scholarly journals Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

2018 ◽  
Vol 32 (2) ◽  
pp. 501-529 ◽  
Author(s):  
Kazuaki Yasunaga ◽  
Satoru Yokoi ◽  
Kuniaki Inoue ◽  
Brian E. Mapes
Keyword(s):  
Positive Real Part ◽  
Radiative Heating ◽  
Imaginary Component ◽  
Moist Static Energy ◽  
Coherent Signals ◽  
Positive Real ◽  
Real Component ◽  
The Real ◽  
Budget Equation ◽  
Static Energy

Abstract The budget of column-integrated moist static energy (MSE) is examined in wavenumber–frequency transforms of longitude–time sections over the tropical belt. Cross-spectra with satellite-derived precipitation (TRMM-3B42) are used to emphasize precipitation-coherent signals in reanalysis [ERA-Interim (ERAI)] estimates of each term in the budget equation. Results reveal different budget balances in convectively coupled equatorial waves (CCEWs) as well as in the Madden–Julian oscillation (MJO) and tropical depression (TD)-type disturbances. The real component (expressing amplification or damping of amplitude) for horizontal advection is modest for most wave types but substantially damps the MJO. Its imaginary component is hugely positive (it acts to advance phase) in TD-type disturbances and is positive for MJO and equatorial Rossby (ERn1) wave disturbances (almost negligible for the other CCEWs). The real component of vertical advection is negatively correlated (damping effect) with precipitation with a magnitude of approximately 10% of total latent heat release for all disturbances except for TD-type disturbance. This effect is overestimated by a factor of 2 or more if advection is computed using the time–zonal mean MSE, suggesting that nonlinear correlations between ascent and humidity would be positive (amplification effect). ERAI-estimated radiative heating has a positive real part, reinforcing precipitation-correlated MSE excursions. The magnitude is up to 14% of latent heating for the MJO and much less for other waves. ERAI-estimated surface flux has a small effect but acts to amplify MJO and ERn1 waves. The imaginary component of budget residuals is large and systematically positive, suggesting that the reanalysis model’s physical MSE sources would not act to propagate the precipitation-associated MSE anomalies properly.

scholarly journals Moist Static Energy Budget of the MJO during DYNAMO

2014 ◽  
Vol 71 (11) ◽  
pp. 4276-4291 ◽  
Author(s):  
Adam Sobel ◽  
Shuguang Wang ◽  
Daehyun Kim
Keyword(s):  
Indian Ocean ◽  
Energy Budget ◽  
Active Phase ◽  
Turbulent Fluxes ◽  
Radiative Heating ◽  
Moist Static Energy ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Moist Static Energy Budget ◽  
Static Energy

Abstract The authors analyze the column-integrated moist static energy budget over the region of the tropical Indian Ocean covered by the sounding array during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY2011)/Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment in late 2011. The analysis is performed using data from the sounding array complemented by additional observational datasets for surface turbulent fluxes and atmospheric radiative heating. The entire analysis is repeated using the ECMWF Interim Re-Analysis (ERA-Interim). The roles of surface turbulent fluxes, radiative heating, and advection are quantified for the two MJO events that occurred in October and November using the sounding data; a third event in December is also studied in the ERA-Interim data. These results are consistent with the view that the MJO’s moist static energy anomalies grow and are sustained to a significant extent by the radiative feedbacks associated with MJO water vapor and cloud anomalies and that propagation of the MJO is associated with advection of moist static energy. Both horizontal and vertical advection appear to play significant roles in the events studied here. Horizontal advection strongly moistens the atmosphere during the buildup to the active phase of the October event when the low-level winds switch from westerly to easterly. Horizontal advection strongly dries the atmosphere in the wake of the active phases of the November and December events as the westerlies associated with off-equatorial cyclonic gyres bring subtropical dry air into the convective region from the west and north. Vertical advection provides relative moistening ahead of the active phase and drying behind it, associated with an increase of the normalized gross moist stability.

The Absorption and Reflection of Microwave Radiation by a Mercury-Vapour Discharge

1952 ◽  
Vol 5 (4) ◽  
pp. 592
Author(s):  
HA Prime
Keyword(s):  
Discharge Current ◽  
Power Transmission ◽  
Imaginary Component ◽  
Mercury Vapour ◽  
Ionized Gas ◽  
Real Component ◽  
The Real ◽  
Transmission And Reflection Coefficients ◽  
Rate Of Increase ◽  
Transmission And Reflection

The power transmission and reflection coefficients of a limited volume of ionized gas (a mercury-vapour discharge) located within a waveguide have been measured at a frequency of approximately 10,000 Mc/s. by a microwave method. From these coefficients the real and imaginary components of the complex conductivity of the discharge are evaluated. The results show that the real component of the conductivity бr is a linearly increasing function of the discharge current, whereas the rate of increase of the imaginary component бi, which is negative, decreases with increasing discharge current. The ratio бi/бr, decreases with increase in current, but is of the order of unit;- due to the fact that the gas pressure is sufficiently high (?1 atm.) to make бr comparable with бi. The theoretical basis of the work is presented in an appendix in which the particular case of high pressure conditions is discussed.

scholarly journals Satellite Perspectives of Sea Surface Temperature Diurnal Warming on Atmospheric Moistening and Radiative Heating During MJO

2020 ◽  
pp. 1-56
Author(s):  
Kyle Itterly ◽  
Patrick Taylor ◽  
J. Brent Roberts
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Large Scale ◽  
Active Phase ◽  
Radiative Heating ◽  
Sea Surface ◽  
Integrated Analysis ◽  
Moist Static Energy ◽  
Diurnal Warming ◽  
Static Energy

AbstractDiurnal air-sea coupling affects climate modes such as the Madden-Julian Oscillation (MJO) via the regional moist static energy budget. Prior to MJO initiation, large-scale subsidence increases (decreases) surface shortwave insolation (winds). These act in concert to significantly warm the uppermost layer of the ocean over the course of a single day and the ocean mixed layer over the course of 1-2 weeks. Here, we provide an integrated analysis of multiple surface, top-of-atmosphere, and atmospheric column observations to assess the covariability related to regions of strong diurnal sea surface temperature (dSST) warming over 44 MJO events between 2000-2018 to assess their role in MJO initiation. Combining satellite observations of evaporation and precipitation with reanalysis moisture budget terms, we find 30-50% enhanced moistening over high dSST regions during late afternoon using either ERA5 or MERRA-2 despite large model biases. Diurnally developing moisture convergence, only modestly weaker evaporation, and diurnal minimum precipitation act to locally enhance moistening over broad regions of enhanced diurnal warming, which rectifies onto the larger scale. Field campaign ship and sounding data corroborate that strong dSST periods are associated with reduced middle tropospheric humidity and larger diurnal amplitudes of surface warming, evaporation, instability, and column moistening. Further, we find greater daytime increases in low cloud cover and evidence of enhanced radiative destabilization for the top 50th dSST percentile. Together, these results support that dSST warming acts in concert with large-scale dynamics to enhance moist static energy during the suppressed to active phase transition of the MJO.

High-Resolution Simulation of Shallow-to-Deep Convection Transition over Land

2006 ◽  
Vol 63 (12) ◽  
pp. 3421-3436 ◽  
Author(s):  
Marat Khairoutdinov ◽  
David Randall
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
High Resolution ◽  
Deep Convection ◽  
Radiative Heating ◽  
Moist Static Energy ◽  
Cold Pools ◽  
Shallow Clouds ◽  
The Mean ◽  
Static Energy

Results are presented from a high-resolution three-dimensional simulation of shallow-to-deep convection transition based on idealization of observations made during the Large-Scale Biosphere–Atmosphere (LBA) experiment in Amazonia, Brazil, during the Tropical Rainfall Measuring Mission (TRMM)-LBA mission on 23 February. The doubly periodic grid has 1536 × 1536 × 256 grid cells with horizontal grid spacing of 100 m, thus covering an area of 154 × 154 km2. The vertical resolution varies from 50 m in the boundary layer to 100 m in the free troposphere and gradually coarsens to 250 m near the domain top at 25.4 km. The length of the simulation is 6 h, starting from an early morning sounding corresponding to 0730 local time. Convection is forced by prescribed surface latent and sensible heat fluxes and prescribed horizontally uniform radiative heating Despite a considerable amount of convective available potential energy (CAPE) in the range of 1600–2400 J kg−1, and despite virtually no convective inhibition (CIN) in the mean sounding throughout the simulation, the cumulus convection starts as shallow, gradually developing into congestus, and becomes deep only toward the end of simulation. Analysis shows that the reason is that the shallow clouds generated by the boundary layer turbulence are too small to penetrate deep into the troposphere, as they are quickly diluted by mixing with the environment. Precipitation and the associated cold pools are needed to generate thermals big enough to support the growth of deep clouds. This positive feedback involving precipitation is supported by a sensitivity experiment in which the cold pools are effectively eliminated by artificially switching off the evaporation of precipitation; in the experiment, the convection remains shallow throughout the entire simulation, with a few congestus but no deep clouds. The probability distribution function (PDF) of cloud size during the shallow, congestus, and deep phases is analyzed using a new method. During each of the three phases, the shallow clouds dominate the mode of the PDFs at about 1-km diameter. During the deep phase, the PDFs show cloud bases as wide as 4 km. Analysis of the joint PDFs of cloud size and in-cloud variables demonstrates that, as expected, the bigger clouds are far less diluted above their bases than their smaller counterparts. Also, thermodynamic properties at cloud bases are found to be nearly identical for all cloud sizes, with the moist static energy exceeding the mean value by as much as 4 kJ kg−1. The width of the moist static energy distribution in the boundary layer is mostly due to variability of water vapor; therefore, clouds appear to grow from the air with the highest water vapor content available. No undiluted cloudy parcels are found near the level of neutral buoyancy. It appears that a simple entraining-plume model explains the entrainment rates rather well. The least diluted plumes in the simulation correspond to an entrainment parameter of about 0.1 km−1.

scholarly journals Open-Ended Coaxial Probe Measurements of Complex Dielectric Permittivity in Diesel-Contaminated Soil during Bioremediation

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6677
Author(s):  
Andrea Vergnano ◽  
Alberto Godio ◽  
Carla Maria Raffa ◽  
Fulvia Chiampo ◽  
Jorge A. Tobon Vasquez ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Moisture Content ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Complex Dielectric Permittivity ◽  
Imaginary Component ◽  
Real Component ◽  
The Real ◽  
Coaxial Probe

In the bioremediation field, geophysical techniques are commonly applied, at lab scale and field scale, to perform the characterization and the monitoring of contaminated soils. We propose a method for detecting the dielectric properties of contaminated soil during a process of bioremediation. An open-ended coaxial probe measured the complex dielectric permittivity (between 0.2 and 20 GHz) on a series of six soil microcosms contaminated by diesel oil (13.5% Voil/Vtot). The microcosms had different moisture content (13%, 19%, and 24% Vw/Vtot) and different salinity due to the addition of nutrients (22 and 15 g/L). The real and the imaginary component of the complex dielectric permittivity were evaluated at the initial stage of contamination and after 130 days. In almost all microcosms, the real component showed a significant decrease (up to 2 units) at all frequencies. The results revealed that the changes in the real part of the dielectric permittivity are related to the amount of degradation and loss in moisture content. The imaginary component, mainly linked to the electrical conductivity of the soil, shows a significant drop to almost 0 at low frequencies. This could be explained by a salt depletion during bioremediation. Despite a moderate accuracy reduction compared to measurements performed on liquid media, this technology can be successfully applied to granular materials such as soil. The open-ended coaxial probe is a promising instrument to check the dielectric properties of soil to characterize or monitor a bioremediation process.

A Mechanism of Tropical Convection Inferred from Observed Variability in the Moist Static Energy Budget

2014 ◽  
Vol 71 (10) ◽  
pp. 3747-3766 ◽  
Author(s):  
Hirohiko Masunaga ◽  
Tristan S. L’Ecuyer
Keyword(s):  
Energy Budget ◽  
Large Scale ◽  
Deep Convection ◽  
Vertical Motion ◽  
Tropical Convection ◽  
Radiative Heating ◽  
Moist Convection ◽  
Baroclinic Mode ◽  
Moist Static Energy ◽  
Static Energy

Abstract Temporal variability in the moist static energy (MSE) budget is studied with measurements from a combination of different satellites including the Tropical Rainfall Measuring Mission (TRMM) and A-Train platforms. A composite time series before and after the development of moist convection is obtained from the observations to delineate the evolution of MSE and moisture convergences and, in their combination, gross moist stability (GMS). A new algorithm is then applied to estimate large-scale vertical motion from energy budget constraints through vertical-mode decomposition into first and second baroclinic modes and a background shallow mode. The findings are indicative of a possible mechanism of tropical convection. A gradual destabilization is brought about by the MSE convergence intrinsic to the positive second baroclinic mode (congestus mode) that increasingly counteracts a weak MSE divergence in the background state. GMS is driven to nearly zero as the first baroclinic mode begins to intensify, accelerating the growth of vigorous large-scale updrafts and deep convection. As the convective burst peaks, the positive second mode switches to the negative mode (stratiform mode) and introduces an abrupt rise in MSE divergence that likely discourages further maintenance of deep convection. The first mode quickly dissipates and GMS increases away from zero, eventually returning to the background shallow-mode state. A notable caveat to this scenario is that GMS serves as a more reliable metric when defined with a radiative heating rate included to offset MSE convergence.

scholarly journals Intercomparison of MJO column moist static energy and water vapor budget among six modern reanalysis products

2021 ◽  
pp. 1-65
Author(s):  
Pengfei Ren ◽  
Daehyun Kim ◽  
Min-Seop Ahn ◽  
Daehyun Kang ◽  
Hong-Li Ren
Keyword(s):  
Water Vapor ◽  
Critical Role ◽  
Radiative Heating ◽  
Moist Static Energy ◽  
Model Parameterization ◽  
The Mean ◽  
Static Energy ◽  
Two Parameters ◽  
Water Vapor Budget ◽  
Radiation Feedback

AbstractThis study conducts an intercomparison of the column-integrated moist static energy (MSE) and water vapor budget of the Madden-Julian Oscillation (MJO) among six modern global reanalysis products (RAs). Inter-RA differences in the mean MSE, MJO MSE anomalies, individual MSE budget terms and their relative contributions to the propagation and maintenance of MJO MSE anomalies are examined. Also investigated is the relationship between the MJO column water vapor (CWV) budget residuals with the other CWV budget terms as well as the two parameters that characterize cloud-radiation feedback and moisture-convection coupling.Results show a noticeable inter-RA spread in the mean state MSE, especially its vertical structure. In all RAs, horizontal MSE advection dominates the propagation of the MJO MSE while column-integrated longwave radiative heating and vertical MSE advection are found to be the key processes for MJO maintenance. The MSE budget terms directly affected by the model parameterization schemes exhibit high uncertainty. The differences in anomalous vertical velocity mainly contribute to the large differences in vertical MSE advection among the RAs. The budget residuals show large inter-RA differences and have non-negligible contributions to MJO maintenance and propagation in most RAs.RAs that underestimate (overestimate) the strength of cloud-radiation feedback and the convective moisture adjustment timescale tend to have positive (negative) MJO CWV budget residual, indicating the critical role of these processes in the maintenance of MJO CWV anomalies. Our results emphasize that a correct representation of the interactions among moisture, convection, cloud, and radiation is the key for an accurate depiction of the MJO MSE and CWV budget in RAs.

scholarly journals Moisture and Moist Static Energy Budgets of South Asian Monsoon Low Pressure Systems in GFDL AM4.0

2018 ◽  
Vol 75 (6) ◽  
pp. 2107-2123 ◽  
Author(s):  
Ángel F. Adames ◽  
Yi Ming
Keyword(s):  
General Circulation ◽  
Deep Convection ◽  
Linear Regression Analysis ◽  
Maximum Amplitude ◽  
Circulation Model ◽  
Radiative Heating ◽  
Eastern Coast ◽  
Energy Budgets ◽  
Moist Static Energy ◽  
Static Energy

Abstract The mechanisms that lead to the propagation of anomalous moisture and moist static energy (MSE) in monsoon low and high pressure systems, collectively referred to as synoptic-scale monsoonal disturbances (SMDs), are investigated using daily output fields from GFDL’s atmospheric general circulation model, version 4.0 (AM4.0). On the basis of linear regression analysis of westward-propagating rainfall anomalies of time scales shorter than 15 days, it is found that SMDs are organized into wave trains of three to four individual cyclones and anticyclones. These events amplify over the Bay of Bengal, reach a maximum amplitude over the eastern coast of India, and dissipate as they approach the Arabian Sea. The structure and propagation of the simulated SMDs resemble those documented in observations. It is found that moisture and MSE anomalies exhibit similar horizontal structures in the simulated SMDs, indicating that moisture is the leading contributor to MSE. Propagation of the moisture anomalies is governed by vertical moisture advection, while the MSE anomalies propagate because of horizontal advection of dry static energy by the anomalous winds. By combining the budgets, we interpret the propagation of the moisture anomalies in terms of lifting that is forced by horizontal dry static energy advection, that is, ascent along sloping isentropes. This process moistens the lower free troposphere, producing an environment that is more favorable to deep convection. Ascent driven by radiative heating is of primary importance to the maintenance of the moisture anomalies.

scholarly journals Effect of small heat release and viscosity on thermal-diffusive instability

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Keigo Wada
Keyword(s):  
Growth Rate ◽  
Heat Release ◽  
Stokes Equations ◽  
Positive Real Part ◽  
Thermal Reaction ◽  
Oscillatory Instability ◽  
Stable Range ◽  
Positive Real ◽  
The Real ◽  
Stabilization Effect

AbstractThe linear stability of a thermal reaction front has been investigated based on the thermal-diffusive model proposed by Zel’dovich and Frank-Kamenetskii, which is called ZFK model. In the framework of ZFK model, heat-conduction and mass-diffusion equations are treated without the effect of hydrodynamic flow. Then, two types of instability appear: cellular and oscillatory instabilities. The cellular instability has only positive real part of growth rate, while the oscillatory instability is accompanied with non-zero imaginary part. In this study, the effect of heat release and viscosity on both instabilities is investigated asymptotically and numerically. This is achieved by coupling mass-conservation and Navier–Stokes equations with the ZFK model for small heat release. Then, the stable range of Lewis number, where the real part of growth rate is negative, is widened by non-zero values of heat release for any wavenumber. The increase of Prandtl number also brings the stabilization effect on the oscillatory instability. However, as for the cellular instability, the viscosity leads to the destabilization effect for small wavenumbers, opposed to its stabilization effect for moderate values of wavenumber. Under the limit of small wavenumber, the property of viscosity becomes clear in view of cut-off wavenumber, which makes the real part of growth rate zero.

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