Aircraft observations in a tropical supercluster over the equatorial Indian Ocean during MISO-BOB field campaign

Jayesh Phadtare; Harindra J S Fernando; Garrett Black; Kaitlyn McLaughlin; Jeremy Dehart; Raghavendra Krishnamurthy; G S Bhat; Emily Shroyer; Amit Tandon; Jaynise M Pérez Valentín; S U P Jinadasa

doi:10.1038/s41598-024-51527-4

Aircraft observations in a tropical supercluster over the equatorial Indian Ocean during MISO-BOB field campaign

Sci Rep. 2024 Jan 25;14(1):2182. doi: 10.1038/s41598-024-51527-4.

Authors

Jayesh Phadtare¹, Harindra J S Fernando^{2

3}, Garrett Black⁴, Kaitlyn McLaughlin⁴, Jeremy Dehart⁴, Raghavendra Krishnamurthy^{2

5}, G S Bhat⁶, Emily Shroyer^{7

8}, Amit Tandon⁹, Jaynise M Pérez Valentín², S U P Jinadasa¹⁰

Affiliations

¹ Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA. jayesh.phadtare@gmail.com.
² Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.
³ Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.
⁴ 53rd Weather Reconnaissance Squadron, Keesler Air Force Base, Biloxi, MS, 39534, USA.
⁵ Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
⁶ Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru, 560012, India.
⁷ College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, 97331, USA.
⁸ Office of Naval Research, Arlington, VA, 22203, USA.
⁹ Department of Mechanical Engineering, University of Massachusetts Dartmouth, North Dartmouth, MA, 02744, USA.
¹⁰ Faculty of Engineering and Management, Ocean University of Sri Lanka, Colombo, 15, Sri Lanka.

Abstract

The Monsoon Intra-Seasonal Oscillations in the Bay of Bengal (MISO-BOB) field campaign was conducted in the Indian Ocean during the 2018 and 2019 summer monsoon seasons. WC-130J aircraft of the 53rd Weather Reconnaissance Squadron of the US Air Force participated in the campaign in June 2018. The dropsonde observations across a tropical supercluster showed zonal wind variations in association with the structure of the convectively coupled Kelvin wave (CCKW). Within the supercluster, easterlies (westerlies) were observed in the upper (lower) troposphere; this transformation occurred just below the 0[Formula: see text] C level. The cold pool had an easterly component throughout, and it was coldest (by 2.5[Formula: see text] C) at the center of the supercluster, deepest ([Formula: see text] [Formula: see text]) at its rear/western end, and shallowest ([Formula: see text] 300 m) at the front/eastern end. The level of free convection (LFC) at the front end was at [Formula: see text] altitude. At the eastern flank of the supercluster, zonal convergence in the lower troposphere occurred between 500-1500 m levels above the surface between the westerlies within the supercluster and opposing ambient easterlies. Thus, the uplifting of conditionally unstable air parcels above LFC to the east of the supercluster was likely to occur due to this convergence rather than the cold pool influence. Conversely, the western flank of the supercluster had low-level zonal divergence. These observations support the notion of 'self-similarity' among the mesoscale convective systems and large-scale waves.

Grants and funding

N00014-17-1-2334/Office of Naval Research