Effluent, fancy talk for chemtrail. :P ATTENTION K-MART SHOPPERS!! THE BLUE LIGHT SPECIAL IS ON, ON THIS ONE!! Recent experiments with the chemical transport model used by Weaver et al. suggest that the assimilation kinematic vertical velocities may generate excessive diffusion (S. Strahan, personal communication, 1997) A Lagrangian estimate of aircraft effluent lifetime M. R. Schoeberl and C. H. Jackman NASA Goddard Space Flight Center, Greenbelt, Maryland Abstract. The lifetime of aircraft exhaust is estimated using multiyear diabatic trajectory integrations using United Kingdom Meteorological Office and Goddard Space Flight Center (GSFC) Data Assimilation Office winds. Instantaneous January trajectory parcel releases in the midlatitude stratosphere at 19, 16, 14, 13, and 11 km are compared. The first two cases correspond to the proposed flight altitudes of high-speed supersonic aircraft. The last two cases correspond to subsonic flight altitudes. Parcels descending below 250 hPa are eliminated as would occur when aircraft effluent reaches the troposphere. After a transient adjustment period the total number of parcels in most experiments decays exponentially with a decay period (lifetime) of about 1 year. This is the lifetime of the longest-lived eigenmode as discussed by Prather [1996]. Our 1-year lifetime is shorter than the 1.5 year GSFC two-dimensional (2-D) model lifetime for the same release, but in good agreement with the 1.13 year GSFC 3-D model lifetime. We also find that the effluent lifetime is slightly longer in the southern hemisphere midlatitude stratosphere than in the northern. Both the 13 and 11 km releases are mostly within the stratospheric middle world and rapidly leave the stratosphere. We conclude that there will be a small impact of subsonic aircraft exhaust on the larger stratosphere. Finally, we find that our overall lifetime results are fairly sensitive to the lower stratospheric heating rates. Instantaneous January trajectory parcel releases in the midlatitude stratosphere at 19, 16, 14, 13, and 11 km are compared. After a transient adjustment period the total number of parcels in most experiments decays exponentially with a decay period (lifetime) of about 1 year. ---------- YEP. 2. The Trajectory Model and Experiment Scenarios. For our effluent studies, parcels are released instantaneously on a regular grid in the northern henrisphere (N}t). Parcels arc spaced every 5 ø in latitude and 5 ø in longitude from 20øN to 60øN; 642 parcels are released. The release distribution is based upon the projected zonal mean release scenarios reported by NASA [1995, Figure 17] and is equivalent to the 2-D model release scenarios except that the parcel density with respect to latitude is not weighted toward the higher latitude emission region as suggested by Wuebbles et al. [1993]. The release distribution also does not include the cross-equatorial emissions. The zonal symmetry of the release is justified by Sparling et al. [1995], who showed that a North Atlantic winter release rapidly becomes zonally symmetric; however, the main reason for such a simplified release scenario is to allow for clear interpretation of the results. An instantaneous release is used so that the decay time can be unambiguously estimated. We have also performed one computationally intensive zonal release with 7380 parcels (E19M) to test the statistics of our release numbers. The computed global decay rates for E19M and El9 (Table 1) were found to be the same to within the uncertainty of the fit to the exponential tail. This indicates that the number of parcels used was sufficient to provide a statistically robust representation of the longest-lived eigenmode. We have also performed one computationally intensive zonal release with 7380 parcels (E19M) to test the statistics of our release numbers. -- HEH HEH HEH, HERE COMES THE DISCOUNT. ASSUME in this paragraph = ASS YOU ME ;) Every 10 days after the release the air parcels are checked to see if they have moved below the 250 hPa level. which is the approximate altitude of the midlatitude tropopause. Parcels found at altitudes below 250 hPa are assumed to be removed by rainout. With this simple removal algorithm it is possible for parcels to enter the tropical troposphere from the midlatitude stratosphere and be relofted rather than be eliminated. In practice, this happens very rarely. Most parcels entering the tropical troposphere quickly follow isentropes to pressures above 250 hPa and are removed. A test of this removal algorithm against a more complex tropopause-following algorithm shows that this simple procedure gives virtually the same results as the more complex one. Ten experiments are described below (Table 1). For each of the instantaneous aircraft exhaust releases, we start on January 2, 1994, and run the experiment until at least December 25, 1996. The experiment using the GEOS-STRAT winds begins on October 1, and the winds are recycled after the first year (i.e., the winds on October 1 are the same for each year of integration). -- The first experiment, El9, is our base experiment, a 19 km release. This release corresponds to the maximum emission altitude of the combined HSCT (high-speed civil transport) fleet. -- The tracer is initialized in the same height and latitude region as the 2-D model. -- The more rapid dispersal of the tracer by the trajectory model into the tropics and then to the southern hemisphere is consistent with the results from Rasch et al. [1994]. After roughly 2 years, the 2-D model tracer has reached high altitudes, but is still mostly confined to the northern hemisphere -- The 14C experiment is a bomb debris release to allow us to compare results with the 2-D and 3-D model bomb release studies [Mahlman and Moxim, 1978; Johnston, 1989; NASA, 1993]. The parcels are released at 520 K (about 22 km) from 20øN to 70øN. For this experimenthe release begins in October 1992 [see NASA, 1993, Figure I-la] and is run until December 15, 1996 -- 4. Summary and Conclusions A series of 3-year integrations of adiabatic trajectory model is used to study the lifetime of instantaneous, northern hemisphere, aircraft effluent releases at a variety of altitudes. Most of the experiments are performed using UKMO assimilated wind fields for horizontal transport. Cross-isentropic motion is calculated for globally balanced net heating rates derived from the UKMO temperature and climatological ozone and cloud fields. Parcels descending below 250 hPa are assumed to be in the troposphere and are removed. acd-ext.gsfc.nasa.gov/People/Jackman/Schoeberl_1998.pdf -- Okay...memory is pertinent in this game of hard ball. For our effluent studies, parcels are released instantaneously on a regular grid in the northern henrisphere (N}t). A series of 3-year integrations of adiabatic trajectory model is used to study the lifetime of instantaneous, northern hemisphere, aircraft effluent releases at a variety of altitudes. Smart Dust, Northern Hemishpere. Coincidence? Bullshit. https://facebook/photo.php?fbid=597972890254376&set=a.125829707468699.39410.100001250107977&type=3&theater Smart Dust (chaff, ha ha) over Florida: https://facebook/photo.php?fbid=597955043589494&set=a.125829707468699.39410.100001250107977&type=3&theater _____________ Ben Dodds, Max Bliss, Marie McLoughlin, Amanda Williams, Gerri Mcloughlin, Amber Salvati, Dinah Everett Snyder, Timothy Borgman, Chris Swiatek, Zach Hamilton, ImagenesXtomas Xt, Kate Magdalena Willens, Mindy Kristoff, Alex Hunter, Poppy Lilly, Elizabeth Smith
Posted on: Sat, 29 Mar 2014 07:52:08 +0000
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