WorldCat Identities

Marsham, John H.

Overview
Works: 14 works in 17 publications in 1 language and 31 library holdings
Roles: Author
Publication Timeline
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Most widely held works by John H Marsham
Can explicit convection improve modelled dust in summertime West Africa? by Alexander J Roberts( )

2 editions published in 2018 in English and held by 4 WorldCat member libraries worldwide

A detailed characterization of the Saharan dust collected during the Fennec campaign in 2011: in situ ground-based and laboratory measurements by Adriana Rocha-Lima( )

2 editions published between 2017 and 2018 in English and held by 4 WorldCat member libraries worldwide

Status and future of Numerical Atmospheric Aerosol Prediction with a focus on data requirements by Angela Benedetti( )

2 editions published in 2018 in English and held by 4 WorldCat member libraries worldwide

A meteorological and chemical overview of the DACCIWA field campaign in West Africa in June-July 2016 by Peter Knippertz( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall by Dean P Walker( )

1 edition published in 2019 in English and held by 2 WorldCat member libraries worldwide

Enhanced future changes in wet and dry extremes over Africa at convection-permitting scale by Elizabeth J Kendon( )

1 edition published in 2019 in English and held by 2 WorldCat member libraries worldwide

Clouds over the summertime Sahara: an evaluation of Met Office retrievals from Meteosat Second Generation using airborne remote sensing by John C Kealy( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low by John H Marsham( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

The early summertime Saharan heat low: sensitivity of the radiation budget and atmospheric heating to water vapour and dust aerosol by Netsanet K Alamirew( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

Future changes and uncertainty in decision-relevant measures of East African climate by F. Jorge Bornemann( )

1 edition published in 2019 in English and held by 2 WorldCat member libraries worldwide

Spatial and temporal CCN variations in convection-permitting aerosol microphysics simulations in an idealised marine tropical domain by Céline Planche( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

Large-eddy simulation of dust-uplift by a haboob density current( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Abstract: Cold pool outflows have been shown from both observations and convection-permitting models to be a dominant source of dust emissions ("haboobs") in the summertime Sahel and Sahara, and to cause dust uplift over deserts across the world. In this paper Met Office Large Eddy Model (LEM) simulations, which resolve the turbulence within the cold-pools much better than previous studies of haboobs with convection-permitting models, are used to investigate the winds that uplift dust in cold pools, and the resultant dust transport. In order to simulate the cold pool outflow, an idealized cooling is added in the model during the first 2h of 5.7h run time. Given the short duration of the runs, dust is treated as a passive tracer. Dust uplift largely occurs in the "head" of the density current, consistent with the few existing observations. In the modeled density current dust is largely restricted to the lowest, coldest and well mixed layers of the cold pool outflow (below around 400m), except above the "head" of the cold pool where some dust reaches 2.5km. This rapid transport to above 2km will contribute to long atmospheric lifetimes of large dust particles from haboobs. Decreasing the model horizontal grid-spacing from 1.0km to 100m resolves more turbulence, locally increasing winds, increasing mixing and reducing the propagation speed of the density current. Total accumulated dust uplift is approximately twice as large in 1.0km runs compared with 100m runs, suggesting that for studying haboobs in convection-permitting runs the representation of turbulence and mixing is significant. Simulations with surface sensible heat fluxes representative of those from a desert region during daytime show that increasing surface fluxes slows the density current due to increased mixing, but increase dust uplift rates, due to increased downward transport of momentum to the surface. Highlights: Large eddy simulations of dust uplift within a cold-pool outflow (haboob). Decreasing the model horizontal grid-spacing resolves more turbulence with reducing the propagation speed of the density current. For haboobs in convection-permitting runs the representation of turbulence and mixing is significant. Increasing surface heat fluxes slows the density current, but increase dust uplift rates
Severe weather over East Africa by Bethany Jane Woodhams( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Characteristics of mid-level clouds over West Africa( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Abstract : Mid-level clouds, located between 2 and 9 km height, are ubiquitous in the tropical belt. However, few studies have documented their characteristics and tried to identify the associated thermodynamic properties, particularly in West Africa. This region is characterized by a strong seasonality with precipitation occurring in the Sahel from June to September (monsoon season). This period also coincides with the annual maximum of the cloud cover. Here, we document the macro- and microphysical properties of mid-level clouds, the environment in which such clouds occur, as well as their radiative properties across West Africa. To do so, we combined high-resolution observations from two ground-based sites (including lidar and cloud radar) in contrasted environments: one in the Sahel (Niamey, AMMA campaign, 2006) and the other in the Sahara (Bordj Badji Mokhtar, Fennec campaign, June 2011) along with the merged CloudSat-CALIPSO satellite products. The results show that mid-level clouds are found throughout the year with a predominance around the monsoon season early in the morning. They also are preferentially observed in the southern and western parts of West Africa. They are usually thin (most of them are less than 1000 m deep) and as observed in Niamey, mainly composed of liquid water. A clustering method applied to Niamey data allows us to distinguish three different types of cloud: one with low bases, one with high bases and another with large thicknesses. The two first cloud families are capped by an inversion. The last family is associated with a large vertical moisture transport and likely has the highest radiative effect at the Earth's surface among the three cloud types. Abstract : This article gathers several sources of observations of mid-level clouds in West Africa in order to document the frequency of occurrence, diurnal cycle, macro- and microphysical properties, thermodynamic environments and radiative impacts of mid-level clouds. One unique feature of our study is to combine high-resolution observational data from two ground sites (Niamey and Bordj Badji Mokhtar) with merged CALIPSO-CloudSat satellite products to provide a better knowledge and understanding of these cloud processes over West Africa
 
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Languages
English (17)