DOI: 10.5061/dryad.qbzkh18qq
title: Lifetimes and timescales of tropospheric ozone: Ozone emission experiments

description: The lifetime of tropospheric O3 is difficult to quantify because we model
 O3 as a secondary pollutant, without direct emissions.  For other
 reactive greenhouse gases like CH4 and N2O, we readily model lifetimes and
 timescales that include chemical feedbacks based on direct
 emissions.  Here, we devise a set of artificial experiments with
 a chemistry-transport model where O3 is directly emitted into the
 atmosphere at a quantified rate.  We create three primary
 emission patterns for O3, mimicking secondary production by surface
 industrial pollution, that by aviation, and primary injection through
 stratosphere-troposphere exchange (STE).  The perturbation
 lifetimes for these O3 sources includes chemical feedbacks and varies from
 6 to 27 days depending on source location and season.  Previous
 studies derived lifetimes around 24 days estimated from the mean
 odd-oxygen loss frequency.  The timescales for decay of excess O3
 varies from 10–20 days in NH summer to 30–40 days in NH winter. 
 For each season, we identify a single O3 chemical mode applying to all
 experiments.  Understanding how O3 sources accumulate (the
 lifetime) and disperse (decay timescale) provides some insight into how
 changes in pollution emissions, climate, and stratospheric O3 depletion
 over this century will alter tropospheric O3.  This work
 incidentally found two distinct mistakes in how we diagnose tropospheric
 O3, but not how we model it.  First, the chemical pattern of an
 O3 perturbation or decay mode does not resemble our traditional view of
 the odd-oxygen family of species that includes NO2.  Instead, a
 positive O3 perturbation is accompanied by a decrease in NO2. 
 Second, heretofore we diagnosed the importance of STE flux to tropospheric
 O3 with a synthetic ‘tagged’ tracer O3S, which had full stratospheric
 chemistry and linear tropospheric loss based on odd-oxygen loss
 rates.  These O3S studies predicted that about 40 % of
 tropospheric O3 was of stratospheric origin, but our lifetime and decay
 experiments show clearly that STE fluxes add about 8 % to tropospheric O3,
 providing further evidence that tagged tracers do not work when the tracer
 is a major species with chemical feedbacks on its loss rates, as shown for
 CH4. 
description: Here we present the results from the UC Irvine
 chemistry-transport model (UCI CTM) used in the study of direct, primary
 ozone emissions.  There are 16 *.nc data files that provide a 3-D (every
 modeled grid cell, 320x160x57) snapshot of O3 or other key variables (air
 mass, e90(tropopause tracer), T and, surface pressure (2D only, 320x160). 
 The netcdf variables are 4-D, being sampled every 5 days for 5 years
 (320x160x57x365), for 4 years (320x160x57x292), or for 6 months
 (320x160x57x36). The 17<sup>th</sup> *.nc file gives the
 relative differences (RD) for the trace chemical species between the
 control run (CTRL) and the aviation direct-O3 emissions (EO3A) on July
 1.  The direct O3 emission case shorthand is:
 EO3A = uses aviation NOx pattern for O3
 emissions EO3B = not direct O3 emissions, but a
 doubling of aviation NOx EO3S = surface pollution
 pattern (NH Asia) EO3T = stratosphere-troposphere
 exchange pattern EO3U = revised
 stratosphere-troposphere exchange pattern 
 The Matlab scripts that read, process, and plot the results are
 in the accompanying zenodo archive.  The figures in the publication as
 well as supplementary figures (in both *.png and *.eps format) generated
 by these scripts are in the xenodo supplement.  The figure files are
 labeled in shorthand and match the plotid's in the Matlab plotting
 script.
description: # Lifetimes and timescales of tropospheric ozone: Ozone emission
 experiments 17 netcdf files with UCI CTM output Each has one primary
 variable as noted, except that EO3_EO3A_1Jul2003.nc has Relative
 Differences for all species as explained below. EO3_CTRL_prs.nc         
 43,391,995 EO3_CTRL_tem.nc       2,311,030,348 EO3_CTRL_ozo.nc      
 2,955,392,239 EO3_CTRL_e90.nc       3,051,450,892 EO3_CTRL_air.nc      
 1,519,051,040 EO3_EO3A_ozo.nc       2,364,511,906 EO3_EO3B_ozo.nc      
 2,364,326,446 EO3_EO3S_ozo.nc       2,364,489,251 EO3_EO3T_ozo.nc      
 2,364,599,147 EO3_EO3U_ozo.nc       2,364,330,292 EO3_EO3Td2_ozo.nc      
 291,719,936 EO3_EO3Td1_ozo.nc       291,582,443 EO3_EO3Sd2_ozo.nc      
 291,704,163 EO3_EO3Sd1_ozo.nc       291,576,627 EO3_EO3Ad2_ozo.nc      
 291,712,609 EO3_EO3Ad1_ozo.nc       291,582,195 EO3_EO3A_1Jul2003.nc     
 5,072,744   Source: G:\\...\\**EO3_CTRL_ozo.nc** Format:  netcdf4
 Dimensions:            Lngs = 320            Lats = 160            Alts =
 57            Days = 365 Variables:     **ozone**            Size:      
 320x160x57x365            Dimensions: Lngs,Lats,Alts,Days           
 Datatype:   single            Attributes: direct O3 emission = 'CTRL
 Jan 2000 - Dec 2004'                        **variable           =
 'ozone (kg per cell)**'     **day**            Size:       365x1
            Dimensions: Days            Datatype:   int32           
 Attributes: direct O3 emission = 'CTRL Jan 2000 - Dec 2004'
                        **variable           = 'Days since 1 Jan
 2000'** \**                            day(1)   = 5    = Jan 5,
 2000** \**                            day(365) = 1826 = end of Dec 31,
 2004**   Source: G:\\...\\**EO3_CTRL_air.nc**     **airmass**           
 Size:       320x160x57x365            Dimensions: Lngs,Lats,Alts,Days
            Datatype:   single            Attributes: direct O3 emission =
 'CTRL Jan 2000 - Dec 2004'                       
 **variable           = 'air mass (kg per cell)'**      **day**
            Size:       365x1            Dimensions: Days           
 Datatype:   int32            Attributes: direct O3 emission = 'CTRL
 Jan 2000 - Dec 2004'                        **variable           =
 'Days since 1 Jan 2000'** \**                            day(1)
   = 5    = Jan 5, 2000** \**                            day(365) = 1826 =
 end of Dec 31, 2004**   Source: G:\\...\\**EO3_CTRL_e90.nc** Variables:
     **e90**            Size:       320x160x57x365            Dimensions:
 Lngs,Lats,Alts,Days            Datatype:   single            Attributes:
 direct O3 emission = 'CTRL Jan 2000 - Dec 2004'
                        **variable           = 'e90 mass (kg per
 cell)'**     **e90 = tropopause tracer:** **&gt;  90 ppb =
 troposphere ; &lt;= 90 ppb = stratosphere**   Source:
 G:\\...\\**EO3_CTRL_tem.nc**     **temp**            Size:      
 320x160x57x365            Dimensions: Lngs,Lats,Alts,Days           
 Datatype:   single            Attributes: direct O3 emission = 'CTRL
 Jan 2000 - Dec 2004'                        **variable           =
 'temperature (K)'**   Source: G:\\...\\**EO3_CTRL_prs.nc**    
 **press**            Size:       320x160x365            Dimensions:
 Lngs,Lats,Days            Datatype:   single            Attributes: direct
 O3 emission = 'CTRL Jan 2000 - Dec 2004'                      
  **variable           = 'surface pressure (hPa)'**   Source:
 G:\\...\\**EO3_EO3U_ozo.nc** Format: netcdf4 Dimensions:            Lngs =
 320            Lats = 160            Alts = 57            Days = 292
 Variables:     **ozone**            Size:       320x160x57x292           
 Dimensions: Lngs,Lats,Alts,Days            Datatype:   single           
 Attributes: direct O3 emission = 'EO3T Jan 2000 - Dec 2003'
                        **variable           = 'ozone (kg per
 cell))'**     **day**            Size:       292x1           
 Dimensions: Days            Datatype:   int32            Attributes:
 direct O3 emission = 'EO3T Jan 2000 - Dec 2003'
                        **variable           = 'Days since 1 Jan
 2000'** Source: G:\\...\\**EO3_EO3A_ozo.nc**   Dimensions:           
 Lngs = 320            Lats = 160            Alts = 57            Days =
 292 Variables:     **ozone**            Size:       320x160x57x292
            Dimensions: Lngs,Lats,Alts,Days            Datatype:   single
            Attributes: direct O3 emission = 'EO3A Jan 2000 - Dec
 2003'                        **variable           = 'ozone (kg
 per cell))**'     **day**            Size:       292x1           
 Dimensions: Days            Datatype:   int32            Attributes:
 direct O3 emission = 'EO3A Jan 2000 - Dec 2003'
                        **variable           = 'Days since 1 Jan
 2000'** Source: G:\\...\EO3_EO3B_ozo.nc     ozone           
 Size:       320x160x57x292            Dimensions: Lngs,Lats,Alts,Days
            Datatype:   single            Attributes: direct O3 emission =
 'EO3A Jan 2000 - Dec 2003'          
              **variable           = 'ozone (kg per cell))'**  
 Source: G:\\...\EO3_EO3S_ozo.nc     ozone            Size:      
 320x160x57x292            Dimensions: Lngs,Lats,Alts,Days           
 Datatype:   single            Attributes: direct O3 emission = 'EO3S
 Jan 2000 - Dec 2003'                        **variable           =
 'ozone (kg per cell))'** Source: G:\\...\EO3_EO3T_ozo.nc    
 ozone            Size:       320x160x57x292            Dimensions:
 Lngs,Lats,Alts,Days            Datatype:   single            Attributes:
 direct O3 emission = 'EO3T Jan 2000 - Dec 2003'
                        **variable           = 'ozone (kg per
 cell))'**   Source: G:\\...\EO3_EO3U_ozo.nc     ozone           
 Size:       320x160x57x292            Dimensions: Lngs,Lats,Alts,Days
            Datatype:   single            Attributes: direct O3 emission =
 'EO3T Jan 2000 - Dec 2003'                           ***Note
 mislabel as EO3T instead of EO3U***                     
   **variable           = 'ozone (kg per cell))'** Source:
 G:\\...\EO3_EO3Ad1_ozo.nc Dimensions:            Lngs = 320           
 Lats = 160            Alts = 57            Days = 36 Variables:     ozone
            Size:       320x160x57x36            Dimensions:
 Lngs,Lats,Alts,Days            Datatype:   single            Attributes:
 direct O3 emission = 'decay Jan 2004 - Dec 2004' \***          
 &gt;&gt;&gt;&gt;&gt;&gt; dates mislabeled: decay from Jul 1 2003 to Dec 31
 2003***                        **variable           = 'ozone (kg per
 cell))'**     day            Size:       36x1            Dimensions:
 Days            Datatype:   int32            Attributes: direct O3
 emission = 'decay Jan 2004 - Dec 2004'                       
 **variable           = 'Days since 1 Jan 2000'**   Source:
 G:\\...\EO3_EO3Ad2_ozo.nc     ozone            Size:       320x160x57x36
            Dimensions: Lngs,Lats,Alts,Days            Datatype:   single
            Attributes: direct O3 emission = 'decay Jan 2004 - Dec
 2004' \***           &gt;&gt;&gt;&gt;&gt;&gt; dates mislabeled: decay
 from Jan 1 2004 to Jun 30 2004***                       
 **variable           = 'ozone (kg per cell))'**   Source:
 G:\\...\EO3_EO3Sd1_ozo.nc   &gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;  day= 292 or 365 points (every 5 days)    only CTRL has 5 years, A/B/S/T/U have 4 years                                         d2 decay     day # snapshot @ end of day)          Jan 5   Y2000 Y2001 Y2002 Y2003 Y2004           Y2004       5   371   736  1101  1466            1466      10   376   741  1106  1471            1471      15   381   746  1111  1476            1476      20   386   751  1116  1481            1481      25   391   756  1121  1486            1486      30   396   761  1126  1491            1491      35   401   766  1131  1496            1496      40   406   771  1136  1501            1501      45   411   776  1141  1506            1506      50   416   781  1146  1511            1511      55   421   786  1151  1516            1516      60   426   791  1156  1521            1521      65   431   796  1161  1526            1526      70   436   801  1166  1531            1531      75   441   806  1171  1536            1536      80   446   811  1176  1541            1541      85   451   816  1181  1546            1546      90   456   821  1186  1551            1551      95   461   826  1191  1556            1556     100   466   831  1196  1561            1561     105   471   836  1201  1566            1566     110   476   841  1206  1571            1571     115   481   846  1211  1576            1576     120   486   851  1216  1581            1581     125   491   856  1221  1586            1586     130   496   861  1226  1591            1591     135   501   866  1231  1596            1596     140   506   871  1236  1601            1601     145   511   876  1241  1606            1606     150   516   881  1246  1611            1611     155   521   886  1251  1616            1616     160   526   891  1256  1621            1621     165   531   896  1261  1626            1626     170   536   901  1266  1631   d1 decay 1631     175   541   906  1271  1636    Jul 5   1636     180   546   911  1276  1641    Y2003   1641     185   551   916  1281  1646     1281     190   556   921  1286  1651     1286     195   561   926  1291  1656     1291     200   566   931  1296  1661     1296     205   571   936  1301  1666     1301     210   576   941  1306  1671     1306     215   581   946  1311  1676     1311     220   586   951  1316  1681     1316     225   591   956  1321  1686     1321     230   596   961  1326  1691     1326     235   601   966  1331  1696     1331     240   606   971  1336  1701     1336     245   611   976  1341  1706     1341     250   616   981  1346  1711     1346     255   621   986  1351  1716     1351     260   626   991  1356  1721     1356     265   631   996  1361  1726     1361     270   636  1001  1366  1731     1366     275   641  1006  1371  1736     1371     280   646  1011  1376  1741     1376     285   651  1016  1381  1746     1381     290   656  1021  1386  1751     1386     295   661  1026  1391  1756     1391     300   666  1031  1396  1761     1396     305   671  1036  1401  1766     1401     310   676  1041  1406  1771     1406     315   681  1046  1411  1776     1411     320   686  1051  1416  1781     1416     325   691  1056  1421  1786     1421     330   696  1061  1426  1791     1426     335   701  1066  1431  1796     1431     340   706  1071  1436  1801     1436     345   711  1076  1441  1806     1441     350   716  1081  1446  1811     1446     355   721  1086  1451  1816     1451     360   726  1091  1456  1821     1456     365   731  1096  1461  1826