Contents

1 OVERVIEW ATMOSPHERIC CHEMISTRY 3 1 Stratospheric Chemistry Understanding the Ozone Layer 4 2 Tropospheric Chemistry A Complex Interaction of Biogeochemical Cycles 11 5 Atmospheric Chemistry within Global Carbon Cycle 16 6 Carbon Monoxide, Nitrogen Oxides, and Oxidizing Capacity of Troposphere 18 7 Atmospheric Chemistry and Global Warming 21 8 Stratosphere-Troposphere Chemical and Climate Interaction 21 9 Stratosphere-Trophosphere Exchange 24 References 28

Constraints

The search for a better (or best) parameter set is facilitated greatly by specifying upper and lower limits for each of the parameters this defines the feasible region in which an optimal parameter set is expected to lie. A useful perspective is to consider this feasible region to be the initial uncertainty in the parameter estimates, based on available prior information. For certain parameters, these upper and lower limits are easily selected based on physical considerations related to the...

Climate Change Hypothesis

Today, most Russian scientists believe that climatic factors are the real cause of the Caspian Sea level rise. Studies by Golitsyn (1989) and Golitsyn and McBean (1992) indicate that recent changes of the Caspian Sea level are 90 associated with corresponding changes in the water balance components of the sea, as opposed to possible tectonic activity. The volume of inflow from rivers to the sea increased sharply after 1978. During certain years (e.g., 1979, 1985, and 1990), more than 350 km3 of...

Contrast Transmittance in Real Space

Any landscape feature can be thought of as consisting of many small pieces, or elements, with a variety of physical characteristics. For instance, the reflectivity of an element as a function of wavelength, along with characteristics of the incident radiation, determines its color and brightness. The brightness of an element at some observing distance and at one wavelength is referred to as monochromatic apparent spectral radiance. The monochromatic apparent spectral radiance of any element is...

References

Tarazona, Bolet n El Ni o Su Impacto en la Fauna Marina (Volumen Extraordinario), IMARPE, Callao, 1985. Bakun, A., Patterns in the Ocean Ocean Processes and Marine Population Dynamics, California Sea Grant College System, 1996. Barber, R. T., and F. P. Chavez, Biological consequences of El Ni o, Science, 222, 1203-1210, 1983. Bjerknes, J. A possible response of the atmospheric Hadley Circulation to equatorial anomalies of ocean temperature, Tellus, 8, 820-829, 1966....

Approaches For Estimating Evaporation Using Remote Sensing

An alternative means of estimating the spatial distribution of evaporation is through the use of remotely sensed images, obtained by either aircraft- or spacecraft-based sensors. Images obtained from existing satellite sensors can cover swaths ranging from 60 to 2050 km (at resolutions ranging from 10 m to 1 km) and include information about surface reflectance, temperature, and general backscatter properties (Table 2). In this section, recent developments in the evaluation of evaporation using...

Biological Aerosols

The winds not only generate aerosols but also scatter preformed particles, including pollen grains, spores, bacteria, viruses, algae, fungi, nematodes, protozoa, and fragments of plant and animal tissues. The concentrations of certain kinds of biological aerosols are monitored for allergy sufferers through the familiar air quality indices of fungal spores and pollen. More generally, however, investigations of biological aerosols have been limited despite their relevance for studies of air...

Banana Prawns

The prawn season in the Gulf of Carpentaria extends from March to June. Prawn catch is related to the amount of rainfall. Mature prawns require a saline environment. With the advent of heavy wet-season rainfall, salinity in the rivers where the prawns breed is lowered, and they are forced to migrate offshore. Once offshore the prawns may be harvested. If wet-season rainfall is very low, then fewer prawns leave the rivers, leading to a low catch. The relationship between the SOI and rainfall in...

Atmospheric Observations

Atmospheric concentrations of methane have been measured systematically for nearly 20 years (Rasmussen and Khalil, 1981 Khalil and Rasmussen, 1983, 1990a Blake and Rowland, 1988 Steele et al., 1992 Khalil et al., 1993 Dlugokencky et al, 1994). There is an additional record from many independent measurements spanning another 15 years or so back to the early 1960s (Khalil et al., 1989). For earlier times, the ice core record is the only source of information. It extends back over 150,000 years,...

Airborne Snow Surveys by State 198098

National Operational Hydrologie Remote Sensing Center Figure 4 Number of airborne snow survey flight lines by state (1980-1998). National Operational Hydrologie Remote Sensing Center (NOHRSC). Figure 4 Number of airborne snow survey flight lines by state (1980-1998). National Operational Hydrologie Remote Sensing Center (NOHRSC). pack, thereby providing an opportunity to collect volume integrated data (e.g., SWE). Because of the difficulty of making field measurements in snow-covered...

Aerosol Microphysics

The atmosphere subjects aerosol particles to an array of transport and transformation processes that alter their size, number, and composition. Advective and turbulent transport of particles is nearly identical to that of the interstitial gas. Transformation processes include condensation and evaporation, which result from diffusion of vapors between the particle and the interstitial gas, homogeneous nucleation to produce new particles from supersaturated vapors, coagulation, which combines two...

Approaches for Determining Available Energy

A number of approaches using remote sensing have been developed for estimating the available energy components in Eq. (10). Generally, Rn is evaluated in terms of its four radiation components (Sellers et al., 1990), namely, Rn (l -i)Rs + sRld- saT h (11) where Rs is the incoming shortwave solar radiation (W m2), is the incoming longwave radiation (W m2), a is the surface shortwave albedo, ss is the surface Reflective Thermal Microwave Satellite Advanced Very High-Resolution Radiometer...

Cch3

Figure 1 Selected nonmethane hydrocarbons emitted from natural sources. typical Arrhenius temperature kinetics with species-dependent temperature optima that range from 36 to 40 C (Guenther et al., 1993). Long-term factors that influence isoprene emission rates include light and temperature conditions in which leaves develop, water and nutrient availability, and disease (Monson et al., 1994 Lerdau and Throop, 2000 Anderson et al, 2000 Harley et al, 1994). Although plants may lose a significant...

[03 H0x0jAm

Combining the kinetic and solubility data permits the rate of reaction to be evaluated for known or assumed conditions of cloud liquid water content and partial pressures of reagent gases (Fig. 3). Here the left-hand ordinate gives the rate of aqueous-phase reaction. The right-hand ordinate gives the effective first-order rate coefficient of aqueous-phase reaction, referred to the gas-phase mixing ratio for indicated conditions, expressed in units of percent per hour. Note the strong pH...

Background Aerosol

The aerosol in the mid and upper troposphere, the so-called free troposphere, is often termed background aerosol. It is well-aged aerosol with a composition and size distribution reflecting the simultaneous effects of gas-to-particle conversion, longrange transport, and removal processes. The number concentration of background aerosol is in the range of 300 cm3 (Raes et al., 2000), and its size distribution is nearly monodisperse with peak diameters in the 0.2 to 0.5 pm range (Leaitch and...

Australian Encephalitis

Australian encephalitis (AE) is a severe, often fatal, viral illness transmitted to humans by mosquitoes and influenced by the ENSO (Nicholls, 1986). Since 1917 when the clinical symptoms of the illness were first diagnosed, there have been only 7 years when cases of AE were observed in southeastern Australia. Cases occur between January and April and follow widespread flooding over several seasons. Flooding leads to increased mosquito numbers by increasing the numbers of breeding sites and...

Chapter

REMOTE SENSING AND GEOGRAPHICAL INFORMATION SYSTEMS APPLICATIONS IN HYDROLOGY EDWIN T. ENGMAN AND NANDISH MATT IK AL LI Remote sensing and associated image-processing technology provide access to spatial and temporal hydrologie information from watershed to global scales. Advances in sensor and imaging technology are increasing the capability of remote sensing for specific hydrologie application. There are two general areas where remote sensing can be used in hydrologie modeling (l) determining...

Changing Approaches for Handling the Flood Hazard

National recognition emerged in the 1950s that the structural approach to flood control was inadequate (White, 1958). This led to the development of a new thrust based on floodplain management through altering land use in floodplains and use of flood insurance, or working with the river. The National Flood Insurance Program was established by Congress in 1968. Emerging environmental concerns in the 1960s led to the National Environmental Protection Act (NEPA) in 1968, bringing environmental...

Chemistry Of Tropospheric Ozone Formation

Photodissociation of N02 by (visible) sunlight is the only significant anthropogenic source of 03 in the troposphere N02 + hv -> NO + O (A < 420 nm) (1) where the M in reaction (2) represents any nonreactive molecule that absorbs some of the excess energy of the intermediate product formed in the reaction (2). 2 CHEMISTRY OF TROPOSPHERIC OZONE FORMATION The atmospheric oxidation of a hydrocarbon, RH, is initiated by reaction with the hydroxyl radical (OH) where RH can be any molecule...

Carbon Monoxide In The Atmosphere

Carbon monoxide (CO) is present in trace quantities in the atmosphere. Although first detected in the late 1940s using solar spectroscopic methods,1'2 few measurements of CO were made during the period between the early 1950s and the mid-1960s. However, as chromatographic and related detection techniques were developed, discrete measurements of CO were made in many locations around the world. These provided considerable insight on global tropospheric distributions most notable among these was...

Climate Variability and Streamfiow

At a given point along a river, streamfiow is the product of the total catchment area above the gage and the average rate at which runoff is generated from snow and or rain in that catchment. Runoff within a basin depends not only on rainfall but on its temporal distribution, vegetation cover (amounts and types), vapotranspiration, soil moisture storage capacity, rate of groundwater outflow, amount of paved area, etc. The seasonality of streamfiow varies widely from river to river and is...

Cloud Physical Properties Pertinent To Cloud Chemistry

Clouds consist of a suspension of liquid or solid (ice) particles in air. Thus, formally, a cloud is an aerosol, a suspension of particles in air. However, it is useful to distinguish clouds from clear-air (noncloud) aerosols. The cloud environment is slightly supersaturated with respect to liquid water or ice, respectively. The typical amount of condensed-phase water is 0.1 to 1 g m3 (roughly equivalent to 0.1 to 1 kg This chapter has been co-authored under Contract No. DE-AC02-98CH10886 with...

Classifying Droughts

With this background, the focus narrows to consider the character of droughts and drought impacts in South Africa in more detail. Defining what is meant by drought is not an easy task. Droughts can be classified as meteorological, agricultural, hydro-logical, or sociological (Wilhite and Glantz, 1985 Dent et al., 1987 Erasmus, 1987 Bruwer, 1989, 1990). Drought, moreover, is also a relative rather than an absolute condition. Droughts can be described as being either an agricultural drought (a...

Conclusion

Despite significant progress in our understanding of the global aerosol system over the past two decades, our knowledge of the sources and dynamics of atmospheric aerosols remains limited. Difficulties associated with measurement of the aerosol size composition distribution, combined with the significant spatial and temporal variability of tropospheric aerosol, have resulted in only scattered knowledge of its global distribution. Aerosols in remote locations and in the middle and upper...

Biomass Burning

Biomass burning in tropical and subtropical regions is a significant source of NO.,. as well as other chemically and radiatively important species such as C02, CO, CH4, NMHC, N20, and aerosols. Recent estimates of NOx emissions are based on emission factors from laboratory as well as field measurements of burning vegetation coupled with biomass inventories, land-use data, estimates of tropical deforestation, and occurrence of wild fires. Burning in the tropical latitudes is estimated to account...

Atmospheric Chemistry Within Global Carbon Cycle

Despite its dominance as a member of the global carbon cycle, carbon dioxide does not play any significant role in atmospheric chemistry. The most abundant carbon species that is an active player in atmospheric chemistry is methane (CH4), which reacts in the troposphere with the hydroxyl radical (OH) to initiate a series of reactions that were shown to play important roles in the global cycles of a number of atmospheric trace species. The seminal work in tropospheric chemistry was published by...

Basin Characteristics

Surface characteristics influence infiltration and runoff rates (Roberts, 1989 Kuhnle et al., 1996). Impervious surfaces such as exposed bedrock or a paved road accelerate surface runoff, thus decreasing lag time between the precipitation event and entrance of water into a nearby channel. Urbanized areas, therefore, with large percentages of impervious surface such as roofs, streets, and parking lots coupled with an engineered drainage system designed to move water quickly to stream channels...

Carbon Monoxide Nitrogen Oxides And Oxidizing Capacity Of Troposphere

In some of the chapters that follow, there are detailed discussions on many individual trace gases such as CO, the oxides of nitrogen, and tropospheric ozone. Additionally, these three trace gases are of particular interest as they interact to a major degree to determine the oxidizing capacity of the troposphere. One of the most important This relatively simple catalytic cycle shows how the global budgets of CO and ozone in the troposphere are intertwined if there is a sufficient amount of NO...

Calibration

The gas chromatographic methods, NDIR, and some TDLS techniques require calibration against samples with known gas amounts. As far as we are aware, there is no national or commercial laboratory that provides certified CO reference gases at levels found in the background atmosphere. Groups measuring CO must therefore dilute high concentration certified gases to atmospheric levels or obtain standards from other laboratories. Laboratory intercom pari sons of the reference gases used by various...

Box 1 Definitions of Food Security

Food security is defined in its most basic form as access by all people at all times to the food needed for a healthy life. Achieving food security has three dimensions first, it is necessary to ensure a safe and nutritionally adequate food supply both at the national level and at the household level. Second, it is necessary to have a reasonable degree of stability in the supply of food both from one year to the other and during the year. Third, and most critical, is the need to ensure that...

Chemical Transformations And Speciation Of Reactive Nitrogen

Almost all reactive nitrogen is introduced into the atmosphere as NO, but within minutes, NO reaches equilibrium with N02. This NO, is subsequently transformed into other NOy species that can be removed, transported, or recycled back to NO,. A general outline of these transformations is represented in Figure 1, which accompanies the following discussion of the behavior and importance of various NOy species. 1. NOx NO + N02). During the day, NO and N02 experience rapid interconversion via the...

Cloud and Aerosol Oxidants

Water-soluble atmospheric species incorporated in cloud droplets and aqueous aerosols may dissociate into ions, and the resulting aqueous-phase redox chemistry provides yet another pathway for oxidation of species in the atmosphere. The importance of this pathway has been established for S02, which dissociates in water to HSO3- and S032 (pKaX 1.9, pKa2 7.2). Rapid oxidation of S02 by H202 in cloud was first suggested by Penkett et al. (1979) Aircraft measurements by Daum et al. (1984)...

Ecological Impacts Of El Ninosouthern Oscillation

The widespread effect of the ENSO on Australian climate variations suggests that there should be strong responses to the phenomenon in Australian biota, including crops. There is ample evidence that the high variability the ENSO imposes on Australian climate impacts the wildlife and vegetation populations of many Australian animals are maintained at levels well below the carrying capacity of the good years. Populations typically increase dramatically during periods of good rainfall and fall...

Desert Aerosol

Large amounts of dust are emitted to the atmosphere from deserts, especially during high wind periods. Most of these particles are coarse (Dp > 1 pm), and many are deposited close to their source some fraction of the smaller particles can be transported over large distances (Prospero, 1990). For example, dust from the Sahara is regularly detected on Barbados Island across the Atlantic Ocean (Andreae, 1995). The chemical composition of desert aerosol reflects its soil source and is often rich...

Conclusions

Drought is endemic to the southern African region. Changes in sea surface temperatures together with realignments of pressure systems can, in some cases, trigger a severe drought period such as occurred in the early 1980s and the 1990s. The impacts of such droughts usually result in severe constraints on food production at regional, national, and local levels impacting on GDP, commercial food supply, and water availability. Reductions in water aggravate such problems creating ripple effects...

Conventional Approaches For Measuring Evaporation

Theoretical developments such as those described in the previous section are generally dependent upon experimental data for verification. There are a variety of conventional approaches for measuring evaporation, ranging from simple to complex and having a range of accuracies and spatial scales. Most simply, evaporation can be measured under field conditions by monitoring the change in soil water storage over a period of time. Though this can be accomplished fairly easily with a neutron soil...

Ck T7 Tytk yy y m i

Where N is the sample size and k is the time lag. The plot of rk versus k, i.e., the correlogram, may give an idea of the degree of persistence of the underlying time series, and it may be useful for choosing the type of stochastic model that may represent the series. When the correlogram decays rapidly to zero after a few lags, it may be an indication of small persistence or short memory in the series, while a slow decay of the correlogram is an indication of large persistence or long memory....

Concluding Remarks

All the methods and models reviewed in this chapter have potential for operational evaluation of the spatial distribution of evaporation for agricultural and hydrological applications. Toward that goal, relatively simple methods using one-time-of-day remote sensing observations for quantifying daily ET have been applied operationally (Seguin et al., 1989, 1991). However, for many regions of Earth's land surface, meteorological data (primarily wind speed and air temperature) essential for...

Current Conditions

As of the completion of the first report to Congress, several observations have been made regarding the success of Title IV It appears that the market-based approach has lowered compliance costs. Costs are lower than expected, probably due to a number of factors such as railroad deregulation, technological innovation, and lower operating costs for scrubbers. In addition, all affected utilities have fulfilled the compliance requirements of Title IV In the first annual reconciliation of...

Generation Of Subsurface Runoff Role of Soil in Runoff Processes

When rainfall falls on the land surface, in many environments the first thing it hits will be a vegetation canopy. This has the effect of retaining some of the rain on leaf surfaces as interception and redistributing the rest down to the ground surface as through all and stemflow. At the ground surface, therefore, the rate of supply of water will no longer be spatially uniform. There may be local concentrations at the base of stems or trunks there may be other areas that receive lower intensity...

Current Understanding Of Tropospheric Ozone Budget

The global distribution of tropospheric ozone presented earlier in this chapter illustrates its heterogeneity and underscores the difficulty of quantifying a global budget using the simplistic assumptions about its vertical distribution that had been employed when budgets neglecting photochemical processes were formulated. It is clear from the depiction in Figure 1 that local-scale photochemical generation of ozone has had a considerable impact on the global distribution as evidenced by the...

Cyclonic Storm Created Surges

In low-lying coastal locations a temporary increase in sea level associated with the approach and landfall of storms with significantly high winds and low central pressure can cause significant damage. Sea level rises in response to low pressure as it passes over ocean surfaces. Additionally, the upper portion of the water column is pushed into waves by the high winds. Storm surges can be more than 5 m above the normal high tide (Rappaport, 1994). In some areas such as bays coupled with...

Downstream Boundary

For subcritical flow, a specified discharge or water-surface elevation time series or a tabular relation between discharge and water-surface elevation (single-valued rating curve) can be used as the downstream boundary condition. Another downstream boundary condition can be a computed loop-rating curve based on the Manning equation, i.e., Qi+X - M 4+1(4+l)2 3(5i)1 2 0 (61) The loop is produced by using the friction slope (Sf) rather than the channel bottom slope (So) in the Manning equation....

Current Agreement And Prospects For The Future

The 1999 agreement represents a dramatic break from the previous approach. Rather than relying on short-lived, ceiling-based regimes whose frequent renegotiation provided ample opportunity for disagreement and brinkmanship, the new agreement establishes a long-term commitment to define harvest shares as a function of the abundance of each salmon species in the areas covered by the treaty. For example, for the next 12 years, the U.S. share of Fraser River sockeye will be fixed at 16.5 of the...

D D Davis G Chen And M Chin

The focus of this chapter is that of providing the reader with an overview of atmospheric sulfur. It will address the issues of where sulfur comes from, how it is processed, and how it gets returned to the planetary surface. It will also endeavor to show how sulfur, during its atmospheric cycle, plays a significant role in helping to maintain a stable global environment. Sulfur is an element that is essential to life on this planet. Living organisms at nearly all levels of sophistication ingest...

Divers

Some divers simply hold their breath while hunting and gathering, while others use surface-supplied compressors to collect oysters and scallops, sea urchins, octopus and to spear a variety of finfish along the rocky shores in relatively shallow water (30 m or less). Their boats or rafts are usually rowed out to the fishing ground, powered by small outboards, by sail, or the fishermen simply dive from shore. The catch is then sold to middlemen back at the home port, where it is transported in...

Decaying Tropical Cyclones

Some of the largest precipitation amounts received as the result of a single meteorological event have been associated with the movement of tropical cyclones (e.g., hurricanes, cyclones, and typhoons) poleward and over continents. These powerful cyclonic storms carry large amounts of warm moist air over land surfaces. While wind speeds associated with these storms decrease quickly after landfall, these decaying storms are capable of delivering precipitation over wide areas during a relatively...

Determination of XE Directly from the Remote Sensing Data

Many approaches for determination of XE directly from remote-sensing data use the surface energy balance equation as the primary boundary condition to be satisfied that is, where Rn + G is often termed the available energy and H + XE are the turbulent fluxes. Evaluation of the available energy is relatively straightforward and will be addressed first, followed by the discussion of more complex evaluation of the turbulent fluxes H and XE.

Controls On Infiltration And Soil Moisture

To characterize soil moisture and infiltration, the physical controls on these processes must be considered. The primary soil controls will be considered in this chapter however, other factors such as soil chemistry, thickness, soil layering or horizons, and preferential flow paths, as well as vegetation cover, tillage, roughness, topography, temperature, and rainfall intensity also exert important controls.4 A soil's particle size distribution has a large impact on its hydraulic properties....

DAVldx dAldt

And the conservation of momentum equation dV dt + V dV dx + g(dh dx + Sf) 0 (2) in which t is time, x is distance along the longitudinal axis of the waterway, A is cross-sectional area, V is velocity, g is the gravity acceleration constant, and h is the water-surface elevation above a datum Sf is the friction slope, which may now be Handbook of Weather, Climate, and Water Atmospheric Chemistry, Hydrology, and Societal Impacts, Edited by Thomas D. Potter and Bradley R. Colman. ISBN 0-471-21489-2...

Dependence of Contrast Transmittance Tr on Atmospheric Optical Variables

Because the contrast transmittance is the one variable that contains all the information required to describe how various physical descriptors of scenic landscape features are modified as a function of aerosol loading, illumination, and observer-vista geometry, it is of interest to examine how sensitive ir is to changes in atmospheric aerosol loading as a function of aerosol mass and average scene radiance. The average scene radiance, N, was identified as a in Eq. (23). Malm and Henry (1987)...

Evapotranspiration

In general, remote-sensing techniques cannot measure evaporation or vapotranspiration directly. However, remote sensing does have two potentially very important roles in estimating vapotranspiration. First, remotely sensed measurements offer methods for extending point measurements or empirical relationships, such as the Thornthwaite (1948), Penman (1948), and Jensen and Haise (1963) methods, to much larger areas, including those areas where measured meteorological data may be sparse. Secondly,...

Dedication And Acknowledgments

Many people have assisted in the production of this Handbook the Contributing Editors, the Authors, our editors at Wiley, friends too numerous to mention, and our families who supported us during the long process of completing this work. Professor Peter Shaffer, University of Washington, is owed deep appreciation for his untiring generosity in sharing his experience and talent to solve many problems associated with this large project. They all deserve much credit for their contributions and we...

Floods Exceeding Past Experience and Design Extremes Continue to Occur

These extreme events caused unusual effects on riverine systems, extreme damage to containment structures, unexpected social and economic impacts, and assessments of the cause of the events came under scrutiny. Many system failures due to the floods were no one's fault the design values were simply exceeded by conditions never or very infrequently experienced since river records have been kept. Several scientific and technical actions are needed to improve understanding, mitigation, and...

Dp2 f urn

Figure 1 Residence times of tropospheric aerosols as a function of particle radius Dp 2. I, small atmospheric ions A, so-called Aitken particles, radii 0,001 to 0.1 jim, residence time estimated from geographical distributions C, residence time calculated based on Brownian coagulation of particles R. radioactivity R precipitation removal F, sedimentation. The three curves shown correspond to the three altitude levels indicated based on F.q. (5). Adapted from Jaenicke (I98S). 1983). Typical sea...

Efforts To Control Flooding 1851 To Present Levees and Warnings

Extensive floods in 1849 and 1850 (followed by an all-time record flood in 1858) led to action in Washington. Congress established the Delta Survey in 1851 to address the design and construction of works to control floods and to aid navigation on the Lower Mississippi River. The river's massive 1858 flood gave the survey team of army engineers a benchmark to work from. The Delta Survey team recommended a levee-only policy in 1861, a policy followed well into the twentieth century. The...

Global Mean OH Concentration

The short lifetime of OH implies that its concentration is highly variable. Deriving the atmospheric lifetimes of gases removed by oxidation by OH requires an estimate of OH concentrations averaged appropriately over time and space. Mass-balance arguments for proxy species with known sources can assist for this purpose. The most successful application, first proposed by Singh (1977) and Lovelock (1977), has been the use of the industrial solvent CH3CC13 to estimate the global mean OH...

Diffusion Wave Model

Another simplified distributed routing model, known as the diffusion wave (zero inertia) model, is based on Eq. (1) along with an approximation of the momentum equation that retains only the last two terms in Eq. (2), i.e., Finite-difference approximation techniques, both explicit and implicit (Strelkoff and Katopodes, 1977), have been used to obtain simultaneous solutions to Eqs. (1) and (27). The diffusion-simplified routing model considers backwater effects however, its accuracy is deficient...

Groundwater Flow Processes

3 Flow Equation for a Confined or Leaky Aquifer 4 Flow Equation for an Unconfined Aquifer 5 Initial and Boundary Conditions 7 Selection of Numerical Models 8 Parameter Estimation (Parameter Identification) 10 Parameter Uncertainty, Parameter Structure, and Optimum Parameter Dimension 11 Model Structure Error (Parameter Structure Error) 12 Generalized Inverse Procedure

Environmental Impacts

Many impacts on the environment were difficult to measure, some remain unmeasured, and many are tertiary and will take many more years before they are fully evident. The 1993 flood sizably altered the natural ecosystem of the Upper Mississippi and Missouri Rivers and their floodplains, changing many environmental conditions forever. The 1997 flooding also did enormous environmental damage in the floodplains in Kentucky, Ohio, Indiana, and Illinois. The 1996 flood did only minimal environmental...

Global Co Distributions Surface CO

Background Atmosphere, CO varies both temporally and spatially. Figure I presents a smoothed representation of the surface distribution of CO in the background marine boundary layer (MBLI as a function of latitude and time. The surface illustrates that CO mixing ratios in both hemispheres exhibit seasonal variation, and Figure 1 Smooth surface representing she distribution of CO in the marine boundary layer. The surface was created from 38 time series determined from sampling locations in the...

Global Tropospheric Ozone Budget

The components of the global tropospheric ozone budget can be broken into four general categories transport from the stratosphere, destruction at Earth's surface, photochemical destruction, and in situ photochemical production. The primary mechanism by which ozone is transported from the stratosphere into the troposphere is through meteorological events referred to as stratospheric intrusions. These events occur in conjunction with the movement of air associated with rapid changes in the...

HiH1M1fh18

In which k is the iteration counter and f(hJk+l) is the left-hand side of Eq. (7) evaluated with the first estimate for h + , which for k 1 is either hJ or a linear extrapolated estimate of hJ+l f'(hJk+i) is the derivative of Eq. (7) with respect to z7+1. It can be approximated by using a numerical derivative as follows f K+X) mi+X + < 0 -m+X - m(H+l +B) (h(+l - e) (9) in which e is a small value, say 0.1 ft (0.03 m). Using Eq. (8), only one or two iterations are usually required to solve Eq....

Flood Information Was Often Incomplete Incorrect or Not Timely

Loss Values Data on flood conditions and losses were typically poor and generally inaccurate (often on the low side), and estimates remained highly inaccurate for considerable time after the floods. Means for obtaining more accurate near real-time data on conditions and losses should be developed to improve planning for in-flood adjustments and for relief and restoration activities. Forecasts by Government Agencies The operational hydrologic models used for flood predictions on all time scales...

Extended Wet Periods

In many cases flooding is caused by the reception of precipitation over an extended time period, on the order of weeks to months, that leads to the saturation of soils in a large-scale region (Rodda, 1970b Smith and Ward, 1998). This saturation leads to increased runoff at a time when streams are at capacity (Ward and Robinson, 1990). Additional water introduced to stream channels cannot be conveyed in the channel but is spread across the floodplain. Wet periods are related to synoptic...

Generalized Inverse Procedure

The generalized inverse procedure seeks to minimize the weighted composite objective function as represented by Eq. (28). In this procedure, the unknown model structure (parameter structure) and its corresponding parameter values are determined not only from prior information and observations but also by the accuracy requirement in model applications. Sun et al. (1997, 1998) presented a stepwise regression procedure for a simultaneous estimation of parameter structure and its corresponding...

Infiltration Estimation

Some basic principles that govern the movement of water into the soil can be used to predict infiltration. The infiltration capacity, f (L), is the maximum rate that a soil in a given condition can absorb water and generally decreases as soil moisture increases. If the rainfall rate is less than the infiltration capacity, then infiltration proceeds at the capacity rate. However, if the rainfall rate exceeds the infiltration capacity, then infiltration proceeds at the capacity rate, and the...

Free Troposphere

Deep convective flux into BL +29.8 to +37.5 deep convective flux to free trop. -39.6 to-63.9 Units 10 kg month Area 32.5-50N, 90-105W Figure 9 Regional boundary layer CO budget for the central United States (32.5 N to 50 N 90 N to 105 W). Note magnitudes of upward and downward deep convective transport components. Question marks signify that relative amounts of CO flux due to shallow convection and synoptic-scale systems are unknown. From Thompson et al. (1994). aqueous chemistry, scavenging,...

Human Judgments of Visual Air Quality

The previous section discussed methodologies for establishing the change in atmospheric particulate loading required to be noticeable either as a layered haze or as a change in scenic quality. It should be emphasized that calculations of detection thresholds and JNCs are statements about changes in information content in an image. JNC changes in the appearance of an image are not necessarily good indicators of judged image quality. For instance, a change in 10 JNCs in a scene with low overall...

I1

Figure 1 The x-t solution domain for the weighted four-point implicit scheme. See ftp site for color image. parallel to the t axis represent locations of cross sections they have a spacing of Ax, which need not be the same between each pair of cross sections. Those parallel to the x axis represent time lines they have a spacing of At, which also need not be the same between successive time lines. Each point in the rectangular network can be identified by a subscript (i), which designates the x...

Halogen Radical Oxidants

There has been longstanding interest in the possible role of halogen radicals as tropospheric oxidants (Singh and Kasting, 1988 Chatfield and Crutzen, 1990). The best evidence so far comes from measurements of alkanes and acetylene in Arctic surface air (Jobson et al., 1994), which indicate a sink in April (polar sunrise) consistent with oxidation by CI atoms present at a concentration of l x 104 atoms cm3. The data also suggest the presence of Br atoms to oxidize acetylene. The source of the...

Inland Impacts

Inland, away from the coast, the largest threat to life and property occurs as a result of flash flooding and large-scale riverine flooding from excessive rainfall. Particularly dangerous are tropical cyclones whose rainfall is initially light and benign after landfall only to erupt a couple of days later into torrential downpours when the environment becomes favorable for precipitation of the large quantities of tropical moisture that have moved inland with the storm. A particularly extreme...

Impacts to Government

Government entities at all levels from local to federal levels experienced severe impacts due to the flooding. Many government activities fell within the broad definition of responses, but many others were more impacts. In 1993, 532 counties were identified as federal disaster areas 11 counties in 1996 and in 1997, 79 counties were similarly declared. The federal government ultimately paid 6.2 billion for flood aid, insurance, and loans in 1993, and the total for 1997 is estimated at over 0.4...

Impacts From Flooding

The failure of 150 years of national policies to solve the problems of flooding in the Mississippi River system was clearly illustrated by the impacts of three recent floods. A major summer (June and July) 1993 flood affected the Upper Mississippi and Lower Missouri Rivers (Changnon, 1996a), leading to 18 billion in losses and responses. In July 1996 a record-setting 43 cm rainstorm in 24 h occurred in Illinois with a large flash flood covering 15,000 km2 in a matter of hours, engulfing a third...

Human Setting

Today's human setting is a result of the basin's settlement patterns and the ensuing human development and use of the land and the river system. The original 13 American states claimed lands extending west to the Mississippi River well before any settlers had moved westward from the nation's east coast. As the eighteenth century ended, rapid settlement of the area began by westward movement into the Ohio River basin. The Louisiana Purchase of lands west of the Mississippi River from France for...

Green Turtles

The number of green turtles observed nesting around northern Australia varies widely from year to year, and these interannual fluctuations are in phase at widely separated rookeries, with large numbers of turtles breeding 2 years after major El Ni o episodes (Limpus and Nicholls, 1988). Preparation for breeding commences well over a year before oviposition. Atmospheric or oceanic anomalies associated with El Ni o (perhaps increased availability of food due to the reduced number of tropical...

Importance Of Runoff In Gridscale Land Surface Modeling For Gcms

In all past general circulation model (GCM) land surface model components, runoff has not been considered to be very important. It has generally been treated simply as an excess of water that magically disappears from the local water balance. In real catchments, of course, runoff does not disappear but may have an effect on the hydrology and energy balance of areas downslope or downstream. Far more effort, computer time, and parameters have been devoted to formulating the controls on the local...

Human Responses to Flooding

There are no accurate estimates of the population in the world's floodplains. Even in the United States, only broad estimates are available, but the trends to increased vulnerability are clear. In 1955 U.S. floodplains had 10 million occupants. Thirty years later the number doubled to 20 million and by the mid-1990s about 12 of the national population lived in areas of periodic inundation. One sixth of the nation's floodplains are urbanized, and they contain more than 20,000 communities...

Info

Figure 1 Peru annual small pelagic catch 1950-2000 (includes anchovy, sardine and mackerel). (Sources 1950-1990 Csirke et al., La ordenaci n y planificaci n pesquera y la reactivaci n del sector pesquero en el Per Rome Jun 92. 1991-1996 Per desembarque de recursos mar timos, seg n especie 90-96 INEI Jul 97. 1997-1999 Statistical Reference Book, No. 13 FEO Proceedings from 1999 FEO Annual Conference, Hong Kong, April 8-9, 1999. Paris Fishmeal Exporters Organization.) Research Programme (WCRP)...

Hurricanes Defined

One of the most powerful natural phenomena on the face of Earth, the hurricane is a member of a broader class of phenomena called cyclones.* The term cyclone refers to any weather system that circulates in a counterclockwise direction in the Northern Hemisphere and in a clockwise direction in the Southern Hemisphere. Tropical cyclones typically form over ocean waters of the tropics. The tropics are the area on Earth's surface between the Tropic of Capricorn and the Tropic of Cancer, 23 27 south...

Initial Conditions

Values of water-surface elevation (h) and discharge (Q) for each cross section must be specified initially at time t 0 to obtain solutions to the Saint-Venant equations. Initial conditions may be obtained from any of the following (a) observations at gaging stations and using interpolated values between gaging stations for intermediate cross sections in large rivers (b) computed values from a previous unsteady-flow solution (used in real-time flood forecasting) and (c) computed values from a...

Hydrology Overview

WHITAKER This chapter provides a brief overview of the hydrologic cycle and discusses the role of hydrology, not only in the global contexts of weather and climate but also in the local and regional contexts of weather as it affects water resources management. This chapter contains a description of the hydrologic cycle and the identification of its specific reservoirs and fluxes. In each description, their relevance to various scales of the hydrologic cycle...

Infiltration And Soil Moisture Processes

Infiltration is the process of water entry from surface sources such as rainfall, snowmelt, or irrigation into the soil. The infiltration process is a component in the overall unsaturated redistribution process (Fig. I)1 that results in soil moisture availability for use by vegetation transpiration, exfiltration (or evaporation) processes, chemical transport, and groundwater recharge. Soil moisture, in turn, controls the partitioning of subsequent precipitation into infiltration and runoff, and...

Introduction

The atmospheric aerosol is a suspension of solid and liquid particles in the air that displays a degree of stability with respect to gravitational settling. Aerosol particles originate from a large number of sources whose influences can change dramatically over time scales of minutes to hours or can remain relatively constant for years. Although the term aerosol technically applies to both the solid and liquid particles and the gases in which they are suspended, common usage allows aerosol to...

Internal Boundaries

Often along the channel floodplain, there are locations such as a dam, bridge, or waterfall (short rapids) where the flow is rapidly varied in space rather than gradually varied. At such locations (internal boundaries), the Saint-Venant equations are not applicable since gradually varied flow is a necessary condition for their derivation. Empirical water elevation-discharge relations such as weir flow are utilized for simulating rapidly varying flow. At internal boundaries, cross sections are...

Integrated Ozone in Dobson Units

Figure 1 (see color insert) Climntological distribution of tropospheric ozone derived from satellite measurements between 1979 and 2000 (from Fishman et al, 2002). Units of contours and Dobson Units (DU). Regions greater than 40 DU have been shaded. See ftp site for color image. 4 TROPOSPHERfC OZONE TRENDS IN NONURBAN TROPOSPHERE 4 TROPOSPHERfC OZONE TRENDS IN NONURBAN TROPOSPHERE Figure 2 (a) (Upper left) monthly mean surface ozone at Barrow and the linear trend tor the entire data record....

Introduction Understanding Societal Responses To Extreme Weather Events

In the 1970s, many decision makers became increasingly interested in climate because of numerous weather-related impacts around the world. Events that helped to stimulate this interest included the failed Peruvian anchovy harvest in 1972 and 1973, the 1968 to 1973 drought in the African Sahel, a severe winter freeze in 1972 in the Soviet Union, and in 1974 floods, drought, and early frost in the U.S. Midwest. In 1977, winter in the eastern United States was the coldest ever recorded and summer...

Industrial Subsector

The industrial subsector is characterized by a purse seine fleet of about 750 vessels with an average capacity of 225 metric tons, employing about 26,000 fishermen and plant workers. Most of these vessels target small pelagic species (primarily anchovy), of which more than 90 is processed into fishmeal, a flourlike substance high in protein that is then used throughout the world primarily as an animal feed supplement and in aquaculture farming. The majority of nonmanagement laborers are fishing...

Measurements of OH Concentrations and Comparisons to Models

The past few years have seen the development of a number of methods for direct measurement of tropospheric OH (special issue of Journal of Atmospheric Science, October 1995). Two of these methods, a long-path absorption (LPA) instrument (Mount, 1992) and a chemical ionization mass spectrometry (CIMS) instrument (Eisele and Tanner, 1991) were intercompared formally at a mountain site in Colorado during the Tropospheric OH Photochemistry Experiment (TOHPE). Under well-mixed atmospheric conditions...

Ocean Impacts

Winds of hurricane speed over the ocean can create monstrous waves. For example, in 1995, the cruise ship Queen Elizabeth II was rocked by a 70-ft (21-m) wave caused by distant hurricane Luis. The sea near a hurricane is chaotic, and an extreme hazard to shipping can occur in response to wave motion moving in many directions. For comparison, strong winds, of course, also occur in winter storms over the open ocean. The risk to shipping and other activities from wave action, however, is generally...

Intense Thunderstorms

Thunderstorms are usually intense, short-lived storms that produce high winds, hail, and heavy rainfall. These storms can be caused by convection in moist tropical air masses over continental surfaces or fast-moving cold fronts that displace those moist air masses (Hirschboeck, 1987). When these storms develop over mountainous areas where the precipitation is concentrated by the topography the potential for large, catastrophic floods is great (Hall, 1981). For example, see Figure 4. The eastern...

Model Structure Error Parameter Structure Error

Sun et al. (1998) presented a procedure whereby the model structure error of using one model structure to replace another model structure is defined by a max -min problem that is based on the distance between the two models measured in the parameter, observation, and prediction management space. Parameter structure error resulting from a different level of parameterization is a special case of model structure error. Without losing generality, we will use parameter structure error to represent...

Levee Overtopping Floodplain Interactions

Flows that overtop levees located along either or both sides of a main-stem river and or its tributaries can be treated as lateral flow (q) in Eqs. (29) and (30) where the lateral flow diverted over the levee is computed as broad-crested weir flow. This overtopping flow is corrected for submergence effects if the floodplain water-surface elevation sufficiently exceeds the levee crest elevation. After the flood peak passes, the overtopping flow may reverse its direction when the floodplain...

Lake Ontario Moisture Storage cm 10

Figure 5 Example of hycirologic forecasts using climate outlooks (from Croley. 1997, 2000 , See ftp site for color image. Figure 5 Example of hycirologic forecasts using climate outlooks (from Croley. 1997, 2000 , See ftp site for color image. Jan 96 Apr Jul Oct Jan 97 Apr Jul Oct Jan 98 Apr Ocl I Nov 1 Dec I Jan 1 Feb I Mar 1 Apr 1 May 1 Jun 1 Jul 1 Aug 1 Figure 6 Example of ensemble streamflow prediction application (taken from Lettenmaier and Wood 1993). Ocl I Nov 1 Dec I Jan 1 Feb I Mar 1...

Observational Techniques

Their rates of exchange with the overlying atmosphere. There are many ways to measure fluxes in the PBL. However, the two most widely used platforms are (l) tower measurements in the surface layer and (2) airplane measurements in the mixed layer. There are, of course, other platforms that are used. For example, in the marine surface layer, ship-mounted instruments are used and in the mixed layer tethered balloons and neutrally buoyant airships have been used. The most direct and fundamental...

Major Unexpected Impacts Occurred

Unique Impacts to All Forms of Transportation The nation's surface transportation systems, particularly the railroads and highway systems, experienced unusual and extensive damages from these three floods. The barge industry and shippers who depend on commercial navigation should seek improved river forecasting models and flood-monitoring systems. Approaches to many critical highway bridges need to be rebuilt to higher levels. Structural Damage Exceeds Expectations These floods with record...

Nitrogen is thought to be in the form of molecular nitrogen with the remainder

Possibly representing mineralized ash (10 ) and high-molecular-weight compounds containing substantial amounts of nitrogen (Lobert et al., 1991 Yokelson et al., 1996). It is unclear whether these latter compounds might act as a source of NO or NOx to the remote troposphere. Of the known fixed nitrogen compounds, NOx is the dominant species (54 ), having an estimated emission factor of approximately 2.1 gN kgC (carbon fuel). This is significantly smaller than the emission factors reported for...

Lightning

Of all NOx sources, improving our understanding of lightning is most critical since it has one of the largest uncertainties and represents what appears to be the dominant source of NOx in the free troposphere. Lightning NO is generated by recombination reactions that occur as this 20,000 K or hotter, 10-MPa pressurized plasma super-sonically expands and cools. Quantifying NOx production from such events is still quite problematic. Much of the current debate stems directly from estimating the...

Nitrate Radical

The nitrate radical (N03) is a strong radical oxidant formed in the oxidation of N02 by 03 A detailed review of its atmospheric chemistry is given by Wayne (1991). During the daytime, N03 photolyzes on a time scale of l min to return N02 At night the lifetime of N03 is much longer. In high-NOt regions such as the eastern United States, N03 accumulates to concentrations of 10 to 100 parts per trillion by volume (pptv) during the nighttime hours (Wayne, 1991). At these concentrations, N03 can...

N1

First lag autocorrelation Number of sign changes (Count the number of times the sequence of residuals changes sign) nonhomogenous variance. The advantage of the ML approach is that the validity of the underlying assumptions can be verified by a postcalibration residual analysis. It is important to note that each of these scalar measures defines a different way to gauge the size of the error vector, and the minimum value for each will define a simulated streamflow sequence that is close to the...