Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237

Contents lists available at SciVerse ScienceDirect

Journal of Atmospheric and Solar-Terrestrial Physics

1364-68

doi:10.1

n Corr

E-m

journal homepage: www.elsevier.com/locate/jastp

Short Communication

Impact of a noon-time annular solar eclipse on the mixing layer height andvertical distribution of aerosols in the atmospheric boundary layer

Manoj Kumar Mishra, K. Rajeev n, Anish Kumar M. Nair, K. Krishna Moorthy, K. Parameswaran

Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022, India

a r t i c l e i n f o

Article history:

Received 9 April 2011

Received in revised form

7 October 2011

Accepted 12 October 2011Available online 29 October 2011

Keywords:

Annular solar eclipse

Atmospheric boundary layer

Aerosols

Mixing layer height

26/$ - see front matter & 2011 Elsevier Ltd. A

016/j.jastp.2011.10.012

esponding author. Tel.: þ91 471 2563886.

ail address: k_rajeev@vssc.gov.in (K. Rajeev).

a b s t r a c t

Impact of the long duration noontime annular solar eclipse on 15 January 2010 on the vertical

distribution of aerosols and mixing layer height (HM) in a well-developed convective atmospheric

boundary layer (ABL) has been investigated using continuous Lidar observations over a tropical coastal

station, Thumba (8.51N, 76.91E). This study shows that HM has decreased from its peak value of

�1800 m at 12:00 h to �1000 m following the annular phase of the eclipse (13:17 h), while the

corresponding decrease in the total aerosol abundance of ABL is �29%. The post-eclipse increase of HM

is rapid compared to that during forenoon.

& 2011 Elsevier Ltd. All rights reserved.

1. Introduction

One of the main features of atmospheric boundary layer (ABL)is the mixing layer height (HM), below, which aerosols are nearlywell mixed by the turbulence generated because of thermalinstabilities and wind shears (Stull, 1988). Temporal evolutionof HM is a potential tool for characterizing the ABL. The mixinglayer height undergoes a strong diurnal variation, primarilydriven by a corresponding variation in the vertical flux of energyand momentum caused by the balance between the heating ofearth’s surface by the incoming solar radiation and radiativecooling of the surface. Under cloud-free conditions, the mixinglayer can continue to grow for few hours even after the surfacevirtual potential temperature flux has reached its maximum,since the energy is still substantial even with low solar zenithangle (Yi et al., 2001). Knowledge of the mixing layer height andits temporal evolution are of substantial importance for under-standing the dispersion of pollutants and modeling of ABL (e.g.Kunhikrishnan et al., 1993; Parameswaran et al., 1997).

The noontime annular solar eclipse on 15 January 2010 pro-vided a unique opportunity to investigate the responses of theboundary layer processes, vertical distribution of pollutants in ABLand the mixing layer height, to the rapid but systematic variationsin the incoming solar radiation, which is one of the primary drivingforces that regulates the surface heating and convection. Thisnoontime event is expected to produce significant impact on theABL since it has occurred at the time when the maximum solar

ll rights reserved.

heating of the surface takes place. During the annular solar eclipse,the moon geometrically hides the solar disk, so that the solarradiation reaching the earth is rather quickly switched off and on.The effect of such an event will be considerably different from thatassociated with the diurnal variation of solar radiation intensity,which is rather slow and accompanied by the time-dependentchanges in the atmospheric features. Though studies dealing withthe ABL characteristcs during the solar eclipse events are reportedin the literature (e.g., Sethuraman, 1982; Eaton et al., 1997;Dolas et al., 2002; Krishnan et al., 2004; Ratnam et al., 2010;Subrahamanyam and Anurose, 2011), investigations on the impactof solar eclipse on the vertical distribution of aerosols is highlylimited (Kolev et al., 2005; Amiridis et al., 2007; Babu et al., 2011).

Main objective of the present study i‘s to investigate theimpact of the noontime annular solar eclipse on 15 January2010 on the vertical distribution of aerosols and mixing layerheight over a tropical coastal station using continuous lidarobservations of the altitude profiles of aerosol backscatter coeffi-cient during the eclipse and adjacent control days having similarmeteorological conditions. Importance of this event is furtherenhanced by the calm and cloud-free wintertime conditions thatprevailed during this event, which provided ideal environment fordriving the daytime evolution of ABL through the solar heating ofsurface and its identification without any significant influence ofprominent weather systems and clouds.

2. Experimental setup, data and method of analysis

Details of the annular solar eclipse event on 15 January 2010are given in Table 1. The path of maximum obscuration during

Table 1Details of the annular solar eclipse event on 15 January 2010 over Thumba.

First contact 05:35 UTC 11:05 IST

Second contact 07: 40 UTC 13:10 IST

Maximum contact 07:44 UTC 13:14 IST

Third contact 07:47 UTC 13:17 IST

Fourth contact 09:35 UTC 15:05 IST

Umbral Duration 07 min 16 s.

Obscuration at maximum contact 84.3%

Magnitude of the eclipse 91.8%

M.K. Mishra et al. / Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237 233

this eclipse passed through Thumba (8.51N, 76.91E), a coastalstation located in the southwest Peninsular India at �500 minland from the Arabian Sea. At Thumba, first contact of theeclipse occurred at 11:05 Indian Standard Time (IST), attainedannularity during 13:10 to 13:17 IST (second to third contacts,lasting for 7.2 min) with a maximum magnitude of �91.8%(�84.3% obscuration) and ended at 15:05 IST (fourth contact).

A Micropulse Lidar (MPL) with dual polarization capability(model: MPL-4B of Sigma Space Corporation, USA) was operatedalmost continuously during 14, 15, 16 January 2010 (except forshort breaks of o1 h duration at approximately 6 hourly inter-vals) for studying the altitude distribution of aerosols and its timeevolution. This system consists of a diode-pumped frequency-doubled solid state Nd:YAG laser transmitter emitting laser pulsesat the wavelength of 532 nm having a pulse width of 7 ns at apulse repetition frequency of 2500 Hz and maximum pulseenergy of 8 mJ. During this experiment, the MPL observationswere carried out with a range resolution of 30 m and timeintegration of 60 s. A Maksutov–Cassegrain type telescope havingdiameter of 178 mm is used for transmitting the laser beam aswell as receiving the backscattered lidar signal. The receiverchannel incorporates two identical narrow band interferencefilters (having spectral width of 0.14 nm) to minimize the back-ground radiation, which enables the daytime observations usingMPL. The detector is a Silicon Avalanche Photodiode (Si-APD)operated in photon counting mode. The lidar system alternatesbetween two states of polarization (co-polarized and cross-polarized) at an interval of 60 s.

The MPL system uses same telescope as both transmitter andreceiver and hence the lidar signals are obtained from a reason-ably short range of 90 m onwards. The raw data are subsequentlycorrected for the detector noise and dead-time (Rajeev et al.,2010). In addition to these corrections, lidar signals from the nearfield also require a range-dependent geometrical correction factor(Welton et al., 2002). This geometrical correction factor g(r) (‘r’being the range) was determined experimentally by sending thelaser beam horizontally from top of a 30 m tall building on a hill(close to the coast) and observing the lidar signal at 30 m rangeresolution. In order to reduce the effect of atmospheric inhomo-geneity, the observations were carried out in six different direc-tions (all into the sea) for about 15 min in each direction. Therange compensated signal F(r) (¼r2P(r), where P(r) is the lidarsignal after background subtraction) exponentially increases withrange up to about 1 km followed by a relatively weak exponentialdecrease. The atmospheric extinction coefficient is estimatedusing the slope method over the range of 1500–2000 m (whichis significantly more than 1 km). Assuming the horizontal homo-geneity, the values of F(r) for each profile are corrected for thetwo-way atmospheric transmittance using the value of extinctioncoefficient derived for that profile. The above parameter normal-ized with respect to its peak value (the peak value is observed at1080 m in all directions) directly provides the geometric correc-tion factor. The value of g(r) increases up to a range of 1080 m andis very close to unity (within 2%) beyond this. The dispersion inthe values of g(r) derived from observations taken at different

directions is significantly small (o3%), which indicates thereliability of the experimentally derived value of geometricalcorrection factor. The average values of g(r) obtained in differentdirections are used for the geometric correction of the lidar dataup to a range of 1080 m, beyond, which g(r)¼1. By applying thiscorrection, useful information can be derived from MPL foraltitudes above 135 m.

For each altitude profile of lidar signal, the average photoncount observed between the altitudes of 50–60 km is consideredas the background, which is subtracted from the measured signalto estimate the true backscattered signal. The altitude profiles ofaerosol backscatter coefficient (ba) are derived using Fernald’smethod (Fernald, 1984), assuming a mean value of 40 Sr for theextinction-to-backscatter ratio (S). Altitude profiles of the lineardepolarization ratio (LDR) are estimated from the co- and cross-polarized backscattered lidar signals following the methoddescribed by Flynn et al. (2007). The linear depolarization ratiois an indicator of sphericity of aerosols: LDR increases with non-sphericity of aerosols and is very low (LDRo0.02) for highlyspherical aerosols. Further details of the MPL system, method ofdata processing, estimation of ba and LDR, sources of errors andthe uncertainty limits are described elsewhere (Mishra et al.,2010; Rajeev et al., 2010). Sensitivity analysis (for typical varia-tions in the assumed value of S, and the boundary condition of ba

at the reference altitude) shows a typical uncertainty of �20% inba and �40% in LDR below 5 km.

A quantitative analysis of HM is carried out using the verticalgradient and temporal variations of the attenuated backscattercoefficient (ABC, which is the range corrected lidar signal afterincorporating the necessary corrections and subtracting the back-ground noise) derived from lidar data. The altitude at which thefiltered first order derivative of ABC with respect to altitude[d(ABC)/dz] turns negative is considered as the base of theentrainment zone and HM (Flamant et al., 1997; Menut et al.,1999; Amiridis et al., 2007). However, because of the variations insignal-to-noise ratio as well as presence of transient layers, it isessential that HM determined using the above method is furtherverified using the time variation of ABC at each altitude [d(ABC)/dt], in which ABC is identified as the altitude where suddenchange in the time variation of ABC occurs. The value of ABCdetermined using the above two methods during the presentobservation period are found to be in agreement within 760 m.

A Sunphotometer (Microtop-II, Solar Light Co.) was used toobserve the aerosol optical depths (AOD) at the wavelengths of440, 500, 675 and 1020 nm during cloud-free daytime conditions.Uncertainty in the AOD is less than 70.04. Aerosol optical depthat the MPL wavelength of 532 nm is estimated by fitting a powerlaw type variation of AOD (Angstrom relation) to the abovemeasurements. Altitude profiles of the aerosol backscatter andextinction coefficients, obtained by inverting the MPL data, areweighed by the ratio of AOD observed using Sunphotometer tothat of the column integrated extinction coefficient derived fromMPL data. This ensures that the integrated extinction coefficientderived from MPL is equal to the AOD observed using Sunphot-ometer, which further reduces the uncertainty of the altitudeprofiles of aerosol backscatter and extinction coefficients derivedfrom MPL (Rajeev et al., 2010).

Spectral measurements of the direct solar radiation in thewavelength band of 350–2200 nm were carried out using acalibrated spectroradiometer (Model: FieldSpec3, of AnalyticalSpectral Devices, USA). It employs a cosine corrected receptor(RCR) in the fore-optics for the collection of the irradiance, whichis fed to the detector through a fiber optic cable. A directirradiance attachment having a field-of-view of 2.51 is fitted tothe RCR for making measurements of the direct solar irradiance.Radiometric calibration of this system is carried out at subsystem

M.K. Mishra et al. / Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237234

level as well as in the integrating mode, which enables themeasurement of absolute spectral radiance with a maximumuncertainty of 5%.

3. Results and discussion

Thumba and the surrounding regions were free from any majorweather systems during the experiment, though scattered low-level clouds (cumulus) occurred almost throughout the daytime

Fig. 1. Time variations of the direct solar irradiance (integrated in the spectral

band of 350–2200 nm) during 15 and 16 January 2010. The vertical lines indicate

the 1st, 2nd, 3rd, and 4th contacts of the annular solar eclipse (marked as 1, 2,

3 and 4, respectively).

Fig. 2. Time-altitude cross-sections of (a) attenuated backscatter coefficient plotted in

(c) and (d) are same as (a) and (b), respectively, but for 16 January 2010.

on 14 January 2010. However, cloud amount on this day haddecreased considerably by the evening and was generally cloud-free after the midnight. In contrast, the ambient meteorologicalconditions during 15–16 January were generally similar. Theamount of low- and middle-level clouds were considerably smal-ler during both these days, except for the occurrence of isolatedthin boundary layer clouds during the evolution of ABL, whichmake them ideal for investigating the evolution of ABL character-istics using lidar. However, MPL observations showed the occur-rence of thin cirrus clouds on 16 January while such clouds wereabsent on 15th. Considering the above conditions, 16 January isconsidered as the control day against which temporal variations ofthe aerosol profiles during the eclipse day are compared forquantifying the impact of solar eclipse on the aerosol distribution.

Time variations of the direct solar irradiance (Fd, integrated inthe spectral band of 350–2200 nm) at the earth’s surface during15 and 16 January 2010 obtained using spectroradiometer aredepicted in Fig. 1, which show a systematic decrease of Fd afterthe first contact of the eclipse. At the peak of the eclipse (betweenthe second and third contacts) Fd is only �11% of the correspond-ing value observed during the control day. This is followed by anincrease in Fd up to the fourth contact. Before and after the eclipseperiod, the values of Fd during 15 January are very similar to thatduring the control day. In response to the reduction in solarradiation associated with this eclipse, the soil surface tempera-ture has decreased from 40.6 1C at 12:00 IST to 38.5 1C at 14:00IST, which is followed by an increase up to 42 1C at 16:00 IST.

Time-altitude cross sections of ABC and LDR derived from MPLobservations in the altitude band of 135–2000 m during 15 and 16January 2010 are shown in Fig. 2(a,b). The solid lines in thesefigures indicate time variations of HM identified using the filteredfirst order derivative of ABC with respect to altitude. During theearly morning of 16 January (control day), an elevated layer ofaerosols was clearly discernible between 500 and 1000 m with itscentroid located at �700 m. This structure, though with varyingmagnitude, was present since 00:00 IST and continued up to

Log scale (arbitrary unit) and (b) linear depolarization ratio on 15 January 2010.

Fig. 3. Time-altitude cross-sections of aerosol backscatter coefficient (plotted in

Log scale, km�1 sr�1) during the eclipse (top panel) and control (bottom

panel) days.

M.K. Mishra et al. / Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237 235

�10:30 IST. Notwithstanding this, Fig. 2 clearly shows the diurnalevolution of the ABL, notably the upward movement of theconvective boundary layer height after �09:00 IST during thecontrol day. Development of the daytime ABL and the accompany-ing changes in vertical transport of aerosols are well discernible onthis day during 09:00–12:00 IST in both ABC and LDR. The mixedlayer height increases monotonically from �200 m at 09:00 IST to�1600 m at 13:00 IST, which is followed by a quasi-steady state ofHM during the afternoon period. The temporal variations of ABCabove HM are considerably smaller than that below. The magnitudeof LDR and its spatio-temporal variations are only in the range of0.02–0.04, which is significantly less than the corresponding valuesof 0.1–0.3 observed for mineral dust (e.g., Mishra et al., 2010;Rajeev et al., 2010). This shows that the aerosols observed in theABL during this period are more-or-less spherical in nature.Notwithstanding this, the evolution of ABL is clearly discerniblefrom the altitude-time variations of LDR, which shows the verticaltransport of relatively non-spherical aerosols (LDR�0.04), particu-larly during the forenoon period. Though very small, the increase insphericity of aerosols in the upper part of ABL and during theafternoon period might be associated with the hygroscopic growthof aerosols in these altitudes due to increase in humidity of thevertically transported air because of adiabatic cooling. Due to thisreason, the spatio-temporal variations of LDR shown in Fig. 2cannot clearly represent the evolution of ABL and HM at higheraltitudes and afternoon period.

Spatio-temporal variations of the vertical distribution of aero-sols during the eclipse day are generally consistent with thatduring the control day. The elevated aerosol layer observed in thenocturnal ABL during the control day is observed during theeclipse day as well, with ABC showing a broad peak between�400–1000 m during 00:00–10:00 IST. Evolution of the convec-tive ABL is clearly observed in the time-altitude cross sections ofABC and LDR during 09:00–12:00 IST. The value of HM hasincreased from �200 m at 09:00 IST to �1800 m at 12:00 ISTduring the eclipse day. Fig. 2a shows the occurrence of isolatedand thin boundary layer clouds between 1600–1800 m during11:30–12:30 IST. This is a characteristic feature of the daytimeconvective ABL [Stull, 1988], with the cloud bottom representingthe top of the convective ABL and base of the entrainment zone.This further confirms the estimated value of HM and its timeevolution derived from the vertical and temporal variations ofABC. Remarkably, Fig. 2a shows a small but well-discernibledecrease in the values of ABC after attaining the peak value ofHM around 12:00 IST. This depletion initially occurs at �1500–1800 m and spreads to the lower altitudes up to �1000 m at�14:00 IST. Note that the aerosols transported to the ABL by theconvective eddies during the forenoon period cannot be removedsignificantly by the abatement of convection (e.g., Parameswaranet al., 1997). This has resulted in the relatively small vertical andtemporal variations of aerosols after 12:00 IST compared to thatduring the evolution of convective ABL. Notwithstanding this, thereduction of ABC is discernible in the altitude band of 1000–1800 m during 12:00–14:00 IST. Upper boundary of this regionwhere the values of ABC decrease with time is indicated by thedashed line in Fig. 2a and represents shrinking of the mixing layerduring the eclipse. Clearly, this has been primarily driven by thedecrease in surface heating (indicated by a reduction of �2.1 1C insoil temperature) and convection due to the reduction in solarirradiance caused by the eclipse. An overall depletion in aerosolconcentration is observed for �1 h around 13:30 IST over theentire ABL. This also suggests that HM might have lowered to evenbelow �1000 m after the annular eclipse period, though thiscould not be quantitatively estimated from the time-altitudecross section of ABC due to its considerably small variation withtime and altitude. It is highly likely that the weakening of

convection in ABL might strengthen the subsidence of the stableair aloft through a process opposite to that operating during theevolution of convective boundary layer seen during the forenoonperiod. This also might contribute to the decrease in HM observedduring the eclipse period.

Upward transport of aerosols in the lower part of ABL (below�500 m) after the third contact is seen in Fig. 2a, indicating theregeneration of thermals after the annular phase of the eclipse.Increase of HM after �14:00 IST is clearly identifiable in Fig. 2aand is indicated by the solid line (values of HM below �500 m arenot shown here since they could not be determined unambigu-ously). Interestingly, increase in HM after the annular phase of theeclipse is more rapid than that during the forenoon period. Thismight be because of the prevailing thermodynamic state of ABLafter the eclipse, which is significantly modified by the almostfully developed convective ABL before the beginning of theeclipse. This condition would be significantly different from thatduring the forenoon convective evolution of ABL from the stablenocturnal boundary layer. The post-eclipse increase in aerosolconcentration above �1000 m occurs only �40 min after thatobserved in the lower part of ABL. Post-eclipse evolution of ABLeventually led to the formation of isolated low-level clouds in thealtitude band of 1500–2200 m during 15:00–16:30 IST (Fig. 2).This feature further confirms the post-eclipse enhancement of HM

to 41800 m. Remarkably, a small but persistent reduction in LDRoccurs almost throughout the ABL for more than 1 h after thesecond contact of the eclipse, which might be associated with theincreased hygroscopic growth of aerosols.

The lidar signals were inverted using Fernald’s method toderive the altitude profiles of aerosol backscatter coefficient (ba),which provides more quantitative information on the aerosolloading compared to ABC. However, in order to improve thesignal-to-noise ratio and accuracy of the retrieved profiles of ba,particularly at higher altitudes around the noontime, the lidardata were integrated for 30 min before carrying out the Fernald’sinversion. Because of this, the temporal resolution of the profilesof ba is less than that of ABC. Fig. 3 shows the time-altitude cross-sections of ba during the eclipse and control days. During both

Fig. 4. Time variation of the integrated aerosol backscatter coefficient (IABC) in

the altitude band of 300–1500 m during 15 January 2010.

M.K. Mishra et al. / Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237236

these days, the value of ba below �300 m peaks around 09:00 IST,which is followed by lifting up of aerosols to higher altitudes withthe evolution of ABL. Increase in aerosol amount below �1800 maltitude during the convective evolution of ABL before the eclipseand reduction in aerosol abundance during the eclipse are clearlydiscernible in Fig. 3. The increase in aerosol amount in the lowerpart of ABL after the annular phase of the eclipse also is clearlyseen. The above variations in the vertical distribution of aerosolsduring and immediately after the solar eclipse are distinctlydifferent from those observed during the control day.

A quantitative assessment of the effect of solar eclipse on thetotal aerosol loading of ABL is investigated based on temporalvariations of the integrated aerosol backscatter coefficient (IABC)in the altitude band of 300–1500 m during the eclipse day and isshown in Fig. 4. Though the mixing height has increased up to�1600–1800 m during the afternoon, the values of ba in thealtitude range of 300–1500 m only are used for estimating IABC toavoid any influence of low altitude clouds, which were presentabove �1500 m for a while during the evolution of the ABL, asseen in Fig. 2. Fig. 4 shows a consistent increase of IABC during theforenoon period; its value has increased by �50% from 08:30 to11:30 IST and is due to the vertical mixing of aerosols during theevolution of ABL. This is followed by a decrease of IABC, whichattains a minimum value during 13:30–14:30 IST and is clearlylinked to the abatement of convection and vertical transport ofaerosols caused by the solar eclipse. The depletion of aerosolconcentration from its peak (at 11:30 IST) to trough (13:30–14:30IST) is �29%. The convective development of ABL following theannular phase of eclipse enhances the value of IABC by �18%during 14:30–15:30 IST. Timings of the peaks and troughs in thetemporal evolution of IABC are in agreement with those expectedfrom the variations in the surface heating and associated convec-tion inferred from the meteorological observations.

4. Conclusions

At the peak of the eclipse, direct component of the surface-reaching solar irradiance in the spectral band of 350–2200 nm isonly �11% of the corresponding value observed on the controlday. This has resulted in the decrease of surface temperature by�2 1C during the eclipse and consequent abatement of atmo-spheric convection. Time-altitude cross-sections of the aerosol

backscatter coefficient and linear depolarization ratio clearlydepict differences in the evolution of convective ABL during theeclipse and control days. During both these days, the aerosolconcentration in the residual layer peaked in the altitude band of600–1200 m during the post-midnight and morning hours. Not-withstanding this, upward movement of the mixing layer heightfrom �200 m at �09:00 IST to reach a peak altitude of �1600–1800 m around the noontime is discernible during both the days.During the eclipse day, the aerosol backscatter coefficient and HM

show a decrease after attaining their peak values around thenoon. This depletion initially occurs at �1500–1800 m andspreads to the lower altitudes with time. Driven by the decreasein surface heating and weakening of convection during the eclipseevent, the mixing layer height has decreased from �1800 m at12:00 IST to �1000 m after the third contact. Vertical transport ofaerosols caused by the increase in convection after the annulareclipse is observed in the lower part of ABL after the third contact,while increase in aerosol concentration in the upper part of ABLoccurs only �40 min later. The mixing layer height increases to41800 m during the post-eclipse period. This increase is morerapid than that during the forenoon convective evolution of ABL.Eclipse-induced abatement of convection has decreased theintegrated aerosol backscatter coefficient in the altitude band of300–1500 m by �29% from its peak value observed before theeclipse. In contrast, the post-eclipse development of ABL hasenhanced the integrated aerosol backscatter coefficient in theabove altitude band by �18%. A small but persistent reduction inlinear depolarization ratio occurs almost throughout the ABL formore than 1 h after the second contact of the eclipse (13:10 IST).

This study clearly shows the impact of the noontime annularsolar eclipse event in bringing about changes in the verticaltransport of pollutants over a coastal location. In addition toproviding a better understanding of the response time of aerosolsin the convective boundary layer, the results presented here offera test case for the atmospheric models.

Acknowledgments

We are thankful to Prof. R. Sridharan, former Director of SPL,for the overall coordination and planning of the Solar EclipseExperiment. We thank the reviewers for their valuable sugges-tions. K. Parameswaran is Emeritus Scientist supported by CSIRgrant.

References

Amiridis, V., Melas, D., Balis, D.S., Papayannis, A., Founda, D., Katragkou, E.,Giannakaki, E., Mamouri, R.E., Gerasopoulos, E., Zerefos, C., 2007. Aerosol lidarobservations and model calculations of the planetary boundary layer evolutionover Greece, during the March 2006 total solar eclipse. Atmospheric Chemistryand Physics 7, 6181–6189.

Babu, S.S., Sreekanth, V., Moorthy, K.K., Mohan, M., Kirankumar, N.V.P., Subraha-manyam, D.B., Gogoi, M.M., Kompalli, S.K., Beegum, N., Chaubey, J.P., Kumar,V.H.A., Manchanda, R.K., 2011. Vertical profiles of aerosol black carbon in theatmospheric boundary layer over a tropical coastal station: perturbationsduring an annular solar eclipse. Atmospheric Research 99, 471–478.doi:10.1016/j.atmosres.2010.11.019.

Dolas, P.M., Ramachandran, R., Sen Gupta, K., Patil, S.M., Jadhav, P.N., 2002.Atmospheric surface layer processes during the total solar eclipse of 11 August1999. Boundary Layer Meteorology 104, 445–461.

Eaton, F.D., Hines, J.R., Hatch, W.H., Cionco, R.M., Byers, J., Garvey, D., 1997. Solareclipse effects observed in the planetary boundary layer over a desert.Boundary Layer Meteorology 83, 331–346.

Flamant, C., Pelon, J., Flamant, P., Durand, P., 1997. Lidar determination of theentrainment zone thickness at the top of the unstable marine atmosphericboundary layer. Boundary Layer Meteorology 83, 247–284.

Fernald, F.G., 1984. Analysis of atmospheric lidar observations: some comments.Applied Optics 23, 652–653.

Flynn, C.J., Mendoza, A., Zheng, Y., Mathur, S., 2007. Novel polarization-sensitivemicropulse lidar measurement technique. Optics Express 15 (6), 2785–2790.

M.K. Mishra et al. / Journal of Atmospheric and Solar-Terrestrial Physics 74 (2012) 232–237 237

Kolev, N., Tatarov, B., Grigorieva, V., Donev, E., Simenonov, P., Umlensky, V.,Kaprielov, B., Kolev, I., 2005. Aerosol Lidar and in situ ozone observations ofthe planetary boundary layer over Bulgaria during the solar eclipse of 11August 1999. International Journal of Remote Sensing 26, 3567–3584.

Krishnan, P., Kunhikrishnan, P.K., Ravindran Sudha, Ramachandran Radhika,Subrahamanyam D.B. and Ramana M.V., 2004. Observation of the Atmosphericsurface layer parameters over a semi arid region during the solar eclipse ofAugust 11, 1999.In: Proceedings of the Indian Academy Sd (Earth andPlanetary Science), vol. 113, pp. 353–363.

Kunhikrishnan, P.K., Gupta, K.S., Radhika, R., Prakash, J.W.J., Nair, K.N., 1993. Studyon thermal internal boundary layer structure over Thumba, India. AnnualGeophysics 11, 52–60.

Menut, L., Flamant, C., Pelon, J., Flamant, P., 1999. Urban boundary layer heightdetermination from lidar measurements over the Paris area. Applied Optics 38,945–954.

Mishra, M.K., Rajeev, K., Thampi, B.V., Parameswaran, K., Nair, A.K.M., 2010. Micropulse lidar observations of mineral dust layer in the lower troposphere overthe southwest coast of Peninsular India during the Asian summer monsoonseason. J. Atmos. Sol. Terr. Phys. 72, 1251–1259.

Parameswaran, K., Rajeev, K., Sen Gupta, K., 1997. An observational study of nighttime aerosol concentration in the lower atmosphere at a tropical coastalstation. J. Atmos. Solar Terr. Phys. 59, 1727–1737.

Rajeev, K., Parameswaran, K., Thampi, B.V., Mishra, M.K., Nair, A.K.M., Meenu, S.,2010. Altitude distribution of aerosols over Southeast Arabian Sea coast duringpre-monsoon season: elevated layers, long-range transport and atmosphericradiative heating. Atmospheric Environment 44, 2597–2604.

Ratnam, V.M., Shravan Kumar, M., Basha, G., Anandan, V.K., Jayaraman, A., 2010.Effect of the annular solar eclipse of 15 January 2010 on the lower atmosphericboundary layer over a tropical rural station. J. Atmos. Sol Terr. Phys. 72,1393–1400.

Sethuraman, S., 1982. Dynamics of the atmospheric boundary layer during the1980 total solar eclipse. Proceedings of INSA 48, 187–195.

Stull, R.B., 1988. An Introduction to Boundary Layer Meteorology. Kluwer Aca-demic Publishers, Dordrecht, The Netherlands.

Subrahamanyam, D.B., and Anurose, T.J., 2011. Solar eclipse induced impacts onsea/land breeze circulation over Thumba: a case study, Journal of Atmosphericand Solar Terrestrial Physics., 10.1016/j.jastp.2011.01.002.

Welton, E.J., Voss, K.J., Quinn, P.K., Flatau, P.J., Markowicz, K., Campbell, J.R.,Spinhirne, J.D., Gordon, H.R., Johnson, J.E., 2002. Measurements of aerosolvertical profiles and otical properties during INDOEX 1999 using micropulselidars. Journal of Geophysical Research 107, 8019. doi:10.1029/2000JD000038.

Yi, C., Davis, K.J., Berger, B.W., 2001. Long-term observations of the dynamics of thecontinental planetary boundary layer. Journal of Atmospheric Science 58,1288–1299.