We use the APOSTLE and Auriga cosmological simulations to study the star formation histories (SFHs) of field and satellite dwarf galaxies. Despite sizeable galaxy-to-galaxy scatter, the SFHs of APOSTLE and Auriga dwarfs exhibit robust average trends with galaxy stellar mass: faint field dwarfs (10 5 < M star /M < 10 6.5 ) have, on average, steadily declining SFHs, whereas brighter dwarfs (10 7.5 < M star /M < 10 9 ) show the opposite trend. Intermediate-mass dwarfs have roughly constant SFHs. Satellites exhibit similar average trends, but with substantially suppressed star formation in the most recent ∼ 5 Gyr, likely as a result of gas loss due to tidal and ram-pressure stripping after entering the haloes of their primaries. These simple mass and environmental trends are in good agreement with the derived SFHs of Local Group (LG) dwarfs whose photometry reaches the oldest main sequence turnoff. SFHs of galaxies with less deep data show deviations from these trends, but this may be explained, at least in part, by the large galaxy-to-galaxy scatter, the limited sample size, and the large uncertainties of the inferred SFHs. Confirming the predicted mass and environmental trends will require deeper photometric data than currently available, especially for isolated dwarfs.

Aviation is responsible for an estimated 3.5% of anthropogenic effective radiative forcing (ERF) (Lee et al., 2021), a number that has been growing rapidly as air traffic has increased over recent decades. Of this forcing, the largest-and most uncertain-component is the contribution from contrail cirrus, which is estimated to make up 55% E of the total aviation forcing and was calculated at 57 (17, 98) mW/ 2 m E for 2018 in a recent multimodel synthesis (Lee et al., 2021).Contrail cirrus consists of both linear contrails, which form behind aircraft, and the artificial cirrus cloudiness formed when these linear contrails disperse. Because aircraft emission plumes may be temporarily supersaturated with respect to ice (Minnis et al., 2004), contrails can form in conditions where natural cirrus cannot and therefore have the potential to substantially impact regional high-level cloudiness (Burkhardt & Kärcher, 2011;Sassen, 1997). High-level cloud is also affected by the aerosols emitted by aircraft, which can serve as ice nuclei; the ice nucleation efficiency of black carbon, in particular, remains uncertain (Karcher et al., 2007;Kärcher et al., 2021;Voigt et al., 2021). Finally, the formation of contrail cirrus can compete with natural cirrus for water vapor, reducing the formation of the latter (Burkhardt & Kärcher, 2011). In this work, we will refer to the combination of these effects as aviation-induced cirrus (AIC). Like natural cirrus, the radiative impact of AIC is dominated by its longwave effect and is expected to decrease the diurnal surface air temperature range (DTR) (Sassen, 1997;Travis & Changnon, 1997;Travis et al., 2002).Because of its large radiative impact and short lifetime, AIC is a popular target for mitigation strategies aimed at reducing the climate impact of aviation (see, e.g., overview in Kärcher, 2018). One such strategy is navigational avoidance or the diversion of flight paths away from regions where contrails are likely to form (Grewe1 et al., 2017;Kärcher, 2018;Rosenow et al., 2018). However, the efficacy of this approach hinges on contrail cirrus having a substantially larger radiative forcing than other aviation sources such as

The SDSS-III APOGEE DR12 is a unique resource to search for stars beyond the tidal radii of star clusters. We have examined the APOGEE DR12 database for new candidates of the young star cluster Palomar 1, a system with previously reported tidal tails (Niederste-Ostholt et al. 2010). The APOGEE ASPCAP database includes spectra and stellar parameters for two known members of Pal 1 (Stars I and II), however these do not agree with the stellar parameters determined from optical spectra by Sakari et al. (2011). We find that the APOGEE analysis of these two stars is strongly affected by the known persistence problem (Majewski et al. 2015;Nidever et al. 2015). By re-examining the individual visits, and removing the blue (and sometimes green) APOGEE detector spectra affected by persistence, then we find excellent agreement in a re-analysis of the combined spectra. These methods are applied to another five stars in the APOGEE field with similar radial velocities and metallicities as those of Pal 1. Only one of these new candidates, Star F, may be a member located in the tidal tail based on its heliocentric radial velocity, metallicity, and chemistry. The other four candidates are not well aligned with the tidal tails, and comparison to the Besançon model (Robin et al. 2003) suggests that they are more likely to be non-members, i.e. part of the Galactic halo. This APOGEE field could be re-examined for other new candidates if the persistence problem can be removed from the APOGEE spectral database.persed tidal tail extending up to 1 o (∼ 0.4 kpc, or ∼ 80 half-light radii) from either side of the cluster centre, with roughly as many stars in the tails as in the central cluster region.Examination of the chemical abundances of the stars in Pal1 can be used to study the origin of this system. If Pal1 is a globular cluster that has been shredded, then its stars should show a Na-O anti-correlation (Carretta et al. 2010). However, if Pal1 is a captured stellar group from a dwarf galaxy, then it can be expected to show lower ratios of the α-elements (amongst other chemical signatures, e.g., see Venn et al.

Abstract. The Canadian Earth System Model version 5.0 (CanESM5.0), the most recent major version of the global climate model developed at the Canadian Centre for Climate Modelling and Analysis (CCCma) at Environment and Climate Change Canada (ECCC), has been used extensively in climate research and for providing future climate projections in the context of climate services. Previous studies have shown that CanESM5.0 performs well compared to other models and have revealed several model biases. To address these biases, CCCma has recently initiated the ‘Analysis for Development’ (A4D) activity, a coordinated analysis activity in support of CanESM development. Here we describe the goals and organization of this effort and introduce two variants (``p1'' and ``p2'') of a new CanESM version, CanESM5.1, which features substantial improvements as a result of the A4D activity. These improvements include the elimination of spurious stratospheric temperature spikes and an improved simulation of tropospheric dust. Other climate aspects of the p1 variant of CanESM5.1 are similar to those of CanESM5.0, while the p2 variant of CanESM5.1 features reduced equilibrium climate sensitivity and improved ENSO variability as a result of intentional tuning of the atmospheric component. The A4D activity has also led to the improved understanding of other notable CanESM5.0/5.1 biases, including the overestimation of North Atlantic sea ice, a cold bias over sea ice, biases in the stratospheric circulation and a cold bias over the Himalayas. It provides a potential framework for the broader climate community to contribute to CanESM development, which will facilitate further model improvements and ultimately lead to improved climate change information.

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