 |
| Titel |
New fire diurnal cycle characterizations to improve fire radiative energy assessments made from MODIS observations |
| VerfasserIn |
N. Andela, J. W. Kaiser, G. R. van der Werf, M. J. Wooster |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 15 ; Nr. 15, no. 15 (2015-08-12), S.8831-8846 |
| Datensatznummer |
250119958
|
| Publikation (Nr.) |
 copernicus.org/acp-15-8831-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Accurate near real time fire emissions estimates are required for air
quality forecasts. To date, most approaches are based on satellite-derived
estimates of fire radiative power (FRP), which can be converted to fire
radiative energy (FRE) which is directly related to fire emissions.
Uncertainties in these FRE estimates are often substantial. This is for a
large part because the most often used low-Earth orbit satellite-based
instruments such as the Moderate Resolution Imaging Spectroradiometer
(MODIS) have a relatively poor sampling of the usually pronounced fire
diurnal cycle. In this paper we explore the spatial variation of this fire
diurnal cycle and its drivers using data from the geostationary Meteosat
Spinning Enhanced Visible and Infrared Imager (SEVIRI). In addition, we
sampled data from the SEVIRI instrument at MODIS detection opportunities to
develop two approaches to estimate hourly FRE based on MODIS active fire
detections. The first approach ignored the fire diurnal cycle, assuming
persistent fire activity between two MODIS observations, while the second
approach combined knowledge on the climatology of the fire diurnal cycle
with active fire detections to estimate hourly FRE. The full SEVIRI
time series, providing full coverage of the fire diurnal cycle, were used to
evaluate the results. Our study period comprised of 3 years
(2010–2012), and we focused on Africa and the Mediterranean basin to avoid
the use of potentially lower quality SEVIRI data obtained at very far
off-nadir view angles. We found that the fire diurnal cycle varies
substantially over the study region, and depends on both fuel and weather
conditions. For example, more "intense" fires characterized by a fire
diurnal cycle with high peak fire activity, long duration over the day, and
with nighttime fire activity are most common in areas of large fire size
(i.e., large burned area per fire event). These areas are most prevalent in
relatively arid regions. Ignoring the fire diurnal cycle generally resulted
in an overestimation of FRE, while including information on the climatology
of the fire diurnal cycle improved FRE estimates. The approach based on
knowledge of the climatology of the fire diurnal cycle also improved
distribution of FRE over the day, although only when aggregating model
results to coarser spatial and/or temporal scale good correlation was found
with the full SEVIRI hourly reference data set. We recommend the use of
regionally varying fire diurnal cycle information within the Global Fire
Assimilation System (GFAS) used in the Copernicus Atmosphere Monitoring
Services, which will improve FRE estimates and may allow for further
reconciliation of biomass burning emission estimates from different
inventories. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|