Karmakar, N., & Misra, V. (2019). Differences in Northward Propagation of Convection Over the Arabian Sea and Bay of Bengal During Boreal Summer.
J. Geophys. Res. Atmos., 125(3).
Abstract: The governing dynamics that modulate the propagation characteristics of intraseasonal oscillations (ISO) during summer monsoon over the two ocean basins, Bay of Bengal (BoB) and Arabian Sea (AS), are investigated using observational analysis and high‐resolution regional coupled ocean‐atmosphere climate model simulations. ISO features are extracted over the Indian region using a data‐adaptive spectral method called multichannel singular spectrum analysis. ISO exhibits stronger intensity over the BoB than over the AS. But ISO‐filtered rainfall propagates at a faster rate ( urn:x-wiley:jgrd:media:jgrd55983:jgrd55983-math-00011.25°/day) over AS as compared to BoB ( urn:x-wiley:jgrd:media:jgrd55983:jgrd55983-math-0002.74°/day), giving rise to a northwest‐southeast tilted band of rainfall anomalies. However, the composite diagrams of several atmospheric fields associated with northward propagation like vorticity, low‐level convergence, and oceanic variables like sea surface temperature and mixed layer depth do not show this difference in propagation speed and all exhibit a speed of nearly 0.75°/day in both the ocean basins. The difference in speed of ISO‐filtered rainfall is explained through moisture flux convergence. Anomalous horizontal moisture advection plays a major role over AS in preconditioning the atmosphere and making it favorable for convection. Anomalous wind acting on climatological moisture gradient is the dominant term in the moisture advection equation. Easterly wind anomalies associated with a low‐level anticyclone over India helps advect moisture from the eastern side of the domain. The northwest‐southeast tilt of ISO is dictated by the atmospheric processes of moisture advection with the upper ocean playing a more passive role in causing the tilt.
Karmakar, N., & Misra, V. (2019). The Relation of Intraseasonal Variations With Local Onset and Demise of the Indian Summer Monsoon.
J. Geophys. Res. Atmos., 124(5), 2483–2506.
Abstract: Two of the most important hydroclimatic features of the Indian Summer Monsoon (ISM) rainfall are its onset/demise and Intraseasonal Oscillations (ISOs) manifested by the active‐break cycles. In this study, we aim to understand the quantitative association between these two phenomena. An objective definition of local onset/demise of the ISM based on more than a century‐long India Meteorological Department (IMD) rain‐gauge observation is taken into consideration. Using multichannel singular spectrum analysis (MSSA) we isolate northward propagating low‐ (20–60 days; LF‐ISO) and northwestward propagating high‐ (10–20 days; HF‐ISO) frequency ISOs from the daily ISM rainfall. Our results suggest that a large number of local onset (59%) and demise (62%) events occur during positive developing phases and positive decaying phases of two ISOs, respectively, with phase‐locking between LF‐ISO and HF‐ISO being particularly important. Local onset is largely associated with favorable phases of ISOs across India except for LF‐ISO over eastern India and HF‐ISO over western Ghats and central India (CI). We find that local demise is more coherent with the ISO phases, especially with HF‐ISO across the domain. We performed a case study to understand large‐scale association with the onset of the ISM over CI. In 44 of total 58 cases (1948–2005), when CI onset occurred during favorable LF‐ISO or HF‐ISO phase, they are either linked with a northward propagation of convection from the equator in LF‐ISO timescale (28 cases) or westward propagating structures from the western Pacific in HF‐ISO timescale (27 cases).
DiNapoli, S. M., & Misra, V. (2012). Reconstructing the 20th century high-resolution climate of the southeastern United States.
J. Geophys. Res., 117(D19), n/a-n/a.
Li, H., Kanamitsu, M., & Hong, S. - Y. (2012). California reanalysis downscaling at 10 km using an ocean-atmosphere coupled regional model system.
J. Geophys. Res., 117(D12).
Kozar, M. E., Mann, M. E., Camargo, S. J., Kossin, J. P., & Evans, J. L. (2012). Stratified statistical models of North Atlantic basin-wide and regional tropical cyclone counts.
J. Geophys. Res., 117(D18).
Misra, V., Moeller, L., Stefanova, L., Chan, S., O'Brien, J. J., Smith III, T. J., et al. (2011). The influence of the Atlantic Warm Pool on the Florida panhandle sea breeze: FLORIDA SEA BREEZE VARIATIONS.
J. Geophys. Res., 116(D21).
Chan, S. C., Misra, V., & Smith, H. (2011). A modeling study of the interaction between the Atlantic Warm Pool, the tropical Atlantic easterlies, and the Lesser Antilles: ATLANTIC WARM POOL, EASTERLIES, ISLANDS INTERACTIONS.
J. Geophys. Res., 116(D21).
Shin, D. W., Cocke, S., & LaRow, T. E. (2007). Diurnal cycle of precipitation in a climate model.
J. Geophys. Res., 112(D13).
Shin, D. W., Baigorria, G. A., Romero, C. C., Cocke, S., Oh, J. - H., & Kim, B. - M. (2017). Assessing crop yield simulations driven by the NARCCAP regional climate models in the southeast United States.
J. Geophys. Res. Atmos., 122(5), 2549–2558.
Zheng, Y., Bourassa, M. A., Ali, M. M., & Krishnamurti, T. N. (2016). Distinctive features of rainfall over the Indian homogeneous rainfall regions between strong and weak Indian summer monsoons.
J. Geophys. Res. Atmos., 121(10), 5631–5647.