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Abstract The diurnal cycle of precipitation plays a crucial role in regulating Earth's water cycle, energy balance, and regional climate patterns. However, the diurnal precipitation across mainland Southeast Asia (MSEA) and the factors influencing its spatial variations are not fully understood. In this study, we investigated diurnal precipitation patterns in summertime (June–August) from 2002 to 2005 over MSEA using ground‐based observations, satellite products, the global ERA5 reanalysis, and high‐resolution simulations from the Weather Research and Forecasting (WRF) Model at 9‐ and 3‐km grid spacing forced by ERA5 hourly data on ∼0.25° grids. Various observation‐based data sets including GHCN‐Daily, Multi‐Source Weighted‐Ensemble Precipitation (MSWEP), Asian Precipitation ‐ Highly‐Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE), and Integrated Multi‐satellite Retrievals for Global Precipitation Measurement (IMERG) were used. In evaluating daily precipitation over MSEA, MSWEP, and APHRODITE data sets show similar patterns in precipitation amount, frequency, and intensity, while IMERG tends to produce higher amounts but with less frequency. ERA5 overestimates light precipitation compared to the other data sets. The WRF simulations generally produce heavier but less frequent light precipitation, with the 3‐km simulation producing less intense precipitation than the 9‐km simulation. A k‐means classification of IMERG data revealed five distinct spatial regimes with varying diurnal precipitation cycles. The WRF simulations closely match these regimes, capturing key diurnal cycles missed by ERA5 over mountainous regions and coastlines. Additionally, convective activities and near‐surface winds influence these cycles, with WRF simulations better representing coastal and mountain precipitation patterns than ERA5. High‐resolution WRF simulations, especially the 3‐km simulation, capture diurnal precipitation more accurately than ERA5, highlighting the importance of employing convection‐permitting models to simulate precipitation diurnal cycles over complex terrain.
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Precipitation Characteristics of Easterly Waves Across the Global Tropics
Abstract Tropical easterly waves (TEWs) are a recurrent mode of low‐latitude weather that are often convectively coupled and impact precipitation extremes. Previous work has examined the development of TEWs and their associated precipitation for individual seasons or regional domains, but no studies exist that document the importance of TEW precipitation globally. This study quantifies the precipitation associated with TEWs across the entire tropics using satellite (Integrated Multi‐satellitE Retrievals for the Global Precipitation Measurement [IMERG]) and reanalysis (Modern‐Era Retrospective analysis for Research and Applications, Version 2 [MERRA‐2]) data. Traditional space‐time filtering of precipitation reveals a mostly similar climatological power distribution for westward traveling, synoptic period disturbances corresponding to TEWs within all data sets. Using objective tracking, we find that areas with maximum TEW frequency such as the North Atlantic, Equatorial Pacific, and Indian Ocean have the highest accumulation of TEW‐associated precipitation. TEWs account for at most 30% of total annual precipitation in regions where they commonly occur and 1%–5% over much of the tropics. Vertically collocated storms, where the 850 and 700 hPa tracks correspond with each other, have higher conditional rain rates and indicate that waves with vertical development produce stronger and more organized convection. We find similar regional patterns using MERRA‐2 precipitation and latent heating, although the importance and contribution of TEWs to the background are reduced compared to IMERG. While the broad pattern of TEW associated precipitation in MERRA‐2 is like observations, the underestimation of rainfall contributions from TEWs, coupled with occasional false alarms in reanalysis data, suggests that MERRA‐2 does not capture organized convection within TEWs correctly.
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- Award ID(s):
- 1944177
- PAR ID:
- 10512515
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 129
- Issue:
- 7
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2023JD039957
