Climate Monitoring and Diagnostics Laboratory

About: Climate Monitoring and Diagnostics Laboratory is a based out in . It is known for research contribution in the topics: Aerosol & Stratosphere. The organization has 107 authors who have published 263 publications receiving 26434 citations.

Methyl bromide cycling in a warm-core eddy of the North Atlantic Ocean

Abstract: [1] We conducted a detailed investigation of the evolution of methyl bromide concentrations, degradation rates, and ventilation rates for 26 days in a naturally contained, warm-core eddy of the North Atlantic Ocean. This is the first study of the oceanic cycling of methyl bromide in a natural, contained system with a complete suite of supporting measurements of physical and chemical variables. Methyl bromide concentrations in the mixed layer ranged from 2.3 to 4.2 nmol m−3, degradation rates ranged from 0.1 to 0.9 nmol m−3 d−1, net sea-to-air exchange rates ranged from 0 to 0.5 nmol m−3 d−1, and net loss rates through the thermocline were less than 0.1 nmol m−3 d−1. From a mass balance for methyl bromide in the mixed layer, we calculated production rates ranging from <0.1 to 1.3 nmol m−3 d−1. The median of this range, 0.48 nmol m−3 d−1, is higher than the ∼0.15 nmol m−3 d−1 necessary to maintain the reported global oceanic emission of 56 Gg yr−1. This is reasonable, because our study area was supersaturated in methyl bromide, whereas the ocean as a whole is undersaturated.

Evidence for midwinter chemical ozone destruction over Antarctica

Abstract: Two ozone profiles on June 15 and June 19, obtained over McMurdo, Antarctica, showed a strong depletion in stratospheric ozone, and a simultaneous profile of water vapor on June 19 showed the first clear signs of dehydration. The observation of Polar Stratospheric Clouds (PSCs) beginning with the first sounding showing ozone depletion, the indication of rehydration layers, which could be a sign for recent dehydration, and trajectory calculations indicate that the observed low ozone was not the result of transport from lower latitudes. During this time the vortex was strongly distorted, transporting PSC processed air well into sunlit latitudes where photochemical ozone destruction may have occurred. The correlation of ozone depletion and dehydration indicates that water ice PSCs provided the dominant surface for chlorine activation. An analysis of the time when the observed air masses could have formed type II PSCs for the first time limits the time scale for the observed ozone destruction to about 4 days.

Investigation of the short-time variability of tropical tropospheric ozone

Abstract: Since 1998, a ground-based tropospheric ozone lidar has been running at Reunion Island and has been involved with a daily measurement campaign that was performed in the latter part of the biomass burning season, during November–December 1999. The averaged ozone profile obtained during November–December 1999 agrees well with the averaged ozone profile obtained from the ozonesondes launch at Reunion during November–December (1992– 2001). Comparing weekly sonde launches (part of the Southern Hemisphere Additional Ozonesondes: SHADOZ program) with the daily ground-based lidar observations shows that some striking features of the day-to-day variability profiles are not observed in the sonde measurements. Ozone profiles respond to the nature of disturbances which vary from one day to the next. The vertical ozone distribution at Reunion is examined as a function of prevailing atmospheric circulation. Back trajectories show that most of the enhanced ozone crossed over biomass burning and convectively active regions in Madagascar and the southern African continent. The analyses of the meteorological data show that ozone stratification profiles are in agreement with the movement of the synoptic situations in November–December 1999. Three different sequences of transport are explained using wind fields. The first sequence from 23 to 25 November is characterized by northerly transport; during the second sequence from 26 to 30 November, the air masses are influenced by meridional transport. The third sequence from 2 to 6 December is characterized by westerly transport associated with the sub-tropical jet stream. The large, standard deviations of lidar profiles in the middle and upper troposphere are in agreement with the upper wind variabilities which evidence passing ridge and trough disturbances. During the transition period between the dry season and the wet season, multiple ozone sources including stratosphere-troposphere exchanges, convection and biomass burning contribute to tropospheric ozone at Reunion Island through sporadic events characterized by a large spatial and temporal variability.

Symposium on the tropospheric chemistry of the Antarctic Region

Abstract: The Antarctic stroposphere is an important part of the global environment; yet, by virtue of its remoteness, it has not been studied as intensively as its counterparts elsewhere. DOI: 10.1034/j.1600-0889.1992.t01-3-00002.x

Role of NOy as a diagnostic of small‐scale mixing in a denitrified polar vortex

Abstract: [1] Observations of three stratospheric species (N2O, CH4, and NOy) are examined for their suitability as mixing tracers in the inner Arctic vortex region between late February and mid-March 2000. NOy is highly inhomogeneous on isentropic surfaces and has little systematic vertical gradient between the 420 and 470 K potential temperature surfaces due to severe and extensive denitrification. Probability distribution functions of NOy calculated from in situ measurements do not show systematic and significant change as a function of time, indicating that mixing was too slow to substantially homogenize NOy distribution and therefore to strongly affect photochemical O3 destruction rates during the period. We propose that the NOy inhomogeneity is useful for diagnosing small-scale, irreversible mixing rates during the measurement period. A simple kinematic model is used to show that the NOy standard deviation on an isentropic level in the vortex has desirable properties for quantifying these rates. A practical method for deriving mixing rates for chemistry and transport models has been proposed for future studies.