# Presentation: 451780

## Factoring Climate Into Forecast Decision Part II

- Wassila M. Thiaw
**Climate Prediction Center**
**National Centers for Environmental Predictions**
**National Weather Service//NOAA**

- ENSO
- MJO
- Monitoring Impacts

## ENSO

- ENSO is a global phenomena, affecting the atmospheric-oceanic interaction.
- The period between the warm and cold phases of ENSO varies between 2-10 years, with an average of 3 years.

## Walker Circulation Across the Pacific During La Niña

- High pressure dominates the Eastern Pacific, while low pressure is observed in Indonesia. This favors upward motion and convection in Indonesia/Western Pacific, and subsidence in the Eastern Pacific.
- Due to the upward/downward motions, a persistent easterly flow establishes across the Pacific, advecting warm water westward along the South Equatorial Current.
- On average, the mean sea level over Indonesia raises by 40cm (16 inches). Upwelling of cold water is observed along the coast of Peru.  The cold coastal water and the subsidence aloft favors a dry/stable pattern.

**Notes:**
The image depicts the upward motion across the western equatorial Pacific, while downward motion is observed on the eastern Pacific.  This will inhibit organized convection over Colombia-Ecuador-northern Peru.

## El Niño – Warm Phase

- During the warm phase we see the opposite, with high pressure over Indonesia and low pressure across the Ern Pacific.  This favors upward motion and convection over the Ern Pacific, and downward motion over Indonesia.
- Due to the upward/downward motions, a persistent westerly flow establishes across the Pacific, advecting warm water eastward along the Equator to the coast of South America.

## Low level global circulation

- 925 hPa Height & Winds

- Climatology

- Cold Phase

- Warm Phase

## Rainfall Anomaly in DJF during ENSO 

- Rainfall Anomaly in DJF during ENSO

- Cold Phase

- Warm Phase

## Cold Phase

- Rainfall Anomaly in OND during ENSO

- Warm Phase

## Oct-Dec E. Africa and Dec-Feb S. Africa Precipitation, 1951-2005

**Oct-Dec E. Africa and Dec-Feb S. Africa Precipitation, 1951-2005**

## Dipole Years for OND E. Africa and DJF S. Africa, 1951-2005

| 1954 | Dry/Wet | La Nina |
| --- | --- | --- |
| 1955 | Dry/Wet | La Nina |
| 1961 | Wet/Dry | La Nina |
| 1963 | Wet/Dry | El Nino |
| 1967 | Wet/Dry | La Nina |
| 1968 | Wet/Dry | El Nino |
| 1972 | Wet/Dry | El Nino |
| 1973 | Dry/Wet | La Nina |
| 1975 | Dry/Wet | La Nina |
| 1979 | Dry/Wet | Neutral |
| 1982 | Wet/Dry | El Nino |
| 1987 | Dry/Wet | El Nino |
| 1989 | Wet/Dry | Neutral |
| 1994 | Wet/Dry | El Nino |
| 1997 | Wet/Dry | El Nino |
| 2005 | Dry/Wet | Neutral |

**Dipole Years for OND E. Africa and DJF S. Africa, 1951-2005**

## Sea Surface Temperature and 850 mb Wind Anomalies

**Cold ENSO Episodes, East Africa Dry – Southern Africa Wet**

**Cold ENSO Episodes, East Africa Wet – Southern Africa Dry**

**Westerly wind anomalies tend**
**to reduce incoming moisture**
**from Indian Ocean into**
**continental Africa.**

**Easterly wind anomalies tend**
**to bring more moisture**
**into continental Africa: favorable**
**conditions for rainfall.**

**Sea Surface Temperature and 850 mb Wind Anomalies**

## Sea Surface Temperature and 850 mb Wind Anomalies

**Sea Surface Temperature and 850 mb Wind Anomalies**

**Warm ENSO Episodes, East Africa Dry – Southern Africa Wet**

**Warm ENSO Episodes, East Africa Wet – Southern Africa Dry**

**Easterly wind anomalies**
**across the central Indian Ocean**

**Westerly wind anomalies**
**across the central Indian Ocean**

## Precipitation Anomaly Jun 1997 – May 1999

**Precipitation Anomaly Jun 1997 – May 1999**

**Southern Africa**

**East Africa**

- El Nino Signal?

## Dec 97

- Nov97

- Oct 97

- Jan 98

- Agulhas Events mostly developed
- Jan through Mar.
- SAF rainfall associated with SST in
- Agulhas System.

**Sea Surface Temperature Anomalies in the Atlantic and Indian Ocean**

## OND 2005

**OND 2005**

**SON 2006**

**East Africa (5S-5N; 30E-40E Precipitation Anomaly (Percentile)**
**December 2004 – November 2006**

**East Africa (5S-5N; 30E-40E Precipitation Anomaly (Percentile)**
**June 1997 – May 1999**

## Divergent Circulation and Relative Humidity, 5N-5S

**Divergent Circulation and Relative Humidity, 5N-5S**

**Dec 2005**

**Anomaly**

**Dec 1997**

**Mean**

**Mean**

- Indonesia

- Africa and IO

- Africa and IO

- Indonesia

## OND 2005

**OND 2005**

**SON 2006**

**East Africa (5S-5N; 30E-40E Precipitation Anomaly (Percentile)**
**December 2004 – November 2006**

## Hovmoller Diagram 850hPa Zonal Wind Anomaly

**Oct 2005 – Jan 2006**

**Sep 2006 – Dec 2006**

- Blue/Red shade: easterly/westerly wind anomaly

## GPCP Monthly Precipitation Anomaly, Oct-Mar 2005-06

**GPCP Monthly Precipitation Anomaly, Oct-Mar 2005-06**

**Oct 2005**

**Nov 2005**

**Dec 2005**

**Jan 2006**

**Feb 2006**

**Mar 2006**

## Monitoring Intraseasonal Variability

**The Madden Julian Oscillation (MJO)**

## Monitoring the Madden Julian Oscillation

- Characteristics of the MJO
- Eastward propagation of large regions of both suppressed and enhanced tropical rainfall observed mainly over the Indian Ocean and the Pacific Ocean
- MJO becomes first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central Pacific Ocean.  MJO reappears in the tropical Atlantic and IO.  Cycle is 30-60 days.
- Distinct patterns of lower and upper atmospheric circulation extending around the globe accompany the MJO-related rainfall anomaly.  Provide information regarding regions of ascending and descending motion associated with particular phases of the oscillation.
- Strong year-to-year variability in MJO activity with long periods of strong activity followed by periods in which the oscillation is weak or absent.  Interannual variability partly linked to the ENSO cycle.  MJO active during weak La Nina years or during ENSO neutral.  Weak or absent MJO typically associated with strong El Nino episodes

## MJO (Cont’d)

- Monitoring the MJO
- Variety of data and analysis techniques used to monitor the MJO
- NOAA’s polar-orbiting and geostationary satellites
- Regions of strong tropical convective activity
- Regions in which tropical convective activity departs from climatology
- Anomalies are fundamental diagnostic tools to monitor the MJO
- Global radiosonde network: provides crucial information regarding the atmospheric conditions
- Data assimilated into dynamical weather prediction models into highly efficient format  for climate monitoring and weather predictions
- Routinely monitor and assess the MJO and its evolution
- Assess the impacts of the MJO activity

## Diagnostics Tools

Time-Longitude format to reveal propagation, amplitude and location of MJO-related features
Outgoing long wave radiation: satellite derived measure of tropical convection and rainfall
Velocity potential: derived quantity that isolates the divergent component of the wind (upper level of atmosphere
Upper level and lower level wind anomalies
500 –hPa height anomalies to represent atmospheric responses in mid-latitude 

- Time-Longitude format to reveal propagation, amplitude and location of MJO-related features
- Outgoing long wave radiation: satellite derived measure of tropical convection and rainfall
- Velocity potential: derived quantity that isolates the divergent component of the wind (upper level of atmosphere
- Upper level and lower level wind anomalies
- 500 –hPa height anomalies to represent atmospheric responses in mid-latitude

- MJO (Cont’d)

## MJO (Cont’d)

- Predicting the MJO
- Significant impacts on the atmospheric circulation
- Blocking activity (atmospheric circulation that persist near the same location for several days or more)
- Phase of MJO extremely important for assessing tropical cyclone development over the Indian Ocean: MJO-related ascending motion over the Indian Ocean during the austral summer quite favorable for Tropical cyclone development
- MJO routinely monitored to aid in anticipating periods of relative activity or inactivity.

## Slide 24

## Evidence of MJO Activity, 1-7 Jan 2007

**Velocity Potential Anomaly at 200 hPa **

**OLR Anomalies**

- Brown shade indicates
- upper level convergence
- and subsidence
- Blue shade indicates upper
- level divergence and
- ascending motion

- Brown shade indicates
- Suppressed convection
- Blue shade indicates
- enhanced convection

## Wheeler Diagram

**The axes are used to measure the amplitude of the MJO. They represent the time series of the two leading modes of variability **
**The triangular areas indicate the phase or location of the enhanced phase of the MJO.**
**The farther away from the center of the circle the stronger the MJO. Different color lines indicate different months.**

- M. Wheeler

## Characteristics of the MJO 

- Precipitation Composite (Nov-Mar)

- Schematic of MJO

**Characteristics of the MJO**_** **_

- J. Gottschlack

## Austral Summer MJO Important impacts

- MJO affects monsoon areas by modifying onset/decay times and intensity

- MJO can alter regional rainfall patterns

- MJO can lead to period of elevated/suppressed tropical cyclone activity

- CPC Global Hazard Team

## Boreal Summer MJO Important impacts

- MJO affects monsoon areas by modifying onset/decay times and intensity

- MJO can alter regional rainfall patterns

- MJO can lead to period of elevated/suppressed tropical cyclone activity

- CPC Global Hazard Team

## Monitoring the MJO during the 2006-07 AustralSummer Case Study Period

**In late Dec 2006 – Jan 2007, the MJO intensified as negative OLR anomalies shifted eastward from the Maritime continent into the central tropical Pacific. **
**There is an eastward shift of weak velocity potential anomalies near the Indian Ocean and Maritime Continent in early February.**

## SST Mean and Anomaly Jan 14-20 2007

- SST Mean and Anomaly Feb 11-17 2007

## 850 hPa wind Mean and Anom 17-23 Jan 2007

**850 hPa wind Mean and Anom 17-23 Jan 2007**

**850 hPa wind Mean and Anom 11-17 Feb 2007**

## Current ENSO and MJO Status and Evolution

## Current Global SST Anomalies

**Current Global SST Anomalies**

- La Nina conditions Prevail
- during October 2007

- Subsidence will tend to occur in the central Pacific, convection over Indonesia,
- Suppression over coastal East Africa, enhancement over NE southern Africa

- Blue shades indicate colder than normal sea surface
- Red shades indicate warmer than normal sea surface

- Slight warming over the central IO
- and cooling over the South IO
- Warm sea surface off southwest
- coast South Africa

## SST Outlook: NCEP CFS Forecast Issued 1 October 2007

**The CFS ensemble mean (heavy blue line) predicts La Ni****ña conditions to strengthen during October - December.**

## 200-hPa Velocity Potential Anomalies (5oN-5oS)

**200-hPa Velocity Potential ****Anomalies (5****o****N-5****o****S)**

**Negative anomalies (green shading) indicate favorable conditions for precipitation.**

**Positive anomalies (brown shading) indicate unfavorable conditions for precipitation.**

**Longitude**

**Time**

**During May - July, weak-to-moderate MJO activity was observed.**
**Recently, MJO activity has been incoherent.**

## Summary

- The cold phase of ENSO (La Nina) is the current dominant global mode of variability
- Moderate to strong ENSO acts to suppress MJO activity.  MJO tend to dominate during neutral ENSO or weak La Nina episodes
- La Nina tends to inhibit precipitation along coastal East Africa and enhance rainfall in Indonesia and southern Africa
- Blame La Nina for the current weather pattern in South Africa?
- The Indian Ocean response to La Nina is important for tropical cyclogenesis across the IO
- Warm (cold) SST over central IO will favor (suppress) development of TC
- Continued monitoring of IO SST can improve medium and extended range weather forecasting in eastern and southern Africa
- Continued monitoring of magnitude vertical wind shear across the IO can help improve prediction of TC track
- Monitoring	Monitoring	Monitoring........

## NCEP/CPC Web Site for monitoring ENSO, MJO, and global scale climate patterns

- http://www.cpc.ncep.noaa.gov/
- African Desk:	products/african_desk/
- MJO	products/precip/CWlink/MJO/mjo.shtml
- Briefing Page: products/precip/CWlink/MJO/index.primjo.html
- ENSO products/precip/CWlink/MJO/enso.shtml
- Current Conditions
- Historical Information
- Outlooks
- Expert Discussions
- Educational Materials
- Global Monsoon	products/Global_Monsoons/Global-Monsoon.shtml