Filters

20212

More filters

20222
Reset filters

Settings

search.filters.applied.f.access: openAccess × Type: Text × Publisher: Katlenburg-Lindau : European Geosciences Union × WGL Institute: IAP × WGL Institute: TROPOS ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Evaluating stratospheric ozone and water vapour changes in CMIP6 models from 1850 to 2100
    (Katlenburg-Lindau : European Geosciences Union, 2021) Keeble, James; Hassler, Birgit; Banerjee, Antara; Checa-Garcia, Ramiro; Chiodo, Gabriel; Davis, Sean; Eyring, Veronika; Griffiths, Paul T.; Morgenstern, Olaf; Nowack, Peer; Zeng, Guang; Zhang, Jiankai; Bodeker, Greg; Burrows, Susannah; Cameron-Smith, Philip; Cugnet, David; Danek, Christopher; Deushi, Makoto; Horowitz, Larry W.; Kubin, Anne; Li, Lijuan; Lohmann, Gerrit; Michou, Martine; Mills, Michael J.; Nabat, Pierre; Olivié, Dirk; Park, Sungsu; Seland, Øyvind; Stoll, Jens; Wieners, Karl-Hermann; Wu, Tongwen
    Stratospheric ozone and water vapour are key components of the Earth system, and past and future changes to both have important impacts on global and regional climate. Here, we evaluate long-term changes in these species from the pre-industrial period (1850) to the end of the 21st century in Coupled Model Intercomparison Project phase 6 (CMIP6) models under a range of future emissions scenarios. There is good agreement between the CMIP multi-model mean and observations for total column ozone (TCO), although there is substantial variation between the individual CMIP6 models. For the CMIP6 multi-model mean, global mean TCO has increased from ∼300 DU in 1850 to ∼ 305 DU in 1960, before rapidly declining in the 1970s and 1980s following the use and emission of halogenated ozone-depleting substances (ODSs). TCO is projected to return to 1960s values by the middle of the 21st century under the SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, and SSP5-8.5 scenarios, and under the SSP3-7.0 and SSP5-8.5 scenarios TCO values are projected to be ∼ 10 DU higher than the 1960s values by 2100. However, under the SSP1-1.9 and SSP1-1.6 scenarios, TCO is not projected to return to the 1960s values despite reductions in halogenated ODSs due to decreases in tropospheric ozone mixing ratios. This global pattern is similar to regional patterns, except in the tropics where TCO under most scenarios is not projected to return to 1960s values, either through reductions in tropospheric ozone under SSP1-1.9 and SSP1-2.6, or through reductions in lower stratospheric ozone resulting from an acceleration of the Brewer-Dobson circulation under other Shared Socioeconomic Pathways (SSPs). In contrast to TCO, there is poorer agreement between the CMIP6 multi-model mean and observed lower stratospheric water vapour mixing ratios, with the CMIP6 multi-model mean underestimating observed water vapour mixing ratios by ∼ 0.5 ppmv at 70 hPa. CMIP6 multi-model mean stratospheric water vapour mixing ratios in the tropical lower stratosphere have increased by ∼ 0.5 ppmv from the pre-industrial to the present-day period and are projected to increase further by the end of the 21st century. The largest increases (∼ 2 ppmv) are simulated under the future scenarios with the highest assumed forcing pathway (e.g. SSP5-8.5). Tropical lower stratospheric water vapour, and to a lesser extent TCO, shows large variations following explosive volcanic eruptions. © Author(s) 2021.
  • Thumbnail Image
    Item
    Linear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CHUVA campaign
    (Katlenburg-Lindau : European Geosciences Union, 2021) Braga, Ramon Campos; Rosenfeld, Daniel; Krüger, Ovid O.; Ervens, Barbara; Holanda, Bruna A.; Wendisch, Manfred; Krisna, Trismono; Pöschl, Ulrich; Andreae, Meinrat O.; Voigt, Christiane; Pöhlker, Mira L.
    Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth's hydrological cycle.We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The data for this study were collected during the ACRIDICON-CHUVA campaign on the HALO research aircraft in clean and polluted conditions over the Amazon Basin and over the western tropical Atlantic in September 2014. Our results indicate a threshold of re ∼ 13 μm for warm rain initiation in convective clouds, which is in agreement with previous studies. In clouds over the Atlantic Ocean, warm rain starts at smaller re, likely linked to the enhancement of coalescence of drops formed on giant cloud condensation nuclei. In cloud passes where precipitation starts as ice hydrometeors, the threshold of re is also shifted to values smaller than 13 μm when coalescence processes are suppressed and precipitating particles are formed by accretion. We found a statistically significant linear relationship between PWC and re for measurements at cloud tops, with a correlation coefficient of ∼ 0:94. The tight relationship between re and PWC was established only when particles with sizes large enough to precipitate (drizzle and raindrops) are included in calculating re. Our results emphasize for the first time that re is a key parameter to determine both initiation and amount of precipitation at the top of convective clouds. © Author(s) 2021.