Gerhard Kramm

Gerhard Kramm
University of Alaska System

29.97

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93
Publications
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1,317
Citations

Publications

Publications (93)
Article
Full-text available
In the atmospheric boundary layer (ABL), incomplete mixing (i.e., segregation) results in reduced chemical reaction rates compared to those expected from mean values and rate constants derived under well mixed conditions. Recently, segregation has been suggested as a potential cause of discrepancies between modelled and measured OH radical concentr...
Article
Full-text available
In our paper we demonstrate that the filtration equation used by Gorban’ et al. for determining the maximum efficiency of plane propellers of about 30 percent for free fluids plays no role in describing the flows in the atmospheric boundary layer (ABL) because the ABL is mainly governed by turbulent motions. We also demonstrate that the stream tube...
Article
Full-text available
A method was introduced to assess the sustainability of energy production over the lifetime (~20 y) of wind turbines. Community Earth System Model simulations were downscaled for the tourist seasons (mid-May to mid-September) of 2006 to 2012 (CESM-P1) and 2026 to 2032 (CESM-P2) to obtain a reference and projected wind-speed climatology, respectivel...
Article
Full-text available
Evaluated Weather Research and Forecasting model inline with chemistry (WRF/Chem) simulations of the 2009 Crazy Mountain Complex wildfire in Interior Alaska served as a testbed for typical Alaska wildfire-smoke conditions. A virtual unmanned air vehicle (UAV) sampled temperatures , dewpoint temperatures, primary inert and reactive gases and particu...
Article
Full-text available
This study investigated the uncertainty assessing wind-power production in valleys of complex terrain using Juneau, Alaska as the testbed. The wind-speed data stem from evaluated WRF/Chem simulations for seven tourist seasons (May 15 to September 15). The percentage of wind speeds between cut-in and cutout speed differed up to about 11% among touri...
Article
Full-text available
An inhomogeneous mixing of reactants causes a reduction of their chemical removal compared to the homogeneously mixed case in turbulent atmospheric flows. This can be described by the intensity of segregation IS being the covariance of the mixing ratios of two species divided by the product of their means. Both terms appear in the balance equation...
Chapter
This chapter provides the fundamentals of the thermodynamics of irreversible processes as they are used in meteorology. The discussion includes the laws of thermodynamics, kinetic gas theory, atmospheric stability, and thermodynamics charts. The idea of an air parcel and various thermodynamic systems as they are used in meteorology and climate mode...
Chapter
This chapter covers the nomenclature and basic quantities used in meteorology to describe the atmospheric radiation processes. The principle of blackbody radiation, shortwave and long-wave radiation are applied to the atmosphere. The basics of the interaction radiation-atmosphere and the radiative transfer are presented. The radiative transfer equa...
Chapter
This chapter introduces the theoretical basis of the seven microphysical processes and the terms of their sub-processes. It discusses the concepts of conservation of total water mass, as well as bulk-parameterizations and spectral cloud models. The various cloud types and cloud morphology as a result of their microphysical properties and formation...
Chapter
This chapter is a brief introduction to climate and climatology in a sense as it is used in meteorology. It introduces the basic nomenclature used in climate studies and climatology. The chapter provides a brief introduction into basic climate statistics and climate analysis methods and discusses the general circulation in terms of examples of appl...
Chapter
Since the industrial revolution, the anthropogenic emissions of various trace species changed the composition of the atmosphere appreciably. This chapter presents the basics of atmospheric chemistry of the polluted and unpolluted atmosphere including some basic modeling concepts. The sources, transformation in the gas phase and aqueous phase, gas-t...
Chapter
In the chapter Dynamics, and Synoptic, the basic laws for describing the kinematic and dynamic behavior of tropospheric flows are presented and discussed. The conservation equations for momentum (Newton’s 2nd law), total mass (equation of continuity), dry air, water substances, trace constituents, and energy (1st principle of thermodynamics) are pr...
Data
Full-text available
Fifty years ago, Hans A. Panofsky published a paper entitled Determination of stress from wind and temperature meas-urements. In his famous paper, he presented a new profile function for the mean horizontal wind speed under the condi-tion of diabatic stratification that includes his integral similarity function. With his integral similarity functio...
Article
Full-text available
An inhomogeneous mixing of reactants causes a reduction of their chemical removal compared to the homogeneously mixed case in turbulent atmospheric flows. This can be described by the intensity of segregation IS being the covariance of the mixing ratios of two species divided by the product of their means. Both terms appear in the balance equation...
Article
The chemical reaction cycle in the atmosphere can be influenced by the degree of inhomogeneous mixing (segregation) as shown by results from several modeling and field studies based on own measurements and data from literature. As a measure we compare the intensity of segregation IS, the covariance of two reactants divided by the product of their m...
Article
In our comments we explicitly acknowledge the attempt of Hansen et al. to assess various uncertainties inherent in geophysical data being based on different measuring concepts and observation methods. However, with regard to the planetary energy budget, this paper offers some vulnerable points. We will focus our comments on these vulnerable points...
Article
In our comments on the paper of Link and L\"udecke we document that these authors used rather improper quotations of our paper. They also argued on the basis of false claims regarding our mathematical and physical description of both the global energy balance model of Schneider and Mass and the Dines-type two-layer energy balance model for the Eart...
Article
Full-text available
Data from a Doppler SOund Detection And Ranging (SODAR) device, twice-daily radiosondes, 33 surface meteorological and four aerosol sites were used to assess the ability of the Weather Research and Forecasting model inline coupled with a chemistry package (WRF/Chem) to capture atmospheric boundary layer (ABL) characteristics in Interior Alaska duri...
Article
In this paper we discuss the meaning of feedback parameter, greenhouse effect and transient climate response usually related to the globally averaged energy balance model of Schneider and Mass. After scrutinizing this model and the corresponding planetary radiation balance we state that (a) the this globally averaged energy balance model is flawed...
Article
The Weather Research and Forecasting (WRF) model is run in various configurations for a five day cold weather period with multi-day inversions over Interior Alaska. Comparison of the simulations with radiosonde data and surface observations shows that WRF's performance for these inversions strongly depends on the physical packages chosen. Simulated...
Article
Since the prediction of climate is mainly considered as a prediction of second kind, it is indispensable to assess the accuracy with which these boundary conditions can be determined so that we can find a reasonable answer, whether climate is predictable with a sufficient degree of accuracy or not. Therefore, our contribution is mainly focused on t...
Article
Full-text available
The eddy covariance method was applied for the first time to estimate fluxes of OH and HO2 together with fluxes of isoprene, the sum of methyl vinyl ketone (MVK) and methacrolein (MACR) and the sum of monoterpenes above a mixed deciduous forest. Highly sensitive measurements of OH and HO2 were performed by laser induced fluorescence (LIF), and biog...
Article
Full-text available
The eddy covariance method was applied for the first time to estimate fluxes of OH and HO<sub>2</sub> together with fluxes of isoprene, the sum of methyl vinyl ketone (MVK) and methacrolein (MACR) and the sum of monoterpenes above a mixed deciduous forest. Highly sensitive measurements of OH and HO<sub>2</sub> were performed by laser induced fluore...
Article
In this paper it is shown that Smith (2008) used inappropriate and inconsistent formulations in averaging various quantities over the entire surface of the Earth considered as a sphere. Using two instances of averaging procedures as customarily applied in studies on turbulence, it is shown that Smith's formulations are highly awkward. Furthermore,...
Article
This chapter briefly reviews current state-of-the-art in modeling permafrost in numerical weather prediction models (NWPMs), chemistry transport models (CTMs) and in general circulation models (GCMs) and earth system models (ESMs) for projecting the global climate. Pros and cons of various methods are assessed. Deficits of GCM/ESMs permafrost model...
Article
Full-text available
In this paper the Planck function is derived in the frequency domain using the method of oscillators. It is also presented in the wavelength domain and in the wave number domain. The latter is mainly used in spectroscopy for studying absorption and emission by gases. Also the power law of Stephan and Boltzmann is derived for these various domains....
Article
A generalized form of Wien's displacement law and the blackbody radiation laws of (a) Rayleigh and Jeans, (b) Rayleigh, (c) Wien and Paschen, (d) Thiesen and (e) Planck are derived using principles of dimensional analysis. This kind of scaling is expressed in a strictly mathematical manner employing dimensional pi-invariants analysis sometimes call...
Article
It is shown in this comment that considering the Mauna Loa observation of the atmospheric carbon dioxide concentration and the mean near surface temperature anomalies for the period from the beginning of the seventies to recent years only is, clearly, a source of misinterpretation. If we consider the whole period of available data (1958 - 2004), we...
Article
In this paper, so-called alternative mass balance equations for atmospheric constituents published recently are assessed in comparison with the true local mass balance equations deduced from exact integral formulations. It is shown that these "alternative" expressions appreciably violate the physical law of the conservation of mass as expressed by...
Article
It is argued in this note that Lettau’s climatonomy equation that relates the flux balance equations of energy and water at the earth’s surface to each other in a straight-forward manner can be used for classifying droughts. This climatonomy equation is derived, and the pros and cons are discussed in detail. It is emphasized that all relevant quant...
Article
As especially observed during the 2004 Alaska fire season, huge wildfires drastically alter land cover leading to a change in the dynamic (roughness length), radiative (albedo, emissivity), vegetative (vegetation type and fraction, stomatal resistance), thermal (soil heating, thawing of permafrost), and hydrological (water loss due to the fire) sur...
Article
Full-text available
Wildfires drastically modify land cover. Consequently the dynamic (roughness length), radiative (albedo, emissivity), vegetative (vegetation type and fraction, stomatal resistance), thermal (soil heating, thawing of permafrost), and hydrological (water loss due to the fire) surface characteristics are modified. Simulations were performed with MM5 a...
Article
In this paper, dimensional scaling is used to describe the turbulence structure of the velocity and temperature fields in the inertial range and the far dissipation range as well as the intermediate transition range under locally isotropic conditions at sufficiently large Reynolds numbers. This kind of scaling is expressed in a strictly mathematica...
Article
The correction of eddy fluxes of water vapour and trace gases customarily called the Webb correction is presented and assessed. It is shown that the derivation of the conventional Webb correction equation is based on elements of a Boussinesq approximation. Such elements, however, should not be considered while any kind of flux correction equation i...
Article
Full-text available
Statistical uncertainty in soil temperature and volumetric water content and related moisture and heat fluxes predicted by a state-of-the-art soil module (embedded in a numerical weather prediction (NWP) model) is analyzed by Gaussian error-propagation (GEP) principles. This kind of uncertainty results from the indispensable use of empirical soil p...
Article
Full-text available
The vertically averaged balance equation of atmospheric trace constituents that customarily serves as a basis for one- and two-layer (box) models of the atmospheric boundary layer and the whole troposphere is derived and discussed. It is shown that this kind of balance equation is accompanied by several prominent short-comings so that the capabilit...
Article
Full-text available
An earlier version of HTSVS was further developed to numerically investigate the long-term evolution of water budget elements (water supply to the atmosphere, ground water recharge, change in storage) in climate studies. In doing so, parameterizations of root effects, infiltration, soil frost, and snow insulation were included into HTSVS to predict...
Article
Full-text available
Various water budget elements (water supply to the atmosphere, ground water recharge, change in storage) are predicted by HTSVS for a period of 2050 days. The predicted water budget elements are evaluated by routine lysimeter data. The results show that land surface models need parameterizations for soil frost, snow effects and water uptake to catc...
Article
Results from analyzing the uncertainty of bulk parameterized cloud microphysical processes are presented and discussed. These results are based on a set of prognostic equations for uncertainty parameters which can be derived from the set of governing balance equations for dry air, water vapor, cloud water, rain water, ice, and graupel. Both sets of...
Article
Recently, an increasing variety of schemes to represent cloud microphysical processes have been incorporated into mesoscale models. These schemes, which are usually "bulk" approaches to the microphysics in order to reduce computational cost, range from the rather simple to relatively complex in terms of the processes represented and their formulati...
Article
Full-text available
Sublayer-Stanton numbers, Bi, of heat and matter for the interfacial sublayer over aerodynamically smooth surfaces determined for forced convective conditions by elementary and numerical integration are reviewed and evaluated. The results are based on Roth’s modified Heisenberg model for the spectral energy transfer in the equilibrium range under l...
Article
Full-text available
Results of segregation effects determined during the SANA field experiment "Eisdorf" for the chemical reactions of ozone with NO and NO2 are to be presented and their impact on the corresponding reaction rates and the vertical fluxes of these trace species are to be pointed out.
Article
The main differences between two different conditional sampling techniques, namely the eddy accumulation method (CS) and the relaxed eddy accumulation method (RCS), are to be described and their performance to "measure" vertical fluxes of chemically reactive trace constituents is to be evaluated. It will be shown that, in principle, the CS method i...
Article
The vertically averaged balance equation of chemically reactive atmospheric trace constituents as customarily served as a basis for so-called box models is derived and discussed. It is shown that this kind of balance equation has several prominent short-comings so that the capability of box models to predict real situations of photochemical smog fo...
Article
Since especially the parameterisation of the vertical dispersion of trace species in the atmospheric boundary layer has controversially been discussed in the literature, the 1st-order balance equations for matter, momentum, and various energy forms were re-formulated with Hesselberg's density-weighted averaging calculus to point out that this probl...
Article
In this paper the main differences between two different conditional sampling techniques namely the true conditional sampling (CS) method often called eddy accumulation method and the relaxed conditional sampling (RCS) method usually denoted as relaxed eddy accumulation method are described. It is shown that, in principle, the CS method should be a...
Article
Full-text available
One of the earliest observations that air pollution could damage vegetation was made in Los Angeles during 1944 (Finlayson-Pitts and Pitts 1986). It was established by Middleton et al. (1950) that plant damage was associated with air pollution episodes. Haagen-Smit et al. (1952) showed that similar plant damage could be caused by synthetic mixtures...
Article
Two different bulk-parameterization schemes of cloud microphysics alternatively used in a meso-β-scale meteorological model are compared to elucidate their influence on the predicted atmospheric water cycle. The different parameters (e.g., ice crystal types, density of ice) and parameterizations (e.g., terminal velocity, riming, accretion) used by...
Chapter
Full-text available
Substantial progress has been made in the last eight years in the understanding and quantification of ammonia exchange between the atmosphere and biosphere. Much of the work has been linked to the joint EC/EUROTRAC subproject BIATEX (BIosphere ATmosphere EXchange), which has served as the main European forum for work in this area. In the mid-1980s...
Chapter
During the development of the EUROTRAC research programme on atmosphere-surface exchange it was recognised that while for SO2 much valuable progress has been made, there were few published studies of NO2 deposition, a very weak understanding of the processes which regulate NO2 exchange and many problems both in measurement and interpretation. For e...
Article
Full-text available
Summary A soil/vegetation/atmosphere transfer (SVAT) scheme for determining the dry deposition and/or emission fluxes of NO, NO2, and O3 in the atmospheric surface layer over horizontally uniform terrain covered with fibrous canopy elements is presented and discussed. This transfer scheme is based on the micrometeorological ideas of the transfer of...
Article
Vertical wind speed, temperature and humidity profile data from three known atmospheric field campaigns are used to determine the surface layer similarity functions for the transport of momentum and heat as well as TKE (turbulent kinetic energy) and pressure fluctuations. The basic principles on which we carry out this determination are a simplifie...
Article
Full-text available
It is well established that the transfer of heat and matter across the interfacial sublayer in the immediate vicinity of any surface is strongly controlled and limited by molecular transfer properties. Whereas a considerable part of the shear stress is transmitted to the surface as a form drag on the individual asperities. The sublayer-Stanton numb...
Article
Dry deposition of ozone and reactive nitrogen species, such as NO, NO2, NO3, N2O5, HNO3, NH3 and NH4NO3, is examined in the context of numerical methods. These methods are based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat, and matter near the Earth's surface, where chemical reactions among these tr...
Article
Numerical experiments with a 3-D-dimensional mesoscale α weather forecast model are performed to investigate the sensitivity of the model to different parameters and the parameterized microphysics. The parameterization considers condensation and deposition of water vapor, sublimation, evaporation of both cloud water and rainwater, riming of ice cry...
Article
Full-text available
Results from a re-evaluation of the flux correction suggested by Webb et al. (Q. J. R. Meteorol. Soc., 106, 85-100, 1980) are presented and discussed. This re-evaluation is based on the equation of continuity as well as the budget equations for dry air, water vapour and atmospheric trace species, where a density-weighted averaging procedure introdu...
Article
Full-text available
The paper gives a survey of the concepts, the methods and the measuring devices currently used to determine the dry deposition and emission of trace gases. Furthermore, problems inherent in these methods are pointed out and discussed. A short description of the essential micrometeorological measurements to determine fluxes for different compounds a...
Article
Results from numerical investigations regarding the exchange of HNO3, NH3, and NH4NO3 between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's s...
Article
Chemical measurements at five levels within and above a predominantly spruce forest at the Bayerischer Wald (Bavarian forest) National Park, Germany, site show that particulate nitrate, as well as nitric acid, is rapidly removed to the forest canopy. The rate of dry removal to the forest canopy for particulate nitrate was nearly as large as that fo...
Article
Modified Bowen ratio and aerodynamic profile techniques based on the constant flux approach were utilized to derive the deposition fluxes and deposition velocities (vd) of gaseous nitric acid from measurements made during two joint field experiments over low vegetation (grassland, LOVENOX, Halvergate, UK, September 1989) and over a wheat canopy (ec...
Article
Full-text available
A modified profile method for determining the vertical deposition (or/and exhalation) fluxes of NO, NO2, ozone, and HNO3 in the atmospheric surface layer is presented. This method is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions amo...
Article
The estimation of the surface-layer parameters u * (friction velocity), * and q * (temperature and humidity scales), r and q r (temperature and humidity reference values), z o (roughness length) and d (zero-displacement) from vertical profiles of wind velocity, temperature and humidity by least-squares methods is described. The estimation is based...
Article
A diagnostic deposition model based on generally accepted micrometeorological ideas on the transfer of momentum, sensible heat and matter near the Earth's surface is presented. The parameterization of fluxes is based on the flux-gradient relationships in the turbulent region of the surface layer and the sublayer Stanton number as well as the Reynol...
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