@Article{NathChenGuha:2015:ClStGr,
               author = "Nath, Debashis and Chen, Wen and Guharay, Amitava",
          affiliation = "{Chinese Academy of Sciences} and {Chinese Academy of Sciences} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Climatology of stratospheric gravity waves and their interaction 
                         with zonal mean wind over the tropics using GPS RO and 
                         ground-based measurements in the two phases of QBO",
              journal = "Theoretical and Applied Climatology",
                 year = "2015",
               volume = "119",
               number = "3/4",
                pages = "757--769",
                month = "Feb.",
             abstract = "The present manuscript deals with the spatial distribution of 
                         gravity wave activity over the tropics using ten years (2001-2010) 
                         of CHAllenging Mini Payloads (CHAMP) and Constellation Observing 
                         System for Meteorology, Ionosphere and Climate (COSMIC) Global 
                         Positioning System (GPS) Radio Occultation (RO) data and 
                         ground-based radiosonde measurements over an equatorial station 
                         Singapore (1.36A degrees N, 103.98A degrees E) and four tropical 
                         stations, Guam (13.48A degrees N, 144.80A degrees E), Palau (7.33A 
                         degrees N, 134.48A degrees E) in the northern hemisphere, Darwin 
                         (12.41A degrees S, 130.88A degrees E) and Pago-Pago (14.33A 
                         degrees S, 170.71A degrees W) in the southern hemisphere from 
                         January 2001-December 2010. It also aims to quantify the 
                         difference in wave activity in the two phases of QBO, 
                         climatologically. Space-time spectra have been constructed over a 
                         latitude band of +/- 10A degrees and decomposing the CHAMP/COSMIC 
                         temperature perturbations into symmetric and antisymmetric modes 
                         about the equator. Clear signature of equatorial waves with higher 
                         wavelength and a constant background of gravity waves (GW) with 
                         inertial frequency are prominent in the spectra. Strong GW and 
                         mean flow interaction can be seen in the lower stratosphere 
                         potential energy density (E (P)) and momentum flux with enhanced 
                         wave activity during the westerly (eastward wind) phase of 
                         quasi-biennial oscillation (QBO) (WQBO) over the equatorial and 
                         tropical stations like Singapore and Palau/Darwin, respectively. 
                         From the latitudinal distribution of energy density, the 
                         occurrence of two-peak structure in energy density can be seen in 
                         the middle and lower latitudes with an enhancement during the WQBO 
                         phase. The E (P) associated with GWs are calculated at lower 
                         stratospheric (19-26 km) heights and are compared with outgoing 
                         longwave radiation (OLR) to correlate the wave events with 
                         tropical deep convection during the easterly, i.e. westward wind 
                         (EQBO) and WQBO phases of QBO. Clear coherence of convection due 
                         to Asian summer monsoon with localized enhancement of wave 
                         activity over Western Pacific, South America and African region 
                         during the WQBO phase is observed at the lower stratospheric 
                         heights. Significant enhancement is observed during Northern 
                         Hemisphere winter months and minimum during summer. The 
                         longitudinally elongated portion of E (P) over the equator is 
                         partially affected by Kelvin wave (KW) like disturbances with 
                         short vertical scales and also by inertia GW.",
                  doi = "10.1007/s00704-014-1146-7",
                  url = "http://dx.doi.org/10.1007/s00704-014-1146-7",
                 issn = "0177-798X",
             language = "en",
           targetfile = "nath_climatology.pdf",
        urlaccessdate = "27 abr. 2024"
}