Five centuries of U.S. West Coast drought: Occurrence, spatial distribution, and associated atmospheric circulation patterns

Wise, Erika K.

doi:10.1002/2016gl068487

Cited by 55 publications

(65 citation statements)

References 41 publications

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“…The connection to humidity, precipitation, and droughts has also been intensively investigated, especially in recent years (e.g. Carrera et al, 2004;Galarneau et al, 2012;Pfahl et al, 2015;Wise, 2016;Sousa et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Brunner

Steiner

2017

Atmos. Meas. Tech.

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Abstract. Atmospheric blocking represents a weather pattern where a stationary high-pressure system weakens or reverses the climatological westerly flow at mid-latitudes for up to several weeks. It is closely connected to strong anomalies in key atmospheric variables such as geopotential height, temperature, and humidity. Here we provide, for the first time, a comprehensive, global perspective on atmospheric blocking and related impacts by using an observation-based data set from Global Positioning System (GPS) radio occultation (RO) from 2006 to 2016. The main blocking regions in both hemispheres and seasonal variations are found to be represented well in RO data. The effect of blocking on vertically resolved temperature and humidity anomalies in the troposphere and lower stratosphere is investigated for blocking regions in the Northern and Southern hemispheres, respectively. We find a statistically significant correlation of blocking with positive temperature anomalies, exceeding 3 K in the troposphere, and a reversal above the tropopause with negative temperature anomalies below −3 K in the lower stratosphere. Specific humidity is positively correlated with temperature throughout the troposphere with larger anomalies revealed in the Southern Hemisphere. At the eastern and equatorward side of the investigated blocking regions, a band of tropospheric cold anomalies reveals advection of cold air by anticyclonic motion around blocking highs, which is less distinct in the Southern Hemisphere due to stronger zonal flow. We find GPS RO to be a promising new data set for blocking research that gives insight into the vertical atmospheric structure, especially in light of the expected increase in data coverage that future missions will provide.

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Section: Introductionmentioning

confidence: 99%

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Brunner

Steiner

2017

Atmos. Meas. Tech.

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“…5). These contrasts have parallels to those observed in instrumental and dendroclimatic data, particularly in the western U.S. where the Pacific Northwest and southwest U.S. often exhibit anti-phased moisture anomalies, because of factors, such as tropical and northern Pacific sea-surface temperatures, which can influence the position of the jet stream (Dettinger et al, 1998;Routson et al, 2016a;Wise, 2010Wise, , 2016. The 30 differences could indicate a tendency for storms to follow more southern tracks since 1000 CE than before, which resulted in Clim.…”

Section: Differences Between the First And Second Millennia 25mentioning

confidence: 64%

Millennial-to-centennial patterns and trends in the hydroclimate of North America over the past 2000 years

Shuman

Routson

McKay

et al. 2017

Preprint

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Abstract.A synthesis of 93 hydrologic records from across North and Central America, and adjacent tropical and Arctic islands, reveals centennial to millennial trends in the regional hydroclimates of the Common Era (CE; past 2000 years). The hydrological records derive from materials stored in lakes, bogs, caves, and ice from extant glaciers, which have the continuity through time to preserve low-frequency (>100 year) climate signals that may not be well represented by other 20 shorter-lived archives, such as tree-ring chronologies. The most common pattern, represented in 46 (49%) of the records, indicates that the centuries before 1000 CE were drier than the centuries since that time. Principal components analysis indicates that millennial-scale trends represent the dominant pattern of variance in the southwest and northeast U.S., the midcontinent, Pacific Northwest, the Arctic, and the tropics, although not all records within a region show the same direction of change. The Pacific Northwest, Greenland, and the southernmost tier of the tropical sites tended to dry toward present, as 25 many other areas became wetter than before. Twenty-two records (24%) indicate that the Medieval period (800-1300 CE) was drier than the Little Ice Age (1400-1900 CE), but in many cases the difference was part of the longer millennial-scale trend, and, in 25 records (27%), the Medieval period represented a pluvial (wet) phase. Where quantitative records permitted a comparison, we found that centennial-scale fluctuations over the Common Era represented changes of 3-7% of the modern inter-annual range of variability in precipitation, but the accumulation of these long-term trends over the entirety of the 30Holocene caused recent centuries to be significantly wetter, on average, than most of the past 11,000 years.

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“…The types of extreme climate events like June 2015 are projected to increase in length and severity across the PNW (Mankin et al, 2017;Wise, 2016). Uncertainties related to ecosystem responses to extreme climate events pose a key challenge for current land-410 surface and ecosystem models to predict future vegetation feedbacks and change to global climate with confidence (Mcdowell et al, 2013;Powell et al, 2013;Sitch et al, 2015).…”

Section: Resultsmentioning

confidence: 99%

Influence of concurrence of extreme drought and heat events on carbon and energy fluxes in dominant ecosystems in the Pacific Northwest region

Kwon

Creason

Law

et al. 2018

Preprint

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Abstract. The impacts of drought intensity and vapor pressure deficit (VPD) beyond historic norms in PacificNorthwest (PNW), USA, are critical in understanding the potential future function and resilience of ecosystems in the region. While ecosystems in this region are adapted to seasonal droughts, June 2015 temperatures were the highest 10 recorded in the region and strongly coupled with relatively low soil moisture. June is usually the best month for growth in the PNW. Here, we examined the impact of the June 2015 climate extremes on carbon and energy fluxes at sagebrush in the high desert, young and mature ponderosa pine in the semi-arid Great Basin, and Douglas-fir in the mesic ecoregion compared to an average climate year (2014). We assessed if the ecosystems recover from extreme climate stress within the growing season. The monthly anomalies in temperature and VPD were 3 standard deviations, 15 and precipitation was 1standard deviationoutside the 30-year mean at all sites. In sagebrush, the carry-over effect of precipitation (i.e., intensive precipitation prior to the drought and heat) mitigated the immediate impact of extreme climate stress, leading to 25-40% increase in net ecosystem production (NEP) and gross primary production (GPP), with little change in ecosystem respiration (RE) and 65% increase in latent heat flux, compared to the June 2014. The drought and heat lowered NEP by 35-65% and GPP by 15-33% in ponderosa pine and Douglas-fir. A greater increase 20 in latent heat flux was observed in Douglas-fir (110%) than in ponderosa pine (<10%) driven by increased evaporation. were corresponding with 30-40% decline and were greater than in mature ponderosa pine (5-20% decline), when compared to the long-term seasonal means (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015), respectively. Our results suggest that the responses of carbon and energy fluxes to climate extremes differ depending on site-and species-specific characteristics. Douglas-fir is likely to experience more constraints on carbon fluxes than ponderosa pine if the hot and dry season intensifies in the PNW. Given the likelihood of future drought and heat extremes, identifying these anomalous ecological responses to 30 anomalous climate (e.g., the combination of VPD, heat, and dry soil) is critical to improve predictions of physiological thresholds and tolerance of different tree species.Biogeosciences Discuss., https://doi

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Five centuries of U.S. West Coast drought: Occurrence, spatial distribution, and associated atmospheric circulation patterns

Cited by 55 publications

References 41 publications

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Millennial-to-centennial patterns and trends in the hydroclimate of North America over the past 2000 years

Influence of concurrence of extreme drought and heat events on carbon and energy fluxes in dominant ecosystems in the Pacific Northwest region

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