Mesoscale eddy fluxes play an important role in ocean transport. Coarse resolution climate models parameterize these fluxes in terms of diffusion coefficients, and improving such parameterizations remains an active topic of research. Recently, significant progress has been made in both describing and understanding the spatial variability in mesoscale diffusivity. The latter has mainly been in terms of monochromatic models, which describe eddy Read more about ClimaTea Lecture: "The Phase-Speed Signature of Mesoscale Eddy Fluxes in the Pacific"
This week GS Yang Tian will lead the discussion on the attached paper titled ”weakening of the stratospheric polar vortex by Arctic sea-ice loss." Attached is also a related review paper by Cohen et al (2014).
GS Jiahua Guo will be discussing Lewis and Karoly (2013) and Perkins et al. (2014), attached. She summarizes the discussion below:
The Australian ‘angry summer” of 2012/2013 was the warmest on record since1910. Such high temperatures are also coincident with bush fires and severe flooding. Before the summer, late onset of the Australian monsoon and below average rainfall primed the continent for extremely hot summer weather. This paper (Lewis and Karoly 2013) is trying to consider the possible anthropogenic contribution to extreme seasonal temperatures in Read more about ClimaTea Journal Club: "Attributing extreme events to anthropogenic forcing"
The recent release of a remarkable dataset of hourly climate observations of temperature, RH, precipitation, opaque cloud cover and snow depth from 13 climate stations across the Canadian Prairies (1953-2011) is transforming our understanding of land-atmosphere-climate coupling. By calibrating the opaque cloud data to give the shortwave and longwave radiative fluxes, we are able for the first time to understand Read more about ClimaTea Lecture: "Understanding land-atmosphere-climate coupling"
This week GS Alex Robel will discuss Roe & Baker (2014), and he summarizes the attached paper as the following:
There has been focus recently on the length changes of mountain glaciers around the world. In this week's ClimaTea, we will discuss work by Roe and colleagues exploring how glaciers integrate noise from the climate system, producing fluctuations in length. They make the basic observation that glaciers have memory, which responds to local temperature and precipitation through the glacier mass balance. This can be captured by models of Read more about ClimaTea Journal Club: "Response of glaciers to random climate forcing"
GS Leah Birch will be presenting the attached two papers, and her summary is below:
Clouds have a two-fold effect in the atmosphere, as they promote both cooling and heating. Due to their size, they are often a great source of uncertainty in GCMs, so it is important to look at results critically. This week I will focus on the warming effect that clouds may have in the context of deglaciation from a Snowball Earth. We will discuss two papers by Abbot et. al. (2012) and Abbot (2014) in an effort to understand the heating ability of clouds and the limitations we think are present Read more about ClimaTea Journal Club: "Warming effect of clouds on snowball Earth"
This week GS Chris Horvat is going to lead the discussion and explore how modern GCMs simulate sea ice, and two ways modelers have been led into traps while modeling it. First, Moon and Wettlaufer (2014) (attached) explore modeling of growth and decay in variable ice-cover regions in GCMs, showing that the when simple sea ice models were extended to these regions (which constitute a majority of the Arctic and Antarctic regions), the extension: (a) "violates the basic rules of calculus" (b) "neglects a leading order latent heat flux" and therefore (c) cannot capture the influence of the ice Read more about ClimaTea Journal Club: "On the nature of the sea ice albedo feedback in simple models"