Measurement of NOx gases using MIPAS-ENVISAT
Joanne Walker(1) and Dudhia Anu(1)
(1) University of Oxford, Clarendon Laboratory, OX1 3PU Oxford, United Kingdom
MIPAS is a high spectral resolution fourier transform spectrometer operating in the near to mid-infrared capable of detecting a large number of atmospheric species.
The NOx gases: NO, NO2 and N2O5 play a central role in stratospheric chemistry. Retrievals of NO2 and N2O5 using MORSE (MIPAS Orbital Retrieval using Sequential Estimation) are presented. However, the retrieval of NO which is present almost exclusively during daylight hours is complicated by conditions of non-local thermodynamic equilibrium. Here, we use indirect methods to infer daytime NO concentrations. On the diurnal time-scale nitrogen is approximately conserved between NO2, N2O5 and NO during the day and NO2 and N2O5 at night. By retrieving NO2 and N2O5 at suitable points during the diurnal cycle, we are able to estimate daytime NO concentrations.
Selected rate constants for NOx interconversion are also determined using NO2 and N2O5 retrivals through consideration of time since sunrise and sunset.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,