Understanding the Changes of Convection and Rainfall in the Future

Contact: Wang, Yi-Chi / yichiwang@gate.sinica.edu.tw / +886-2-2787-5946

Key words: convection and rainfall variability; climate models; climate changes; parameterization of moist physics

Figures: (Right) Diurnal rainfall magnitude observed by Tropical Rainfall Measurement Mission (TRMM) . Very strong diurnal amplitudes of rainfall in the tropics and storm tracks over the west side of ocean. (Left) Model biases of simulating diurnal rainfall amplitude compiled from the state-of-the-art the Coupled Model Intercomparison Project Phase 6 (CMIP6) archive.

Atmospheric convection is one of the most important part of climate systems. Ranging from a few kilometers to tropospheric top, atmospheric convection is manifested by cumulus clouds with significant vertical extension compared with its horizontal scale. By transporting heat, moisture, and momentum vertically, it serves as an important driver for atmospheric circulations. Its coupling with surface processes and hydrological cycles has strong impacts on human society and ecological systems.

However, the climate models used for future climate projection still have difficulty predicting convective rainfall variability. For example, figure 1 shows the geographical distribution of diurnal rainfall amplitude from satellite observations (left). Convection rainfall varies strongly within one day over tropical lands and storm tracks over the oceans (figure 1 right). But large model biases of diurnal amplitude still exist, which can be up to 50% of mean rainfall among the state-of-the-art climate models. The CMIP6 archive show large amount of underestimation of diurnal amplitude over maritime continent and central America (figure 1 left). As productive ecological systems existing over the tropical lands, such rainfall uncertainty in future projection can lead to large uncertainty in future governance in preparation for future climate changes in these regions.

Our lab aims to understand the physical understanding of rainfall and atmospheric convection by utilizing growing satellite observations (figure 2 left) and increasing computational power with numerical models (figure 2 right). Moreover, such understanding can help Such effort will contribute to improvements of weather forecast, climate projection, and other societal and economical applications.

Key points

  • Convection activity is an important part of transporting moisture, energy, and momentum within the earth system.
  • Temporal and spatial patterns of convection and rainfall
  • We can better predict changes of convection and rainfall variability under anthropogenic forcing by analyzing satellite observations and numerical model simulations.

More information

  • *Y.-C. Wang, H.-L. Pan, and H.-H. Hsu (2015): doi:10.1002/2015JD023337 Publication Link
  • Lee and Wang (2020) : in preparation.

Figures: (Right) Diurnal rainfall magnitude observed by Tropical Rainfall Measurement Mission (TRMM) . Very strong diurnal amplitudes of rainfall in the tropics and storm tracks over the west side of ocean. (Left) Diurnal rainfall
Figures used here are from public domain.
https://celebrating200years.noaa.gov/breakthroughs/climate_model/welcome.html; Link
http://www.freestockphotos.biz/stockphoto/15144; Link
https://www.esa.int/ESA_Multimedia/Images/2019/12/NASA_s_suite_of_operational_Earth_science_missions Link

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