Measurement of ambient NH<sub>3</sub> over Bay of Bengal during W_ICARB Campaign

Abstract

Abstract. Concentrations of ambient NH 3 , NO, NO 2 and SO 2 were measured over Bay of Bengal (BoB) during 28 December 2008 to 25 January 2009 to study their diurnal variation and relationship of NH 3 with other trace gases over BoB. The measurements were done under the winter phase of Integrated Campaign on Aerosols and Radiation Budget (W ICARB). For the first time, ambient NH 3 was monitored precisely over BoB based on chemiluminescence method, having estimation efficiency more precise than the chemical trap method. The average concentration of ambient NH 3 , NO, NO 2 and SO 2 were recorded as 4.78 ± 1.68, 1.89 ± 1.26, 0.31 ± 0.14 and 0.80 ± 0.30 µg m −3 , respectively, over BoB. The prominent latitudinal and longitudinal variations of the trace gases were observed over BoB, whereas NH 3 and NO showed the non-significant diurnal variation. Results reveal that the concentration of ambient NH 3 negatively correlated with ambient NO 2 (r 2 = −0.56), SO 2 (r 2 = −0.58) and ambient temperature (r 2 = −0.27) during the study.

Global distributions, time series and error characterization of atmospheric ammonia (NH<sub>3</sub>) from IASI satellite observations

“…Furthermore, these surface automated measuring devices are expensive and not always reliable, putting a limit on what can be expected from these in situ measurements (Erisman et al, 2003;Laj et al, 2009). It is worth noting that airborne (e.g., Nowak et al, 2007Nowak et al, , 2010 as well as ship (e.g., Norman and Leck, 2005;Sharma et al, 2012) NH 3 observations have recently been reported but these are restrained to campaigns with limited temporal and spatial coverage. The recently discovered capability of advanced IRsounders to probe atmospheric NH 3 (Beer et al, 2008;Coheur et al, 2009;Clarisse et al, 2009Clarisse et al, , 2010Shephard et al, 2011) is an important step towards addressing this observational gap.…”

“…oceans (Norman and Leck, 2005) and for the Bay of Bengal (Sharma et al, 2012) during ship campaigns.…”

Towards validation of ammonia (NH<sub>3</sub>) measurements from the IASI satellite

“…Airborne data sets are beginning to become available (e.g., Nowak et al, 2010;Leen et al, 2013) and provide information about the vertical distribution of NH 3 . It is worth noting that a few ship campaigns (e.g., Norman and Leck, 2005;Sharma et al, 2012) have also supplied NH 3 observations in oceanic atmosphere and that on-road measurements have recently been performed at landscape scale (Sun et al, 2014). The measurement gap identified above is of special importance considering the large variability of NH 3 in time and space.…”

Global distributions and trends of atmospheric ammonia (NH<sub>3</sub>) from IASI satellite observations

“…The source processes have been attributed by comparing the distribution with fire radiative power (FRP) measurements from the MODerate resolution Imaging Spectroradiometer (MODIS) instrument (Justice et al, 2011). Such export of NH 3 from biomass combustion and other continental sources to ocean has already been reported for Atlantic and Indian Oceans (Norman and Leck, 2005) and for the Bay of Bengal (Sharma et al, 2012) during ship campaigns. The griding method used for the global distribution in Fig.…”

“…Nowak et al, 2007Nowak et al, , 2010 as well as ship (e.g. Norman and Leck, 2005;Sharma et al, 2012) NH 3 measurements have been also reported but are restrained to campaigns limited in time and spatial coverage. The recently discovered capability of advanced IR-sounders to probe atmospheric NH 3 (Beer et al, 2008;Clarisse et al, 2009Clarisse et al, , 2010Shephard et al, 2011) is an important step forward in solving this ob- servational gap.…”