Validation of nitrogen dioxide results measured by the Limb Infrared Monitor of the Stratosphere (LIMS) Experiment on NIMBUS 7

Abstract

The LIMS experiment launched on NIMBUS 7 measured vertical profiles of temperature and the concentrations of 0 3, H20, HNO 3, and NO 2 during the period from late October 1978 until late May 1979. This paper discusses the validation of results from the NO, channel and th.e quality of the data.The discussion includes channel characteristics, experiment errors due to instrument and spacecraft effects, predicted and measured precision, predicted accuracy, and comparisons with correlative measurements made in a series of balloon underflights. All balloon measurements used for comparisons were made using the solar occultation technique, and since NO 2 varies significantly over the diurnal cycle, a photochemical model was used to time translate the data to the LIMS time. Because of this the comparisons were primarily qualitative. Features such as profile shape and slope of the mixing ratio altitude distribution are in good agreement. The mean difference between LIMS results and the balloon data is well within the range of the sum of the error bars for the two data sets. Comparisons are also made with past balloon measurements taken in the 40øN to 50øN latitude band and with photochemical model predictions of the vertical profile. The LIMS data fall within the range of previous mixing ratio measurements, and they are consistent with model estimates. The calculated on-orbit precision is •0.3 ppbv and the estimated accuracy from simulations is •2 ppbv over the 3-mbar to 10-mbar range. Accuracy degrades at higher and lower pressure levels. These results provide the first day-night set of NO 2 measurements from space. INTRODUCTIONThe limb infrared monitor of the stratosphere (LIMS) instrument launched on NIMBUS 7 is a six-channel thermal infrared limb-scanning radiometer. Two channels are centered spectrally in the 15-#m CO: band for sounding the vertical temperature profile, and the others are located at 11.3 #m for nitric acid (HNO3), 9.6 #m for ozone (03), 6.9 #m for water vapor (H20), and 6.2 #m for nitrogen dioxide (NO:) [see Russell and Gille, 1978; Gille et al., 1980]. The LIMS experiment operated virtually without flaw from the time of launch on October 24, 1978 until it was turned off May 28, 1979. At this time, the ammonia-methane solid cryogen used for detector cooling had depleted as planned. The horizon was scanned almost continuously during the LIMS operation, and data were collected night and day over the latitude range from 64øS to 84øN. An experiment overview by J. C. Gille and J. M. Russell (unpublished manuscript, 1983) describes the instrumentation in more detail and discusses fundamental experiment objectives, orbital performance, duty cycle, types of data products, and typical results for each of the five parameters measured.The chemistry objectives of the LIMS experiment are focused on the effects of nitrogen compounds on the stratospheric ozone layer. These compounds arise in the strato-

First simultaneous global measurements of nighttime stratospheric NO2 and NO3 observed by Global Ozone Monitoring by Occultation of Stars (GOMOS)/Envisat in 2003

“…A few nighttime observations are available for limited periods. They were obtained from the detection of the limb infrared emission by Limb Infrared Monitor of the Stratosphere (LIMS) from October 1978 to May 1979 [ Russell et al , 1988], Improved Stratospheric and Mesospheric Sounder (ISAMS) from September 1991 to July 1992 [ Reburn et al , 1996] and Cryogenic Limb Array Etalon Spectrometer (CLAES) from October 1991 to May 1993 [ Danilin et al , 1999]. Michelson Inteferometer for Passive Atmospheric Sounding (MIPAS) [ Fischer and Oehlaf , 1996] on board Envisat is also providing such observations since July 2002.…”

A detailed evaluation of the stratospheric heat budget: 2. Global radiation balance and diabatic circulations

“…The useful vertical range is from 30 hPa to 3 hPa [Russell et al, 1984a]. No other sources were used to extend vertical and latitudinal coverage.…”

Improvements in the profiles and distributions of nitric acid and nitrogen dioxide with the LIMS version 6 dataset

“…The calculated precision values for the V6 NO 2 in Table 2 were adopted from those of V5 in Russell et al (1984a), after accounting for the improvements due to the use of all the samples within the measured radiance profiles. Random uncertainties from single profiles of the retrieved H 2 O were adopted from Remsberg et al (2009) and are included because H 2 O is a major source of interfering emission, especially for daytime NO 2 in the upper and the lowermost stratosphere.…”

“…A linear scaling was applied to the entries of the V5 NO 2 error table in Russell et al (1984a) for its V6 bias errors, based on a model-generated, daytime profile at 32 • N. Its primary sources of systematic uncertainty are from temperature bias and from the interfering effects of H 2 O, based on the V6 uncertainties in Remsberg et al (2004) and Remsberg et al (2009), respectively. There are uncertainties in the lower stratosphere due to the O 2 interference, but they should be considered as an upper limit because corrections for the O 2 emission were applied to the retrievals of both the LIMS H 2 O and NO 2 and therefore carry the same sign.…”

“…An extensive validation of the V6 products was not conducted, although their daily zonal mean cross sections have been assessed against those of the V5 data that had been compared with the few correlative measurements available during the LIMS timeframe (e.g., Gille, 1987;Russell et al, 1984a;Remsberg and Russell, 1987). Qualitative improvements have been found for all the V6 data products.…”