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Studies of solar variability improve our knowledge of the internal structure and dynamical processes taking place within the Sun that lead to solar irradiance changes. Becuase of the astrophysical and climatic significance of irradiance variability, considerable effort has been devoted to model and understand its physical origin.
Stable oxygen isotopes measured in tree rings are useful for reconstructing climate variability and explaining changes in physiological processes occurring in forests, complementing other tree-ring parameters such as ring width. Here, we analyzed the relationships between different climate parameters and annually resolved tree-ring δ(18)O records (δ(18)O(TR)) from white spruce (Picea glauca [Moench]Voss) trees located near Tungsten (Northwest Territories, Canada) and used the NASA GISS ModelE2 isotopically-equipped general circulation model (GCM) to better interpret the observed relationships. We found that the δ(18)O(TR) series were primarily related to temperature variations in spring and summer, likely through temperature effects on the precipitation δ(18)O in spring, and evaporative enrichment at leaf level in summer. The GCM simulations showed significant positive relationships between modelled precipitation δ(18)O over the study region and surface temperature and geopotential height over northwestern North America, but of stronger magnitudes during fall-winter than during spring–summer. The modelled precipitation δ(18)O was only significantly associated with moisture transport during the fall-winter season. The δ(18)O(TR) showed similar correlation patterns to modelled precipitation δ(18)O only during spring–summer when water matters more for trees, with significant positive correlations with surface temperature and geopotential height, but no correlations with moisture transport. Overall, the δ(18)O(TR) records for northwestern Canada reflect the same significant large-scale climate patterns as precipitation δ(18)O for spring–summer, and therefore have potential for reconstructing past atmospheric dynamics in addition to temperature variability in the region.
The climate of the thermosphere is controlled in part by cooling to space driven by infrared radiation from carbon dioxide (CO2, 15μm), nitric oxide (NO, 5.3μm), and atomic oxygen (O, 63μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been measuring infrared cooling from CO2 and NO in the thermosphere since January 2002. These data provide integral constraints on the energy budget and climate of the atmosphere above 100 km. Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes, however, are driven by changes in solar irradiance and changes in geomagnetic conditions.
Obtaining accurate and widespread measurements of the vertical structure of the Earth’s forests has been a longsought goal for the ecological community. Such observations are critical for accurately assessing the existing biomass of forests, and how changes in this biomass caused by human activities or variations in climate may impact atmospheric CO2 concentrations. Additionally, the three-dimensional structure of forests is a key component of habitat quality and biodiversity at local to regional scales. The Global Ecosystem Dynamics Investigation (GEDI) was launched to the International Space Station in late 2018 to provide high-quality measurements of forest vertical structure in temperate and tropical forests between 51.6 N & S latitude. The GEDI instrument is a geodetic-class laser altimeter/waveform lidar comprised of 3 lasers that produce 8 transects of structural information. Over its two-year nominal lifetime GEDI is anticipated to provide over 10 billion waveforms at a footprint resolution of 25 m. These data will be used to derive a variety of footprint and gridded products, including canopy height, canopy foliar profiles, Leaf Area Index (LAI), sub-canopy topography and biomass. Additionally, data from GEDI are used to demonstrate the efficacy of its measurements for prognostic ecosystem modeling, habit and biodiversity studies, and for fusion using radar and other remote sensing instruments. GEDI science and technology are unique: no other space-based mission has been created that is specifically optimized for retrieving vegetation vertical structure. As such, GEDI promises to advance our understanding of the importance of canopy vertical variations within an ecological paradigm based on structure, composition and function.
Leith has suggested that climatic response to change in external forcing parameters of the climate system may be estimated via the fluctuation-dissipation theorem (FDT). The method, which uses the natural fluctuations of the atmosphere to probe its dynamics, is tested here using a twenty-variable truncation model of the barotropic vorticity equation. Dissipative terms are added to the equations, so that the model is pushed away from the region where it is expected to satisfy the FDT. It is found that, even though the FDT is no longer satisfied in every detail, the FDT continues to provide an excellent estimate of the climatic sensitivity of the model.
Replacement of grasslands and savannas by shrublands and woodlands has been widely reported in tropical, temperate and high-latitude rangelands worldwide (Archer 1994). These changes in vegetation structure may reflect historical shifts in climate and land use; and are likely to influence biodiversity, productivity, above- and below ground carbon and nitrogen sequestration and biophysical aspects of land surface-atmosphere interactions. The goal of our proposed research is to investigate how changes in the relative abundance of herbaceous and woody vegetation affect carbon and nitrogen dynamics across heterogeneous savannas and shrub/woodlands. By linking actual land-cover composition (derived through spectral mixture analysis of AVIRIS, TM, and AVHRR imagery) with a process-based ecosystem model, we will generate explicit predictions of the C and N storage in plants and soils resulting from changes in vegetation structure. Our specific objectives will be to (1) continue development and test applications of spectral mixture analysis across grassland-to-woodland transitions; (2) quantify temporal changes in plant and soil C and N storage and turnover for remote sensing and process model parameterization and verification; and (3) couple landscape fraction maps to an ecosystem simulation model to observe biogeochemical dynamics under changing landscape structure and climatological forcings.
Current understanding and knowledge of the composition and structure of cirrus clouds are reviewed and documented in this paper. In addition, the radiative properties of cirrus clouds as they relate to weather and climate processes are described in detail. To place the relevance and importance of cirrus composition, structure and radiative properties into a global perspective, pertinent results derived from simulation experiments utilizing models with varying degrees of complexity are presented; these have been carried out for the investigation of the influence of cirrus clouds on the thermodynamics and dynamics of the atmosphere. In light of these reviews, suggestions are outlined for cirrus-radiation research activities aimed toward the development and improvement of weather and climate models for a physical understanding of cause and effect relationships and for prediction purposes.
The interactions that take place in the stratosphere and the troposphere which are important to the maintenance of the chemical, dynamic, and thermal state and of the middle atmosphere, and which may be important in the determination of the state of the lower atmosphere are reviewed. Examples of these interactions due to either natural or anthropogenic processes are discussed, and promising areas for future research are indicated. Specific topics include: (1) coupling between temperature and chemistry via temperature dependent rate constants; (2) the effect of latitudinal temperature variations on zonal winds; (3) the effect of clouds, surface albedo, and the lower atmosphere on stratospheric chemistry due to the scattering and reflection of solar radiation; (4) the effect of trace constituents on thermal structure and thermal balance; (5) the effect of the stratosphere on tropospheric climate; (6) the effect of solar UV variability on stratospheric chemistry and temperature; and (7) the effect of trace constituents on stratospheric dynamics.
Since the pioneer works of Bjerknes (1966,1969) many studies have been conducted to understand the El Nino and Southern Oscillation (ENSO) phenomenon. These studies have led to a basic understanding of the dynamics of El Nino. Central to the couple dynamics of ENSO is the delayed action oscillator theory (Suarez and Schopf 1988), which successfully describes the cyclic feature of El Nino. While the oscillatory feature of El Nino is reasonably well understood, the irregularity of El Nino, the effect of monsoon on ENSO, and the response of coupled system to the global warming are still under debate. In the present study, we attempt to provide some theoretical understanding of possible impacts of seasonal cycle, monsoon, and climate changes on ENSO using intermediate coupled model.
The GFDL (Geophysical Fluid Dynamics Laboratory, NOAA - National Oceanic and Atmospheric Administration) Finite-Volume Cubed-Sphere Dynamical Core (FV3) is a scalable and flexible dynamical core capable of both hydrostatic and non-hydrostatic atmospheric simulations. FV3 has been chosen as the dynamical core for the Next Generation Global Prediction System project (NGGPS), designed to upgrade the current NCEP (National Centers for Environmental Prediction, NOAA) operational Global Forecast System (GFS) to run as a unified, fully-coupled system in NOAA's Environmental Modeling System infrastructure. FV3 dynamic core has a long history of serving as the main engine for global atmospheric models at various Government and Academic Research Laboratories including NOAA: GFDL Climate Modeling Suite (AM4 (Atmosphere Modeling 4), CM4 (Climate Model 4) ESM4 (Earth System Model 4), Hiram (HIgh Resolution Atmospheric Model)); NASA: GMAO (Global Modeling and Assimilation Office) Goddard Earth Observing System Model (GEOS); and NCAR (National Center for Atmospheric Research) Community Earth System Model (CESM). The three primary stakeholders in FV3 (GFDL, GMAO, EMC (Environmental Modeling Center - NOAA)) have embarked on synergistic and collaborative strategies with focus on the advancement of non-hydrostratic dynamic core, physics, chemistry, and data assimilation efforts, leveraging collective strengths of each of the partnering agencies. This talk presents the ongoing plans for model advancements at GFDL, GMAO and EMC, with special emphasis on contributions towards developing community based unified global modeling system for operational and research applications at respective organizations. Future plans include extending the collaborations to the development of earth system components including GMAO's aerosol chemistry models (GOCART/MAM (Goddard Chemistry Aerosol Radiation and Transport / Modal Aerosol Model)), Land Information System (LIS), and advanced data assimilation techniques; and GFDL's Modular Ocean Model (MOM) and Sea Ice Simulator (SIS) for transition to operations at NCEP.
In Asian monsoon countries such as China and India, human health and safety problems caused by air-pollution are worsening due to the increased loading of atmospheric pollutants stemming from rising energy demand associated with the rapid pace of industrialization and modernization. Meanwhile, uneven distribution of monsoon rain associated with flash flood or prolonged drought, has caused major loss of human lives, and damages in crop and properties with devastating societal impacts on Asian countries. Historically, air-pollution and monsoon research are treated as separate problems. However a growing number of recent studies have suggested that the two problems may be intrinsically intertwined and need to be studied jointly. Because of complexity of the dynamics of the monsoon systems, aerosol impacts on monsoons and vice versa must be studied and understood in the context of aerosol forcing in relationship to changes in fundamental driving forces of the monsoon climate system (e.g. sea surface temperature, land-sea contrast etc.) on time scales from intraseasonal variability (~weeks) to climate change (~ multi-decades). Indeed, because of the large contributions of aerosols to the global and regional energy balance of the atmosphere and earth surface, and possible effects of the microphysics of clouds and precipitation, a better understanding of the response to climate change in Asian monsoon regions requires that aerosols be considered as an integral component of a fully coupled aerosol-monsoon system on all time scales. In this paper, using observations and results from climate modeling, we will discuss the coherent variability of the coupled aerosol-monsoon climate system in South Asia and East Asia, including aerosol distribution and types, with respect to rainfall, moisture, winds, land-sea thermal contrast, heat sources and sink distributions in the atmosphere in seasonal, interannual to climate change time scales. We will show examples of how elevated absorbing aerosols (dust and black carbon) may interact with monsoon dynamics to produce feedback effects on the atmospheric water cycle, leading to in accelerated melting of snowpacks over the Himalayas and Tibetan Plateau, and subsequent changes in evolution of the pre-monsoon and peak monsoon rainfall, moisture and wind distributions in South Asia and East Asia.
A climatological model of the earth-sun system based on an analogy to Planck's law of quantum mechanics is developed. The role of the diabatically important trace gases O3, H2O, and CO2 in the complex processes by which solar cycles affect tropospheric-stratospheric stability, and the value of the resonance concept in understanding these phenomena are examined. Consideration is given to climate complexity and the Laplace transform of the solar cycle, direct versus indirect solar signals, intense convection in coupled dynamics, the basic mechanisms of solar-terrestrial interaction, and the Planck's-law analog. The quantum approach, taking complexity into account, is shown to be more appropriate for evaluating the effects of anthropogenic modifications of the atmosphere (e.,g., increasing CO2) than the linear bulk-heating approaches usually applied.
The Stratospheric Aerosol Measurement II and Stratospheric Aerosol and Gas Experiment satellite systems have provided to date more than five years and almost three years, respectively, of data on atmospheric aerosol profiles on a near-global scale. Studies with these unique data sets are developing a global aerosol climatology for the first time and have shown the existence and quantification of polar stratospheric clouds and tropical stratospheric cirrus. In addition, a tropospheric cirrus climatology is evolving. Since these two experiments were launched, a series of large volcanic eruptions have occurred which have greatly impacted the stratospheric aerosol loading. The aerosol layer produced by the eruption of El Chichon, for example, increased the 30 mb temperatures in the northern tropics by as much as 4 C for six months after the eruption. This paper describes in detail, from a climate perspective, the evolving aerosol and cloud climatologies as a function of space and time, and shows the stratospheric dynamics of volcanic injections and their enhancements on stratospheric optical depth and mass loading.
Statistical methods have been used to show quantitatively that the transition in mean and variance observed in delta O-18 records during the middle of the Pleistocene was abrupt. By applying these methods to all of the available records spanning the entire Pleistocene, it appears that this jump was global and primarily represents an increase in ice mass. At roughly the same time an abrupt decrease in sea surface temperature also occurred, indicative of sudden global cooling. This kind of evidence suggests a possible bifurcation of the climate system that must be accounted for in a complete explanation of the ice ages. Theoretical models including internal dynamics are capable of exhibiting this kind of rapid transition.
The importance of the interaction of chemistry and dynamics in the upper troposphere and lower stratosphere for chemical species like ozone is investigated using two chemistry-climate models. Species emitted in the upper troposphere, like NOx (=NO+NO2) by lightning or aircraft, have the chance to be transported into the lowermost stratosphere. Trajectory calculations suggest that the main transport pathway runs via the Inter Tropical Convergence Zone, across the tropical tropopause and then to higher latitudes, i.e. into the lowermost stratosphere. Longer lifetimes of NOx in the lower stratosphere yield an accumulation of NO. there, which feeds back on upper troposphere chemistry. This effect has been estimated for lightning NO. emissions and reveals a contribution of at least 25% to 40% to the total northern hemisphere mid-latitude lightning increase of either NOx and ozone.
This section on Urban Climates provides a basic understanding of what comprises the urban climate and what factors control the overall development of the urban climate. We also discuss in this section, methods for evaluating urban climate characteristics and forcing functions as well as how the urban heat island effect comes into play as a dynamic influence on urban climatology. Additionally, we examine and discuss the major radiation and energy balance of city (i.e., shortwave and longwave radiation, albedo, net all-wave radiation, total energy balance, and sensible latent, and storage heat) and the interactions of these energy balances with the lower atmosphere. The use of remote sensing to measure urban surface temperatures as a driving force in the development of the urban heat island effect is presented. We also discuss how the overall moisture, precipitation, humidity, and air movement in cities (i,e,, wind speeds and wind direction) and wind environment of the city affects urban climatology.
The unique chemical, dynamical, and microphysical processes that occur in the winter polar lower stratosphere are expected to interact strongly with changing climate and trace gas abundances. Significant changes in ozone have been observed and prediction of future ozone and climate interactions depends on modeling these processes successfully. We have conducted an off-line model simulation of the stratosphere for trace gas conditions representative of 1975-2025 using meteorology from the NASA finite-volume general circulation model. The objective of this simulation is to examine the sensitivity of stratospheric ozone and chemical change to varying meteorology and trace gas inputs. This presentation will examine the dependence of ozone and related processes in polar regions on the climatological and trace gas changes in the model. The model past performance is base-lined against available observations, and a future ozone recovery scenario is forecast. Overall the model ozone simulation is quite realistic, but initial analysis of the detailed evolution of some observable processes suggests systematic shortcomings in our description of the polar chemical rates and/or mechanisms. Model sensitivities, strengths, and weaknesses will be discussed with implications for uncertainty and confidence in coupled climate chemistry predictions.
We have been producing near-red time tropospheric ozone satellite maps from the TOMS (Total Ozone Mapping Spectrometer) sensor since 1997. Maps for 1996-2000 for the operational Earth-Probe instrument are at: . Pollution in the tropics is influenced by biomass burning and by transport patterns that favor recirculation and in other cases reflect climate variability like the El-Nino-Southern Oscillation [Thompson et al., 2001]. The satellite view of chemical-dynamical interactions in tropospheric ozone is not adequate to capture vertical gradients in pollution. Thus, in 1998, NASA's Goddard Space Flight Center and a team of international sponsors established the SHADOZ (Southern Hemisphere ADditional OZonesondes) project to address the gap in tropical ozone soundings. SHADOZ augments launches and provides a public archive of ozonesonde data from twelve tropical stations at http://croc.gsfc.nasa.gov/shadoz. Further insights into the role of chemical and dynamical influences have emerged from the first 4-5 years of SHADOZ data (more than 2000 ozone profiles). Highly variable tropospheric ozone and a zonal wave-one pattern in tropospheric ozone suggest that dynamics is as important as pollution in determining tropical ozone distributions.