drought in the midwest by anthony r. lupo department of soil, environmental, and atmospheric...

Drought in the Drought in the MidwestMidwest

byby

Anthony R. LupoAnthony R. LupoDepartment of Soil, Environmental, and Atmospheric Department of Soil, Environmental, and Atmospheric

SciencesSciences302 E ABNR Building302 E ABNR Building

University of Missouri – ColumbiaUniversity of Missouri – ColumbiaColumbia, MO 65211Columbia, MO 65211

Drought in the MidwestDrought in the Midwest

Why is it important to discuss it?Why is it important to discuss it?

Source: NOAA – USDA – Missouri Climate Source: NOAA – USDA – Missouri Climate CenterCenter

Drought in the MidwestDrought in the Midwest Anatomy of a warm, dry summer – Anatomy of a warm, dry summer –

20052005

Let’s look at the mid-western drought of Let’s look at the mid-western drought of 2005 and discern the causes2005 and discern the causes

Spring season (March – May) Avg over mid-Spring season (March – May) Avg over mid-MO = 11.6 inchesMO = 11.6 inches

Actual rain = 7.3 inches, 63% of normal – Actual rain = 7.3 inches, 63% of normal – this was typical across the region.this was typical across the region.

Drought in the MidwestDrought in the Midwest It was not particularly warm during the It was not particularly warm during the

spring, but the lack of precipitation still spring, but the lack of precipitation still leaves the ground water supplies low! leaves the ground water supplies low!

A look at the long term record reveals that A look at the long term record reveals that the current dryness began in Dec. 2004the current dryness began in Dec. 2004

In early June 2005, the rains stopped In early June 2005, the rains stopped coming ( at least less frequently – which is coming ( at least less frequently – which is normal). normal).


the ground dried out, the temperatures the ground dried out, the temperatures rose, etc… (“drought begets drought”)rose, etc… (“drought begets drought”)

A “classical” large-scale ridge (drought A “classical” large-scale ridge (drought pattern) settled over the central USA.pattern) settled over the central USA.

The following map is the mean The following map is the mean conditions from 15 June – 10 August conditions from 15 June – 10 August average.average.


And what was the assessment? And what was the assessment?


Summer 2005 - a year to confound Summer 2005 - a year to confound climatologists in the future! climatologists in the future!

Why? Why?

The summer precipitation across the The summer precipitation across the region was actually above normal! region was actually above normal!


Summer precipitation was at 15.3” in Summer precipitation was at 15.3” in mid-Missouri, normal is 11.7 inches. mid-Missouri, normal is 11.7 inches. But 10” of this occurred during 14 days But 10” of this occurred during 14 days in August!in August!

What was the cause?What was the cause?

A rare case of summer blocking!A rare case of summer blocking!


The jet stream was pushed southward The jet stream was pushed southward – by 10 August.– by 10 August.


By August 13, rains were falling By August 13, rains were falling across the midwest.across the midwest.

Drought in the MidwestDrought in the Midwest Q: What is blocking? Q: What is blocking?

A: It is a large-scale, persistent, nearly A: It is a large-scale, persistent, nearly stationary, mid-latitude, dynamically driven stationary, mid-latitude, dynamically driven ridging in the jet-stream. ridging in the jet-stream.

The dynamics of blocking are not completely The dynamics of blocking are not completely understood, even though the climatological understood, even though the climatological behavior is well-understood (see Lupo and behavior is well-understood (see Lupo and Smith, 1995a,b, Tellus; Weidenmann et al.m Smith, 1995a,b, Tellus; Weidenmann et al.m 2002, J. Climate; Burkhardt and Lupo, 2005, J. 2002, J. Climate; Burkhardt and Lupo, 2005, J. of Atms. Sci.) of Atms. Sci.)


Blocking unusual in August, and Blocking unusual in August, and when they occur in the Alaska when they occur in the Alaska region, they force cooler air into region, they force cooler air into North America.North America.

This event was unusual because This event was unusual because prolonged blocking usually CAUSES prolonged blocking usually CAUSES drought, e.g., Europe 2003, or drought, e.g., Europe 2003, or Alaska, 2004!Alaska, 2004!


Blocking is one of the keys to Blocking is one of the keys to understanding seasonal variations in the understanding seasonal variations in the weather, both observed and for weather, both observed and for predictive purposes. (El Nino is the predictive purposes. (El Nino is the other, more later)other, more later)

This is well-known in the climatological This is well-known in the climatological community during the winter, but we community during the winter, but we sometimes forget about summer season sometimes forget about summer season blocking.blocking.


Summer, 2004 – a study in contrast Summer, 2004 – a study in contrast (blocking was favorable to the mid-west). (blocking was favorable to the mid-west).

20052005 20042004


Temperatures for Summer 2004 – 3Temperatures for Summer 2004 – 3rdrd coolest summer on record for mid-MO and coolest summer on record for mid-MO and a “top 5” for most of the mid-west and a “top 5” for most of the mid-west and plains. (Source of picture: Midwest plains. (Source of picture: Midwest Regional Climate Center)Regional Climate Center)


June 2004 July 2004June 2004 July 2004 August August 20042004


Summer 2004 upper air pattern. Summer 2004 upper air pattern.


Summer 2004 versus Summer 2005 Summer 2004 versus Summer 2005 (source Missouri Agricultural (source Missouri Agricultural Statistics service)Statistics service)

2004 20052004 2005


Soybeans – trend from 1965 – 2005 Soybeans – trend from 1965 – 2005 (source Missouri Agricultural (source Missouri Agricultural Statistics service)Statistics service)


The impact of El Nino.The impact of El Nino.

El Nino, what is it?El Nino, what is it?

El NiEl Niñño –means literally “the child”, in this o –means literally “the child”, in this case, THE Child as El Nicase, THE Child as El Niñño typically sets in o typically sets in around Christmas on the coast of South around Christmas on the coast of South America!America!


El NiEl Niñño (or ENSO – El Nio (or ENSO – El Niñño and o and Southern Oscillation) is the generic Southern Oscillation) is the generic term referring to the see-saw of warm term referring to the see-saw of warm (El Ni(El Niñño) and cold (La Nio) and cold (La Niña)ña) sea sea surface temperature patterns in the surface temperature patterns in the eastern Tropical Pacificeastern Tropical Pacific

This occurs every 2 – 7 years!This occurs every 2 – 7 years!


El Nino:El Nino:

Drought in the MidwestDrought in the Midwest Currently: (ENSO-neutral) (Source: Climate Currently: (ENSO-neutral) (Source: Climate

Prediction Center)Prediction Center)

Forecasts persist in projecting neutral Forecasts persist in projecting neutral conditions for the rest of the year and conditions for the rest of the year and range from weak La Nina to weak El Nino range from weak La Nina to weak El Nino conditions conditions

Drought in the MidwestDrought in the Midwest Ratley (Ratley, Baxter, Lupo) et al. 2002 Ratley (Ratley, Baxter, Lupo) et al. 2002

discussed the onset of the summer regime discussed the onset of the summer regime in the mid-west and it’s relation to ENSO. in the mid-west and it’s relation to ENSO.

They noticed that before the summer They noticed that before the summer regime becomes “established”, significant regime becomes “established”, significant rains (widespread and more than 0.25 rains (widespread and more than 0.25 inches) fall on average every 7 days. inches) fall on average every 7 days.

This becomes every 12 days after the This becomes every 12 days after the onset of the summer pattern. onset of the summer pattern.

Drought in the MidwestDrought in the Midwest They then found that in summers involving They then found that in summers involving

the transition into a (future) El Nino the transition into a (future) El Nino situation, the mean precipitation frequency situation, the mean precipitation frequency in spring and summer is 6 days and 10 days, in spring and summer is 6 days and 10 days, respectively. (e.g., summer 1993, summer respectively. (e.g., summer 1993, summer 2004)2004)

For the transition into a La Nina situation, For the transition into a La Nina situation, the corresponding numbers are 8 days, and the corresponding numbers are 8 days, and 19 days, respectively. (e.g., summer 1983, 19 days, respectively. (e.g., summer 1983, 1988, 1999, 2005, and historically, the 1988, 1999, 2005, and historically, the severe dry spell of the 1950’s)severe dry spell of the 1950’s)

Drought in the MidwestDrought in the Midwest Thus, they found that in the Missouri Thus, they found that in the Missouri

region, there is not a significant region, there is not a significant difference region-wide in precipitation difference region-wide in precipitation amounts year-to-year, but the frequency amounts year-to-year, but the frequency of heavy precipitation is markedly of heavy precipitation is markedly different.different.

It is well-known in the agricultural It is well-known in the agricultural community that lighter, more frequent community that lighter, more frequent (regular) precipitation events are much (regular) precipitation events are much better for crops. better for crops.


The results of Ratley et al. (2002) are The results of Ratley et al. (2002) are based on 30 years worth of data. based on 30 years worth of data. We’re currently working on extending We’re currently working on extending this analysis back to 1900.this analysis back to 1900.

Initial results from this extended work Initial results from this extended work (future Birk and Lupo paper) support (future Birk and Lupo paper) support the results given here.the results given here.


What’s in store for 2006? What’s in store for 2006?


Our group predicted a relatively dry Our group predicted a relatively dry and warm summer regionally based on and warm summer regionally based on a few factors.a few factors.

1) For 11 of the past 18 months have 1) For 11 of the past 18 months have had precipitation amounts below (3) to had precipitation amounts below (3) to well-below normal (8), while only two well-below normal (8), while only two months have been very wet. months have been very wet.

Drought in the MidwestDrought in the Midwest 2) During the late winter, early spring, 2) During the late winter, early spring,

weak La Nina conditions persisted in the weak La Nina conditions persisted in the eastern tropical Pacific. At the time, this eastern tropical Pacific. At the time, this was expected to persist through the was expected to persist through the spring and summer.spring and summer.

3) We’ve noticed that we’re in the dry 3) We’ve noticed that we’re in the dry portion of a long – term cycle. The portion of a long – term cycle. The Missouri Tree Ring Laboratory bolstered Missouri Tree Ring Laboratory bolstered our impressions here.our impressions here.


4) we’d also projected a drier spring, 4) we’d also projected a drier spring, which did occur. So far, the summer which did occur. So far, the summer (June) has also been in-line with our (June) has also been in-line with our predictions. predictions.

5) one piece of information arguing 5) one piece of information arguing against this forecast is the recent against this forecast is the recent migration of the Pacific region SSTs migration of the Pacific region SSTs back to ENSO-neutral from La Nina back to ENSO-neutral from La Nina conditions.conditions.


What is the role of climate and What is the role of climate and climate change on drought? climate change on drought?

Let’s look at the decadal record for Let’s look at the decadal record for the USA. We had drought years in the USA. We had drought years in this part of the country during the this part of the country during the 1930s, 1950’s, 1980, 1983, 1988, 1930s, 1950’s, 1980, 1983, 1988, 1999, 2003, 2005 (but wet years in 1999, 2003, 2005 (but wet years in 1993 and 1995).1993 and 1995).


Climate of the USA as measured Climate of the USA as measured using temperature (source National using temperature (source National Assessment) Assessment)


Borrowed from Karl and Knight (1998), BAMS

Borrowed from Hu et al. (1998), BAMS


Climate change may impact the Climate change may impact the temporal and/or spatial distribution temporal and/or spatial distribution and severity of drought, however, and severity of drought, however, drought and pluvials (wet spells) will drought and pluvials (wet spells) will still occur.still occur.

Let’s look at a couple centuries…….Let’s look at a couple centuries…….


Temperatures (source: IPCC)Temperatures (source: IPCC)


year

1930 1940 1950 1960 1970 1980 1990 2000

Pal

mer

Dro

ught

Sev

erity

Ind

ex (

PD

SI)

-8

-6

-4

-2

0

2

4

6

8

• Borrowed from the Missouri Tree-Ring Laboratory

• Stambaugh, M.C. and R.P. Guyette. (in prep). 1000 years of tree-ring reconstructed drought in the Central United States.

Paleoecological understandingPaleoecological understanding

16th Century Megadrought

Little Ice Age

Maunder Minimum

1816, Year without summer

Medieval Warm Period

Dust Bowl

Stambaugh, M.C. and R.P. Guyette. (in prep). 1000 years of tree-ring reconstructed drought in the Central United States.


Borrowed from Fye et al. (2003), Borrowed from Fye et al. (2003), BAMSBAMS


Precipitation in the Northern Plains Precipitation in the Northern Plains (Borrowed from Woodhouse and (Borrowed from Woodhouse and Overpeck, (1998), BAMSOverpeck, (1998), BAMS

Drought in the MidwestDrought in the Midwest Studies have shown that the US climate Studies have shown that the US climate

has been getting wetter.has been getting wetter.

What does the future hold? Model studies What does the future hold? Model studies have shown our region may be drier have shown our region may be drier (e.g., IPCC), and some studies have (e.g., IPCC), and some studies have shown it may be wetter (e.g. Semenov et shown it may be wetter (e.g. Semenov et al., 2003, Climate Dynamics). al., 2003, Climate Dynamics).


Many regions of the country give Many regions of the country give similar mixed results, but since similar mixed results, but since drought and wet spells are seasonal drought and wet spells are seasonal in nature (and driven by SST and in nature (and driven by SST and atmospheric variations) they will atmospheric variations) they will continue to occur regardless of what continue to occur regardless of what the climate does!the climate does!


Questions?Questions?

Comments?Comments?

Criticisms?Criticisms?

[email protected]@missouri.edu

Climate, Climate Change & Climate, Climate Change & HurricanesHurricanes

2005 (27) versus 1933 (21)2005 (27) versus 1933 (21)

drought in the midwest by anthony r. lupo department of soil, environmental, and atmospheric...

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