Meteorologische Zeitschrift Vol 10 No 3 165-170 (June 2001)c by Gebruder Borntraeger 2001 Article

The BAYSOFI Campaign ndashMeasurements carried out during the total solar eclipseof August 11 1999

PETER FABIAN1 MARTIN WINTERHALTER1 BERNHARD RAPPENGLUCK1 HEINRICH REITMAYER1 ANDREAS STOHL1 PETER KOEPKE2 HANS SCHLAGER3 HARALD BERRESHEIM4 THOMAS FOKEN5 BODO WICHURA5 KARL-HEINZ HABERLE6 RAINER MATYSSEK6 and THOMAS KARTSCHALL7

1 Technische Universitat Munchen Bioklimatologie und Immissionsforschung Germany2 Universitat Munchen Germany3 Institut fur Physik der Atmosphare DLR Oberpfaffenhofen Germany4 Meteorologisches Observatorium Hohenpeiszligenberg Germany5 Universitat Bayreuth Germany6 Technische Universitat Munchen Forstbotanik Germany7 Potsdam Institut fur Klimafolgenforschung (PIK) Potsdam Germany

(Manuscript received May 31 2000 in revised form November 28 2000 accepted December 3 2000)

AbstractThe total solar eclipse of August 11 1999 provided a unique opportunity to observe the input of fast day-nightand night-day transitions under high solar elevation around noon on the earth-atmosphere-biosphere systemWithin the interdisciplinary eld campaign BAYSOFI measurements of radiation boundary layer microme-teorology and photochemistry photosynthesis and transpiration were carried out at Freising-Weihenstephanand several locations nearby focusing on short-term effects of the eclipse Although the overall grosswetter-lage on August 11 was not favourable for viewing the eclipse with clouds covering most of central Europeobservational conditions at Weihenstephan were fair due to a large hole in the cloud layer which appeared justhalf hour before totality lasting for more than one hour Thus signi cant effects of the eclipse on radiationphotolysis rates OH the temperature wind turbulence structure and strati cation ozone and CO2 uxesphotosynthesis transpiration and sap ow of trees could be observed which are reported and discussed in thefollowing sequence of papers

ZusammenfassungDie totale Sonnen nsternis am 11 August 1999 bot die einmalige Gelegenheit den Ein uss schneller Tag-Nacht- und Nacht-Tag-Ubergange bei hohem mittaglichem Sonnenstand auf das System Erdober ache-Atmosphare-Biosphare zu beobachten Im Rahmen der interdisziplinaren Feldmesskampagne BAYSOFI wur-den in Freising-Weihenstephan und einigen benachbarten Orten Messungen zur Strahlung Grenzschicht-Mikrometeorologie und Photochemie Photosynthese und Transpiration die auf kurzzeitige Effekte der Son-nen nsternis fokussiert waren durchgefuhrt Wenngleich die Groszligwetterlage am 11 August ungunstig undZentraleuropa von einer mehr oder weniger dichten Wolkenschicht uberdeckt war herrschten in Weihen-stephan recht gute Beobachtungsbedingungen dank eines groszligen Wolkenlochs das sich eine halbe Stundevor der Totalitat auftat und uber eine Stunde reichte Dadurch konnten signi kante Effekte der Sonnen ns-ternis auf Strahlung Photolyseraten OH die Partitionierung von NOx Ozon- und PAN-Produktion Tem-peratur Wind Turbulenzstruktur und Schichtung Ozon- und CO2-Flusse Photosynthese Transpiration undSaftstrom in Baumen beobachtet werden die in der folgenden Sequenz von Artikeln prasentiert und diskutiertwerden

1 Introduction

The phenomenon of a solar eclipse is one of na-turersquos most spectacular events Its astronomical back-ground is well understood for long and accounted for

Corresponding author Peter Fabian Lehrstuhl fur Bioklimatolo-gie und Immissionsforschung Technische Universitat MunchenAm Hochanger 13 85354 Freising-Weihenstephan Germany e-mail fabianmetforsttu-muenchende

in many books for instance those of MITCHELL (1951)LITTMAN and WILLCOX (1991) and ZIRKER (1984)A total solar eclipse causing almost complete darknessand lasting for up to a few minutes is even more spec-tacular but quite a rare event If the sky is clear a widerange of optical phenomena can be observed such asthe changing colour of the sky the moving shadowshadow bands the Sunrsquos chromosphere the corona andits prominences the diamond ring as well as planets and

DOI 1011270941-294820010010-01650941-2948010010-0165 $ 0270

c Gebruder Borntraeger Berlin Stuttgart 2001

166 P Fabian et al The BAYSOFI Campaign Meteorol Z 10 2001

Figure 1 Measurement locations (Lehrstuhl fur Bioklimatolo-gie und Immissionsforschung (LfBIM) nearby maize eldKranzberger Forst and Forschungszentrum fur Umwelt undGesundheit (GSF)) for the BAYSOFI campaign The dotted line in-dicates the centre of the solar eclipse

stars that suddenly become visible against the darkeningsky

Eclipses also provide a unique opportunity to inves-tigate the reaction of the atmosphere or the biospherewhen the incident solar radiation is suddenly turned offand then on again While the responses are similar tothose that occur as night falls the eclipse is much moreabrupt than the gradual decrease in solar energy as theevening sun approaches the horizon Thus observationsof changes in surface temperature and wind are docu-mented related to solar eclipses temperature falls rang-ing between 2 and almost 10 K depending on season andlatitude (see review by ANDERSON 1999) and declinein surface wind speed from 25 ms before the eclipseto 1 ms about 10 minutes after totality (FERNANDEZ etal 1996)

A wide range of observations is documented forthe upper atmosphere too CHIMONAS (1971) pre-dicted the formation of stratospheric gravity waves butsearches for the pressure wave associated with thesepredictions did not provide consistent results (see re-view by DAVIES 1982) Ozone measurements gener-ally show a slow decline in column-ozone during thedarkening phase followed by a sharp peak at or justafter totality with a slow recovery to pre-eclipse val-ues thereafter (BOJKOV 1968 CHAKRABARTY et al1997) although other patterns have been reported aswell Eclipse-related changes are also documented forthe ionosphere such as sudden drops of the ion andelectron densities HORVATH and THEON 1972) A re-cent paper by JAKOBI and KURSCHNER (2000) reports astrong decrease of D-region (60ndash90 km) ionization dur-ing the August 11 1999 solar eclipse enabling windmeasurements at mesopause level which normally canbe achieved during night only

2 The BAYSOFI-Campaign

The total solar eclipse of August 11 1999 providedthe potential for new ndings since the lunar shadowpassed over highly instrumented parts of Europe (for de-tails see ESPENAK and ANDERSON 1997) At our in-stitute site at Freising-Weihenstephan (Lat 48 24rsquo5rdquoNLong 11 43rsquo10rdquoE) about 30 km NE of Munichin southern Germany it occurred at 103720 UT(1237 CEST) with totality lasting about 23rsquo minutesat a solar zenith angle of 34 It thus provided an in-teresting opportunity for investigating the impact of theeclipse during high solar elevation conditions

Within BAYSOFI (Bayerische Sonnen nsternis) aninterdisciplinary eld campaign focused on the effectsof the total solar eclipse on radiation and air chemistrymicrometeorology as well as physiology coordinatedmeasurements were carried out at the institute site (Lf-BIM) in a nearby maize eld at a forest site about 5 kmtowards NW (Kranzberger Forst) and at the GSF labora-tory site at Neuherberg some 20 km towards SW Theselocations are shown in Fig 1

Additional measurements of photosynthesis and sap ow were carried out at two forest sites close to Ober-ammergau (80 km SW) and LandauIsar (80 km NE)respectively Simultaneously measurements of meteo-rological and chemical parameters were conducted at a50 m mast in Garching and at the Meteorological Obser-vatory Hohenpeiszligenberg (MOHp) a site of the WMOGlobal Atmospheric Watch program about 70 km SWof Weihenstephan Although the eclipse at this placereached 99 of totality only these additional measure-ments proved to be very important

At the time of the eclipse the centre of an upperlevel trough was located over Central Europe (Fig 2)

Figure 2 Geopotentialat the 500 hPa (shadedevery 100 gpdm withlight colours denoting low values) and at the 1000 hPa (isolines ev-ery 40 gpdm) surfaces over Europe on 11 August 1999 at 12 UTCThe plot is based on analysis data from the European Center forMedium-Range Weather Forecasts (ECMWF) The location of themeasurement site at Weihenstephan is marked with rdquoWldquo

166 P Fabian et al The BAYSOFI Campaign Meteorol Z 10 2001

Figure 1 Measurement locations (Lehrstuhl fur Bioklimatolo-gie und Immissionsforschung (LfBIM) nearby maize eldKranzberger Forst and Forschungszentrum fur Umwelt undGesundheit (GSF)) for the BAYSOFI campaign The dotted line in-dicates the centre of the solar eclipse

stars that suddenly become visible against the darkeningsky

Eclipses also provide a unique opportunity to inves-tigate the reaction of the atmosphere or the biospherewhen the incident solar radiation is suddenly turned offand then on again While the responses are similar tothose that occur as night falls the eclipse is much moreabrupt than the gradual decrease in solar energy as theevening sun approaches the horizon Thus observationsof changes in surface temperature and wind are docu-mented related to solar eclipses temperature falls rang-ing between 2 and almost 10 K depending on season andlatitude (see review by ANDERSON 1999) and declinein surface wind speed from 25 ms before the eclipseto 1 ms about 10 minutes after totality (FERNANDEZ etal 1996)

A wide range of observations is documented forthe upper atmosphere too CHIMONAS (1971) pre-dicted the formation of stratospheric gravity waves butsearches for the pressure wave associated with thesepredictions did not provide consistent results (see re-view by DAVIES 1982) Ozone measurements gener-ally show a slow decline in column-ozone during thedarkening phase followed by a sharp peak at or justafter totality with a slow recovery to pre-eclipse val-ues thereafter (BOJKOV 1968 CHAKRABARTY et al1997) although other patterns have been reported aswell Eclipse-related changes are also documented forthe ionosphere such as sudden drops of the ion andelectron densities HORVATH and THEON 1972) A re-cent paper by JAKOBI and KURSCHNER (2000) reports astrong decrease of D-region (60ndash90 km) ionization dur-ing the August 11 1999 solar eclipse enabling windmeasurements at mesopause level which normally canbe achieved during night only

2 The BAYSOFI-Campaign

The total solar eclipse of August 11 1999 providedthe potential for new ndings since the lunar shadowpassed over highly instrumented parts of Europe (for de-tails see ESPENAK and ANDERSON 1997) At our in-stitute site at Freising-Weihenstephan (Lat 48 24rsquo5rdquoNLong 11 43rsquo10rdquoE) about 30 km NE of Munichin southern Germany it occurred at 103720 UT(1237 CEST) with totality lasting about 23rsquo minutesat a solar zenith angle of 34 It thus provided an in-teresting opportunity for investigating the impact of theeclipse during high solar elevation conditions

Within BAYSOFI (Bayerische Sonnen nsternis) aninterdisciplinary eld campaign focused on the effectsof the total solar eclipse on radiation and air chemistrymicrometeorology as well as physiology coordinatedmeasurements were carried out at the institute site (Lf-BIM) in a nearby maize eld at a forest site about 5 kmtowards NW (Kranzberger Forst) and at the GSF labora-tory site at Neuherberg some 20 km towards SW Theselocations are shown in Fig 1

Additional measurements of photosynthesis and sap ow were carried out at two forest sites close to Ober-ammergau (80 km SW) and LandauIsar (80 km NE)respectively Simultaneously measurements of meteo-rological and chemical parameters were conducted at a50 m mast in Garching and at the Meteorological Obser-vatory Hohenpeiszligenberg (MOHp) a site of the WMOGlobal Atmospheric Watch program about 70 km SWof Weihenstephan Although the eclipse at this placereached 99 of totality only these additional measure-ments proved to be very important

At the time of the eclipse the centre of an upperlevel trough was located over Central Europe (Fig 2)

Figure 2 Geopotentialat the 500 hPa (shadedevery 100 gpdm withlight colours denoting low values) and at the 1000 hPa (isolines ev-ery 40 gpdm) surfaces over Europe on 11 August 1999 at 12 UTCThe plot is based on analysis data from the European Center forMedium-Range Weather Forecasts (ECMWF) The location of themeasurement site at Weihenstephan is marked with rdquoWldquo

Meteorol Z 10 2001 P Fabian et al The BAYSOFI Campaign 167

At 1000 hPa a high pressure ridge extended from theAtlantic towards Western Europe and the British IslesA cold front occlusion was located over Southern Ger-many nearly parallel to the totality path of the eclipsewhich produced dense clouds penetrating southeast-wards along the backside of the upper-level trough Oc-casional rain showers and thunderstorms also occurredin the region due to the instability caused by the upper-level cold air advection (Fig 3)

Nevertheless observational conditions were fairFrom 1000 UTC until 1110 UTC a window in the oth-erwise dense cloud cover allowed viewing the eclipseat Weihenstephan during its most interesting phase AtHohenpeiszligenberg a few short rain showers occurredwhich however did not severely disturb the measure-ments (see FABIAN et al 2001 WINKLER et al 2001)

Photochemistry in the boundary layer and the ef-fect of the reduced solar radiation during the eclipsewas one of the issues of interest Simultaneous mea-surements of radiation photolysis frequencies O3 COPAN NOx and meteorological parameters carried out atWeihenstephan show the interactions between radiationand photochemistry under fast rdquoday-nightldquo and rdquonight-dayldquo transitions at high solar elevation The instrumentsused during BAYSOFI and their characteristics are listedin Table 1

Figure 3 AVHRR image aboard a NOAA polar orbiting satellite inthe visible channel on 11 August 1999 at 1336 UTC Image cour-tesy of the Dundee Satellite Receiving Station Dundee UniversityScotland

Concurrently with the rapid darkening of the atmo-sphere most photochemical reactions are also dramat-ically reduced mainly because of the rapid decline ofthe hydroxyl radical (OH) concentration OH the ma-jor oxidant in the atmosphere was measured during theeclipse at Hohenpeiszligenberg in conjunction with a broadrange of other gaseous as well as meteorological andaerosol parameters The contribution of the major OHsource ie ozone photolysis to the observed OH levelscan be estimated Furthermore the effects of decliningOH levels on the concentrations and atmospheric life-times of other important compounds can be estimatedAs an example the temporal changes of gaseous sulfu-ric acid concentrations which were also measured duringthe eclipse can be compared with model calculations ofthe H2SO4 balance The photochemical cycle control-ling the interconversion between the highly reactive NOand NO2 also adjusts very rapidly to the radiation envi-ronment To study the interchange of NO and NO2 dur-ing the solar eclipse the parameters of the so-called pho-tostationary state ratio

NO2 NO k O3 jNO2

were measured simultaneously with a high time resolu-tion ( 1 s) Here k is the temperature dependent re-action rate coef cient of the reaction of NO with ozoneand jNO2 is the rate coef cient of the photodissociationof NO2 In order to monitor the expected decrease ofthe NO volume mixing ratio to zero over a wide rangeof concentrations a high-sensitivity chemiluminescenceinstrument with a very low detection limit of only 3 pptvwas used (see Table 1) Thereby the partitioning be-tween NO and NO2 as a function of jNO2 could be mea-sured over the entire period of the solar eclipse Ad-ditionally simple box model simulations were used toshow the effect of reduced solar radiation on the pho-tochemical production of O3 and PAN (FABIAN et al2001 KOEPKE et al 2001)

The aim of the micrometeorological programme wasnot merely focused on classical meteorological mea-surements (radiation temperature) as during the last im-portant partial ( 80) solar eclipse on June 30 1954 inGermany (HINZPETER and WORNER 1955) but ratheron phenomena which can only be observed during a totaleclipse Therefore the eclipse was used as a rsquolaboratorylsquoexperiment carried out in nature The main differencebetween a cloud covered sun and an eclipse is a negativenet radiation (night time conditions) during the eclipseThe change of the irradiation conditions from day tonight occurs during a much shorter time period and con-siderably faster during an eclipse than at nightfall Thisoffers the possibility to study time response functionsdependant on the forcing by the sunrsquos radiation Suchfunctions are of special interest for the energy transitionto turbulent and plant physiological processes This wasthe inspiration for including a micrometeorological andplant ecological programme into the BAYSOFI experi-ment and the cluster of resulting publications The mi-

168 P Fabian et al The BAYSOFI Campaign Meteorol Z 10 2001

Table 1 Instruments used during BAYSOFI

Air Chemistry Type of instrument Detection Accuracy Temporal Site Referencelimit resolution

O3 ML 8810 1 ppb 2 1 min WHS

PAN Scintrex LPA-4 30 ppt 5 5 min WHS

NO2 Scintrex LMA-3 5 ppt 5 1 min WHS KELLYet al (1990)

NO CLD 780 TR 3 ppt 10 1 s WHS

NOx CLD 780 TR 5 ppt 15 5 s WHS SCHLAGER+ PLC 762 et al (1997)

CO AL5001 2 ppb 15 3 s WHS GERBIGet al (1996)

OH H2SO4 CIMS 0015 ppt 52 5 min MOHp BERRESHEIMet al (2000)

Radiation Type of instrument Detection Accuracy Temporal Site Referencelimit resolution

global radiation Kipp amp Zonen 03ndash3 microm 1 min WHSpyranometer

UV radiation Eppley UV 295ndash385 nm 1 min WHSradiometer

jO 1D lter radiometer 290ndash325 nm 15 10 s WHS JUNKERMANN

et al (1989)

jO 1D lter radiometer 290ndash325 nm 15 1 min MOHp MULLER (1994)

jNO2 lter radiometer 290ndash420 nm 10 10 s WHS REUDER (1999)

diffuse sky pyranometer CM11 integral 1 min WHSirradiance (D) Kipp amp Zonen 03ndash3microm

spectral UV double spectral 10 s NHirradiance monochromator 310 nm

BENTHAM DM300

Meteorology Type of instrument Temporal Siteresolution

dry temperature Th Friedrichs 1 min WHSFrankenbergerPsychrometer

Wind velocity Th Friedrichs 1 min WHSwind velocity

sensor

Wind direction Th Friedrichs 1 min WHSwind direction

sensor

crometeorological measuring programme with measure-ments of sensible and latent heat carbon dioxide andozone uxes using the eddy covariance method was oneof the rst carried out during a total solar eclipse condi-

tion A similar experiment was made in the USA duringa partial (94) eclipse on May 10 1994 (EATON et al1997) yet with partial success only because net radia-tion did not turn negative

168 P Fabian et al The BAYSOFI Campaign Meteorol Z 10 2001

Table 1 Instruments used during BAYSOFI

Air Chemistry Type of instrument Detection Accuracy Temporal Site Referencelimit resolution

O3 ML 8810 1 ppb 2 1 min WHS

PAN Scintrex LPA-4 30 ppt 5 5 min WHS

NO2 Scintrex LMA-3 5 ppt 5 1 min WHS KELLYet al (1990)

NO CLD 780 TR 3 ppt 10 1 s WHS

NOx CLD 780 TR 5 ppt 15 5 s WHS SCHLAGER+ PLC 762 et al (1997)

CO AL5001 2 ppb 15 3 s WHS GERBIGet al (1996)

OH H2SO4 CIMS 0015 ppt 52 5 min MOHp BERRESHEIMet al (2000)

Radiation Type of instrument Detection Accuracy Temporal Site Referencelimit resolution

global radiation Kipp amp Zonen 03ndash3 microm 1 min WHSpyranometer

UV radiation Eppley UV 295ndash385 nm 1 min WHSradiometer

jO 1D lter radiometer 290ndash325 nm 15 10 s WHS JUNKERMANN

et al (1989)

jO 1D lter radiometer 290ndash325 nm 15 1 min MOHp MULLER (1994)

jNO2 lter radiometer 290ndash420 nm 10 10 s WHS REUDER (1999)

diffuse sky pyranometer CM11 integral 1 min WHSirradiance (D) Kipp amp Zonen 03ndash3microm

spectral UV double spectral 10 s NHirradiance monochromator 310 nm

BENTHAM DM300

Meteorology Type of instrument Temporal Siteresolution

dry temperature Th Friedrichs 1 min WHSFrankenbergerPsychrometer

Wind velocity Th Friedrichs 1 min WHSwind velocity

sensor

Wind direction Th Friedrichs 1 min WHSwind direction

sensor

crometeorological measuring programme with measure-ments of sensible and latent heat carbon dioxide andozone uxes using the eddy covariance method was oneof the rst carried out during a total solar eclipse condi-

tion A similar experiment was made in the USA duringa partial (94) eclipse on May 10 1994 (EATON et al1997) yet with partial success only because net radia-tion did not turn negative

Meteorol Z 10 2001 P Fabian et al The BAYSOFI Campaign 169

Figure 4 Time shift between the net radiation air temperature andsoil temperature

Our micrometeorological programme focused onmeasurements of all parameters determining both the ra-diation balance equation and the energy balance equa-tion Therefore the sensible and latent heat uxes weredirectly measured by means of the eddy covariance tech-nique (FOKEN et al 2001) For comparison with thephysiological measurements the carbon dioxide ux wasalso measured The programme was completed by pro- le measurements of wind temperature and humidityalong with soil temperatures For the combination withplant physiological measurements a maize eld was se-lected because of the high transpiration rate (even non-irrigated) in mid August

Fig 4 shows the time shift between the net radiationair temperature and soil temperature The decrease of theair temperature by about 2 K is in a good agreement withdata of a large number of solar eclipses observed earlier(ANDERSON 1999) It is considerably smaller howeverthan the temperature drop of up to 7 K predicted forthe upper Rhine valley for the August 11 1999 eclipsebased on cloudless conditions (VOGEL et al 2001) Ata depth of 2 cm in a grass-covered soil the decrease wasonly 05 K Moreover a strong decrease of the wind ve-locity with low values persisting up to 30 minutes aftertotality was measured Due to this effect all uxes wereforced by net radiation and turbulence (FOKEN et al2001)

In contrast to the crop plantation photosynthesis andtranspiration of leaves in tall forest trees were exam-ined for effects of the solar eclipse Of special interestwere the responses of canopy transpiration and water ux through the whole tree as the latter was uncertain tobe affected by the short transitional impact of the total-ity on the stomatal regulation One point of interest wasthe question does the tall dimension of forest trees withits water storage rsquo lter outlsquo effects of canopy responseon the water transport through the trunk Measurementswere conducted on mature individuals of spruce beechand oak at low and high-altitudinal sites near Freis-ing Oberammergau and LandauIsar (HABERLE et al2001)

The differences in short term responses for these pro-cesses elucidates our insight into ecophysiological pro-cesses and can be used for scaling purposes Thereforethe physiological programme was aimed at identifyingthe different time scales of physiological and meteo-rological responses to the rapidly changing irradiation(Photosynthetic active Photon Flux Density IPPFD) andenvironmental conditions during the total solar eclipsearound noon It was focused on the water ndash and CO2 ndashexchange in the selected Zea maize on the leaf level Theassimilatory ux AL measured for ve selected leavesfollows the variation observed for the photosyntheticallyactive radiation (Fig 5) with a time delay of about 35

15 s due to the physiological behaviour of the stom-atal conductance It is interesting to note that assimila-tory uxes turned negative during totality indicating thatphotosynthesis switched to respiration during this shortperiod of darkness

In the following separate contributions experimentsand the main results obtained during the eclipse on Au-gust 11 1999 are described and discussed We con-cede that no breathtaking new discoveries were madeduring the event The total solar eclipse as a rdquolabora-tory experimentldquo carried out by nature however pro-vided the unique opportunity to test our understandingof radiation photochemical micrometeorological andphysiological processes Neither measurements carriedout during dusk or dawn nor those performed duringtemporal cloud cover provide these ideal conditions ofa total solar eclipse around noon with rapid darken-ing complete darkness and rapid brightening thereafterat high solar elevation Our results show with few ex-ceptions due to lacking complete information that theobserved variations can be explained Moreover obser-vations related to the limb darkening effect photolysisrates and fast radical photochemistry the fast transitionsof the thermal strati cation of the boundary layer radia-tive budget photosynthesis and transpiration triggeredby the eclipse are important and interesting case studiesA total solar eclipse being a very rare event of shortduration only certainly has no lasting impact on theatmosphere-biosphere system But just because it hap-pens once in a long while only observations carried outduring such a rare event certainly deserve publication

Figure 5 Observed IPPFD (line) and AL (circles) between dawn anddusk during the total solar eclipse on August 11 1999

170 P Fabian et al The BAYSOFI Campaign Meteorol Z 10 2001

Acknowledgments

ECMWF provided access to their database within thespecial project ldquoValidation of trajectory calculationsrdquo

References

ANDERSON J 1999 Meteorologicalchanges during a solareclipse ndash Weather 54 207ndash215

BERRESHEIM H T ELSTE C PLASS-DULMER FLEISELE DJ TANNER 2000 Chemical ionization massspectrometer for long-term measurements of atmosphericOH and H2SO4 ndash Int J Mass Spec 202 91ndash109

BOJKOV RD 1968 The ozone variations during the solareclipse of 20 May 1966 ndash Tellus 20 417ndash421

CHAKRABARTY DK NC SHAH KV PANDYA 1997Fluctuations in ozone column over Ahmedabad during thesolar eclipse of 24 October 1995 ndash Geophys Res Lett 243001ndash3003

CHIMONAS G 1971 Atmospheric gravity waves inducedby a solar eclipse ndash J Geophys Res 76 7003ndash7005

DAVIES K 1982 Atmospheric gravity waves produced bya solar eclipse-a review ndash Proc Indian Natl Acad 48 aSuppl No 3 342ndash355

EATON FD JR HINES WH HATCH RM CIONCO JBYERS D GARVEY DR MILLER 1997 Solar eclipseeffects in the planetary boundary layer over a dessert ndashBoundary-LayerMeteorol 83 331ndash346

ESPENAK F J ANDERSON 1997 Total solar eclipse of1999 August 11 ndash NASA Reference Publication 1398NASA USA

FABIAN P B RAPPENGLUCK A STOHL H WERNERH SCHLAGER P STOCK H BERRESHEIM U KAMIN-SKI P KOEPKE J REUDER W BIRMILI 2001 Bound-ary Layer PhotochemistryDuring total Solar Eclipse ndash Me-teorol Z 10 187ndash192

FERNANDEZ W H HIDALGO G CORONEL EMORALES 1996 Changes in meteorological variables inCoronel Oviedo Paraguay during the total solar eclipse of3 November 1994 ndash Earth Moon and Planets 74 49ndash59

FOKEN TH 1998 Die scheinbar ungeschlosseneEnergiebi-lanz am Erdboden ndash eine Herausforderung an die Ex-perimentelle Meteorologie ndash Sitzungsbericht der Leibniz-Sozietat 24 131ndash150

FOKEN TH B WICHURA O KLEMM J GERCHAU MWINTERHALTER T WEIDINGER 2000 Micrometeoro-logical measurements during the total solar eclipse of Au-gust 11 1999 ndash Meteorol Z 10 171ndash178

GERBIG C D KLEY A VOLZ-THOMAS J KENT KDEWEY DS MCKENNA 1996 Fast response resonance uorescence CO measurements aboard the C-130 In-strument characterisation and measurements made duringNARE 1993 ndash J Geophys Res 101 29229ndash29238

HABERLE K-H I REITER K PATZNER C HEYNE RMATYSSEK 2000 Switching the light off A break in pho-tosynthesis and sap ow of forest trees under total solareclipse ndash Meteorol Z 10 201ndash206

HINZPETER H H WORNER 1955 Die Strahlungsmes-sung in Potsdam und Persnas ndash In SKEIB G (Ed) DieFinsternis am 30 Juni 1954 Veroff Meteorol amp HydrolDienst DDR 16 5ndash23

HORVATH JJ JS THEON 1972 Response of the neutralparticle upper atmosphere to the solar eclipse of 7 March1970 ndash J Atmos Terr Phys 34 593ndash599

JAKOBI C D KURSCHNER 2000 Ergebnisse ionospha-rischer Messungen am Observatorium Collm wahrend dertotalen Sonnen nsternis vom 118 1999 ndash Wiss Mitt ausdem Met Inst der Univ Leipzig 17 88ndash94

JUNKERMANN W U PLATT A VOLZ-THOMAS 1989 APhotoelectric Detector for the Measurement of PhotolysisFrequencies of Ozone and Other Atmospheric Moleculesndash J Atmos Chem 8 203ndash227

KELLY TJ CW SPICER GF WARD 1990 An assess-ment of the luminol chemiluminescencetechniquefor mea-surement of NO2 in ambient air ndash Atmos Environ 212163ndash2177

KOEPKE P J REUDER J SCHWEEN 2000 Spectral vari-ation of the solar radiation during an eclipse ndash Meteorol Z10 179ndash186

KUKHARETS VP VG PEREPELKIN LR TSVANG SHRICHTER U WEISENSEE TH FOKEN 1998 Energiebi-lanz an der Erdober ache und Warmespeicherung im Bo-den ndash In FOKEN Th (Ed) Ergebnisse des LINEX-971Experiments Deutscher Wetterdienst Forschung und Ent-wicklung Arbeitsbericht 53 19ndash26

LITTMAN M K WILLCOX 1991 Totality Eclipses of theSun ndash Univ of Hawaii Press 224 pp

MITCHELL SA 1951 Eclipses of the Sun (5th Edition) ndashColumbia University Press New York 482 pp

MULLER M 1994 Messung der aktinischen ultraviolettenStrahlung und der Ozon-Photolysefrequenz in der Atmo-sphare mittels Filterradiometrie und Spektralradiometrie ndashPhD Thesis Rheinische Friedrich-Wilhelms-UniversitatBonn 196 pp

REUDER J 1999 Untersuchungenzur Variabilitat von Pho-tolysefrequenzenndash PhD Thesis Brandenburgische-Tech-nische-Universitat Cottbus BTUC-AR 499 ISSN 1434-6834 126 pp

SCHLAGER H P KONOPKA P SCHULTE U SCHU-MANN H ZIEREIS F ARNOLD M KLEMM DE HA-GEN PD WHITEFIELD J OVARLEZ 1997 In situ obser-vations of air traf c emissions in the North Atlantic ightcorridor ndash J Geophys Res 102 10739-10750

VOGEL B M BALDAUF F FIEDLER 2001 The in uenceof a solar eclipse on temperature and wind in the Upper-Rhine Valley ndash a numerical case study ndash Meteorol Z 10207ndash214

WINKLER P U KAMINSKI U KOHLER J RIEDL HSCHROERS D ANWENDER 2000 Development of mete-orological parameters and total ozone during total eclipseof August 11 1999 ndash Meteorol Z 10 193ndash199

ZIRKER JB 1984 Total eclipses of the Sun ndash Van Nos-trand Reinhold New York 228 pp