Hintsa
Eric J.
Hintsa
Eric J.
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ArticleCO2 deposition over the multi-year ice of the western Weddell Sea(American Geophysical Union, 2006-07-13) Zemmelink, Hendrik J. ; Delille, Bruno ; Tison, Jean-Louis ; Hintsa, Eric J. ; Houghton, Leah A. ; Dacey, John W. H.Field measurements by eddy correlation (EC) indicate an average uptake of 0.6 g CO2 m−2 d−1 by the ice-covered western Weddell Sea in December 2004. At the same time, snow that covers ice floes of the western Weddell Sea becomes undersaturated with CO2 relative to the atmosphere during early summer. Gradients of CO2 from the ice to the atmosphere do not support significant diffusive fluxes and are not strong enough to explain the observed CO2 deposition. We hypothesize that the transport of air through the snow pack is controlled by turbulence and that undersaturation of CO2 is caused by biological productivity at the ice-snow and snow-atmosphere interface. The total carbon uptake by the multi-year ice zone of the western Weddell Sea in December could have been as high as 6.6 Tg C y−1.
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ArticleRelaxed eddy accumulation measurements of the sea-to-air transfer of dimethylsulfide over the northeastern Pacific(American Geophysical Union, 2004-01-30) Zemmelink, Hendrik J. ; Gieskes, Winfried W. C. ; Klaassen, Wim ; Beukema, Wim J. ; de Groot, Henk W. ; Baar, Hein J. W. de ; Hintsa, Eric J. ; McGillis, Wade R. ; Dacey, John W. H.Gas transfer rates were determined from relaxed eddy accumulation (REA) measurements of the flux of dimethylsulfide (DMS) over the northeastern Pacific Ocean. This first application of the REA technique for the measurement of DMS fluxes over the open ocean produced estimates of the gas transfer rate that are on average higher than those calculated from commonly used parameterizations. The relationship between the total gas transfer rate and wind speed was found to be gas kgas = 0.53 (±0.05) U102. Because of the effect of the airside resistance, the waterside transfer rate was up to 16% higher than kgas. Removal of the airside transfer component from the total transfer rate resulted in a relation between wind speed and waterside transfer of k660 = 0.61 (±0.06) U102. However, DMS fluxes showed a high degree of scatter that could not readily be accounted for by wind speed and atmospheric stability. It has to be concluded that these measurements do not permit an accurate parameterization of gas transfer as a function of wind speed.
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ArticleSea-to-air fluxes from measurements of the atmospheric gradient of dimethylsulfide and comparison with simultaneous relaxed eddy accumulation measurements(American Geophysical Union, 2004-01-30) Hintsa, Eric J. ; Dacey, John W. H. ; McGillis, Wade R. ; Edson, James B. ; Zappa, Christopher J. ; Zemmelink, Hendrik J.We measured vertical profiles of dimethylsulfide (DMS) in the atmospheric marine boundary layer from R/P FLIP during the 2000 FAIRS cruise. Applying Monin-Obukhov similarity theory to the DMS gradients and simultaneous micrometeorological data, we calculated sea-to-air DMS fluxes for 34 profiles. From the fluxes and measured seawater DMS concentrations, we calculated the waterside gas transfer velocity, kw. Gas transfer velocities from the gradient flux approach are within the range of previous commonly used parameterizations of kw as a function of wind speed but are a factor of 2 smaller than simultaneous determinations of transfer velocity using the relaxed eddy accumulation technique. This is the first field comparison of these different techniques for measuring DMS flux from the ocean; the accuracy of the techniques and possible reasons for the discrepancy are discussed.
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ArticleDefinitions and sharpness of the extratropical tropopause : a trace gas perspective(American Geophysical Union, 2004-12-04) Pan, L. L. ; Randel, W. J. ; Gary, B. L. ; Mahoney, M. J. ; Hintsa, Eric J.Definitions of the extratropical tropopause are examined from the perspective of chemical composition. Fine-scale measurements of temperature, ozone, carbon monoxide, and water vapor from approximately 70 aircraft flights, with ascending and descending tropopause crossings near 40°N and 65°N, are used in this analysis. Using the relationship of the stratospheric tracer O3 and the tropospheric tracer CO, we address the issues of tropopause sharpness and where the transitions from troposphere to stratosphere occur in terms of the chemical composition. Tracer relationships indicate that mixing of stratospheric and tropospheric air masses occurs in the vicinity of the tropopause to form a transition layer. Statistically, this transition layer is centered on the thermal tropopause. Furthermore, we show that the transition is much sharper near 65°N (a region away from the subtropical jet) but spans a larger altitude range near 40°N (in the vicinity of the subtropical jet). This latter feature is consistent with enhanced stratosphere-troposphere exchange and mixing activity near the tropopause break.
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ArticleDirect measurements of biogenic dimethylsulphide fluxes from the oceans : a synthesis(National Research Council Canada, 2004-06-24) Zemmelink, Hendrik J. ; Dacey, John W. H. ; Hintsa, Eric J.This paper provides a brief overview of the state-of-the-art of techniques that are currently used for field measurements of trace gas fluxes and the subsequent derivation of gas transfer rates over the oceans. Special attention is given to the relaxed eddy accumulation (REA) and gradient flux (GF) techniques, which rely on empirical functions thus far mainly validated over land. The universality of these functions and their application at sea have not yet been fully evaluated. New experiments have shown that the emission of dimethylsulphide (DMS) can be measured by the REA and GF techniques. Moreover, these measurements have provided parameterizations of gas exchange rates that are within the range of relationships between wind speed and gas transfer that have recently been derived from eddy correlation (EC) and deliberate tracer measurements. Using DMS as a model, gas is potentially a powerful approach to intercalibrate the REA, GF, and EC techniques, test their applicability in the marine environment, and investigate processes that determine trace gas exchange across the ocean surface.
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ArticleDetection of a tropospheric ozone anomaly using a newly developed ozone retrieval algorithm for an up-looking infrared interferometer(American Geophysical Union, 2009-03-25) Lightner, K. J. ; McMillan, W. W. ; McCann, K. J. ; Hoff, R. M. ; Newchurch, M. J. ; Hintsa, Eric J. ; Barnet, C. D.On 2 June 2003, the Baltimore Bomem Atmospheric Emitted Radiance Interferometer (BBAERI) recorded an infrared spectral time series indicating the presence of a tropospheric ozone anomaly. The measurements were collected during an Atmospheric Infrared Sounder (AIRS) validation campaign called the 2003 AIRS BBAERI Ocean Validation Experiment (ABOVE03) conducted at the United States Coast Guard Chesapeake Light station located 14 miles due east of Virginia Beach, Virginia (36.91°N, 75.71°W). Ozone retrievals were performed with the Kurt Lightner Ozone BBAERI Retrieval (KLOBBER) algorithm, which retrieves tropospheric column ozone, surface to 300 mbar, from zenith-viewing atmospheric thermal emission spectra. KLOBBER is modeled after the AIRS retrieval algorithm consisting of a synthetic statistical regression followed by a physical retrieval. The physical retrieval is implemented using the k-Compressed Atmospheric Radiative Transfer Algorithm (kCARTA) to compute spectra. The time series of retrieved integrated ozone column on 2 June 2003 displays spikes of about 10 Dobson units, well above the error of the KLOBBER algorithm. Using instrumentation at Chesapeake Light, satellite imaging, trace gas retrievals from satellites, and Potential Vorticity (PV) computations, it was determined that these sudden increases in column ozone likely were caused by a combination of midtropospheric biomass burning products from forest fires in Siberia, Russia, and stratospheric intrusion by a tropopause fold occurring over central Canada and the midwestern United States.
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ArticleDimethylsulfide emissions over the multi-year ice of the western Weddell Sea(American Geophysical Union, 2008-03-20) Zemmelink, Hendrik J. ; Dacey, John W. H. ; Houghton, Leah A. ; Hintsa, Eric J. ; Liss, P. S.This study, conducted in December 2004, is the first to present observations of DMS in a snow pack covering the multi-year sea ice of the western Weddell Sea. The snow layer is important because it is the interface through which DMS needs to be transported in order to be emitted directly from the ice to the overlying atmosphere. High concentrations of DMS, up to 6000 nmol m−3, were found during the first weeks of December but concentrations sharply decline as late spring-early summer progresses. This implies that DMS contained in sea ice is efficiently vented through the snow into the atmosphere. Indeed, field measurements by relaxed eddy accumulation indicate an average release of 11 μmol DMS m−2 d−1 from the ice and snow throughout December.
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ArticleFluxes and gas transfer rates of the biogenic trace gas DMS derived from atmospheric gradients(American Geophysical Union, 2004-06-30) Zemmelink, Hendrik J. ; Dacey, John W. H. ; Hintsa, Eric J. ; McGillis, Wade R. ; Gieskes, Winfried W. C. ; Klaassen, Wim ; de Groot, Henk W. ; Baar, Hein J. W. deGas transfer rates were determined from vertical profile measurements of atmospheric dimethylsulfide (DMS) gradients over the equatorial Pacific Ocean obtained during the GasEx-2001 cruise. A quadratic relationship between gas transfer velocity and wind speed was derived from the DMS flux measurements; this relationship was in close agreement with a parameterization derived from relaxed eddy accumulation measurements of DMS over the northeastern Pacific Ocean. However, the GasEx-2001 relationship results in gas transfer rates that are a factor 2 higher than gas transfer rates calculated from a parameterization that is based on coincident eddy correlation measurements of CO2 flux. The measurement precision of both the profiling and eddy correlation techniques applied during GasEx-2001 is comparable; the two gas transfer data sets are in agreement within their uncertainty. Differences in the number of samples and the wind speed range over which CO2 and DMS fluxes were measured are likely causes for the observed discrepancy.
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ArticleEnvironmental turbulent mixing controls on air-water gas exchange in marine and aquatic systems(American Geophysical Union, 2007-05-17) Zappa, Christopher J. ; McGillis, Wade R. ; Raymond, Peter A. ; Edson, James B. ; Hintsa, Eric J. ; Zemmelink, Hendrik J. ; Dacey, John W. H. ; Ho, David T.Air-water gas transfer influences CO2 and other climatically important trace gas fluxes on regional and global scales, yet the magnitude of the transfer is not well known. Widely used models of gas exchange rates are based on empirical relationships linked to wind speed, even though physical processes other than wind are known to play important roles. Here the first field investigations are described supporting a new mechanistic model based on surface water turbulence that predicts gas exchange for a range of aquatic and marine processes. Findings indicate that the gas transfer rate varies linearly with the turbulent dissipation rate to the inline equation power in a range of systems with different types of forcing - in the coastal ocean, in a macro-tidal river estuary, in a large tidal freshwater river, and in a model (i.e., artificial) ocean. These results have important implications for understanding carbon cycling.