Search

The authors examine the distribution and variation of carbon monoxide (CO) in the tropics from the surface to the lower stratosphere. By analyzing space-borne microwave limb sounder (MLS) measurements, measurements of pollution in the troposphere (MOPITT) and modern-era retrospective analysis for research and applications (MERRA) meteorological products, and atmospheric chemistry and climate model intercomparison project (ACCMIP) surface emission inventories, the influences of atmospheric dynamics and surface emissions are investigated. The results show that there are four centers of highly concentrated CO mixing ratio over tropical areas in different seasons: two in the Northern Hemisphere and another two in the Southern Hemisphere. All of these centers correspond to local deep convective systems and monsoons/anticyclones. The authors suggest that both deep convections and anticyclones affect CO in the tropical troposphere and lower stratosphere — the former helping to transport CO from the lower...

Using reanalysis data as a benchmark, the authors evaluate the performance of an Atmospheric General Circulation Model (AGCM) named GAMIL (Grid-point Atmospheric Model of LASG/IAP). GAMIL is used to simulate the tropospheric temperature anomalies associated with the El Nino-Southern Oscillation (ENSO) in boreal winters for the period 1980–99. The results show that the symmetrical components of temperature anomalies simulated by GAMIL closely resemble those in the reanalysis data in spatial patterns, especially in the Northern Hemisphere. The limitation of the model is that the simulated cold anomaly over South Asia is located to the east of the reanalysis. The observed temperature anomalies in the South Pacific and the high latitudes of the Southern Hemisphere are not evident in the simulation. The maximum value is 0.8 K smaller and the minimum value is –0.4 K smaller than the reanalysis. The difference between the simulation and the reanalysis is more evident in the regional features of the asymm...

The South Asia High (SAH) is the dominant feature of the circulation in the upper troposphere and lower stratosphere (UTLS) during the boreal summer, and the upper tropospheric anticyclonic circula...

Using HALOE O3 and H2O vertical profiles in 40°N~50°N of the Northern Hemisphere, considering chemical lifetime and transport temporal constant of O3 and H2O, the structure and seasonal characteristic of O3/H2O mixing relationships between 300 K to 390 K near the tropopause and the lowest stratosphere have been constructed in the isentropic coordinates. The results are as follows: (1) The slope of O3 mixing ratios profile has a spatial sudden change between 320~380 K isentropic surfaces of the tropopause translation layer, while the slope of H2O mixing ratios profile exhibits a spatial gradual change. The source region of O3 is stratosphere but H2O is troposphere near tropopause. So on the two sides of 320~380 K isentropic surfaces, mixing ratios of O3 and H2O show distinctly different vertical gradient. (2) In the vicinity of the tropopause where O3/H2O relationships reach best least square fitting, the troposphere and stratospheric branch of the non-regular “L” relationship show seasonal and intra-seasonal changes with a negative slope in tropospheric branch, but positive and negative slopes alter with seasons in stratospheric branch. At the same time, based on the “L” corner, the characteristic of chemopause with seasons can be confirmed. (3) The O3/H2O mixing relationship indicates that the transition layer is formed by stratospheric mixing with tropospheric air masses from different regions, and the mixing line of the transition layer is not constant. The transition layer mixing is equivalent in January, April 2003 and in January 2005, about 30 K isentropic thickness, that is between 320~350 K isentropic surfaces. Mixing height increases in November 2005, and the H2O coming into the stratosphere is less than in January 2003 and 2005, with about 30 K isentropic thickness, between 330~360 K isentropic surfaces. The change of mixing isentropic thickness is small in different seasons, but mixing height changes with seasons. The stratospheric branch of O3/H2O mixing relationship obviously changes with seasons, for which the significant reason is the lowest stratospheric air dehydration in January.

The seasonal variation of inertia gravity-wave activity in the lower stratosphere (17―24 km) over Beijing is studied based on the high vertical resolution radionsonde observations (from De-cember 2001 to February 2003) of Beijing Observatory (116°28′E, 39°48′N). Some of the important gravity-wave parameters, such as intrinsic frequency, and propagation direction, are estimated according to the polarized relation among gravity-wave wind components and temperature. Time series of wave energy show that the largest wave amplitudes occur during the winter and the least during the summer, and the average of the KE:PE ratios is about 2.6. Zonal and meridional wind perturbations have almost the same roots of mean variances, which shows that the wave energy in the lower stratosphere is isotropic horizontally. The motion and tem-perature fields are dominated by waves with vertical wavelengths of 1.5―3 km, which occupy above 80% samples, with a mean value of about 2.3 km. The horizontal wavelengths are mainly distributed between 100―800 km, averaging 445 km. The ratio of the mean horizontal to vertical wavelength is about 200:1, which indicates that the wave propagates nearly horizontally, with a very small vertical angle. The intrinsic frequency is estimated by fitting a polarized ellipse to the wind perturbations after band-filtering waves with a wavelength of 1.5―3 km, and the results show that the intrinsic frequency is dominated by 1 f ―3.5 f , with an averaging value of 2 f , corre-sponding to an intrinsic time period of 9 hours. Wave energy is found to propagate mainly upward, and in the horizontal direction, there is clear azimuthal anisotropy, with predominate northwest propagation against the prevailing wind.

Phase delays between two Nino indices—sea surface temperatures in Nino regions 1+2 and 3.4 (1950–2001)—at different time scales are detected by wavelet analysis. Analysis results show that there are two types of period bifurcations in the Nino indices and that period bifurcation points exist only in the region where the wavelet power is small. Interdecadal variation features of phase delays between the two indices vary with different time scales. In the periods of 40–72 months, the phase delay changes its sign in 1977: Nino 1+2 indices are 2–4 months earlier than Nino 3.4 indices before 1977, but 3–6 months later afterwards. In the periods of 20–40 months, however, the phase delay changes its sign in another way: Nino 1+2 indices are 1–4 months earlier before 1980 and during 1986–90, but 1–4 months later during 1980–83 and 1993–2001.

About 20 years of Dobson and TOMS data are used to analyze the variation characteristics of total atmospheric ozone in Beijing (39.93°N, 116.40°E) and Kunming (25.02°N, 102.68°E). It is shown that: (1) the long-term change trends for 1979 (or 1980)–2000 period are −0.642 DU/year and −0.009 DU/year respectively in Beijing and Kunming, (2) there are strong intra-seasonal variations especially in wintertime, which are comparable to seasonal variations both in Beijing and Kunming, (3) the long-term trend deduced from shorter time period of record is significantly different from that for longer time period, both in Kunming and Beijing, (4) there are significant QBO signals both in Beijing (mid latitude) and Kunming (low latitude), (5) the inter-annual variations of atmospheric ozone in both stations are mainly composed of the long-term trend and QBO signals, and (6) our Dobson and TOMS measurements of total ozone are generally in good agreement.

A regional prediction experiment on the distribution of the atmospheric ozone column over China is performed by means of a spatiotemporal artificial neural network system (STANNS) built by using the monthly mean values of Total Ozone Mapping Spectrometer (TOMS) data from the Nimbus 7 satellite. The experiment region is situated from 72.5°E to 128.75°E and from 22°N to 49°N and divided into a rectangular grid net of 16×10. The data used cover 174 months from November 1978 to April 1993; those from the first 150 months were used to construct STANNS, and those from the last 24 months were used to test the prediction ability. The experiment results are encouraging. All the values of the correlation coefficient between the prediction and the actual fields for 24 or more samples exceed 90% at the lead time of not more than 6 months. This shows that there exists a good agreement between the prediction and the actual fields. In addition, some important features in the ozone distribution, such as the unusual depletion area over the Tibetan Plateau in summer, are also predicted very well. The results also show that, in a rough sense, the prediction accuracy decreases with the increasing of lead time.

A Self-Organizing Feature Mapping (SOM) network model was developed for the retrievals of rain-rate (RR) over oceans from SSM / I measurement, by using the SSM / I and corresponding radar-derived rain-rate data provided by National Space Development Agency of Japan (NASDA). Based on the frequency-distribution of rain-rate samples, the SOM model was constructed in different rain-rate ranges. The model was first trained by five-sixths of the data, and the other data were used to test the retrieval ability of the model. The retrieval results of the SOM model were compared with two statistically-based algorithms. It is shown that the SOM model provides better retrievals of rain-rate.

In this study, BRL 3A cells were treated with different Cd concentrations (0, 10, 20, and 40 μmol/L) for 12 h and preincubated with or without N-acetyl-L-cysteine (NAC) (2 mmol/L) for 30 min, and cells were treated with Cd (0 and 20 μmol/L), pretreated with p38 inhibitor (SB203580), JNK (c-Jun NH2-terminal kinases) inhibitor (SP600125), and extracellular signal-regulated kinase (ERK) inhibitor (U0126) for 30 min, and then treated with 20 μmol/L Cd for 12 h. Cd decreased cell viability, SOD, and GSH-Px activity in a concentration-dependent manner. Increased MDA level, ROS generation, nuclear condensation, shrinkage, and fragmentation in cell morphology were inhibited by NAC. Cd-induced apoptosis was attenuated by pretreatment with SB203580, SP600125, and U0126. The results of western blot showed that NAC preincubation affected Cd-activated MAPK pathways, p38 and ERK phosphorylation. Cd treatment elevated the mRNA levels of Bax and decreased the mRNA levels of Bcl-2, respectively. The same effect was found in their protein expression levels. These results suggest that oxidative stress and MAPK pathways participate in Cd-induced apoptosis and that the balance between pro- and antiapoptotic genes (Bax and Bcl-2) is important in Cd-induced apoptosis.

In this report the research results by Chinese scientists in 2014–2016 are summarized. The focuses are placed on the researches of the middle and upper atmosphere, specifically the researches associated with ground-based observation capability development, dynamical processes, and properties of circulation and chemistry-climate coupling of the middle atmospheric layers.