1 / 17

Understanding the MJO: From Software Development to Atmospheric Research

Kate Thayer-Calder, a CMMAP graduate student, shifted from software development in pharmaceutical robotics to atmospheric research. Her focus is on the Madden-Julian Oscillation (MJO), a crucial yet poorly understood phenomenon that many climate models struggle to simulate. Thayer-Calder's research aims to bridge gaps in understanding the MJO, using different model simulations to explore its mechanisms. As she progresses into her PhD, she plans to integrate climate change aspects into her work, while continuing her passion for studying clouds.

tanuja
Télécharger la présentation

Understanding the MJO: From Software Development to Atmospheric Research

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. So, what happens next? Kate Thayer-Calder CMMAP Grad Student Clqm July 23, 2008

  2. What Happened Before? • Undergraduate degree in Computer Science • Spent 3 years working as a software developer on pharmaceutical robotic systems • Joined the group knowing basically nothing other than “I like clouds!”

  3. What Happened Next? • The MJO is an important and poorly understood phenomenon • Many GCMs are unable to simulate the MJO • We have two versions of the same model - one produces an MJO and one does not • GOALS: understand more about the models and more about the MJO

  4. Basics of the MJO • 30 to 70 day Oscillation, aka the intraseasonal oscillation • Starts in the Indian Ocean and slowly travels eastward (at 4-6 m/s or 9-13 mi/hr) • Spans 10º-20º of latitude and 50º-100º of longitude • Zonal wavenumbers 1-4 • Generally equatorially trapped, but can move northward or southward in certain cases. • More commonly appears in boreal winter Lin et al. 2006

  5. Basics of the MJO

  6. Current MJO Status You Are Here • EOF analysis used at BMRC to determine the current phase of the MJO • Forecasts done using a statistical model instead of traditional model MJO

  7. Lin et al. 2006 The Problem • The MJO is well observed, but not necessarily well understood • Many models have difficulty simulating the MJO • Only 2 of 14 IPCC AR4 models came close to having realistic MJO variability • Study suggests that the convective parameterizations in the models are the source of the differences • It is difficult to accurately simulate the MJO if we do not understand it!

  8. CAM Deep Convection Zhang and McFarlane (1995) • Triggered by instability, clouds persist until CAPE is mostly depleted • All detrainment occurs at cloud top, which must be above minimum of saturated MSE • All downdrafts exit below cloud base, and all clouds in the ensemble have the same base * * * * *

  9. SP-CAM Clouds and Convection • A 2-D Cloud Resolving Model is embedded in each GCM gridcell. • Clouds are explicitly simulated, allowing for many types, heights, and sizes of clouds. • Nudging from the LS values keeps the CRMs from drifting. • Results are returned to the LS as sub-grid scale tendencies due to clouds and radiation. • Currently, momentum is not fedback to the LS, and only the LS surface parameterizations are used.

  10. Moistening Through Many Levels 82% 96% 84% 80% 96% 60% >70%

  11. Discharge-Recharge Oscillation From Bladé and Hartman 1993 Figure from Benedict and Randall 2007 • Proposes MJO is an intrinsic oscillatory state of the tropics • During suppressed convection regimes, shallow clouds moisten and destabilize the area • Extra-tropical stochastic forcing sets off large-scale convection • Huge convective systems travel through the tropics restabilizing the area and suppressing convection after their passage.

  12. Discharge-Recharge Oscillation

  13. Moistening Through Many Levels • CRM in the SP-CAM does a better job of increasing relative humidity through the column, and loading the lowest levels with vapor • Heaviest rain occurs in a column with very high relative humidity, downdrafts are not as effective here • The CAM is much dryer through all layers 75% 65%

  14. Cycle of the MJO TPW (kg/m2) Rainrate (mm/hr) Rainrate (mm/hr) Rainrate (mm/hr) • Basic shape of SP-CAM, TC and ERA-40 are all very similar, well correlated precipitation and moistening keeps the cycle running • Disconnect between precipitation and increasing moisture breaks the Discharge-Recharge Oscillation in the CAM

  15. What’s Happening Now? • Defended my thesis last spring • Accepted into the Phd program • Taught a class on global climate change to undergraduates at Colorado College • Working on the paper from my thesis • Have to take the Prelims

  16. What Happens Next? • I have to decide exactly what I’m going to propose for my Phd dissertation • Will probably continue working with tropical dynamics • Will continue working with models, would like to add in some new observational toys • Would like to add an aspect of studying climate change to my research as well • Hope to continue to like clouds

  17. Questions?

More Related