2012 CIRA Seminars
NASA's Atmospheric Infrared Sounder (AIRS) has the ability to provide atmospheric temperature and water vapor information at higher resolution and accuracy than previous systems, which may be very beneficial for improving forecasts of high impact weather and cloud and precipitation systems.
The statistical connection between strong surface cyclones over Europe and long-lived upper-tropospheric Rossby wave trains is examined for the Northern Hemisphere winter season using 45 years of reanalysis data. Dates are selected for which the surface pressure anomaly over Central Europe is below a threshold yielding the 5%-percentile of the lowest values. Composites of upper tropospheric meridional wind for these dates (including a lead or lag in time) display clear signs of a wave train.
Despite the importance of ice formation in determining the properties of many clouds our quantitative understanding of ice nucleation is poor. Our knowledge of the ice nucleating ability of important aerosol types such as mineral dusts, soot and various biological materials has improved in recent years, but there remain significant gaps in our knowledge. For example, at temperatures above about -15C it is unclear which aerosol species can trigger ice nucleation (Murray et al., 2012).
Ozone is a natural component of the stratosphere and a minor component in the lower atmosphere, but anthropogenic smog significantly enhances the concentrations in the troposphere. As a strong oxidizer, ozone will react with many substances including plant and animal tissues. Numerous health studies have demonstrated significant impacts on lung function from ozone exposure. As a result, over the last 40 years, the U.S. has made the ozone standard increasingly strict, in accordance with the available health data. But meeting this standard will be very challenging.
Following a discussion on the framing of how climate extremes relate to climate change, an examination will be given of a number of large impact climate extremes that occurred in 2010 and 2011. The main focus is on the Russian heat wave and the Pakistan floods, and how both were driven by natural variability, especially ENSO, and global warming from human influences. Together these resulted in very high sea surface temperatures (SSTs) in several places that played a vital role in subsequent developments.
Developed in collaboration with CIRA scientists, the Monte Carlo wind speed probability (MCWSP) model estimates the probabilities of 34-kt (39-mph), 50-kt (58-mph), and 64-kt (74-mph) wind speeds occurring at a given point within the next 12, 24, 36, ..., 120 hours. For each tropical cyclone, the MCWSP model generates 1,000 forecast realizations by sampling from track and intensity forecast errors from the last 5 years and determines the wind radii of each realization using a simple climatology and persistence scheme.
An important process with regard to climate change is the prevalence of multi-decadal periods of fluctuations in both global and local temperature, precipitation, and other climate elements. The usual period of these variations is about 50-70 years or roughly 25-35 years between low to high or high to low periods. The weather 25-35 years ago can often seem different from what we experience today. Such multi-decadal periods have always been part of the Earth's climate system.
Across NOAA and other government agencies, there exists a wide variety of environmental data and information systems meeting various agency missions. To meet NOAA's mission - to understand and predict changes in climate, weather, oceans, and coasts, to share that knowledge and information with others, and to conserve and manage coastal and marine ecosystems and resources - NOAA's data and systems need to be easily accessible and interoperable. Achieving this would lead to a more efficient organization.
Organization and structure of orographic convection producing flash floods in Southern Switzerland.
The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for over twelve years. Among the retrieved quantities are the amount and type of wildfire smoke, desert dust, volcanic effluent, urban and industrial pollution particles, and other aerosols. However, the broad scientific challenges of understanding aerosol impacts on climate and health place different, and very exacting, demands on our measurement capabilities.
My main focus will be on the analysis of changes in the atmospheric water budget components over the Mediterranean and the Mid-East. I will show our results for the climatic trends to extremes and regional modeling over the E. Mediterranean.
The present generation of satellite products has revealed the near-constant presence of supercooled liquid water (SLW) over the Southern Ocean. A climatology of these clouds has been developed using MODIS, CloudSat, Calipso and the merged data product DARDAR-MASK to reveal the dominance of boundary layer clouds across the region. The thermodynamic structure of these clouds and the boundary layer has then been examined through the historical sounding records at Macquarie Island (54 S) to demonstrate the importance of wind shear through the region.
Arctic amplification, broadly defined as greater-than-global Arctic warming in response to external forcing and/or internal climate variability, is ubiquitous in climate models and observations. Despite a long and rich history of numerical model experiments and observational analysis, the relative importance of the processes controlling Arctic amplification is still subject to debate. In this talk, I use coupled climate model experiments to identify the influence of atmospheric processes and ocean model complexity (slab ocean vs.
An exposure/sensitivity/adaptation framework is used to allow all stakeholders in an industry or situation to contribute their expert knowledge to develop an understanding of key areas of vulnerability to climate change impacts. The Climate Change Risk Management Matrix was used by stakeholders to identify climate impacts and identify possible adaptation options. The adaptation options derived from this process can guide businesses, researchers, and resource managers in their response to climate change impacts and increase resilience of businesses, industries and communities.
Resilient-Sustainable Cities at NCAR cordially invites you to a presentation by the esteemed sociologist and human geographer Karen O'Brien on ethical transformation in response to climate change. The talk will address the following issues:
I will discuss various examples of the use Empirical Orthogonal Function analysis of filtered global tropical (20S-20N) brightness temperature (Tb) data to isolate equatorial disturbances. We have found that this technique is very objective and leads to some interesting insights about the relationship between equatorial and extratropical wave activity. One example reveals out of phase variations in convection on either side of the equator within the west Pacific ITCZ and SPCZ, with a period of around 4 days.
Clouds transport water, trace gases, and momentum through the atmosphere in a way that is not at all "diffusive". Instead, clouds transport these things in a "transilient" way, jumping across whole layers of the atmosphere. As a result, the convective tendencies of water, dust, trace gases, momentum, etc. are most accurately diagnosed - and modeled - using the so-called "transilient matrix" as a framework.
The South American Monsoon System (SAMS) is now clearly recognized as one of the major features of the tropical circulation. The South Atlantic Convergence Zone (SACZ) and the Amazon Heat Source are major features of the SAMS and constitute important heat sources with regional and remote influences, with significant diurnal, synoptic, intraseasonal, decadal or multi-decadal variability.
On the global scale, the dominant dynamical feature that influences the zonally averaged distribution of temperature and species in the stratosphere is the Brewer-Dobson circulation (BDC), a wave-driven, Lagrangian mean, meridional mass circulation linking the tropics to the higher latitudes. The circulation can be broken down into three main parts; ascent in the tropics bringing tropospheric air into the stratosphere, poleward transport in the stratosphere and descent at middle and polar latitudes, ultimately bringing stratospheric air back into the troposphere.
The standard Kalman filter observational update requires the inversion of the observation error covariance matrix, which is computationally prohibitive regarding its size. Most implementations of the Ensemble Kalman filter circumvent this difficulty by assuming the diagonality of the observation error covariance matrix, making the analysis calculation numerically tractable. However, when observation errors are actually correlated spatially, such hypothesis yields too much weight to the observations, and may lead to the collapse of the ensemble.
Societal vulnerability to weather arises largely from relatively rare events at the extremes of the spectrum. Examples include: extended droughts, heat waves, major hurricanes, extreme local rainfall and snowfall, ice storms, European wind storms, and severe local storms and tornadoes. Our vulnerability to property loss and societal disruption also is increasing as society becomes more complex and interconnected, and as private, industrial and commercial development expands in high-risk areas.
Our ability to predict climate change is fundamentally connected to our understanding of the processes that govern global energy balance. Changes in global temperature are ultimately governed by the net flux of energy into the Earth-atmosphere system while the time-scales of responses to energy imbalances is largely governed by the partitioning of this energy between the atmosphere and the oceans.
Recent idealized cloud resolving numerical simulations of the transformation of a weak mid-level vortex over a warm ocean into a tropical cyclone suggest that there may be two distinct pathways that can occur. The first pathway proceeds by spin up of surface winds that become greater than those of the initial weak mid-level vortex until they become large enough that they reach tropical cyclone strength. Development is characterized by a gradual decrease of the radius of maximum winds at the surface.
Observations suggest that the latitudinal location, longitudinal extent, and overall strength of the North Pacific subtropical jet (STJ) can vary on intraseasonal and synoptic time scales in response to poleward-directed diabatically driven upper-level outflow associated with tropical heating anomalies and tropical cyclones (TCs), and equatorward-directed flow associated with the passage of higher latitude transient baroclinic disturbances.
Most reduced trace gases emitted into the atmosphere are removed by oxidation including greenhouse gases, air pollutants, and aerosol precursors. The primary atmospheric oxidants, the hydroxyl radical (OH) and ozone (O3), play critical roles in chemistry-climate feedbacks. Peroxyacetyl nitrate (PAN), formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs), serves as a thermally unstable reservoir for nitrogen oxide radicals (NOx = NO + NO2), permitting anthropogenic NOx emissions to impact the global distribution of O3 and OH.