Skillful Subseasonal Prediction of United States Extreme Warm Days and Standardized Precipitation Index in Boreal Summer

2021 ◽  
pp. 1-34
Author(s):  
Douglas E. Miller ◽  
Zhuo Wang ◽  
Bo Li ◽  
Daniel S. Harnos ◽  
Trent Ford
Keyword(s):  
United States ◽  
Heat Flux ◽  
Soil Moisture ◽  
Statistical Model ◽  
North Pacific ◽  
Standardized Precipitation Index ◽  
Boreal Summer ◽  
The North ◽  
Moisture Conditions ◽  
The North Pacific

AbstractSkillful subseasonal prediction of extreme heat and precipitation greatly benefits multiple sectors, including water management, public health, and agriculture, in mitigating the impact of extreme events. A statistical model is developed to predict the weekly frequency of extreme warm days and 14-day standardized precipitation index (SPI) during boreal summer in the United States (US). We use a leading principal component of US soil moisture and an index based on the North Pacific sea surface temperature (SST) as predictors. The model outperforms the NCEP’s Climate Forecast System version 2 (CFSv2) at weeks 3-4 in the eastern US. It is found that the North Pacific SST anomalies persist several weeks and are associated with a persistent wave train pattern (WTZ500), which leads to increased occurrences of blocking and extreme temperature over the eastern US. Extreme dry soil moisture conditions persist into week 4 and are associated with an increase in sensible heat flux and decrease in latent heat flux, which may help maintain the overlying anticyclone. The clear sky conditions associated with blocking anticyclones further decrease soil moisture conditions and increase the frequency of extreme warm days. This skillful statistical model has the potential to aid in irrigation scheduling, crop planning, reservoir operation, and provide mitigation of impacts from extreme heat events.

scholarly journals The mean meridional circulation and midlatitude ozone buildup

2005 ◽  
Vol 5 (3) ◽  
pp. 4223-4256
Author(s):  
G. Nikulin ◽  
A. Karpechko
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Meridional Circulation ◽  
Residual Velocity ◽  
The North ◽  
Eddy Heat Flux ◽  
Mean Meridional Circulation ◽  
The Mean ◽  
Temperature Tendency ◽  
The North Pacific

Abstract. The development of wintertime ozone buildup over the Northern Hemisphere (NH) midlatitudes and its connection with the mean meridional circulation in the stratosphere are examined statistically on a monthly basis from October to March (1980–2002). The ozone buildup begins locally in October with positive ozone tendencies over the North Pacific, which spread eastward and westward in November and finally cover all midlatitudes in December. During October–January a longitudinal distribution of the ozone tendencies mirrors a structure of quasi-stationary planetary waves in the lower stratosphere and has less similarity with this structure in February–March when chemistry begins to play a more important role. From November to March, zonal mean ozone tendencies (50°–60° N) show strong correlation (|r|=0.7) with different parameters used as proxies of the mean meridional circulation, namely: eddy heat flux, the vertical residual velocity (diabatically-derived) and temperature tendency. The correlation patterns between ozone tendency and the vertical residual velocity or temperature tendency are more homogeneous from month to month than ones for eddy heat flux. A partial exception is December when correlation is strong only for the vertical residual velocity. In October zonal mean ozone tendencies have no coupling with the proxies. However, positive tendencies averaged over the North Pacific correlate well, with all of them suggesting that intensification of northward ozone transport starts locally over the Pacific already in October. We show that the NH midlatitude ozone buildup has stable statistical relation with the mean meridional circulation in all months from October to March and half of the interannual variability in monthly ozone tendencies can be explained by applying different proxies of the mean meridional circulation.

The North Pacific Pacemaker Effect on Historical ENSO and Its Mechanisms

2019 ◽  
Vol 32 (22) ◽  
pp. 7643-7661 ◽  
Author(s):  
Dillon J. Amaya ◽  
Yu Kosaka ◽  
Wenyu Zhou ◽  
Yu Zhang ◽  
Shang-Ping Xie ◽  
...  
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Southern Oscillation ◽  
Deep Convection ◽  
Boreal Summer ◽  
Enso Events ◽  
The North ◽  
The North Pacific

Abstract Studies have indicated that North Pacific sea surface temperature (SST) variability can significantly modulate El Niño–Southern Oscillation (ENSO), but there has been little effort to put extratropical–tropical interactions into the context of historical events. To quantify the role of the North Pacific in pacing the timing and magnitude of observed ENSO, we use a fully coupled climate model to produce an ensemble of North Pacific Ocean–Global Atmosphere (nPOGA) SST pacemaker simulations. In nPOGA, SST anomalies are restored back to observations in the North Pacific (>15°N) but are free to evolve throughout the rest of the globe. We find that the North Pacific SST has significantly influenced observed ENSO variability, accounting for approximately 15% of the total variance in boreal fall and winter. The connection between the North and tropical Pacific arises from two physical pathways: 1) a wind–evaporation–SST (WES) propagating mechanism, and 2) a Gill-like atmospheric response associated with anomalous deep convection in boreal summer and fall, which we refer to as the summer deep convection (SDC) response. The SDC response accounts for 25% of the observed zonal wind variability around the equatorial date line. On an event-by-event basis, nPOGA most closely reproduces the 2014/15 and the 2015/16 El Niños. In particular, we show that the 2015 Pacific meridional mode event increased wind forcing along the equator by 20%, potentially contributing to the extreme nature of the 2015/16 El Niño. Our results illustrate the significant role of extratropical noise in pacing the initiation and magnitude of ENSO events and may improve the predictability of ENSO on seasonal time scales.

New Nanaimo Group ammonites (Cretaceous, Santonian–Campanian) from British Columbia and Washington State

1989 ◽  
Vol 63 (2) ◽  
pp. 218-227 ◽  
Author(s):  
James W. Haggart ◽  
Peter D. Ward
Keyword(s):  
United States ◽  
British Columbia ◽  
North Pacific ◽  
Washington State ◽  
Western Canada ◽  
Pacific Region ◽  
The North ◽  
North Pacific Region ◽  
The North Pacific

The ammonite species Puzosia (Mesopuzosia) densicostata Matsumoto, Kitchinites (Neopuzosia) japonicus Spath, Anapachydiscus cf. A. nelchinensis Jones, Menuites cf. M. menu (Forbes), Submortoniceras chicoense (Trask), and Baculites cf. B. boulei Collignon are described from Santonian–Campanian strata of western Canada and northwestern United States. Stratigraphic occurrences and ranges of the species are summarized and those taxa important for correlation with other areas in the north Pacific region are noted.

scholarly journals Seasonal variation of trans-Pacific transport of carbon monoxide (CO) in the upper troposphere: MLS observations and GEOS-Chem and GEM-AQ simulations

2011 ◽  
Vol 11 (1) ◽  
pp. 3219-3250 ◽  
Author(s):  
J. J. Jin ◽  
N. J. Livesey ◽  
J. H. Jiang ◽  
A. Lupu ◽  
J. W. Kaminski ◽  
...  
Keyword(s):  
Air Pollution ◽  
Carbon Monoxide ◽  
Seasonal Variation ◽  
Southeast Asia ◽  
North Pacific ◽  
Tropospheric Chemistry ◽  
Boreal Summer ◽  
Boreal Spring ◽  
The North ◽  
The North Pacific

Abstract. Multi-year Microwave Limb Sounder (MLS) carbon monoxide (CO) measurements at 215 hPa are employed to present a climatological view of seasonal variation of upper tropospheric trans-Pacific transport of Asian air pollution. The measurements show that the transport peaks in late boreal spring and early boreal summer. Although the strongest Asian air pollution outflow occurs in boreal summer, the "transport pathway" over the northeast Pacific is narrower in summer than in spring. Results from two tropospheric chemistry models GEOS-Chem and GEM-AQ are compared to MLS observations. Both models reproduce the strong trans-Pacific transport in boreal spring and summer well, but show different morphologies over Southeast Asia in winter and fall. A tagged CO simulation using GEOS-Chem indicates that Asian fossil fuel is the biggest source of upper tropospheric CO over the north Pacific in all seasons, excepting methane (CH4) and non-methane hydrocarbons, although there are large fires in Southeast Asia in boreal spring and fall. A sensitivity test indicates that deep convection has a large effect on upper tropospheric CO abundances, increasing the abundances by more than 40%, over the north Pacific in boreal spring. In boreal summer, however, the increase is not significant over the north Pacific although it is large over continental Asia.

Circulation and Heat Flux along the Western Boundary of the North Pacific

2019 ◽  
Vol 19 (1) ◽  
pp. 1-12
Author(s):  
Xia Ju ◽  
Chao Ma ◽  
Xuejun Xiong ◽  
Yanliang Guo ◽  
Long Yu
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Western Boundary ◽  
The North ◽  
The North Pacific
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