Wasserdampfprofile in der zentralen Arktis bei verschiedenen AO-Indizes

<p align="justify"><span lang="de-DE">Wasserdampf trägt als Treibhausgas zum Strahlungsbudget der Atmosphäre bei und ist im atmosphärischen Energietransport, bei Wolkenprozessen und der Niederschlagsbildung von Bedeutung. Die Kenntnis der vertikalen Wasserdampfprofile in der Arktis ist ein wichtiger Beitrag zum Verständnis des arktischen Klimasystems und seines Wandels. <br /></span><span lang="de-DE">Im Rahmen der MOSAiC-Kampagne wurden vom Oktober 2019 bis Oktober 2020 über ein Jahr verschiedenste klimarelevante Parameter gemessen. Mit dem Raman-Lidar PollyXT konnten erstmals nördlich von 85°N vertikal hochaufgelöste Profile des atmosphärischen Wasserdampfes aufgenommen werden. Die Dunkelheit der Polarnacht und niedrige Sonnenstände ermöglichten kontinuierliche Messungen des Wasserdampfes von Oktober 2019 bis März 2020. Die Kalibrierung der Raman-Lidar-Daten erfolgt mit Radiosondenprofilen oder dem integrierten Wasserdampf eines Mikrowellenradiometers.<br /></span><span lang="de-DE">Die gemessenen Absolutwerte des Wasserdampfmischungsverhältnisses in der Arktis sind sehr gering, die vertikale Verteilung ist jedoch hoch variabel und die relative Feuchte erreicht aufgrund der tiefen Temperaturen bodennah häufig Werte nahe 100%. </span><span lang="de-DE">Die vertikale Struktur des Wasserdampfes und der verschiedenen in unterschiedlichen Höhen gemessenen Feuchteschichten lässt auf unterschiedliche Quellen des Wasserdampfes schließen. Zum einen gibt es lokale Quellen wie Verdunstung und Kondensation, die vor allem bodennah auftreten und zum anderen wird im Bereich der freien Troposphäre Wasserdampf aus entfernteren Regionen herantransportiert. Die Stärke des Transports wird dabei hauptsächlich von der allgemeinen Zirkulation in der Atmosphäre bestimmt, welche in der Arktis durch die Arktische Oszillation (AO) beschrieben werden kann. Mit Hilfe des AO Indexes lassen sich positive Phasen (AO>0) mit einem starken Polar Vortex und wenig meridionalem Transport und negative Phasen (AO<0) mit einem stark mäandrierenden Jetstream und viel meridionalem Transport unterscheiden. Der Winter 2019/20 kann so in eine vorwiegend negative und eine stark positive Phase unterteilt werden. Erste Fallbeispiele zeigen </span><span lang="de-DE">deutliche </span><span lang="de-DE">Unterschiede in der Vertikalstruktur und der Gesamtmenge des Wasserdampfes für die beiden Phasen. Während der negativen Phase der arktischen Oszillation werden mehrere zeitlich sehr variable Wasserdampfschichten beobachtet. Bei positivem AO Index ist dagegen nur eine homogene Schicht erkennbar und die Werte des Wasserdampfmischungsverhältnisses sind </span><span lang="de-DE">deutlich </span><span lang="de-DE">geringer. Zudem lassen sich in beiden Phasen Zusammenhänge zwischen Wasserdampf- und Temperaturprofilen erkennen. In der Höhe von Feuchteinversionen treten zum Beispiel häufig auch Temperaturinversionen auf. </span><span lang="de-DE">Mit der Untersuchung weiterer Fallbeispiele</span><span lang="de-DE"><em> </em></span><span lang="de-DE">soll die vertikale Struktur des Wasserdampfes in der Atmosphäre, deren zeitliche Veränderung und der Zusammenhang zur Arktischen Oszillation weiter analysiert werden.</span></p>

The leading mode and factors for coherent variations among the sub-systems of tropical Asian summer monsoon onset

Previous studies on the Asian summer monsoon (ASM) onset mainly focused on each monsoon sub-system. Mainly based on the monthly mean rainfall and low-level winds in May, this study investigated the dominant onset mode from the perspective of the entire tropical ASM region, which reveals the coherent features among the regional-scale onsets. The results of multivariate empirical orthogonal function (MV-EOF) analysis indicate that the MV-EOF1 presents reduced rainfall and anomalous low-level easterly winds at 850 hPa over the tropical ASM region in May during its positive phase. The corresponding principal component (PC1) is highly correlated with the local monsoon onset dates over Arabian Sea, Bay of Bengal, Indo-China Peninsula, and South China Sea, where the mean monsoon onsets occur in May. The only exception is India subcontinent, where the mean monsoon onsets occur in June. The results indicate that the leading mode captures the synchronized variation of monsoon onset over most of Asian monsoon sub-systems, which exhibits remarkably interannual and interdecadal changes. The factors that modulate the coherent variation of the tropical ASM onset are further examined. The simultaneously delayed ASM onset tends to occur during the easterly phase of the 30- to 80-day oscillation, the decaying phase of El Niño, and the positive phase of Pacific Decadal Oscillation (PDO). The 30- to 80-day oscillation serves as a background condition for the synchronized delayed or advanced ASM onset. El Niño-related sea surface temperature anomalies modulate the tropical ASM onset mode by modulating the tropical Walker Circulation and inducing an atmospheric Rossby wave response. The PDO affects the tropical ASM onset mode mainly via the equatorial Rossby wave response and the extratropical Rossby wave train.

Is the Atlantic Ocean driving the recent variability in South Asian dust?

This study investigates the large-scale factors controlling interannual variability in dust aerosols over South Asia during 2001–2018. We use a parameter DA%, which refers to the frequency of days in a year when high dust activity is experienced over a region, as determined by a combination of satellite aerosol optical depth and the Ångström exponent. While a positive sea surface temperature (SST) anomaly in the central Pacific Ocean was important in controlling DA% over South Asia during 2001–2010; in recent years, the North Atlantic Ocean has assumed a dominant role. Specifically, high DA% is associated with warming in the midlatitude and cooling in the subtropical North Atlantic SSTs: the location of the two southern arms of the North Atlantic SST tripole pattern. This shift towards a dominant role of the North Atlantic SST in controlling DA% over South Asia coincides with a recent shift towards a persistently positive phase of the North Atlantic oscillation (NAO) and a resultant positive phase of the springtime SST tripole pattern. Interestingly, there has also been a shift in the relation between the two southern arms of the SST tripole and NAO, which has resulted in weakening of the southwest monsoon circulation over the northern Indian Ocean and strengthening of the dust-carrying westerlies and northerlies in the lower troposphere and mid-troposphere. Simulations with an Earth system model show that the positive phase of the North Atlantic SST tripole pattern is responsible for a 10 % increase in the dust optical depth over South Asia during May–September; with increases as high as 30 % during the month of June. This increase is mainly due to transport by the westerlies at the 800 hPa pressure level, which increases the dust concentration at this pressure level by 20 % on average during May–September and up to 50 % during June.

Most ASH Abstracts Reporting Phase II Studies Lead to Peer-Reviewed Publications, but Less Than 50% of "Positive" Abstracts Lead to Phase III Investigations: An Analysis of 371 Abstracts 2013 - 2015

Reports of "positive" results in early phase trials as presented at ASH presumably herald therapeutic advances, or at a minimum, a larger, potentially confirmatory, randomized trial. However, the predictive value of an ASH abstract reporting positive results in AML for subsequent clinical utility seems low (Estey 2006, ASH). Furthermore, not all results presented at ASH are published in peer-reviewed journals, and selectively publishing positive results leads to publication bias. Moreover, truly negative studies may be scientifically more rigorous and accurate than positive studies given the unequivocal findings. The extent of publication bias is unknown as is the frequency with which positive or negative abstracts lead to subsequent investigation in phase III and the reasons why positive phase II studies might not progress to phase III. We downloaded all 2013 - 2015 ASH abstracts (N = 17,251) and evaluated all abstracts reporting phase II clinical trials (N = 371) of novel drugs and therapeutic regimens presented at ASH in these years, covering investigational treatments of MM, CLL, AML, DLBCL, MDS, NHL, ALL, CML, MCL, SLL, other lymphomas and POEMS. We first scored abstracts "positive", "negative" or "inconclusive". Criteria for a positive abstract were words/phrases such as "encouraging", "promising", "could represent a novel therapeutic option" and "warrants investigation in a randomized trial". Negative abstracts included terms such as "does not support further research" and "demonstrates no clinical activity". The remainder were scored as inconclusive. Using this approach, we scored 296/371 (80%) abstracts as positive, 37/371 (10%) as negative, and 38/371 (10%) as inconclusive. 292/371 abstracts (79%) were published in peer-reviewed journals. The abstract conclusion (positive, negative or inconclusive) was not associated with publication in a peer-reviewed journal. Most frequently, studies were published in Blood (34/292 [11.6%]) and British Journal of Haematology (39/292 [13.4%]) . In Blood, 91% (31/34) of the studies were positive. British Journal of Haematology published significantly more negative studies than Blood (26%, Fisher Exact p = 0.02). Abstracts reporting studies with larger sample sizes tended to be published more often (p = 0.066). Differences exist between the abstract conclusion and later peer-reviewed publications. Of positive ASH abstracts, 6% changed to a negative conclusion in the peer-reviewed publication. Similarly, 6.5% of the initial negative abstract later reversed to a positive conclusion. 53% of positive abstracts did not lead to phase III studies, as registered on clinicaltrials.gov. Subsequently, regimens described in positive peer-reviewed publications did not proceed to phase III research in 48%. To explore why, we sent questionnaires to the first and/or last authors of positive studies not prompting phase III trials. 52% responded. Failure of positive phase II trials to proceed to phase III was due to the decision by the pharmaceutical company to halt clinical investigation (44%), lack of any intent to study the drug in phase III in the first place (40%), insufficient funding (35%), insufficient efficacy (despite the "positive" abstract; 33%) and safety concerns (4%) (Figure). Additional reasons for not proceeding to phase III were the availability of newer regimens, the rarity of the disease, or when regulatory approval had already been obtained after phase II. In conclusion, "positive" and "negative" ASH abstracts are published as full papers equally often, although the positive ones may be published more often in journals with higher "impact factors". More than half of the regimens presented in positive ASH abstracts remain unevaluated in randomized phase III trials. A separate problem is the likely tendency to disproportionately submit (and/or accept) positive, rather than negative, studies to ASH in the first place. We believe our findings raise issues in clinical research that may not be in the best interest of patients. This demands more consideration than it currently receives. Figure 1 Figure 1. Disclosures Ossenkoppele: Astellas: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Abbvie, AGIOS, BMS/Celgene Astellas,AMGEN, Gilead,Servier,JAZZ,Servier Novartis: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Gilead: Consultancy, Honoraria. Rowe: Biosight Inc.: Consultancy.

STABILITAS PELAT ORTHOTROPIK AKIBAT BEBAN LEDAKAN FRIEDLANDER DAN BEBAN IN-PLANE

Slab behavior due to static and dynamic load needs to be considered when designing a slab. Friedlander is one of the examples of dynamic loads. This dynamic load can give different responses on slab. This research discusses about orthotropic plate on Pasternak foundation with fixed boundary condition and in-plane and Friedlander load. Three phases on Friedlander load are positive phase, negative phase, and free vibration phase. This research is conducted to find out critical buckling load due to variation of Pasternak foundation parameters which is spring coefficient and shear coefficient. The system responses are deflection and bending moment due to variation of Pasternak foundation parameter, critical loading, position of loads, depth of soil, and duration of positive phase. Analysis is carried out using Modified Bolotin Method to obtain natural frequencies and mode shape of the system. Result of this research are displayed in graphics and tables. Based on the results, the maximum limit of the critical compressive load is 77% of the critical load used. The increasing of soil coefficient, the greater the deflection that occurs. The position of the load that is close to the center of the span will make the deflection even greater. The deflection that occurs is greater when the depth of the soil increases and the duration of the blast load is getting longer. The greater the thickness of the plate, the smaller the deflection. Keywords : Modified Bolotin Method, Friedlander blast load, plate deflection, critical load, Pasternak FoundationAbstrakPerilaku pelat akibat adanya beban statik dan beban dinamik perlu menjadi pertimbangan pada saat mendesain pelat. Salah satu contoh beban dinamik adalah beban ledakan setempat (Friedlander). Beban dinamik dapat memberikan respon yang beragam pada pelat. Penelitian ini membahas mengenai pelat orthotropik di atas pondasi Pasternak dengan kondisi jepit dengan beban in-plane dan beban ledakan setempat (Friedlander). Beban ledakan setempat (Friedlander) dianalisis dalam tiga fase yaitu fase positif, fase negatif, dan fase getaran bebas. Penelitian dilakukan untuk mengetahui beban tekuk kritis akibat variasi koefisien pondasi Pasternak yaitu koefisien pegas dan koefisien geser. Respons sistem yang diamati adalah lendutan dan momen yang dihasilkan akibat adanya variasi terhadap parameter pondasi Pasternak, besaran beban kritis, posisi beban, kedalaman tanah, dan durasi fase positif beban. Analisis dilakukan dengan Modified Bolotin Method untuk mendapatkan frekuensi alami dan ragam getar yang terjadi. Hasil analisis akan dibandingkan dalam bentuk grafik dan tabel. Berdasarkan hasil penelitian, batas maksimum beban tekan kritis adalah 77% dari beban kritis yang digunakan. Koefisien tanah yang semakin besar akan membuat lendutan yang terjadi semakin besar. Posisi beban yang mendekati tengah bentang akan membuat lendutan semakin besar. Lendutan yang terjadi semakin besar apabila kedalaman tanah semakin meningkat dan durasi beban ledakan yang semakin lama. Apabila semakin besar tebal pelat maka lendutan yang terjadi semakin kecil.

Influence of Decadal Ocean Signals on Meteorological Conditions Associated With the Winter Haze Over Eastern China

The possible influence of the Atlantic multidecadal oscillation (AMO) and the Pacific decadal oscillation (PDO) on the meteorological conditions associated with haze over central eastern China at decadal time scale was investigated using reanalysis and observational dataset for 1979–2018. Four indices, including Siberian high (SH) strength and position indices (SHI/SHPI), a normalized near-surface wind-speed index (WSI) and a potential air temperature gradient index (ATGI), are adopted to denote the meteorological conditions associated with haze. Results shown that the AMO and PDO are both highly correlated with the fluctuation of meteorological factors associated with haze on decadal scale. Although AMO and PDO were in opposite phases during the whole period, since 1997, they both changed phases (AMO shifted to a positive phase and PDO changed to negative) and became favorable for an anomalous dipole-type SLP pattern in the middle-high latitudes of East Asia. The AMO has played a leading role in decadal variation of the large-scale circulation system, while the PDO has had a closer relationship with the lower ventilation condition in eastern China. On the decadal time scale, the AMO stimulates a zonal teleconnection wave train (the AMO northern Hemisphere pattern, ANH) that originates from the North Atlantic Ocean and passes through central Europe, the northern Ural Mountains, Lake Balkhash-Baikal, and central eastern China. During the positive phase of AMO, the ANH induces a stronger and westward shifted SH, with the central eastern China controlled by the anomalous high pressure. In addition, affected by the cyclone (anticyclone) anomaly over Hetao region and North China (the Sea of Japan), southerly wind anomalies dominate over central eastern China. Compared with the AMO, the wave train generated by the negative (positive) PDO phase mainly propagates in the Pacific region, and there is a strong anticyclonic (cyclonic) anomaly over the Northeast Pacific, guiding the air flow southward (northward) along the East Asian coast and thus suppressing (encouraging) the dispersion of pollutants and resulting in above (below)-normal haze episodes.

Approaching of May maximum surface air temperature to characteristic summer season for Baghdad city

Seasonal variability is the complex non-linear response of the physical climate system. There are two types of natural variability: those external and internal to the climate system. In any given season, natural variability may cause the climate to be different than its long-term average. This study examines with the seasonal variation of the maximum temperatures during the summer season. In addition, the maximum temperatures in May become close to the characteristics of the summer season. The monthly data for maximum temperature of May, June and July were used from Iraqi Meteorological Organization and Seismology (IMOS) for 47 years from 1970 to 2017 for Baghdad city. This period was long enough to estimate the range of approaching maximum temperature (Tmax) May to summer. Results revealed a significant Tmax for Baghdad during the second period (1992–2017) and ‎shown similar behavior of Tmax in May to June and July; on the contrary that first period (1970–1991). In second period, two phases have been found out, positive phase and negative phase. The positive phase were happened in 1995, 1999, and 2006, and the negative phase was four cases (1992, 2004, 2013, and 2016), while a few cases recorded in first period. The amplitudes of monthly variability had same distance of leaner correlation especially in 1999 and 2013 that represent coherent wave with summer seasons. The variance difference for Tmax between May and June approximately was 2°C for second study’s period, while exceed this range in first period. This variance change to 7.5°C when found difference between July and May.

Wind-SST Dipole Mode in the Caribbean and Gulf of Mexico: Large-Scale Features and Drivers

The Dipole Mode (DM) is the leading pattern of springtime wind-SST coupled interannual variability in the Intra-Americas Seas, characterized by SST anomalies of opposite sign between the Caribbean Sea and the Gulf of Mexico. Using the standard deviation (STD) of the wind in a Maximum Correlation Analysis (MCA), this study aims to provide a more dynamic view of the role of the atmosphere in its coupling with the SST. The MCA reveals that the positive phase of the DM is associated with an increase in atmospheric instability, while the negative phase emerges under more stable atmospheric conditions. The DM is preceded by changes in the subtropical high-pressure belt during the previous winter, particularly in the North Atlantic Subtropical High (NASH), and reflects shifts in the latitudinal position of the subtropical jet stream. The DM positive phase tends to occur after an El Niño winter, under negative North Atlantic Oscillation (NAO) conditions. El Niño modulates the DM through a weakening in the meridional pressure gradient and a southward shift of the jet stream. A negative NAO implies a weaker NASH and, therefore, a more irregular circulation over the region. Both El Niño and negative NAO conditions favor the increase in wind STD during the DM positive phase, consistent with an increment in atmospheric disturbances. The DM negative phase responds more to a positive NAO in the previous winter, revealing a stronger NASH acting as an atmospheric block, which justifies the decrease in STD and a more stable circulation.

Meridional Tripole Mode of Winter Precipitation over the Arctic and Continental North Africa–Eurasia

Wintertime precipitation is vital to the growth of glaciers in the northern hemisphere. We find a tripole mode of precipitation (PTM), with each pole of the mode extending zonally over the eastern hemisphere roughly between 30°W and 120°E, and the positive/negative/positive structure for its positive phase extending meridionally from the Arctic to the continental North Africa–Eurasia. The large-scale dynamics associated with the PTM is explored. The positive phase of the PTM is associated with the negative while eastward-shifted phase of the North Atlantic Oscillation (NAO) and a zonal band of positive SST anomaly in the tropics, together with a narrowed Hadley cell and weakened Ferrel cell. While being north-eastward tilted and separated from their North Africa-Eurasia counterpart in the climatological mean, the upper-tropospheric westerly jets over the east Pacific and north Atlantic become extending zonally and shifting southward and hence form a circumpolar subtropical jet as a whole by connecting with the westerly jets over the North Africa-Eurasia. The enhanced zonal winds over the north Atlantic promote more synoptic-scale transient eddies which are waveguided by the jet streams. The polar vortex weakens and cold air dips southward from the North Pole. Further diagnosis of the E-vectors suggests that transient eddies have a positive feedback on the weakening of Ferrel cell. Opposite features are associated with the negative phase of the PTM. The reconstructed time series using multiple linear regression on the NAO index and the tropical SST averaged over 20°S– 20°N, can explain 62.4% of the variance of the original the original precipitation time series.