IMIT   21220
INSTITUTO DE MODELADO E INNOVACION TECNOLOGICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A multiyear analysis of gravity wave drag estimated from global MERRA reanalyses using data assimilation
Autor/es:
SCHEFFLER, G AND M. PULIDO
Lugar:
Bern
Reunión:
Workshop; ISSI Gravity wave workshop; 2013
Institución organizadora:
International Space Science Institute
Resumen:
A variational data assimilation technique is used to estimate missing gravity wave drag (GWD) in the middle atmosphere from  MERRA global reanalysis dataset for the period between 1991 and 2010. The 20-year averaged zonal mean GWD shows that strongest GWD is $-49\gwdunit$ and is found around $54^\circ$S during the austral winter. This peak exceeds on average a 1.8 factor to the deceleration peak found in the northern hemisphere at the same season. The wave momentum flux at $100\punit$ has a global peak at 55 degrees in the southern hemisphere during October. The GWD estimated with ASDE is compared with the GWD given by a nonorographic gravity wave parameterization.  The estimated GWD is mostly associated with filtering process by background winds above 1hPa, when the winter and summer jets are well established. On the other hand, during the transition from the summer to winter state the estimated GWD is not comparable with the one given by the parameterization suggesting that gravity wave source variability plays an important role below 1hPa.