Preprints
Filtering by Subject: Climate
Dynamics of ITCZ width: Ekman processes, non-Ekman processes and links to sea-surface temperature
Published: 2019-01-22
Subjects: Atmospheric Sciences, Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The dynamical processes controlling the width of the intertropical convergence zone (ITCZ) are investigated using idealized simulations. ITCZ width is defined in terms of boundary-layer vertical velocity. The tropical boundary layer is approximately in Ekman balance suggesting that wind stress places a strong constraint on ITCZ width. A scaling based on Ekman balance predicts that ITCZ width is [...]
A statistics-based reconstruction of high-resolution global terrestrial climate for the last 800,000 years
Published: 2019-01-18
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Statistical Models, Statistics and Probability
Curated global climate data have been generated from climate model outputs for the last 120,000 years, whereas reconstructions going back even further have been lacking due to the high computational cost of climate simulations. Here, we present a statistically-derived global terrestrial climate dataset for every 1,000 years of the last 800,000 years. It is based on a set of linear regressions [...]
Comparing the Euro 2k reconstruction to a regional climate model simulation
Published: 2018-12-20
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Physical Sciences and Mathematics
We do not expect simulations and reconstructions of past climate change to agree on the exact evolution of past climate variations. Simulations with sophisticated climate models present spatially discrete but complete estimates, which are consistent relative to the implemented physics and their uncertain forcing data. Reconstruction methods statistically infer past changes from natural archives [...]
Attributing Historical and Future Evolution of Radiative Feedbacks to Regional Warming Patterns using a Green’s Function Approach: The Preeminence of the Western Pacific
Published: 2018-12-18
Subjects: Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Global radiative feedbacks have been found to vary in global climate model (GCM) simulations. Atmospheric GCMs (AGCMs) driven with historical patterns of sea-surface temperatures (SST) and sea-ice concentrations produce radiative feedbacks that trend toward more negative values, implying low climate sensitivity, over recent decades. Freely-evolving coupled GCMs driven by increasing CO2 produce [...]
Separating the impact of individual land surface properties on the terrestrial surface energy budget in both the coupled and un-coupled land-atmosphere system
Published: 2018-12-12
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Changes in the land surface can drive large responses in the atmosphere on local, regional, and global scales. Surface properties control the partitioning of energy within the surface energy budget to fluxes of shortwave and longwave radiation, sensible and latent heat, and ground heat storage. Changes in surface energy fluxes can impact the atmosphere across scales through changes in [...]
Extreme weather events in early Summer 2018 connected by a recurrent hemispheric wave-7 pattern.
Published: 2018-11-28
Subjects: Atmospheric Sciences, Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The summer of 2018 witnessed a number of extreme weather events such as heatwaves in North America, Western Europe and the Caspian Sea region and rainfall extremes in South-East Europe and Japan that occurred near-simultaneously. Here we show that these extremes were connected by an amplified hemisphere-wide wavenumber 7 circulation pattern. We show that this pattern constitutes a teleconnection [...]
Spatial variability of late Holocene and 20th century sea-level rise along the Atlantic coast of the United States
Published: 2018-11-06
Subjects: Climate, Earth Sciences, Environmental Sciences, Geology, Geomorphology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Sedimentology
Accurate estimates of global sea-level rise in the pre-satellite era provide a context for 21st century sea-level predictions, but the use of tide-gauge records is complicated by the contributions from changes in land level due to glacial isostatic adjustment (GIA). We have constructed a rigorous quality-controlled database of late Holocene sea-level indices from the U.S. Atlantic coast, [...]
Guidance on the homogenization of climate station data
Published: 2018-11-06
Subjects: Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Draft guidance on the homogenisation of climate station data of the World Meteorological Organisation.
Estimating Transient Climate Response in a large-ensemble global climate model simulation
Published: 2018-10-11
Subjects: Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The transient climate response (TCR), defined to be the warming in near-surface air temperature after 70 years of a 1% per year increase in CO2, can be estimated from observed warming over the 19th and 20th centuries. Such analyses yield lower values than TCR estimated from global climate models (GCMs). This disagreement has been used to suggest that GCMs’ climate may be too sensitive to [...]
Lake area constraints on past hydroclimate in the western United States: Application to Pleistocene Lake Bonneville
Published: 2018-10-09
Subjects: Climate, Earth Sciences, Environmental Sciences, Fresh Water Studies, Geology, Geomorphology, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Lake shoreline remnants found in basins of the western United States reflect wetter conditions during Pleistocene glacial periods. The size distribution of paleolakes, such as Lake Bonneville, provide a first-order constraint on the competition between regional precipitation delivery and evaporative demand. In this contribution we downscale previous work using lake mass balance equations and [...]
Learning about climate change uncertainty enables flexible water infrastructure planning
Published: 2018-09-29
Subjects: Civil and Environmental Engineering, Civil Engineering, Climate, Computer Sciences, Earth Sciences, Engineering, Environmental Sciences, Hydrology, Numerical Analysis and Scientific Computing, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Statistics and Probability, Water Resource Management
Water resources planning requires making decisions about infrastructure development under substantial uncertainty in future regional climate conditions. However, uncertainty in climate change projections will evolve over the 100-year lifetime of a dam as new climate observations become available. Flexible strategies in which infrastructure is proactively designed to be changed in the future have [...]
A climatology of rain-on-snow events for Norway
Published: 2018-09-10
Subjects: Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Rain-on-snow (ROS) events are complex multivariate hydrometeorological phenomena requiring a combination of rain and snowpack. Impacts include floods and landslides, and rain may freeze within the snowpack or on bare ground, potentially affecting vegetation, wildlife, and permafrost. ROS events occur mainly in high-latitude and mountainous areas, where sparse observational networks hinder [...]
Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion
Published: 2018-08-31
Subjects: Atmospheric Sciences, Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Meridional atmospheric heat transport (AHT) has been investigated through three broad perspectives: dynamic perspective, linking AHT to the poleward flux of moist static energy (MSE) by atmospheric motions; an energetic perspective, linking AHT to energy input to the atmosphere by top-of-atmosphere radiation and surface heat fluxes; and a diffusive perspective, representing AHT in terms [...]
Why does Amazon precipitation decrease when tropical forests respond to increasing CO2?
Published: 2018-08-30
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Earth system models predict a zonal dipole of precipitation change over tropical South America, with decreases over the Amazon and increases over the Andes. Much of this has been attributed to the physiological response of the rainforest to elevated CO2, which describes a basin-wide reduction in stomatal conductance and transpiration. While robust in Earth system model experiments, details of [...]
Hamiltonian distributed chaos and predictability in large-scale climate dynamics
Published: 2018-08-14
Subjects: Climate, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
It is shown that the large-scale climate dynamics, represented by the daily indices of the North Atlantic (NAO), Pacific/North American (PNA), Arctic (AO) and Antarctic (AAO) oscillations, Asian-Australian Monsoons (ISM, WNPM and AUSM) and El Nino/La Nina phenomenon (Nino indices) as well as global temperature anomalies (land), is dominated by the Hamiltonian distributed chaos with the stretched [...]