explained in detail by Parameswaran et al (2000). The statistical error due to signal variance is ∼1 K in the lower altitudes (30-50 km) and it increases with altitude (∼2.5 K at 65 km).…”

Section: Datamentioning

confidence: 99%

Observational evidence for the generation of a 4-day oscillation in the low-latitude middle atmosphere associated with an anomalous stratospheric cooling

2007

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Abstract. Altitude profiles of temperature in the stratosphere and lower mesosphere over Gadanki (13.5 • N, 79.2 • E), based on lidar observations during the Equatorial Wave Study campaign (29 February-2 April 2000), showed an anomalous cooling of the stratosphere, lasting for about 4-5 days. Immediately following this stratospheric cooling, a prominent ∼4-day period oscillation is observed in the zonal, as well as meridional wind in the 30-50 km altitude region, obtained from simultaneous rocketsonde and balloon wind measurements. The amplitude of this wave is in the range of 5-15 ms −1 in this altitude region. The altitude profiles of phase of this 4-day oscillation show a constant phase with height indicating that the wave is not propagating vertically. The causative mechanism for the sudden cooling is investigated by examining the day-to-day variation in the total atmospheric column ozone. Zonal and meridional wind components of this oscillation are approximately in quadrature phase, with zonal wind leading the meridional wind. Strikingly, while the 4-day wave is clearly observable in the zonal and meridional winds, it is almost absent in the temperature.

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“…As MST radar provides vertical-wind data generally up to an altitude of 25 km, lidar and MST radar operated together can provide altitude pro les of temperature in the entire altitude range from the troposphere to the mesosphere. Parameswaran et al (2000) derived temperature pro les from 4 to 70 km making use of the collocated experiments with MST radar and lidar at Gadanki (13.5 ± N, 79.2 ± E), a near-equatorial station. An experimental campaign was conducted from 18 January 1999 to 5 March 1999 using MST radar and lidar at Gadanki to study equatorial waves in temperature in the altitude range »4 km to 70 km.…”

Section: Introductionmentioning

confidence: 99%

Equatorial waves in temperature in the altitude range 4 to 70 km

Murthy

Satheesan

Parameswaran

et al. 2002

Quart J Royal Meteoro Soc

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SUMMARYUsing altitude pro les of temperature in the range 4 to 70 km derived from Mesosphere-StratosphereTroposphere radar and lidar observations at Gadanki (13.5 ± N, 79.2 ± E) from 18 January 1999 to 5 March 1999, characteristics of equatorial waves are studied. Two-dimensional Fourier-transform analysis of the temperature pro les is carried out to identify the periodicities and their vertical wave numbers. From the characteristics obtained, equatorial slow Kelvin waves with periodicities 15.7 d, 9.4 d, 7.8 d and 6.7 d are identi ed in the troposphere and stratosphere regions and among these 7.8 d and 6.7 d periodicities are found to penetrate into the mesosphere. Equatorial waves with smaller periodicities in the range 5.2 d to 3.6 d are also observed. The vertical ux of horizontal momentum (zonal) of the identi ed slow Kelvin-wave periodicities in the altitude region 4-25 km is estimated. It is found that equatorial waves modulate tropical tropopause temperature and altitude.

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Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar

Cited by 35 publications

References 13 publications

Validation of the COSMIC Radio Occultation Data over Gadanki (13.48°N, 79.2°E): A Tropical Region

Validation of the COSMIC Radio Occultation Data over Gadanki (13.48°N, 79.2°E): A Tropical Region

Observational evidence for the generation of a 4-day oscillation in the low-latitude middle atmosphere associated with an anomalous stratospheric cooling

Equatorial waves in temperature in the altitude range 4 to 70 km

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