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Brandon Kerns

Senior Meteorologist





Department Affiliation

Ocean Physics


Bachelor of Science Physics and Applied Mathmatics, University of Miami, 2001

Master of Science Meteorology, University of Hawaii, 2003

Doctor of Philosophy Meteorology, University of Utah, 2008


2000-present and while at APL-UW

A 20-year climatology of Madden-Julian oscillation convection: Large-scale precipitation tracking from TRMM-GPM rainfall

Kerns, B.W., and S.S. Chen, "A 20-year climatology of Madden-Julian oscillation convection: Large-scale precipitation tracking from TRMM-GPM rainfall," J. Geophys. Res., 125, doi:10.1029/2019JD032142, 2020.

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16 Apr 2020

This study presents a 20‐year climatology of the Madden‐Julian Oscillation (MJO) convection based on Large‐scale Precipitation Tracking (LPT) using TRMM‐GPM Multisatellite Precipitation Analysis (TMPA) data from 1998–2018 over the global tropics‐midlatitudes (50°S–50°N). A total of 215 convective events are identified as MJO LPT systems over the 20 years, extending the results of Kerns and Chen (2016, https://doi.org/10.1002/2015JD024661). MJO LPT systems provide quantitative information regarding size, intensity, and location of the MJO convection in both the longitudinal and meridional directions. The MJO contributes up to 40–50% of the annual precipitation over the tropical Indo‐Pacific warm pool. MJO LPT systems have distinct seasonal and interannual variability. While MJO LPT systems are generally confined over the equatorial tropics during Boreal winter, some MJO LPT systems propagate northeast in the Bay of Bengal or from the South China Sea to the western North Pacific during Boreal summer. MJO LPT systems are more than doubled over the Indian Ocean (IO) and Maritime Continent (MC) during La Nina compared to El Nino. The 63% of MJO LPT systems initiate over the tropical IO, 26% over the MC and western Pacific, and 11% from the central Pacific to South America. About 40%% of the MJO LPT systems that initialized over the IO were unable to propagate through the MC, namely, the barrier effect. The MC barrier effect is most pronounced during the spring and autumn transitions. This 20‐year MJO LPT climatology product will be provided as a supplement to this publication.

Diurnal cycle of precipitation and cloud clusters in the MJO and ITCZ over the Indian Ocean

Kerns, B.W., and S.S. Chen, "Diurnal cycle of precipitation and cloud clusters in the MJO and ITCZ over the Indian Ocean," J. Geophys. Res., 123, 10,140-10,161, doi:10.1029/2018JD028589, 2018.

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27 Sep 2018

Satellite observations of the diurnal cycle of precipitation and cloud clusters show a dominant nighttime maximum over the tropical Indian Ocean, similar to other basins. The nighttime maximum is associated with the relatively long lifetime of large convective systems that initiated during the afternoon when the sea surface temperature (SST) reached its diurnal maximum as first showed in Chen and Houze (1997, https://doi.org/10.1002/qj.49712353806). Shipborne and island‐based radar data from Dynamics of the Madden‐Julian Oscillation show distinct characteristics of the diurnal cycle in the equatorial region and Intertropical Convergence Zone (ITCZ). A secondary afternoon precipitation maximum occurs under light surface winds (< 5 m/s) when the diurnal cycle of SST is large (0.5–1.7°C) in the equatorial region during the suppressed phase of the Madden‐Julian Oscillation (MJO). The afternoon maximum was from short‐lived convective systems with rain rates > 10 mm/hr. In contrast, during the active MJO and in the ITCZ, the secondary afternoon maximum is mostly absent as the surface winds were generally > 5 m/s and reduced afternoon SST warming to less than 0.5°C. The Tropical Rainfall Measurement Mission Multiplatform Precipitation Analysis does not resolve the secondary afternoon maximum in heavier rain rates from short‐lived small systems, but it suggests a more pronounced night‐morning maximum in the ITCZ than in the MJO. Infrared 208‐K cloud cluster analysis show that this difference in the morning maximum was due to the greater number of long‐lasting, large convective systems (> ~200 km in diameter) persisting into the morning in the ITCZ.

Evaluation of satellite surface winds in relation to weather regimes over the Indian Ocean using DYNAMO observations

Kerns, B.W., and S.S. Chen, "Evaluation of satellite surface winds in relation to weather regimes over the Indian Ocean using DYNAMO observations," J. Geophys. Res., 123, 8561-8580, doi:10.1029/2018JD028292, 2018.

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27 Aug 2018

Satellites provide the most extensive surface wind data over the tropical oceans, but sampling limitations, rain contamination, and algorithm uncertainties remain. In this study, scatterometer and passive microwave swath data, and multisatellite products are evaluated using Dynamics of the Madden‐Julian Oscillation (DYNAMO) ship and moored buoy wind speed data over the Indian Ocean from September 2011 to January 2012. Each of the satellite products has < 2 m/s error, consistent with previous studies. Blended products have error and bias characteristics comparable with swath data and provide better coverage. The errors and biases depend on the prevailing weather regime. The equatorial region is characterized by weeks of winds < 5 m/s with little rain punctuated by episodes of winds > 10 m/s and heavy rainfall associated with MJO events. The blended products resolve the episodic enhanced equatorial winds associated with the active phase of the MJO. However, due to limited sampling and rain contamination, the swath data did not fully resolve the peak MJO winds. In the Southern Hemisphere trade wind regime, rain contamination is less of a factor and winds are steadier. Satellite wind estimates of equatorial (trade wind) regime tended to be biased low (high). The surface wind products underestimate higher winds during the active MJO due to limited sampling and have high wind bias in the trade wind regime. These weather regime‐dependent biases should be taken into account for applications using these wind products for ocean circulation studies and estimating air‐sea fluxes over the Indian Ocean.

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center