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Zoey Rosen

Abstract

The narratives of emerging adults, such as university students, can reveal aspects of their professional and academic identities that explain their career paths. While narrative has been studied as a tool in the meteorological classroom, narrative has not been used to study why students choose to become meteorologists. This study aims to identify the narrative features about what draws students to pursue meteorology as a career and reflect upon how the telling of these narratives can help career counselors and other stakeholders, like universities, to understand this discipline of students. This study is a qualitative textual analysis of N = 34 video clips of meteorology students from around the United States submitted for the 2020 AMS Student Conference welcome video, #MyFieldMyStory campaign. The findings show that formative experiences like early childhood memories, mediated experiences with the weather, and family interactions were major life themes in the students’ stories. Other reasons students chose this career path were concerns over local climatic effects, a desire to control their course of study, curiosity stemming from internships and research opportunities, confidence from their personal math/science propensity in school, and a commitment to do work that can mitigate the effects of severe weather or inform people of impending threats. The students’ narratives also showed optimism around future jobs and graduate school, as well as an exploration of their identity through finding their passion in this career path. This study is an interesting initial delve into narratively analyzing stories from emerging meteorologists.

Free access
Kwang-Hyung Kim
,
Chris D. Hewitt
,
Hideki Kanamaru
,
Jorge Alvar-Beltrán
,
Ana Heureux
,
Sook-Young Park
,
Min-Hye Jung
, and
Robert Stefanski

Abstract

Agricultural stakeholders can effectively manage the risks and opportunities arising from climate change and variability by enhancing climate services in agriculture. Key to understanding and addressing the climate challenge is the provision and the use of climate information to aid decision-makers and policy-makers. Climate services are now integral to the United Nations Framework Convention on Climate Change, the Intergovernmental Panel on Climate Change’s Assessment Reports, governments’ national adaptation plans, funding bodies, and a growing number of sectors and industries worldwide. The article provides our personal perspective, experience, and views on the important and timely issue of managing better the risks and opportunities to the agriculture sector and community that are arising from changes in climate. We describe a framework to help drive action to tackle the climate challenge comprising enhanced knowledge and information products, efficient information delivery and use, and assured policy and institutional support, in an iterative loop.

Free access
David Fuchs
,
Steven C. Sherwood
,
Darryn Waugh
,
Vishal Dixit
,
Matthew H. England
,
Yi-Ling Hwong
, and
Olivier Geoffroy

Abstract

Midlatitude weather is largely governed by bands of strong westerly winds known as the midlatitude jets, but what controls the jet properties, particularly their latitudes, remains poorly understood. Climate models show a spread of about 10° in their simulated present-day latitude of the Southern Hemisphere (SH) jet, and a related spread in its predicted poleward shift under global warming. We find that models with more poleward jets simulate more low-level moisture, a warmer upper troposphere, and different precipitation patterns than those with equatorward jets, potentially implicating intermodel differences in moist convection and microphysics. Accordingly, a suite of atmospheric model runs is performed where the deep or shallow convective parameterizations are individually turned off either globally or in specific latitude bands. These experiments suggest that models that produce more shallow convection in the midlatitudes tend to position the jet relatively poleward in SH summer, whereas those that favor deep convection tend to position it equatorward. This accounts for a spread 60% as large as that of the AMIP ensemble during the austral summer. Our results suggest that, in the boreal summer, similar biases appear in the Northern Hemisphere. The presence of shallow convection in the Northern Hemisphere midlatitudes reduces SH jet shift in a warmer climate in accordance to the correlation between jet positions and shift seen in this season. These results can help explain intermodel differences in the position and shift of the jet, and point to an unexpected role for atmospheric moist convection in the midlatitude circulation.

Restricted access
Emma Beer
,
Ian Eisenman
,
Till J. W. Wagner
, and
Elizabeth C. Fine

Abstract

The Arctic Ocean is characterized by an ice-covered layer of cold and relatively fresh water above layers of warmer and saltier water. It is estimated that enough heat is stored in these deeper layers to melt all the Arctic sea ice many times over, but they are isolated from the surface by a stable halocline. Current vertical mixing rates across the Arctic Ocean halocline are small, due in part to sea ice reducing wind-ocean momentum transfer and damping internal waves. However, recent observational studies have argued that sea ice retreat results in enhanced mixing. This could create a positive feedback whereby increased vertical mixing due to sea ice retreat causes the previously isolated subsurface heat to melt more sea ice. Here, we use an idealized climate model to investigate the impacts of such a feedback. We find that an abrupt “tipping point” can occur under global warming, with an associated hysteresis window bounded by saddle-node bifurcations. We show that the presence and magnitude of the hysteresis are sensitive to the choice of model parameters, and the hysteresis occurs for only a limited range of parameters. During the critical transition at the bifurcation point, we find that only a small percentage of the heat stored in the deep layer is released, although this is still enough to lead to substantial sea ice melt. Furthermore, no clear relationship is apparent between this change in heat storage and the level of hysteresis when the parameters are varied.

Restricted access
Liwei Yu
,
Dong Si
,
Dabang Jiang
,
Yihui Ding
,
Xinyong Shen
,
Xianmei Lang
,
Qingquan Li
, and
Zhiping Tian

Abstract

Although influences of the Atlantic multidecadal variability (AMV) and atmospheric heat source over the Tibetan Plateau (TPHS) on the East Asian summer rainfall (EASR) have been previously investigated, the relationship between the AMV and TPHS, and their synergistic impact on the EASR are still unclear. We investigate the distinct relationship between the AMV and TPHS, and the role of Tibetan Plateau (TP) in the impact of AMV on the EASR in this study. Results show that the AMV exerts a remote effect on the EASR through an atmospheric teleconnection, and the TP serves as a booster of this remote effect. The warming of the North Atlantic (positive phase of AMV) enhances the Asian summer monsoon through a zonal wave train along the northern mid-latitudes, yielding an anomalous tripole rainfall pattern over East Asia. The enhanced warm and moist monsoon airflow converges and climbs up along the southern and eastern flanks of the TP, resulting in stronger latent heating over the TP than over other regions along the same latitude due to the orographic effect of the huge plateau. The enhanced TPHS in turn further strengthens the summer monsoon and the East Asian tripole rainfall pattern by exciting a downstream meridional wave train. When the AMV and TPHS are in-phase, the zonal wave train originating from the North Atlantic is strong and propagates eastward to the Asia–Pacific regions, significantly regulating the East Asian summer monsoon. Notably, the TP boosts this remote impact of the AMV through the effect of superimposition.

Restricted access
Rongwang Zhang
,
Weihao Guo
,
Xin Wang
, and
Chunzai Wang

Abstract

The tropical latent heat flux (LHF) has experienced a significant increase under the background of global warming in the past four decades. However, since the years around 1998, the long-term LHF variations in the tropics have been found to be quite different in various flux products. Three different trends in the LHF, climbing, near-zero, and declining, are suggested by five widely used flux products, which hinders our knowledge of the actual LHF variations. Although there are buoy observations in the tropics, these observations are hard to evaluate flux products as they have been assimilated and/or used as benchmarks in the flux data production. This study aims to identify a credible long-term LHF variations since 1998.

A linear model decomposing the LHF variations into contributions from sea surface wind (U) and air-sea humidity differences is firstly applied. The linear model results show that the LHF variations are more positively connected to U variations since 1998. Evidence from in situ and remote sensing observations is subsequently employed to identify how U varies recently. Both 82 Global Tropical Moored Buoy Array (GTMBA) buoy observations and a multi-sensor merged satellite product support a slightly downward trend in U in the last two decades. Such a the weakening of U is not conducive to oceanic evaporation and leads to a reduced LHF. Consequently, a declining LHF under a weakening U since the emergence of the global warming “hiatus” in approximately 1998 might be more convincing in the sense of data accuracy and physical consistency.

Restricted access
Hsiao-Chun Lin
,
Juanzhen Sun
,
Tammy M. Weckwerth
,
Everette Joseph
, and
Junkyung Kay

Abstract

The New York State Mesonet (NYSM) has provided continuous in situ and remote sensing observations near the surface and within the lower troposphere since 2017. The dense observing network can capture the evolution of mesoscale motions with high temporal and spatial resolution. The objective of this study was to investigate whether the assimilation of NYSM observations into numerical weather prediction models could be beneficial for improving model analysis and short-term weather prediction. The study was conducted using a convective event that occurred in New York on 21 June 2021. A line of severe thunderstorms developed, decayed, and then reintensified as it propagated eastward across the state. Several data assimilation (DA) experiments were conducted to investigate the impact of NYSM data using the operational DA system Gridpoint Statistical Interpolation with rapid update cycles. The assimilated datasets included National Centers for Environmental Prediction Automated Data Processing global upper-air and surface observations, NYSM surface observations, Doppler lidar wind retrievals, and microwave radiometer (MWR) thermodynamic retrievals at NYSM profiler sites. In comparison with the control experiment that assimilated only conventional data, the timing and location of the convection reintensification was significantly improved by assimilating NYSM data, especially the Doppler lidar wind data. Our analysis indicated that the improvement could be attributed to improved simulation of the Mohawk–Hudson Convergence. We also found that the MWR DA resulted in degraded forecasts, likely due to large errors in the MWR temperature retrievals. Overall, this case study suggested the positive impact of assimilating NYSM surface and profiler data on forecasting summertime severe weather.

Open access
Joshua D. Sandstrom
,
Jason M. Cordeira
,
Eric G. Hoffman
, and
Nicholas D. Metz

Abstract

Lake-effect precipitation is convective precipitation produced by relatively cold air passing over large and relatively warm bodies of water. This phenomenon most often occurs in North America over the southern and eastern shores of the Great Lakes, where high annual snowfalls and high-impact snowstorms frequently occur under prevailing west and northwest flow. Locally higher snow or rainfall amounts also occur due to lake-enhanced synoptic precipitation when conditionally unstable or neutrally stratified air is present in the lower troposphere. While likely less common, lake-effect and lake-enhanced precipitation can also occur with easterly winds, impacting the western shores of the Great Lakes. This study describes a 15-year climatology of easterly lake-effect (ELEfP) and lake-enhanced (ELEnP) precipitation (conjointly Easterly Lake Collective Precipitation: ELCP) events that developed in east-to-east-northeasterly flow over western Lake Superior from 2003 to 2018. ELCP occurs infrequently but often enough to have a notable climatological impact over western Lake Superior with an average of 14.6 events per year. The morphology favors both single shore-parallel ELEfP bands due to the convex western shoreline of Lake Superior and mixed-type banding due to ELEnP events occurring in association with “overrunning” synoptic-scale precipitation. ELEfP often occurs in association with a surface anticyclone to the north of Lake Superior. ELEnP typically features a similar northerly-displaced anticyclone and a surface cyclone located over the U.S. Upper Midwest that favor easterly boundary-layer winds over western Lake Superior.

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David P. Rowell
and
Ségolène Berthou

Abstract

Convection-permitting (CP) models promise much in response to the demand for increased localization of future climate information: greater resolution of influential land surface characteristics, improved representation of convective storms, and unprecedented resolution of user-relevant data. In practice, however, it is contended that the benefits of enhanced resolution cannot be fully realized due to the gap between models’ computational and effective resolution. Nevertheless, where surface forcing is strongly heterogeneous, one can argue that usable information may persist close to the grid scale. Here we analyze a 4.5-km resolution CP projection for Africa, asking whether and where fine-scale projection detail is robust at sub-25-km scales, focusing on geolocated rainfall features (rather than Lagrangian motion). Statistically significant detail for seasonal means and daily extremes is most frequent in regions of high topographic variability, most prominently in East Africa throughout the annual cycle, West Africa in the monsoon season, and to a lesser extent over Southern Africa. Lake coastal features have smaller but significant impacts on projection detail, whereas ocean coastlines and urban conurbations have little or no detectable impact. The amplitude of this sub-25-km projection detail can be similar to that of the local climatology in mountainous regions (or around a third near East Africa’s lake shores), so potentially beneficial for improved localization of future climate information. In flatter regions distant from coasts (the majority of Africa), spatial heterogeneity can be explained by chaotic weather variability. Here, the robustness of local climate projection information can be substantially enhanced by spatial aggregation to approximately 25-km scales, especially for daily extremes and equatorial regions.

Significance Statement

Recent substantial increases in the horizontal resolution of climate models bring the potential for both more reliable and more local future climate information. However, the best spatial scale on which to analyze such data for impacts assessments remains unclear. We examine a 4.5-km resolution climate projection for Africa, focusing on seasonal and daily rainfall. Spatially fixed fine-scale projection detail is found to be statistically robust at sub-25-km scales in the most mountainous regions and to a lesser extent along lake coastlines. Elsewhere, the model data may be better aggregated to at least 25-km scales to reduce sampling uncertainties. Such evolving guidance on the circumstances and extent of high-resolution data aggregation will help users gain greater benefit from climate model projections.

Open access
Xinyue Hao
,
Yiquan Jiang
,
Xiu-Qun Yang
,
Xiaohong Liu
,
Yang Zhang
,
Minghuai Wang
,
Yuan Liang
, and
Yong Wang

Abstract

Both South Asia and East Asia are the most polluted regions of the world. Unlike East Asia, the aerosol optical depth (AOD) over South Asia keeps increasing for all recent years, which calls for more attentions. This study investigates the impacts of anthropogenic emissions over South Asia on downstream region climate during spring with Community Earth System Model 2 (CESM2). The model results suggest that South Asian pollutants have significant impacts on East Asian spring climate, and the impacts could be even larger than local emitted aerosols. Two possible dynamical pathways (i.e., the northern and the southern pathways) bridging South Asian aerosol forcing and East Asian climate are proposed, and both ways are associated with the black carbon (BC) induced climate feedbacks surrounding Tibetan Plateau (TP).

The northern pathway is mainly due to the TP warming induced by BC snow darkening effect (SDE), which significantly reduces the surface air temperature (SAT) over northern East Asia. BC induced TP warming increases meridional thermal gradient and accelerates middle latitude jet stream, which favors the cold air activities over northern East Asia. The southern pathway is associated with BC’s “Elevated Heat Pump” hypothesis, which mainly affects the precipitation in southern East Asia. BC from South Asia accumulates near the south slope of TP, induces an abnormal ascending motion near Bay of Bengal. A compensating anomalous sinking motion is then forced in South China, which suppresses the precipitation there. A primary observational analysis is also performed to verify both dynamical pathways.

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