A Lagrangian climatology of STE derived from the ERA40 data set Markus Jonas (*), Heini Wernli

1. Z dyn. TP > 96h:  else:  t A Lagrangian climatology of STE derived from the ERA40 data set Markus Jonas (*), Heini Wernli Institute for Atmospheric Physics, University of Mainz (*) now at: Climate Monitoring SAF, Deutscher Wetterdienst, Offenbach Global and hemispherical annual budgets yield values that range at the lower end of literature values (e.g. derived from GCMs). Upward water vapour fluxes have similar patterns, but differ in phase given the temperature dependence of saturation water vapour and the strong annual cycle of tropopause temperature. STE fluxes derived from various ECMWF re-analyses differ. This is due to (a) different assimilation techniques used with distinctions in the weighting of observations (SAT vs. sondes) and (b) resulting different tropopause structures. Consideration of different data sets and other sensitivity experi-ments (not shown) allow an assessment of the regional and zonal uncertainties associated with the diagnosed STE mass fluxes. 1 A Lagrangian diagnostic for STE is applied to the ERA40 data period. STT occurs predominantly in the extratropics, with distinct maxima. In the Southern Hem. and for TST flux, less zonal variability is present. NET fluxes are upward in the tropics (maritime cont.), and mainly downward in the mid-latitudes. North. Extratrop. STT has the most pronounced annual cycle, TST and other regional fluxes are rather constant. There is considerable interannual variability throughout the time series. Deep exchange is a subset of total STE mass flux. Preferred low level sources/destinations are visible in the North. Extratropics. Downward ozone fluxes were also derived. Patterns are similar to mass fluxes, maxima occur in spring, minima in autumn of the resp. Hemisph. 2 6 7 3 8 4 9 5 1 6 A Lagrangian diagnostic of STE (Wernli and Bourqui) is applied tothe ERA40 data set. Input: T, 3d-winds with 1°x1° resolution, L60, 6 hourly PV, O3 and q are tracked along trajectories Calc.: Trajs. start daily on a regular grid (30 hPa, 80x80km), 9-days long Selection: (1) crossing the dyn. TP (2pvu, 380K) and (2) fulfilling residence time criterion for t=96h TOP: Seasonal mean fields of upward WATER VAPOUR fluxes (res. time 96h). Values are in g * km-2 * s-1. RIGHT: time series of hemispherically and annually intergrated upward fluxes of WATER VAPOUR for the ERA40 period. Values are in Pg * yr -1. DJF MAM JJA SON MEAN ~47 Pg/yr ~27 Pg/yr ~20 Pg/yr 2 Annual mean fields of STT (downward, left), TST (upward, middle) and NET (STT-TST) mass fluxes for residence time 96 hours. Values are in kg * km-2 * s-1. 7 STE mass fluxes diagnosed from different ECMWF re-analysis data sets for the time period 1989-1992. Values are in kg * km-2 * s-1. ERA 15 ERA 40 ERA INTERIM TST STT 3 Mean annual cycle and variability of regionally integrated mass fluxes (STT, TST and NET). Boxes contain 50% of all occurring values. Values are in 1010 kg * s-1, TST values are negative. Inner Tropics Southern Extratropics Northern Extratropics 8 Mean analysis increments (ANALYSIS – FIRST GUESS) for DJF 1991 at the dynamical TP for different ECMWF re-analysis data sets. Values are in pvu. ERA 15 ERA 40 ERA INTERIM 4 Destination regions of deep STT (left) and source regions of deep TST (right). Deep fluxes descend to/ascend from levels >700hPa and are a subset of some 10% of the mass fluxes. Values are probabilities in %. Contour length of diffe- rent isentropes on the dyn. TP in ECMWF re- analyses as a proxy for tropopause structure. Values are in 106 km. 300K // ERA15ERA40 ERA INTERIM 360K // ERA15ERA40 ERA INTERIM 5 9 TOP: Seasonal mean fields of downward OZONE fluxes (res. time 96h). Values are in mg * km-2 * s-1. RIGHT: time series of hemispherically and annually intergrated downward OZONE fluxes for the ERA40 period. Note problems within ERA40 ozone data 1991-96. Values are in Tg * yr -1. DJF MAM JJA SON Wernli and Bourqui (JGR, 2002): A Lag-rangian „1-year clima- tology“ of (deep) cross-tropopause ex- change in the North-ern Hemisphere. Sprenger and Wernli (JGR, 2003): A North- ern Hemispheric climatology of cross-tro-popause exchange for the ERA15 period (1979-1993). Mean profile of zonally integra- ted STE mass fluxes (STT and TST) for the ERA40 satellite period (1979-2001) with asso- ciated uncertainties based on sensitivity experiments (shaded areas). Values are in 106 kg * km-1 * s-1. MEAN ~290 Tg/yr ~180 Tg/yr ~110 Tg/yr contact:Markus Jonas, markus.jonas@dwd.de