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The BLISS measurements of NO2 - Some new insights



The present study compares the diurnal variation of NO2 measured near 30 km by the BLISS in situ laser spectrometer with calculations from a photochemical model that includes a detailed description of multiple scattering. Even better agreement is found between the data and the model, both at sunset and during the day. The conclusions of an earlier study that the high-resolution in situ measurements of NO2 facilitated validation of the understanding of the diurnal chemistry of NO2 are confirmed.
D.J. Lary and J.A. Pyle
Department of Chemistry, Cambridge Urdversity, UK.
C.R. Webster and R.D. May
Jet Propulsion Laboratory, California Institute of Technology
Abstract - The diurnal variation of NO 2 measured near
30 km by the BLISS in-situ laser spectrometer is
compared with calculations from a photochemical model
that includes a detailed description of multiple scattering.
In a recent paper, the stratospheric chemistry of NO 2
was studied by combining high resolution tunable diode
laser measurements from the balloon-borne laser in-situ
spectrometer (BLISS) with a numerical model [Webster
et al., 1990]. When the model was constrained with the
measured 03 and temperature, the main features of the
observed diurnal variation of NO 2 were well reproduced
by the model. In general, the study constituted a very
successful confirmation of our present understanding of
this subset of stratospheric chemistry. However, there
were some differences in detail between the model and
observations (Figure 1). In particular, the one daytime
measurement of NO 2 could not be reproduced unless an
unrealistically large value of the ground albedo was used,
and there was a very rapid, but very brief, decline in the
measured NO 2 immediately after the major sunset
increase which the model did not reproduce. Finally some
minor differences between the modelled and observed
nighttime decays were evident with the model slightly
overestimating the values immediately prior to dawn.
This study reconsiders the detailed aspects of the model
data intercomparison. We have used a numerical model
with similar chemical kinetics but a much more sophisti-
cated treatment of scattering than that used in the earlier
study. The radiative transfer model is a new implementa-
tion of the scheme described by Meier et al. (1982). It has
been extended after Anderson (1983) to describe correctly
the radiation field for solar zenith angles greater than 75 ø .
The radiation into any volume element of the model
atmosphere has four contributions: The direct solar flux,
the diffuse flux incident from all directions, the ground
reflection of the direct solar flux and the ground reflection
of the diffuse flux. In this paper clear sky conditions have
been assumed. Excellent validation of the scheme against
various data sets has been achieved [Lary and Pyle, in
press, 1991a,b].
Copyright 1991 by the American Geophysical Union.
Paper number 91 GL02732
In addition to several other species Webster et al. (1990);
May and Webster (1989), made simultaneous in-situ
measurements of NO2, 03, temperature, and pressure
from the balloon based BLISS instrument launched at
Palestine, Texas (32øN, 96øW), on 13 September, 1988.
These measurements allowed a critical test of the
photochemical model to be made, with very small
differences between theory and data as discussed above.
This new study has reproduced some of the finer
BLISS measurement details (Figure 2) with a
model/measurement agreement of < 10%, which is
comparable to the measurement uncertainties of 8% for
sunset and nighttime NO2, and 10% for the daytime NO 2
measurement. The model used to produce Figure 2 has a
ground albedo of 0.25, a constant temperature of 233 K,
a constant ozone concentration of 8.5 ppmv, and a total
reactive nitrogen content of 15.24 ppbv. The model
pressure is kept at 11.0 mb, except for one hour after
sunset, when it is raised to 11.6 mb in accordance with the
observations of Webster et al. (1990).
Firstly, as pointed out by Webster et al. (1990), the
single day time measurement of NO 2 could only be expla-
ined using their scattering scheme based on Kurzeja
(1976), if a ground albedo of 0.5 was used. This is an
unrealistic value for desert like conditions. When the
detailed treatment of multiple scattering is used at all
wavelengths, then the single day time measurement of
NO 2 can be explained to within the measurement
uncertainty by a ground albedo of 0.25 (Figure 2).
Secondly, the peak in NO 2 concentration which
occurred just after sunset can be reproduced if the slight,
but brief, descent of the balloon which occurred then is
included in the model. This descent was accompanied by
an increase in the pressure, and hence, in the total
number density. Note that in their model calculations
Webster et al. (1990) used a constant value for the total
number density of 3.6x1047 molecules cm '3. The observed
peak would be less obvious if the concentration of NO 2
was expressed as a volume mixing ratio.
Finally, in the Webster et al. (1990) study the modelled
NO 2 prior to sunrise slightly overestimated the measured
values, although the measured and modelled nighttime
decay certainly agreed within the experimental error.
Webster et al. (1990), discussed the sensitMty of the decay
to temperature. By using a temperature of 233 K, instead
of 231 K as used in the earlier study, even better agree-
ment is found, especially immediately before dawn.
2262 Lary et al.: New insights into the BLISS measurements of NO 2
. .......... MOOEL NO2
I 'X.// \,
(pro) LOCAL TIME O6 06 10 12
Fig. 1. A comparison of the diurnal variation of NO 2 close to 11 mb measured by BLISS (squares) and
the model of ,,,,Webster et al. (1990). The measurement data is tabulated in Webster et al. (1990).
The ballon descended slightly for a short
period just after sunset, •,
6 9 12 15 8 21 24 4
[½ebster et c•L 19;90. •Sunset
L•ry !990, Model.
3 3
1 0 3 6
._ Sur•yise ø 2
233 K
Palestine, Texas, 32øN.
September 13 1
9 12 15 18 2! 24
Local Time (Hours)
Note that the model has accurately reproduced the rapid
change in NO2 at both sunrise and sunset,
Fig. 2. A comparison of the diurnal variation of NO 2 close to !1 mb measured by Webster et a.1. (1990)
(squares) and the model used in this study (line).
Lary et al.' New insights into the BLISS measurements of NO 2 2263
The data presented by Webster et al. (1990), have been
compared with a new numerical model including an
improved radiative transfer scheme. We now find even
better agracement between the data and the model, both
at sunset and during the day. We confirm the conclusions
of the earlier study that the high resolution in-situ
measurements of NO 2 have enabled a very successful
confirmation of our understanding of the diurnal chemistry
of NO2.
_Acknowledgements. D. Lary thanks SERC for a
studentship and R. Toumi for many helpful discussions.
Anderson, D.E., The troposphere to stratosphere
radiation field at twilight: A spherical model, Planet.
Space...Sci., 1517-1523, 1983.
Lary, D.J., Photochemical studies with a three-
dimensional model of the atmosphere, PhD Thesis,
University of Cambridge, Cambridge, England. 1991.
Lary, D.J., and J.A. Pyle, Diffuse radiation, twilight, and
photochemistry- I, Journal of Atmospheric
.Chemistry., In Press, 1991a.
Lary, D.J., and J.A. Pyle, Diffuse radiation, twilight, and
photochemistry- II, .Journal of Atmospheric
.Chemistry., in Press, 1991b. .
Kurzeja, R., Effects of diurnal variations and scattering
on ozone in the stratosphere for present day and
predicted future chlorine concentrations, J...Atm0s.
Sci., 34, 1120-1129, 1976.
May, R.D, and C.R. Webster, In-situ stratospheric
measurement of HNO3 and HC1 near 30 km using
the balloon-borne laser in-situ sensor tunable diode
laser spectrometer, J. Geoph_vs. Res., 16343-
16350, 1989.
Meier, R.R., D.E. Anderson, and M. Nicolet, The
radiation field in the troposphere and stratosphere
from 240 to 1000 nm: General analysis, Planet. Space
Sci., 923-933, 1982.
Webster, C.R., R.D. May, R. Toumi, and J.A. Pyle,
Active nitrogen partitioning and the nighttime
formation of N20 s in the stratosphere: Simultaneous
in-situ measurements of NO, NO2, HNO3, 0 3 and
N20 using the BLISS diode laser spectrometer, J_:.
Geop. hys. Res_., 13851-13866, 1990.
Di•'. Lary'and S.A. Pyle, Department of Chemistry,
Cambridge University, Lensfield Road, Cambridge, CB2
1EW, UK.
R.D. May and C.R. Webster, Jet Propulsion
Laboratory, California Institute of Technology, USA.
CReceived August 14, 1991;
accepted September 28, 1991)
... The effects of atmospheric sphericity have been studied using multidimensional models with radiative transfer schemes for a spherical atmosphere or with a pseudospherical approximation. The performance of such schemes has been justified by many previous studies Pyle, 1991a, 1991b; Lary et al., 1991; Perner et al., 1991; Dahlback and Stamnes, 1991; Dvortsov et al., 1992; Müller et al., 1994; Rattigan et al., 1996; Chipperfield et al., 1998; Kylling et al., 2003]. [3] Recently, the effects of atmospheric sphericity on the dynamics and chemistry of the global lower stratosphere have been studied by Lamago et al. [2003] with a coupled chemistry-climate model. ...
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Full-text available
A photochemical scheme including a detailed description of multiple seattering up to solar zenith angles of 960 has been used to study a number of different datasets. The good agreement of the model with these datasets and the improvement over previous intercomparisons emphasise the importance of both the diffuse radiation field at wavelengths below 310 nm and multiple scattering at solar zenith angles greater than 90o. These features are ignored in some photochemical models but prove to be very important in modelling photochemistry at dawn and dusk.
Simultaneous in situ measurements of NO, NOâ, HNOâ, Oâ, NâO, pressure, and temperature at 30 km have been made from Palestine. Texas (32°N) on September 13, 1988, using the Jet Propulsion Laboratory Balloon-Borne Laser In-Situ Sensor (BLISS) instrument, with the NOAA dual-channel balloon UV ozone spectrometer on the same gondola. Using tunable diode laser absorption spectroscopy over a long path length, measurements were made during a 24-hour flight of the daytime concentrations of NO, NOâ, and Oâ and of the diurnal variation in the concentration of NOâ. Postsunset measurements of NOâ, made every half minutes throughout much of the night, show the NOâ mixing ratio falling from a sunset value of 10.5 ppbv to 5.2 ppbv at nights end. From the sunset/sunrise difference din the volume mixing ratio of NOâ is derived a value of 2.7 {plus minus} 0.4 ppbv for the sunrise NâOâ mixing ratio, in excellent agreement with the model predictions of 2.9 ppbv at this latitude. The measured daytime NOâ/NO ratio was found to be in good agreement with model predictions at 30 km. The measured presunset sum NO + NOâ of 10.1 {plus minus} 0.8 ppbv agreed well with the measured postsunset NOâ amount of 10.5 {plus minus} 0.8 ppbv. Simultaneous measurements of the mixing ratios of HNOâ and postsunset NOâ allow an estimate of total reactive nitrogen, approximated at this time by NOâ + HNOâ + 2(NâOâ) + ClONOâ, of 16.4 {plus minus} 1.2 ppbv at 30 km, and (from an earlier flight) of 13.7 {plus minus} 1.7 ppbv at 37 km. Using model predictions incorporating corrections for non-steady state and for diurnal chemistry, an OH mixing ratio of 8 {plus minus} 4 pptv is derived from the measured HNOâ/NOâ ratio of 0.72 {plus minus} 0.17 at 30 km.
A description is presented of a method for the rapid calculation of tropospheric and stratospheric multiply scattered solar-induced radiation, in sufficient detail to allow the straightforward incorporation of the mathematical model into photochemical models. Method results show that multiple scattering and ground albedo may yield large amplifications of the radiation field in the photochemically active 240-1000 nm region. The method solves the integral equation of radiative transport theory for the source function, or the enhancement factor by which the solar flux at the top of the atmosphere must be multiplied at each altitude and wavelength to obtain the total flux available for photodissociation processes. In the second part of this paper, the enhancement factors due to multiple scattering are given for the heights, solar zenith angles and 300-800 nm wavelengths playing a role in the photodissociation of various atmospheric constituents.
The effect on ozone of diurnal variations in the concentrations of chlorine, nitrogen, hydrogen and oxygen compounds was studied with a diurnal integration of the photochemical equations at 30° latitude. The vertical distribution of the sum of the nitrogen oxides was specified and ozone was assumed to be in photochemical equilibrium. Calculations were performed for three different distributions of ClX (ClX = Cl + ClO + HCl + ClONO2), in which the maximum ClX mixing ratios were 1.5, 7.5 and 15 ppb.The results were compared with approximate calculations employing average daytime dissociation rates and 24-hour averaged dissociation rates. It was found that the methods employing daytime-averaged dissociation coefficients yielded more accurate O3 concentrations at all attitudes and, more importantly, were more reliable indicators of changes in total ozone amount resulting from chlorofluoromethane pollution.Several useful approximations are developed to improve the accuracy of photochemical models designed to study the effects of chlorine compounds on ozone.The effects of scattering on dissociation at wavelengths > 290 nm were included in the model with the parameterization of Lacis and Hansen. It was found that upward reflection of sunlight from clouds was quite important and that NO, N2O3, ClONO2, HCl, OH, O(1D) and O(3P) were significantly affected. A simple technique for including the effects of scattering and reflection in photochemical calculations is presented.
Time-dependent calculations of trace constituent distributions require as input the dissociating radiation field as a function of altitude and solar zenith angle. An isotropic, spherical, multiple scattering model of the radiation field has been developed to determine the radiation field at twilight. Comparison of the spherical model with a plane parallel model at twilight shows that: (1) for solar zenith angles less than 92°, plane parallel solutions for the source function are suitable if the initial deposition of solar energy is calculated for a spherical atmosphere; (2) for solar zenith angles greater than 92°, the plane parallel radiation field can be several orders of magnitude smaller than that calculated with the spherical model; (3) at altitudes above 40 km and at all solar zenith angles, the spherical model predicts 10–20% less radiation than the radiation field calculated with the plane parallel model. Calculations of the rate of photodissociation of NO2 in the troposphere and stratosphere show that the spherical model yields significantly higher values at solar zenith angles greater than 92°.
Thesis (Ph. D.)--University of Cambridge, 1991.
Simultaneous in situ measurements of NO, NO2, HNO3, O3, N2O, pressure, and temperature at 20km have been made from Palestine, Texas (32°N) on September 13, 1988, using the Jet Propulsion Laboratory Balloon-Borne Laser In-Situ Sensor (BLISS) instrument, with the NOAA dual-channel balloon UV ozone spectrometer on the same gondola. Postsunset measurements of NO2, made every half minute throughout much of the night, show the NO2 mixing ratio falling from a sunset value of 10.5ppbv to 5.2ppbv at night's end. Photochemical model calculations constrained to the measured temperature and O3 values, and incorporating both N2O5 and ClONO2 chemistry predict in detail the observed NO2 diurnal behavior. -from Authors
In situ stratospheric measurements of the concentrations of the reservoir species HNO3 and HCl made during two flights of the high-resolution (0.0005/cm) balloon-borne laser in situ sensor instrument from Palestine, Texas, are reported. A measured HNO3 volume mixing ratio of 4.3 parts per billion by volume (ppbv) at 31 km altitude is about 1 ppbv larger than previously reported measurements at 32 deg N. An HCl mixing ratio of 1.6 ppbv at 29 km is in agreement with values obtained from earlier remote sensing techniques within the experimental uncertainties. Upper limits at 31 km of 0.4 ppbv for H2O2 and 0.2 ppbv for HOCl are also derived from analyses of spectra recorded near 1252/cm.
The troposphere to stratosphere radiation field at twilight: A spherical model Photochemical studies with a three-dimensional model of the atmosphere
  • D E Anderson
  • D J Lary
  • D J Lary
  • J A Pyle
Anderson, D.E., The troposphere to stratosphere radiation field at twilight: A spherical model, Planet. Space...Sci., @BULLET 1517-1523, 1983. Lary, D.J., Photochemical studies with a three-dimensional model of the atmosphere, PhD Thesis, University of Cambridge, Cambridge, England. 1991. Lary, D.J., and J.A. Pyle, Diffuse radiation, twilight, and photochemistry-I, Journal of Atmospheric