scholarly journals Simulation of the direct and semidirect aerosol effects on the southern Africa regional climate during the biomass burning season

2010 ◽  
Vol 115 (D19) ◽  
Author(s):  
F. Tummon ◽  
F. Solmon ◽  
C. Liousse ◽  
M. Tadross
Keyword(s):  
Biomass Burning ◽  
Southern Africa ◽  
Regional Climate ◽  
Aerosol Effects

scholarly journals The biomass burning aerosol influence on precipitation over the Central Amazon: an observational study

2014 ◽  
Vol 14 (13) ◽  
pp. 18879-18904 ◽  
Author(s):  
W. A. Gonçalves ◽  
L. A. T. Machado ◽  
P.-E. Kirstetter
Keyword(s):  
Biomass Burning ◽  
Climate Model ◽  
Regional Climate ◽  
Droplet Size Distribution ◽  
Particulate Material ◽  
Climate Change Scenarios ◽  
Aggregate Information ◽  
Wet Scavenging ◽  
Biomass Burning Aerosol ◽  
Climate Model Simulations

Abstract. Understanding the aerosol influence on clouds and precipitation is an important key to reduce uncertainties in simulations of climate change scenarios with regards to deforestation fires. Here, we associate rainfall characteristics obtained by an S-Band radar in the Amazon with in situ measurements of biomass burning aerosols for the entire year of 2009. The most important results were obtained during the dry semester (July–December). The results indicate that the aerosol influence on precipitating systems is modulated by the atmospheric instability degree. For stable atmospheres, the higher the aerosol concentration, the lower the precipitation over the region. On the other hand, for unstable cases, higher concentrations of particulate material are associated with more precipitation, elevated presence of ice and larger rain cells, which suggests an association with long lived systems. The results presented were statistically significant. However, due to the limitation imposed by the dataset used, some important features such as wet scavenging and droplet size distribution need further clarification. Regional climate model simulations in addition with new field campaigns could aggregate information to the aerosol/precipitation relationship.

scholarly journals Precipitation over southern Africa: Is there consensus among GCMs, RCMs and observational data?

2021 ◽  
Author(s):  
Maria Chara Karypidou ◽  
Eleni Katragkou ◽  
Stefan Pieter Sobolowski
Keyword(s):  
Climate Change ◽  
Southern Africa ◽  
Regional Climate ◽  
Coupled Model ◽  
Added Value ◽  
Rain Gauges ◽  
Climate Simulations ◽  
Observational Uncertainty ◽  
Direct Contrast ◽  
Improved Performance

Abstract. The region of southern Africa (SAF) is highly vulnerable to the impacts of climate change and is projected to experience severe precipitation shortages in the coming decades. Ensuring that our modelling tools are fit for the purpose of assessing these changes is critical. In this work we compare a range of satellite products along with gauge-based datasets. Additionally, we investigate the behaviour of regional climate simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX) – Africa domain, along with simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 6 (CMIP6). We identify considerable variability in the standard deviation of precipitation between satellite products that merge with rain gauges and satellite products that do not, during the rainy season (Oct–Mar), indicating high observational uncertainty for specific regions over SAF. Good agreement both in spatial pattern and the strength of the calculated trends is found between satellite and gauge-based products, however. Both CORDEX-Africa and CMIP5 ensembles underestimate the observed trends during the analysis period. The CMIP6 ensemble displayed persistent drying trends, in direct contrast to the observations. The regional ensemble exhibited improved performance compared to its forcing (CMIP5), when the annual cycle and the extreme precipitation indices were examined, confirming the added value of the higher resolution regional climate simulations. The CMIP6 ensemble displayed a similar behaviour to CMIP5, however reducing slightly the ensemble spread. However, we show that reproduction of some key SAF phenomena, like the Angolan Low (which exerts a strong influence on regional precipitation), still poses a challenge for the global and regional models. This is likely a result of the complex climatic process that take place. Improvements in observational networks (both in-situ and satellite), as well as continued advancements in high-resolution modelling will be critical, in order to develop a robust assessment of climate change for southern Africa.

scholarly journals Seasonal and diurnal variability in air pollutants and short-lived climate forcers measured at the Rwanda Climate Observatory

2018 ◽  
Author(s):  
H. Langley DeWitt ◽  
Jimmy Gasore ◽  
Maheswar Rupakheti ◽  
Katherine E. Potter ◽  
Ronald G. Prinn ◽  
...  
Keyword(s):  
Air Pollution ◽  
East Africa ◽  
Biomass Burning ◽  
Southern Africa ◽  
Ozone Concentration ◽  
Air Pollutants ◽  
Sub Saharan Africa ◽  
Pollution Transport ◽  
Diurnal Variability ◽  
Air Masses

Abstract. Air pollution is still largely unstudied in sub-Saharan Africa, resulting in a gap in scientific understanding of emissions, atmospheric processes, and impacts of air pollutants in this region. The Rwanda Climate Observatory, a joint partnership between MIT and the government of Rwanda, has been measuring ambient concentrations of key long-lived greenhouse gases and short-lived climate-forcing pollutants (CO2, CO, CH4, BC, O3) with state-of-the-art instruments on the summit of Mt. Mugogo (1.586° S, 29.566° E, 2590 m above sea level) since May 2015. Rwanda is a small, mountainous, and densely populated country in equatorial East Africa, currently undergoing rapid development but still at less than 20 % urbanization. The position and meteorology of Rwanda is such that the emissions transported from both the northern and southern African biomass burning seasons affect BC, CO, and O3 concentrations in Rwanda. Black carbon concentrations during Rwanda's two dry seasons, which coincide with the two biomass burning seasons, are higher at Mt. Mugogo than in major European cities. Higher BC baseline concentrations at Mugogo are loosely correlated with fire radiative power data for the region acquired with MODIS satellite instrument. Spectral aerosol absorption measured with a dual-spot Aethalometer also varies in different seasons, likely due to change in types of fuel burned and direction of pollution transport to the site. Ozone concentration was found to be higher in air masses from southern Africa than from northern Africa during their respective biomass burning seasons. These higher ozone concentration in air masses from the south could be indicative of more anthropogenic emissions mixed with the biomass burning emissions from southern Africa as Rwanda is downwind of major East African capital cities in this season. During the rainy season, local emitting activities (e.g., cooking, transportation, trash burning) remain steady, regional biomass burning is low, and transport distances are shorter as rainout of pollution occurs regularly. Thus local pollution at Mugogo can be estimated during this time period. Understanding and quantification of the percent contributions of regional and local emissions is essential to guide policy in the region. Our measurements indicate that air pollution is a current and growing problem in equatorial East Africa that deserves immediate attention.

scholarly journals Chemical apportionment of southern African aerosol mass and optical depth

2009 ◽  
Vol 9 (19) ◽  
pp. 7643-7655 ◽  
Author(s):  
B. I. Magi
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Cross Sections ◽  
Southern Africa ◽  
Climate Models ◽  
Critical Role ◽  
Carbonaceous Aerosol ◽  
Aerosol Optical Properties ◽  
Aerosol Absorption ◽  
Aerosol Mass

Abstract. This study characterizes the aerosol over extratropical and tropical southern Africa during the biomass burning season by presenting an aerosol mass apportionment and aerosol optical properties. Carbonaceous aerosol species account for 54% and 83% of the extratropical and tropical aerosol mass, respectively, which is consistent with the fact that the major source of particulate matter in southern Africa is biomass burning. This mass apportionment implies that carbonaceous species in the form of organic carbon (OC) and black carbon (BC) play a critical role in the aerosol optical properties. By combining the in situ measurements of aerosol mass concentrations with concurrent measurements of aerosol optical properties at a wavelength of 550 nm, it is shown that 80–90% of the aerosol scattering is due to carbonaceous aerosol, and the derived mass scattering cross sections (MSC) for OC and BC are 3.9±0.6 m2/g and 1.6±0.2 m2/g, respectively. Derived values of mass absorption cross sections (MAC) for OC and BC are 0.7±0.6 m2/g and 8.2±1.1 m2/g, respectively. The values of MAC imply that ~26% of the aerosol absorption in southern Africa is due to OC, with the remainder due to BC. The results in this study provide important constraints for aerosol properties in a region dominated by biomass burning and should be integrated into climate models to improve aerosol simulations.

scholarly journals Biomass-burning-induced surface darkening and its impact on regional meteorology in eastern China

2020 ◽  
Vol 20 (10) ◽  
pp. 6177-6191 ◽  
Author(s):  
Rong Tang ◽  
Xin Huang ◽  
Derong Zhou ◽  
Aijun Ding
Keyword(s):  
Biomass Burning ◽  
Surface Albedo ◽  
Near Infrared ◽  
Regional Climate ◽  
Eastern China ◽  
Weather Forecast ◽  
Early Summer ◽  
Adjacent Area ◽  
Infrared Band ◽  
Sharp Drop

Abstract. Biomass burning has attracted great concerns for the emission of particular matters and trace gases, which substantially impacts air quality, human health, and climate change. Meanwhile, large areas of dark char, carbon residue produced in incomplete combustion, can stick to the surface over fire-prone areas after open burning, leading to a sharp drop in surface albedo, so-called “surface darkening”. However, exploration into such surface albedo declines and the radiative and meteorological effects is still fairly limited. As one of the highest-yield agricultural areas, eastern China features intensive straw burning every early summer, the harvest season for winter wheat, which was particularly strong in 2012. Satellite retrievals show that the surface albedo decline over fire-prone areas was significant, especially in the near-infrared band, which can reach −0.16. Observational evidence of abnormal surface warming was found by comparing radiosonde and reanalysis data. Most sites around intensive burned scars show a positive deviation, extending especially in the downwind area. Comparisons between “pre-fire” and “post-fire” from 2007 to 2015 indicated a larger temperature bias of the forecast during the post-fire stage. The signal becomes more apparent between 14:00 and 20:00 LT. Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulations suggest that including surface darkening can decrease model bias and well-captured temperature variation after burning at sites in fire areas and their adjacent area. This work highlights the importance of biomass burning induced albedo change in weather forecast and regional climate.

scholarly journals A Diagnostic Evaluation of Precipitation in CORDEX Models over Southern Africa

2013 ◽  
Vol 26 (23) ◽  
pp. 9477-9506 ◽  
Author(s):  
Evangelia-Anna Kalognomou ◽  
Christopher Lennard ◽  
Mxolisi Shongwe ◽  
Izidine Pinto ◽  
Alice Favre ◽  
...  
Keyword(s):  
Southern Africa ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Precipitation Anomaly ◽  
Ensemble Average ◽  
Climate Projections ◽  
Time Model ◽  
Domain Models ◽  
Model Setup

The authors evaluate the ability of 10 regional climate models (RCMs) to simulate precipitation over Southern Africa within the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework. An ensemble of 10 regional climate simulations and the ensemble average is analyzed to evaluate the models' ability to reproduce seasonal and interannual regional climatic features over regions of the subcontinent. All the RCMs use a similar domain, have a spatial resolution of ~50 km, and are driven by the Interim ECMWF Re-Analysis (ERA-Interim; 1989–2008). Results are compared against a number of observational datasets.In general, the spatial and temporal nature of rainfall over the region is captured by all RCMs, although individual models exhibit wet or dry biases over particular regions of the domain. Models generally produce lower seasonal variability of precipitation compared to observations and the magnitude of the variability varies in space and time. Model biases are related to model setup, simulated circulation anomalies, and moisture transport. The multimodel ensemble mean generally outperforms individual models, with bias magnitudes similar to differences across the observational datasets. In the northern parts of the domain, some of the RCMs and the ensemble average improve the precipitation climate compared to that of ERA-Interim. The models are generally able to capture the dry (wet) precipitation anomaly associated with El Niño (La Niña) events across the region. Based on this analysis, the authors suggest that the present set of RCMs can be used to provide useful information on climate projections of rainfall over Southern Africa.

scholarly journals Simulating midsummer climate over southern Africa using a nested regional climate model

1999 ◽  
Vol 104 (D16) ◽  
pp. 19015-19025 ◽  
Author(s):  
A. M. Joubert ◽  
J. J. Katzfey ◽  
J. L. McGregor ◽  
K. C. Nguyen
Keyword(s):  
Regional Climate Model ◽  
Southern Africa ◽  
Climate Model ◽  
Regional Climate

Evolution of biomass burning aerosol properties from an agricultural fire in southern Africa

2003 ◽  
Vol 30 (15) ◽  
Author(s):  
Steven J. Abel ◽  
Jim M. Haywood ◽  
Eleanor J. Highwood ◽  
Jia Li ◽  
Peter R. Buseck
Keyword(s):  
Biomass Burning ◽  
Southern Africa ◽  
Biomass Burning Aerosol ◽  
Aerosol Properties
Sign in / Sign up

Export Citation Format

Share Document