slide1
Download
Skip this Video
Download Presentation
Variability of Extreme precipitation Events in the Core of the North American Monsoon

Loading in 2 Seconds...

play fullscreen
1 / 18

Variability of Extreme precipitation Events in the Core of the North American Monsoon - PowerPoint PPT Presentation


  • 228 Views
  • Uploaded on

Variability of Extreme precipitation Events in the Core of the North American Monsoon. Tereza Cavazos 1 Cuauhtémoc Turrent 1 Dennis P. Lettenmaier 2 1 CICESE , 2 University of Washington. Fourth Symposium on Southwest Hydrometeorology Tucson, AZ, 20-21 September 2007. 2007 .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Variability of Extreme precipitation Events in the Core of the North American Monsoon' - Anita


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Variability of Extreme precipitation Events in the Core of the North American Monsoon

Tereza Cavazos1

Cuauhtémoc Turrent1

Dennis P. Lettenmaier2

1CICESE, 2University of Washington

Fourth Symposium on Southwest Hydrometeorology

Tucson, AZ, 20-21 September 2007

2007

slide2

Introduction

  • Semiarid climate
  • Annual P < 700 mm y-1
  • Important producers of grains,
  • vegetables, grasses, and cattle
  • Maximum precip variability
  • (Gutzler 2004)
  • Persistent droughts and heavy
  • rains  impact in agriculture
  • and water availability

Core Monsoon

slide3

Core Monsoon

  • Last two decades: strong floods
  •  Severe damage (Bitrán, 2001), but also
  • benefits recharge of major dams (CNA, 2004)
  • Annual increase in heavy rains (P95, P99)
  • (Groisman et al. 2005, Alexander et al. 2006)
  • Future projections:
    • Increase in aridity and much less water
    • availability (IPCC, 2007; Seager et al. 2007)
    • Changes of extremes will be more important
    • than changes in mean precipitation
slide4

Objectives

  • To investigate trends in extreme
  • precipitation events (P95) in the
  • core monsoon
  •  Monsoon derived extremes (non TC)
  •  Tropical cyclone derived extremes (TC)
  • To examine the role of the
  • land-sea thermal contrast in the
  • initiation of extreme events
slide5

Data (JJAS, 1950-2003)

  • Daily precipitation from 39 stations from SMN/IMTA (Eric III)
  • Daily gridded precipitation (1/8o resolution) from the UW
  • Eastern Pacific hurricane tracks – 550 Km from the monsoon (Unisys)
  • Daily composites of atmospheric variables from NCEP Reanalysis (NOAA/CDC composites web page)
  • Weekly SSTs from in situ and satellite data (OISSTV2, Reynolds et al. 2002)
slide6

Methodology

  • Quality control of 39 station data from ERIC III
  • Daily and seasonal index of the core monsoon (CMI)
  • Daily precipitation extremes (top 95% of wet days) Thresholds of P95:
        • CMI: 14.5 mm d-1
        • Coastal stations (0 – 500 m ASL): 50 mm d-1
        • Mountain stations (>500 m ASL): 42 mm d-1
  • Extremes derived from TC rainfall and from monsoon rainfall (non TC)
  • Trends, statistical significant changes (p < 0.05): Mann-Kendall test (Frequency, intensity, and seasonal contribution of extreme events)
slide7

Results

Seasonal rainfall Index (JJAS )

There is not a long term significant linear trend

JJAS P61-90 = 490 mm

JJAS P77-03 = 481 mm

slide8

Change in the intensity of P95

Significant increase in the intensity of extreme events, but not in the frequency

Based period: 1961-1990

slide9

P95 Seasonal Contribution (%)

In 1980-2000 there were 16 TCs that affected the core monsoon and

5 made landfall:

Hurricane Paul in 1982

and Hurricanes Lydia, Ismael, Fausto, and Isis in the 1990s

slide10

Mtn P95 Contribution (%)

Mtn: > 500 m ASL

The total seasonal % contribution of P95 in mountain sites shows a significant increase of 1.5% per decade

Coastal stations did not show any significant changes

slide11

TC-derived extreme rainfall

JJAS: 1981-2003

UW gridded precipitation (mm d-1)

Between 1980 and 2003, Sinaloa was the second most affected state, after Baja California, by TCs (CNA, 2004)

slide12

WHWP, SST > 28.5 oC

(Wang et al. 2006)

Forcings: surface Tan (oC)

One week before onset of extreme events in the core monsoon

(A) TC: surface Tan (oC) (B) non TC: surface Tan (oC)

+

-

Thermal gradient (> 1oC)

TC highest frequency: September non TC highest frequency: Jul-Aug

slide13

(C) TC: air Tan (oC), t=-5d (D) TC: V850an (m s-1), t=1d

Forcing mechanisms

Large land-sea thermal gradient (> 1oC)

slide14

Onset

(E) TC: OLRan (Watts m-2), t=1d (F) TC: air Tan (oC), t=1d

slide16

Hurricane Henriette (Cat 1) 5 Sep 2007

Hurricane Felix (Cat 5)

(mm d-1)

PRECIPITATION:

12Z 05 Sep - 12Z 06 Sep 2007

(CPC-NOAA)

slide17

Conclusions

  • Intensity and seasonal contribution of extreme events in the core monsoon have increased significantly
  • Especially TC-derived extremes and in mountain sites
  • Frequency of extremes and seasonal rainfall do not show a significant linear trends
  • Extreme events in coastal stations do not show significant changes
  • TC-derived extreme events are characterized by
    • La Niña-like conditions
    • Strong land-sea thermal contrast near the study area, and
    • Large Western Hemisphere warm pool
slide18

Ongoing Work

  • Numerical investigation of the land-sea thermal contrast (MM5)
    • Indices to characterize the intensity of monsoon onset (C. Turrent)
    • Seasonal predictability of the monsoon based on soil moisture (Zhu et al.)
    • Sensitivity analyses of different monsoon years (C. Turrent, Zhu et al.)
  • Climate projections of extremes for the 21st Century (S. Arriaga)
ad