scholarly journals Mesospheric temperature inversions over the Indian tropical region

2004 ◽  
Vol 22 (10) ◽  
pp. 3375-3382 ◽  
Author(s):  
S. Fadnavis ◽  
G. Beig
Keyword(s):  
Seasonal Variation ◽  
Inversion Layer ◽  
Temperature Inversion ◽  
Peak Height ◽  
Tropical Region ◽  
Frequency Of Occurrence ◽  
Altitude Range ◽  
Mesospheric Temperature ◽  
Rayleigh Lidar ◽  
Temperature Inversions

Abstract. To study the mesospheric temperature inversion, daily temperature profiles obtained from the Halogen Occultation Experiment (HALOE) aboard the Upper Atmospheric Research Satellite (UARS) during the period 1991-2001 over the Indian tropical region (0-30° N, 60-100° E) have been analyzed for the altitude range 34-86km. The frequency of occurrence of inversion is found to be 67% over this period, which shows a strong semiannual cycle, with a maximum occurring one month after equinoxes (May and November). Amplitude of inversion is found to be as high as 40K. Variation of monthly mean peak and bottom heights along with amplitude of inversions also show the semiannual cycle. The inversion layer is detected most frequently in the altitude range of 70-85km, with peak height ranging from 80 to 83km and that of the bottom height from 72 to 74km. A comparison of frequency of temperature inversion with that obtained from Rayleigh lidar observations over Gadanki (13.5° N, 60-100° E) is found to be reasonable. The seasonal variation of amplitude and frequency of occurrence of temperature inversion indicates a good correlation with seasonal variation of average ozone concentration over the altitude range of the inversion layer.

scholarly journals Methodology for determining multilayered temperature inversions

2015 ◽  
Vol 8 (5) ◽  
pp. 2051-2060 ◽  
Author(s):  
G. J. Fochesatto
Keyword(s):  
Temperature Profile ◽  
Large Scale ◽  
Error Function ◽  
Inversion Layer ◽  
Lower Troposphere ◽  
Temperature Inversion ◽  
Linear Interpolation ◽  
Pollution Dispersion ◽  
Thermal Inversion ◽  
Temperature Inversions

Abstract. Temperature sounding of the atmospheric boundary layer (ABL) and lower troposphere exhibits multilayered temperature inversions specially in high latitudes during extreme winters. These temperature inversion layers are originated based on the combined forcing of local- and large-scale synoptic meteorology. At the local scale, the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling and air pollution dispersion; however, depending upon the large-scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is reported to determine thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extracts from the temperature profile the most important temperature variations defining thermal inversion layers. This is accomplished by a linear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce the multilayered temperature inversion structure with an error fraction set independently.

scholarly journals Influence of gravity waves and tides on mesospheric temperature inversion layers: simultaneous Rayleigh lidar and MF radar observations

2008 ◽  
Vol 26 (12) ◽  
pp. 3731-3739 ◽  
Author(s):  
S. Sridharan ◽  
S. Sathishkumar ◽  
S. Gurubaran
Keyword(s):  
Gravity Wave ◽  
Wave Interaction ◽  
Temperature Inversion ◽  
Lapse Rate ◽  
Wave Interactions ◽  
Tidal Gravity ◽  
Mesospheric Temperature ◽  
Wind Measurements ◽  
Rayleigh Lidar ◽  
Mf Radar

Abstract. Three nights of simultaneous Rayleigh lidar temperature measurements over Gadanki (13.5° N, 79.2° E) and medium frequency (MF) radar wind measurements over Tirunelveli (8.7° N, 77.8° E) have been analyzed to illustrate the possible effects due to tidal-gravity wave interactions on upper mesospheric inversion layers. The occurrence of tidal gravity wave interaction is investigated using MF radar wind measurements in the altitude region 86–90 km. Of the three nights, it is found that tidal gravity wave interaction occurred in two nights. In the third night, diurnal tidal amplitude is found to be significantly larger. As suggested in Sica et al. (2007), mesospheric temperature inversion seems to be a signature of wave saturation in the mesosphere, since the temperature inversion occurs at heights, when the lapse rate is less than half the dry adiabatic lapse rate.

scholarly journals Statistical analysis of the mesospheric inversion layers over two symmetrical tropical sites: Réunion (20.8° S, 55.5° E) and Mauna Loa (19.5° N, 155.6° W)

2017 ◽  
Vol 35 (6) ◽  
pp. 1177-1194 ◽  
Author(s):  
Nelson Bègue ◽  
Nkanyiso Mbatha ◽  
Hassan Bencherif ◽  
René Tato Loua ◽  
Venkataraman Sivakumar ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Mean Amplitude ◽  
Temperature Inversion ◽  
Tropical Region ◽  
Height Range ◽  
Tropical Regions ◽  
Mauna Loa ◽  
Annual Component ◽  
Rayleigh Lidar ◽  
Lidar Observations

Abstract. In this investigation a statistical analysis of the characteristics of mesospheric inversion layers (MILs) over tropical regions is presented. This study involves the analysis of 16 years of lidar observations recorded at Réunion (20.8° S, 55.5° E) and 21 years of lidar observations recorded at Mauna Loa (19.5° N, 155.6° W) together with SABER observations at these two locations. MILs appear in 10 and 9.3 % of the observed temperature profiles recorded by Rayleigh lidar at Réunion and Mauna Loa, respectively. The parameters defining MILs show a semi-annual cycle over the two selected sites with maxima occurring near the equinoxes and minima occurring during the solstices. Over both sites, the maximum mean amplitude is observed in April and October, and this corresponds to a value greater than 35 K. According to lidar observations, the maximum and minimum mean of the base height ranged from 79 to 80.5 km and from 76 to 77.5 km, respectively. The MILs at Réunion appear on average ∼ 1 km thinner and ∼ 1 km lower, with an amplitude of ∼ 2 K higher than Mauna Loa. Generally, the statistical results for these two tropical locations as presented in this investigation are in fairly good agreement with previous studies. When compared to lidar measurements, on average SABER observations show MILs with greater amplitude, thickness and base altitudes of 4 K, 0.75 and 1.1 km, respectively. Taking into account the temperature error by SABER in the mesosphere, it can therefore be concluded that the measurements obtained from lidar and SABER observations are in significant agreement. The frequency spectrum analysis based on the lidar profiles and the 60-day averaged profile from SABER confirms the presence of the semi-annual oscillation where the magnitude maximum is found to coincide with the height range of the temperature inversion zone. This connection between increases in the semi-annual component close to the inversion zone is in agreement with most previously reported studies over tropics based on satellite observations. Results presented in this study confirm through the use of the ground-based Rayleigh lidar at Réunion and Mauna Loa that the semi-annual oscillation contributes to the formation of MILs over the tropical region.

scholarly journals Lidar measurements of mesospheric temperature inversion at a low latitude

2001 ◽  
Vol 19 (8) ◽  
pp. 1039-1044 ◽  
Author(s):  
V. Siva Kumar ◽  
Y. Bhavani Kumar ◽  
K. Raghunath ◽  
P. B. Rao ◽  
M. Krishnaiah ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Inversion Layer ◽  
Temperature Inversion ◽  
Atmospheric Composition ◽  
Statistical Characteristics ◽  
Low Latitude ◽  
Temperature Deviation ◽  
Height Range ◽  
Mesospheric Temperature ◽  
Seasonal Dependence

Abstract. The Rayleigh lidar data collected on 119 nights from March 1998 to February 2000 were used to study the statistical characteristics of the low latitude mesospheric temperature inversion observed over Gadanki (13.5° N, 79.2° E), India. The occurrence frequency of the inversion showed semiannual variation with maxima in the equinoxes and minima in the summer and winter, which was quite different from that reported for the mid-latitudes. The peak of the inversion layer was found to be confined to the height range of 73 to 79 km with the maximum occurrence centered around 76 km, with a weak seasonal dependence that fits well to an annual cycle with a maximum in June and a minimum in December. The magnitude of the temperature deviation associated with the inversion was found to be as high as 32 K, with the most probable value occurring at about 20 K. Its seasonal dependence seems to follow an annual cycle with a maximum in April and a minimum in October. The observed characteristics of the inversion layer are compared with that of the mid-latitudes and discussed in light of the current understanding of the source mechanisms.Key words. Atmospheric composition and structure (pressure, density and temperature). Meterology and atmospheric dynamics (climatology)

scholarly journals Observed and predicted characteristics of equatorial F1 layer during solar minimum

2014 ◽  
Vol 32 (5) ◽  
pp. 571-580 ◽  
Author(s):  
C.-C. Lee
Keyword(s):  
Seasonal Variation ◽  
Diurnal Variation ◽  
Solar Minimum ◽  
Shape Parameter ◽  
Early Morning ◽  
Peak Height ◽  
Time Range ◽  
Occurrence Probability ◽  
Peak Density

Abstract. This study aims to assess the predictability of IRI-2012 on the equatorial F1 layer during solar minimum. The observed characteristics of F1 layer by the Jicamarca digisonde are compared with the model outputs. The results show that the time range for F1-layer appearance of observation is longer than that of IRI-2012, by at least 1 h in the early morning and later afternoon. In IRI-2012, there are three options for the occurrence probability of F1 layer: IRI-95, Scotto-97 no L, and Scotto-97 with L options. The first option predicts the probability well, but the last two underestimate the probability. The peak density of F1 layer (NmF1) of observation is very close to that of IRI-2012. For the F1 peak height (hmF1), the modeled values are smaller than the observed ones. The observed seasonal variation of hmF1 is not found in the modeled results. Nevertheless, the observed diurnal variation of hmF1 is similar to the modeled results with the B0 choices of Bil-2000 and ABT-2009. Regarding the shape parameter, the values of D1 (the shape parameter of F1 layer in observation) are much greater than the values of C1 (the shape parameter of F1 layer in IRI-2012). The D1 values are 3–6 times the C1 values. The diurnal variation of D1 is similar to that of C1, but the seasonal variation of D1 is not.

scholarly journals A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O<sub>2</sub> airglow temperatures measurements

2012 ◽  
Vol 30 (1) ◽  
pp. 27-32 ◽  
Author(s):  
A. Taori ◽  
A. Jayaraman ◽  
K. Raghunath ◽  
V. Kamalakar
Keyword(s):  
Temperature Profile ◽  
Atmospheric Temperature ◽  
New Method ◽  
Temperature Profiles ◽  
Vertical Temperature ◽  
Lidar System ◽  
Mesospheric Temperature ◽  
Simultaneous Measurements ◽  
Rayleigh Lidar ◽  
First Time

Abstract. The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation.

scholarly journals Long-term Lidar Observations of the Gravity Wave Activity near the Mesopause at Arecibo

2018 ◽  
Author(s):  
Xianchang Yue ◽  
Jonathan S. Friedman ◽  
Qihou Zhou ◽  
Xiongbin Wu ◽  
Jens Lautenbach
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Inversion Layer ◽  
Lower Thermosphere ◽  
Temperature Inversion ◽  
Temperature Structure ◽  
Mean Temperature ◽  
The Mean ◽  
Highly Correlated ◽  
Lidar Observations

Abstract. 11-years long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100 km, conducted at the Arecibo Observatory, Puerto Rico (18.35° N, 66.75° W), are used to estimate seasonal variations of the mean temperature, the squared Brunt-Väisälä frequency, and the gravity wave potential energy in a composite year. The following unique features are obtained: (1) The mean temperature structure shows similar characteristics as a prior report based on a smaller dataset: (2) The profiles of the squared Brunt-Väisälä frequency usually reach the maxima at or just below the temperature inversion layer when that layer is present. The first complete range-resolved climatology of potential energy of temperature fluctuations in the tropical MLT exhibits an altitude dependent combination of annual oscillation (AO) and semiannual oscillation (SAO). Between 88 to 96 km altitude, the amplitudes of AO and SAO are comparable, and their phases are almost the same and quite close to day of year (DOY) 100. Below 88 km, the SAO amplitude is significantly larger than AO and the AO phase shifts to DOY 200 and after. At 97 to 98 km altitude, the amplitudes of AO and SAO reach their minima, and both phases shift significantly. Above that, the AO amplitude becomes greater. The annual mean potential energy profile reaches the minimum at 91 to 92 km altitude. The altitude-dependent SAO of the potential energy is found to be highly correlated with the satellite observed mean zonal winds reported in the literature.

scholarly journals Methodology for determining multilayered temperature inversions

2014 ◽  
Vol 7 (10) ◽  
pp. 10559-10583 ◽  
Author(s):  
G. J. Fochesatto
Keyword(s):  
Temperature Profile ◽  
Large Scale ◽  
Thermal Structure ◽  
Error Function ◽  
Inversion Layer ◽  
Meteorological Forcing ◽  
Temperature Variations ◽  
Thermal Inversion ◽  
Upper Level ◽  
Temperature Inversions

Abstract. The atmospheric boundary layer (ABL) exhibit multilayered thermal structure especially in polar atmosphere during extreme winters. These thermal inversions are originated based on the combined forcing of local and large scale synoptic meteorology. At the local scale the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling; however, depending upon the large scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is developed to determine all-thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extract from the temperature profile the most important temperature variations defining thermal layers. This is accomplished by a inear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce all-present inversion layers with an error fraction set independently.

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