Fernando De Sales

Global and Seasonal Assessment of Interactions between Climate and Vegetation Biophysical Processes: A GCM Study with Different Land–Vegetation Representations

Abstract A global and seasonal assessment of regions of the earth with strong climate–vegetation biophysical process (VBP) interactions is provided. The presence of VBP and degree of VBP effects on climate were assessed based on the skill of simulations of observed global precipitation by two general circulation models of the atmosphere coupled to three land models with varying degrees of complexity in VBP representation. The simulated VBP effects on precipitation were estimated to be about 10% of observed precipitation globally and 40% over land; the strongest impacts were in the monsoon regions. Among these, VBP impacts were highest on the West African, South Asian, East Asian, and South American monsoons. The specific characteristics of vegetation–precipitation interactions in northern high latitudes were identified. Different regions had different primary impact season(s) depending on regional climate characteristics and geographical features. The characteristics of VBP effects on surface energy and w...

Improving snow albedo processes in WRF/SSiB regional climate model to assess impact of dust and black carbon in snow on surface energy balance and hydrology over western U.S.

© 2015. American Geophysical Union. All Rights Reserved. Two important factors that control snow albedo are snow grain growth and presence of light-absorbing impurities (aerosols) in snow. However, current regional climate models do not include such processes in a physically based manner in their land surface models. We improve snow albedo calculations in the Simplified Simple Biosphere (SSiB) land surface model coupled with the Weather Research and Forecasting (WRF) regional climate model (RCM), by incorporating the physically based SNow ICe And Radiative (SNICAR) scheme. SNICAR simulates snow albedo evolution due to snow aging and presence of aerosols in snow. The land surface model is further modified to account for deposition, movement, and removal by meltwater of such impurities in the snowpack. This paper presents model development technique, validation with in situ observations, and preliminary results from RCM simulations investigating the impact of such impurities in snow on surface energy and water budgets. By including snow-aerosol interactions, the new land surface model is able to realistically simulate observed snow albedo, snow grain size, dust in snow, and surface water and energy balances in offline simulations for a location in western U.S. Preliminary results with the fully coupled RCM show that over western U.S., realistic aerosol deposition in snow induces a springtime average radiative forcing of 16W/m2 due to a 6% albedo reduction, a regional surface warming of 0.84°C, and a snowpack reduction of 11mm.

Analysis of Climate and Vegetation Characteristics along the Savanna-Desert Ecotone in Mali Using MODIS Data

MODIS data were used in conjunction with 600 ground survey points to create a 500 m resolution land cover product of Mali. It improves upon previously published land cover products for this region in resolution and accuracy. Of particular importance is the ability to detect small-scale, but important, wetland features such as rice cultivation areas. A combination of classical ground survey of vegetation type and structure, meteorological data, and remote sensing was used to quantify the relationship between vegetation and climate along the sensitive Sahel savanna—desert transition. The study demonstrates the effectiveness of using MODIS data for regional-scale studies.

Spring land temperature anomalies in northwestern US and the summer drought over Southern Plains and adjacent areas

Author(s): Xue, Y; Oaida, CM; Diallo, I; Neelin, JD; Li, S; De Sales, F; Gu, Y; Robinson, DA; Vasic, R; Yi, L | Abstract:

Corrigendum: Spring land temperature anomalies in northwestern US and the summer drought over Southern Plains and adjacent areas (2016 Environ. Res. Lett. 11 044018)

Home Search Collections Journals About Contact us My IOPscience Spring land temperature anomalies in northwestern US and the summer drought over Southern Plains and adjacent areas This content has been downloaded from IOPscience. Please scroll down to see the full text. 2016 Environ. Res. Lett. 11 044018 (http://iopscience.iop.org/1748-9326/11/4/044018) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 128.97.194.87 This content was downloaded on 14/04/2016 at 00:07 Please note that terms and conditions apply.

On the effects of wildfires on precipitation in Southern Africa

This study investigates the impact of wildfire on the climate of Southern Africa. Moderate resolution imaging spectroradiometer derived burned area fraction data was implemented in a set of simulations to assess primarily the role of wildfire-induced surface changes on monthly precipitation. Two post-fire scenarios are examined namely non-recovering and recovering vegetation scenarios. In the former, burned vegetation fraction remains burned until the end of the simulations, whereas in the latter it is allowed to regrow following a recovery period. Control simulations revealed that the model can dependably capture the monthly precipitation and surface temperature averages in Southern Africa thus providing a reasonable basis against which to assess the impacts of wildfire. In general, both wildfire scenarios have a negative impact on springtime precipitation. September and October were the only months with statistically significant precipitation changes. During these months, precipitation in the region decreases by approximately 13 and 9% in the non-recovering vegetation scenario, and by about 10 and 6% in the recovering vegetation wildfire scenario, respectively. The primary cause of precipitation deficit is the decrease in evapotranspiration resulting from a reduction in surface net radiation. Areas impacted by the precipitation reduction includes the Luanda, Kinshasa, and Brazzaville metropolitan areas, The Angolan Highlands, which are the source of the Okavango Rive, and the Okavango Delta region. This study suggests that a probable intensification in wildfire frequency and extent resulting from projected population increase and global warming in Southern Africa could potentially exacerbate the impacts of wildfires in the region’s seasonal precipitation.

Evaluation of multi-decadal UCLA-CFSv2 simulation and impact of interactive atmospheric-ocean feedback on global and regional variability

This paper evaluates multi-decadal simulations of the UCLA version of Climate Forecast System version 2, in which the default Noah land surface model has been replaced with the Simplified Simple Biosphere Model version-2. To examine the influence of the atmosphere–ocean (AO) interaction on the variability, two different simulations were conducted: one with interactive ocean component, and the other constrained by the prescribed sea surface temperature. We evaluate the mean seasonal climatology of precipitation and temperature, along with the model’s ability to reproduce atmospheric variability at different scales over the globe, including extratropical modes of atmospheric variability, and long-term trends of global and hemispheric temperature and regional precipitation. Here, we particularly selected two monsoon regions, East Asia and West Africa, where the simulation of multi-decadal variations which has heretofore been a challenging task, to examine decadal variation of monsoon precipitation. In general, temperature anomaly trends were better captured than those of precipitation in both simulations. Results suggest that the AO interaction, represented as latent heat flux, contributes to improve reproducibility of global-wide climatology, extratropical modes of atmospheric variability, and variability in the multi-decadal climate simulation, as well as for inter-decadal variability of the East Asian summer monsoon.