Andries C. Kruger

Identifying biologically meaningful hot-weather events using threshold temperatures that affect life-history.

Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (Tthresh) above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using Tthresh values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (Tthresh = 35.5°C) and the common fiscal Lanius collaris (Tthresh = 33°C). We used these Tthresh values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > Tthresh), in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance) of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the Tthresh technique as a conservation tool.

NOAA CIRES Twentieth Century Global Reanalysis Version 2

The Twentieth Century Reanalysis Project, supported by the Earth System Research Laboratory Physical Sciences Division from NOAA and the University of Colorado CIRES Climate Diagnostics Center, is an effort to produce a global reanalysis dataset spanning a portion of the nineteenth century and the entire twentieth century (1871 - near present), assimilating only surface observations of synoptic pressure, monthly sea surface temperature and sea ice distribution. Products include 6-hourly ensemble mean and spread analysis fields on a 2 by 2 degree global latitude-longitude grid, and 3 and 6-hourly ensemble mean and spread forecast (first guess) fields on a global Gaussian T62 grid. Fields are accessible in yearly time series (1 file per parameter) and monthly synoptic time (all parameters per synoptic hour) files. Ensemble grids, spectral coefficients, and other information will available by offline request in the future.\n\n The Twentieth Century Reanalysis Project used resources of the National Energy Research Scientific Computing Center managed by Lawrence Berkeley National Laboratory and of the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory, which are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and Contract No. DE-AC05-00OR22725, respectively.\n\nNote: Version 2c of this reanalysis (running from 1851 - 2011) is the recommended research version. Please see ds131.2 to access Version 2c.

International Surface Pressure Databank (ISPDv2)

The International Surface Pressure Databank (ISPD; Cram et al. 2015) [http://reanalyses.org/observations/international-surface-pressure-databank] is the worlds largest collection of pressure observations. It has been gathered through international cooperation with data recovery facilitated by the ACRE Initiative and the other contributing organizations and assembled under the auspices of the GCOS Working Group on Surface Pressure and the WCRP/GCOS Working Group on Observational Data Sets for Reanalysis by NOAA Earth System Research Laboratory (ESRL), NOAAs National Climatic Data Center (NCDC), and the Climate Diagnostics Center (CDC) of the University of Colorados Cooperative Institute for Research in Environmental Sciences (CIRES). The ISPDv2 consists of three components: station, marine, and tropical cyclone best track pressure observations. The station component is a blend of many national and international collections.\n\nNOTE: A newer version of this dataset, the International Surface Pressure Databank version 3, is available in RDA dataset ds132.1 [http://rda.ucar.edu/datasets/ds132.1/]. Users are recommended to access this updated dataset.\n\nThe Twentieth Century Reanalysis Project used resources of the National Energy Research Scientific Computing Center [http://www.nersc.gov/] and of the Oak Ridge Leadership Computing Facility [http://www.olcf.ornl.gov/] at Oak Ridge National Laboratory, which are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and Contract No. DE-AC05-00OR22725, respectively.