Monthly Weather Review Research Articles

Quantifying the Volunteer Effort of Scientific Peer Reviewing

A survey of 310 reviewers for Monthly Weather Review addresses how much time and effort goes into the peer-review process and provides insight into how reviewers function. Using these data, the individual and collective contributions of volunteer peer reviewers to the peer-review process can be determined. Individually, respondents to the survey review an average of 2 manuscripts a year for Monthly Weather Review, 4 manuscripts a year for AMS journals, and 8 manuscripts a year in total, although some review more than 20 manuscripts a year. Each review takes an average of 9.6 h. Summing the individual contributions of the reviewers, respondents averaged 18 h yr−1 performing reviews for Monthly Weather Review, 36 h yr−1 for AMS journals, and 63 h yr−1 for all journals. The collective time that all of the reviewers put into the peer-review process for all manuscripts submitted to Monthly Weather Review for each year amounts to 362,179 h, or more than 4 years of voluntary labor valued at over $2.34 million. Nearly all respondents (95%) are comfortable with their current load, but only 30% said that they would be willing to perform more reviews. Because the number of submissions to journals has been increasing over time and is unlikely to decrease in the near future, this burden is anticipated to grow. Options for reducing the burden include using fewer reviewers per manuscript, increasing the number of unilateral decisions made by editors, and increasing the size of the reviewer pool (particularly from active retired and early-career scientists).

An investigation into the contraction of the hurricane radius of maximum wind

The radius of the maximum tangential wind (RMW) associated with the hurricane primary circulation has been long known to undergo continuous contraction during the hurricane development. In this study, we document some characteristic behaviors of the RMW contraction in a series of ensemble real-time simulations of Hurricane Katrina (2005) and in idealized experiments using the Rotunno and Emanuel (Mon Weather Rev 137:1770–1789, 1987) axisymmetric hurricane model. Of specific interest is that the contraction appears to slow down abruptly at the middle of the hurricane intensification, and the RMW becomes nearly stationary subsequently, despite the rapidly strengthening rotational flows. A kinematic model is then presented to examine such behaviors of the RMW in which necessary conditions for the RMW to stop contracting are examined. Further use of the Emanuel’s (J Atmos Sci 43:585–605, 1986) analytical hurricane theory reveals a connection between the hurricane maximum potential intensity and the hurricane eye size, an issue that has not been considered adequately in previous studies.

Impact of MJO on the diurnal cycle of rainfall over the western Maritime Continent in the austral summer

This paper investigates the impact of the Madden-Julian Oscillation (MJO) on the diurnal cycle of rainfall over the western Maritime Continent during the austral summer. For this purpose, cyclostationary empirical orthogonal function analysis is applied to the tropical rainfall measuring mission rain rate and the Japanese Reanalysis-25 data for the period 1998–2008. The real-time multivariate MJO index by Wheeler and Hendon (Mon Wea Rev 132:1917–1932, 2004) is adopted to define the intensity and the phase of MJO. It is demonstrated that the hourly maximum rain rate over the domain tends to increase when convectively active phase of MJO approaches the Maritime Continent. In contrast, the hourly maximum rain rate tends to decrease when convectively suppressed phase of MJO resides over the region. The changes in the rain rate due to MJO differ over the ocean and the land. This difference is the greatest when the MJO is in the mature stage. Throughout the day during this stage, terrestrial rain rates show minimum values while diurnally varying oceanic rain rates record maximum values. Thus, precipitation becomes more intense in the morning over the Java Sea and is weakened in the evening over Borneo and Sumatra during the mature stage of MJO. During the decaying stage of MJO over the Maritime Continent, the diurnal cycle of precipitation weakens significantly over the ocean but only weakly over land. Analyses suggest that the anomalous lower level winds accompanied by MJO interact with the monsoonal flow over the Maritime Continent. Westerlies induced by MJO convection in the mature stage are superimposed on the monsoonal westerlies over the equator and increase wind speed mainly over the Java Sea due to the blocking effect of orography. Mountainous islands induce flow bifurcation, causing near-surface winds to converge mainly over the oceanic channels between two islands. As a result, heat flux release from the ocean to the atmosphere is enhanced by the increased surface wind resulting in instability as described in the wind-induced surface heat exchange mechanism. This may contribute to heavy rainfall over the Java Sea in the morning during the mature stage. On the other hand, convergence and vertical velocity over the islands, which play important roles in inducing nighttime rainfall, tend to be weak in the evening during the mature stage of MJO. Strong westerlies arising from MJO and the seasonal flow during the mature stage tend to interrupt convergence over islands. This interruption of convergence by MJO gives rise to decreased rain rates over the land regions.

The Central European and Russian Heat Event of July–August 2010

No abstract available.

A bulk mass flux convection scheme for climate model: description and moisture sensitivity

A convection scheme for climate model is developed based on Tiedtke’s (Mon Weather Rev 117:1779–1800, 1989) bulk mass flux framework and is evaluated with observational data and cloud resolving model simulation data. The main differences between the present parameterization and Tiedtke’s parameterization are the convection trigger, fractional entrainment and detrainment rate formulations, and closure method. Convection is triggered if the vertical velocity of a rising parcel is positive at the level at which the parcel is saturated. The fractional entrainment rate depends on the vertical velocity and buoyancy of the parcel as well as the environmental relative humidity. For the fractional detrainment rate, a linear decrease in the updraft mass flux above maximum buoyancy level is assumed. In the closure method, the cloud base mass flux is determined by considering both cloud layer instability and subcloud layer turbulent kinetic energy as controlling factors in the strength of the convection. The convection scheme is examined in a single column framework as well as using a general circulation model. The present bulk mass flux (BMF) scheme is compared with a simplified Relaxed Arakawa-Schubert (RAS) scheme. In contrast to the RAS, which specifies the cloud top, cloud top height in BMF depends on environmental properties, by considering the conditions of both the parcel and its environment in a fractional entrainment and detrainment rate formulations. As a result, BMF shows improved sensitivity in depth and strength of convection on environmental humidity compared to RAS, by strengthening coupling between cloud and environment. When the mid to lower troposphere is dry, the cloud resolving model and BMF produce cloud top around the dry layer and moisten the layer. In the framework of general circulation model, enhanced coupling between convection and environmental humidity in BMF results in improved representation of eastward propagating intraseasonal variability in the tropics—the Madden-Julian oscillation.

Urban air pollution: process identification, impact analysis and evaluation of forecast potential

The daily variations in the atmospheric pollutants like suspended particulate matter (SPM), respirable suspended particulate matter (RSPM), sulphur dioxide (SO2) and nitrogen dioxide (NO2) depend on both local meteorological processes and various natural as well as anthropogenic sources and sinks. It was shown in an earlier work (Goswami and Baruah in Mon Wea Rev 136(9):3597–3607, 2008) that the daily variations in SPM over a location could be simulated quite well by considering daily meteorological fields from NCEP Reanalysis in combination with a model for natural and anthropogenic sources over Delhi. In the present work, we extend the scope of the model to include three other pollutants: RSPM, SO2 and NO2. While the basic conservation equations and the meteorological fields are common to all the three (and SPM) pollutants, the sources and sinks for each is modeled in a species-specific manner to obtain maximum skill. As we do not consider active chemistry, the present model provides the minimal dynamics of pollution over an urban location in terms of annual load; the model error is about 10% on the average, with no significant bias for any of the species.

Bridging the ensemble Kalman filter and particle filters: the adaptive Gaussian mixture filter

The nonlinear filtering problem occurs in many scientific areas. Sequential Monte Carlo solutions with the correct asymptotic behavior such as particle filters exist, but they are computationally too expensive when working with high-dimensional systems. The ensemble Kalman filter (EnKF) is a more robust method that has shown promising results with a small sample size, but the samples are not guaranteed to come from the true posterior distribution. By approximating the model error with a Gaussian distribution, one may represent the posterior distribution as a sum of Gaussian kernels. The resulting Gaussian mixture filter has the advantage of both a local Kalman type correction and the weighting/resampling step of a particle filter. The Gaussian mixture approximation relies on a bandwidth parameter which often has to be kept quite large in order to avoid a weight collapse in high dimensions. As a result, the Kalman correction is too large to capture highly non-Gaussian posterior distributions. In this paper, we have extended the Gaussian mixture filter (Hoteit et al., Mon Weather Rev 136:317–334, 2008) and also made the connection to particle filters more transparent. In particular, we introduce a tuning parameter for the importance weights. In the last part of the paper, we have performed a simulation experiment with the Lorenz40 model where our method has been compared to the EnKF and a full implementation of a particle filter. The results clearly indicate that the new method has advantages compared to the standard EnKF.

The real first weather satellite picture

The real first weather satellite picture

Rejection rates for multiple-part manuscripts

Multiple-part manuscripts are those submitted to a journal and intended for publication as a series, usually having “Part 1,” “Part I,” … “Part N” in the title. Although some journals prohibit such submissions, other journals (including Monthly Weather Review) have no such restrictions. To examine how reviewers and editors view multiple-part manuscripts, 308 multiple-part manuscripts submitted to Monthly Weather Review from May 2001 through February 2010 were examined. For multiple-part manuscripts having reached a final decision, 67% were accepted, which was also the average acceptance rate of all manuscripts (67%). Part I manuscripts submitted alone had a lower acceptance rate (61%) than the average, whereas Part II manuscripts submitted alone had a higher acceptance rate (77%) than the average. Two-part manuscripts submitted together had an acceptance rate (67%) comparable to the average. Typical reviewer comments for Part I manuscripts submitted alone included the manuscript being too long for the available results and the author making claims in Part I that would be supported in the unseen Part II. Typical comments for Part II manuscripts submitted alone included the somewhat contradictory statements that material was unnecessarily duplicated in the two manuscripts and more repetition was needed between the two parts. For two-part manuscripts submitted together, reviewers often recommended condensing the two manuscripts and merging them into one. In some cases, editors rejected manuscripts even though no reviewer recommended rejection because the sum of all reviewers’ comments would require substantial reorganization of the manuscripts. The results of this study suggest the following recommendations for authors considering writing multiple-part manuscripts: Write manuscripts that are sensibly independent of each other, make minimal reference to unsubmitted manuscripts, and have sufficient and substantiated scientific content within each manuscript.

Are three heads better than two? How the number of reviewers and editor behavior affect the rejection rate

Editors of peer-reviewed journals obtain recommendations from peer reviewers as guidance in deciding upon the suitability of a submitted manuscript for publication. To investigate whether the number of reviewers used by an editor affects the rate at which manuscripts are rejected, 500 manuscripts submitted to Monthly Weather Review during 15.5 months in 2007–2008 were examined. Two and three reviewers were used for 306 and 155 manuscripts, respectively (92.2% of all manuscripts). Rejection rates for initial decisions and final decisions were not significantly different whether two or three reviewers were used. Manuscripts with more reviewers did not spend more rounds in review or have different rejection rates at each round. The results varied by editor, however, with some editors rejecting more two-reviewer manuscripts and others rejecting more three-reviewer manuscripts. Editors described using their scientific expertise in the decision-making process, either in determining the number of reviews to be sought or in making decisions once the reviews were received, approaches that differ from that of relying purely upon reviewer agreement as reported previously in the literature. A simple model is constructed for three decision-making strategies for editors: rejection when all reviewers recommend rejection, rejection when any reviewer recommends rejection, and rejection when a majority of reviewers recommend rejection. By plotting the probability of reviewer rejection against the probability of editor rejection, the decision-making process can be graphically illustrated, demonstrating that, for this dataset, editors are likely to reject a manuscript when any reviewer recommends rejection.

Numerical investigation of an oceanic resonant regime induced by hurricane winds

The oceanic mixed layer (OML) response to an idealized hurricane with different propagation speeds is investigated using a two-layer reduced gravity ocean model. First, the model performances are examined with respect to available observations relative to Hurricane Frances (2004). Then, 11 idealized simulations are performed with a Holland (Mon Weather Rev 108(8):1212–1218, 1980) symmetric wind profile as surface forcing with storm propagation speeds ranging from 2 to 12 m s−1. By varying this parameter, the phasing between atmospheric and oceanic scales is modified. Consequently, it leads to different momentum exchanges between the hurricane and the OML and to various oceanic responses. The present study determines how OML momentum and heat budgets depend on this parameter. The kinetic energy flux due to surface wind stress is found to strongly depend on the propagation speed and on the cross-track distance from the hurricane center. A resonant regime between surface winds and near-inertial currents is clearly identified. This regime maximizes locally the energy flux into the OML. For fast-moving hurricanes (>6 m s−1), the ratio of kinetic energy converted into turbulence depends only on the wind stress energy input. For slow-moving hurricanes (<6 m s−1), the upwelling induced by current divergence enhances this conversion by shallowing the OML depth. Regarding the thermodynamic response, two regimes are identified with respect to the propagation speed. For slow-moving hurricanes, the upwelling combined with a sharp temperature gradient at the OML base formed in the leading part of the storm maximizes the oceanic heat loss. For fast propagation speeds, the resonance mechanism sets up the cold wake on the right side of the hurricane track. These results suggest that the propagation speed is a parameter as important as the surface wind speed to accurately describe the oceanic response to a moving hurricane.

Ensemble Bayesian model averaging using Markov Chain Monte Carlo sampling

Bayesian model averaging (BMA) has recently been proposed as a statistical method to calibrate forecast ensembles from numerical weather models. Successful implementation of BMA however, requires accurate estimates of the weights and variances of the individual competing models in the ensemble. In their seminal paper (Raftery et al. Mon Weather Rev 133:1155–1174, 2005) has recommended the Expectation–Maximization (EM) algorithm for BMA model training, even though global convergence of this algorithm cannot be guaranteed. In this paper, we compare the performance of the EM algorithm and the recently developed DiffeRential Evolution Adaptive Metropolis (DREAM) Markov Chain Monte Carlo (MCMC) algorithm for estimating the BMA weights and variances. Simulation experiments using 48-hour ensemble data of surface temperature and multi-model streamflow forecasts show that both methods produce similar results, and that their performance is unaffected by the length of the training data set. However, MCMC simulation with DREAM is capable of efficiently handling a wide variety of BMA predictive distributions, and provides useful information about the uncertainty associated with the estimated BMA weights and variances.

The development of extremely dry surface air due to vertical exchanges under the exit region of a jet streak

Observations and numerical model simulations indicate that anomalous surface drying is strongly forced by mass and momentum adjustments under the right exit region of a polar jet streak overtaking and modifying a weak surface cold front. This drying event, which was associated with a wildfire in south-central New Jersey, is related to multi-scale atmospheric forcing that began far upstream and was likely not coupled to the classic cold conveyor belt model, as described by Carlson (Mon Wea Rev 108:1498–1509, 1980). The analyses indicate that both deep tropospheric circulations and boundary layer dry air advection occur in tandem to create a favorable environment for two closely associated extreme surface drying events. The first drying event occurs when lower tropospheric air is transported downwards in the descending branch of the low-level cold front’s thermally direct circulation. This low-level circulation, which is vertically separated from the upper-level jet, is still enhanced by the hydrostatic pressure rises under the velocity convergence in the equatorward exit region of the polar jet. The upper-level convergence phases with the low-level cold air advection to intensify the low-level isallobaric wind. Dry air increases at low levels in conjunction with the isallobaric divergence behind the low-level cold front. Sinking air occurs within the 100-hPa layer centered just above 900 hPa as a result of the isallobaric divergence. The shallow descending circulation within the upstream side of this low-level front produces the first injection of dry air into the surface layer independently of deep-boundary layer mixing. Surface moisture divergence and shallow sinking sustain the dry cold front in the boundary layer. The descending air in the upper tropospheric jet circulation does not immediately couple to the deepening boundary layer accompanying the cold front’s circulation. A second drying event occurs at the surface shortly thereafter, when surface heating deepens the well-mixed layer, such that the boundary layer behind the low-level front (i.e., within its trailing descending air) is linked to the dry air under the jet’s equatorward exit region descending branch. Thus, the first drying event is created by the low-level direct circulation in a region of isallobaric divergence, while the second drying event is created by the coupling between the upper level indirect circulation and the deepening convective boundary layer. The two dry events combine to create a favorable environment for an isolated wildfire as both dry air and increasing surface winds develop during maximum surface heating.

A Monthly Upper-Air Dataset for North America Back to 1922 from the Monthly Weather Review

AbstractUpper-air observations with kites, aircraft, and radiosondes were performed in the United States operationally since the 1890s. In this paper, the authors present a reevaluation of newly digitized monthly mean values from the Monthly Weather Review back to 1922. Data from 46 U.S. weather stations are presented with a focus on early kite and aircraft observations during the 1922–38 period. A quality assessment of the data, based on reconstructed reference series, is carried out and the quality of the monthly mean data is found to be sufficient for analysis of variability in upper-level circulation. Anomalies of upper-level temperatures from the reevaluated station data, together with surface fields, are shown for selected periods.

The Past, Present, and Future of Monthly Weather Review

The Past, Present, and Future of Monthly Weather Review

ACTINOFORM CLOUDS: Overlooked Examples of Cloud Self-Organization at the Mesoscale

Abstract Stratocumulus clouds are common in the tropical and subtropical marine boundary layer, and understanding these clouds is important due to their significant impact on the earth's radiation budget. Observations show that the marine boundary layer contains complex, but poorly understood processes, which, from time to time, result in the observable self-organization of cloud structures at scales ranging from a few to a few thousand kilometers. Such shallow convective cloud features, typically observed as hexagonal cells, are known generally as mesoscale cellular convection (MCC). Actinoform clouds are rarer, but visually more striking forms of MCC, which possess a radial structure. Because mesoscale cloud features are typically too large to be observed from the ground, observations of hexagonal cells historically date only to the beginning of satellite meteorology. Examples of actinoform clouds were shown in the venerable “Picture of the Month” series in Monthly Weather Review in the early 1960s, but...

Snow accretion on overhead wires

Although snow accretion on overhead wires is a serious problem, recognized physical models have not yet been established. In this paper, attempts directed at understanding the mechanism of snow accretion on wires are reviewed. Fundamentals of the meteorological conditions under which snow accretes on wires, inferred mechanisms, mechanics and heat balance of snow accretion are briefly reviewed. A short historical review of research works throughout the world is given. Wind–tunnel tests aiming at examining the dependence of various parameters on the characteristics of accreted snow on wires are introduced and defects of such tests are discussed. Finally, attempts to establish snow–load design on power lines, with some results of observations under natural conditions, are briefly discussed. It should be emphasized that the present paper is characteristic of an interim report and summary about snow accretion on overhead wires, with the purpose of avoiding repetition of the same kind of research efforts and therefore accelerating further progress.

A trajectory-grid approach for solving the condensation and evaporation equations of aerosols

The trajectory-grid method (Chock et al., Atmospheric Environment 30 (1996) 857–868) for solving the transport equation in a grid model can be easily adapted to solve the condensation/evaporation equations of internally mixed multicomponent aerosols based on the sectional approach. Compared to the Bott scheme (Monthly Weather Review 117 (1998) 1006–1015, 2633–2636) often used for solving these equations, the method is significantly more accurate, of comparable speed, but gaining in speed as the number of aerosol components increases. Most notably, there is no mismatch in size change of the different components of the same aerosol. The method is quite flexible, can handle an abrupt change in aerosol size due to evaporation of fog particles, and is ideal for multiply-parallel processors.

The Gulf of Mexico mid-tropospheric response to El Niño and La Niña forcing

This analysis further refines Ropelewski & Halpert's (1987; Mon Wea Rev 115:1606-1626) analysis which investigates the relationship between El Nino-La Nina/Southern Oscillation events and southern United States precipitation. Comparisons are made between eigenvector-derived mid-tropos- pheric (500 mb) flow patterns over North America during extreme El Nino and La Nina months and a base climatology. In addition, the patterns are correlated to regional precipitation anomalies for the southern United States to determine mean surface responses. Cool season (November to March) months are divided into all winter months (AWM), positive anomaly months (PAM), and negative anomaly months (NAM). The extreme anomaly months were determined as any month with a South- ern Oscillation Index (SOI) ± 1 standard deviation from the standardized mean. Therefore, the PAM and NAM anomalies represent the La Nina and El Nino extreme phases of the SOI, respectively. Results suggest that the positive (La Nina) SOI phase elicits a greater surface precipitation response than the El Nino phase. This is caused by substantial changes in the primary longwave flow during opposite SOI phases. During AWMs and NAMs, similar flow patterns, dominated by the Pacific/North American (PNA) teleconnection, prevail which induce similar regional precipitation responses. During PAMs, the mid-tropospheric flow shifts to a hybrid flow pattern which is between the PNA and the Tropical Northern Hemisphere teleconnections. Such displacement in the longwave flow variation centers ultimately affects jet stream flow and precipitation forcing, resulting in negative precipitation anomalies across the southern United States.

Environment, Technology, and the Social Articulation of Risk in West African Agriculture

two preoccupations are not mutually exclusive. Superficially, they share the common concern that liberalization is insufficient to resolve the subSaharan food crisis. At a deeper level, the two preoccupations are more intimately interrelated via the correspondence that links initial wealth to risk exposure and to behavior in both production and asset accumulation. A number of recent empirical studies of risk in low-income countries find that households are able to employ their accumulated assets to smooth consumption in the face of adverse agricultural production shocks. 3 Missing from these studies is explicit attention to the fact that the effective risk from which households insulate consumption is not that of production shocks directly, but of those shocks as socially articulated by institutions and property rights. This article explores the creation and distribution of effective risk, estimating how environment, technology, and social factors interact to construct it endogenously. 4 Put differently, this article develops the notion that the risk from which households ex post try to insulate consumption is not an immutable natural or technical feature of the landscape. As Michael Watt’s contrast between precolonial and colonial Nigeria forcefully demonstrates, the effective risk presented by an unchanged set of environmental and technical circumstances can