Natalia Chubarova

Pan Eurasian Experiment (PEEX) - A research initiative meeting the grand challenges of the changing environment of the Northern Pan-Eurasian Arctic-Boreal areas

The Pan-Eurasian Experiment (PEEX) is a new multidisciplinary, global change research initiative focusing on understanding biosphere-ocean-cryosphere-climate interactions and feedbacks in Arctic and boreal regions in the Northern Eurasian geographical domain. PEEX operates in an integrative way and it aims at solving the major scientific and society relevant questions in many scales using tools from natural and social sciences and economics. The research agenda identifies the most urgent large scale research questions and topics of the land-atmosphere-aquatic-anthropogenic systems and interactions and feedbacks between the systems for the next decades. Furthermore PEEX actively develops and designs a coordinated and coherent ground station network from Europe via Siberia to China and the coastal line of the Arctic Ocean together with a PEEX-modeling platform. PEEX launches a program for educating the next generation of multidisciplinary researcher and technical experts. This expedites the utilization of the new scientific knowledge for producing a more reliable climate change scenarios in regional and global scales, and enables mitigation and adaptation planning of the Northern societies. PEEX gathers together leading European, Russian and Chinese research groups. With a bottom-up approach, over 40 institutes and universities have contributed the PEEX Science Plan from 18 countries. In 2014 the PEEX community prepared Science Plan and initiated conceptual design of the PEEX land-atmosphere observation network and modeling platform. Here we present the PEEX approach as a whole with the specific attention to research agenda and preliminary design of the PEEX research infrastructure.

AEROSOL PROPERTIES IN MOSCOW ACCORDING TO 10 YEARS OF AERONET MEASUREMENTS AT THE METEOROLOGICAL OBSERVATORY OF MOSCOW STATE UNIVERSITY

Different microphysical, optical and radiative properties of aerosol were analyzed according to the 10 years of measurements (2001–2010) at the Meteorological Observatory of Moscow State University within the framework of international AERONET program. Volume aerosol size distribution was shown to have a bimodal character with dominating the fine mode aerosol particles at effective radius of r eff-fine =0.15xa0µm. In smoke conditions reff-fine was shown to increase to 0.25xa0µm at extremely large aerosol optical thickness (AOT). Real and imaginary parts of refractive index are characterized by REFR=1.45, REFI=0.01 respectively, changing to REFR=1.49, REFI=0.006 for smoke aerosol. AOT seasonal changes are characterized by the increase towards warm period with a local minimum in June. The joint analysis of aerosol characteristics with the NOAA_NCEP_CPC_CAMS_OPI climatology shows the nature of these changes. For typical conditions aerosol single scattering albedo (SSA) is about 0.9 at 675xa0nm and is characterized by a distinct decrease with wavelength while in forest fires conditions it is significantly higher (SSA=0.95). The interaction between volume aerosol concentration of different aerosol fractions was obtained with a distinct decrease of variation towards large aerosol content.

Ultraviolet resources over Northern Eurasia

We propose a new climatology of UV resources over Northern Eurasia, which includes the assessments of both detrimental (erythema) and positive (vitamin D synthesis) effects of ultraviolet radiation on human health. The UV resources are defined by using several classes and subclasses - UV deficiency, UV optimum, and UV excess - for 6 different skin types. To better quantifying the vitamin D irradiance threshold we accounted for an open body fraction S as a function of effective air temperature. The spatial and temporal distribution of UV resources was estimated by radiative transfer (RT) modeling (8 stream DISORT RT code) with 1×1° grid and monthly resolution. For this purpose special datasets of main input geophysical parameters (total ozone content, aerosol characteristics, surface UV albedo, UV cloud modification factor) have been created over the territory of Northern Eurasia. The new approaches were used to retrieve aerosol parameters and cloud modification factor in the UV spectral region. As a result, the UV resources were obtained for clear-sky and mean cloudy conditions for different skin types. We show that the distribution of UV deficiency, UV optimum and UV excess is regulated by various geophysical parameters (mainly, total ozone, cloudiness and open body fraction) and can significantly deviate from latitudinal dependence. We also show that the UV optimum conditions can be simultaneously observed for people with different skin types (for example, for 4-5 skin types at the same time in spring over Western Europe). These UV optimum conditions for different skin types occupy a much larger territory over Europe than that over Asia.

A method of estimating cloud transmission in the UV spectral range using data from different satellite measurements and reanalysis

We propose a method for cloud UV transmission evaluating on the base of TOMS/OMI LER (Lambertian Equivalent Reflectivity) dataset, which provides more accurate retrievals of UV levels at ground in conditions with high surface albedo. For the improvement of cloud UV transmission estimates, in addition to TOMS/OMI LER data we used two datasets: low layer cloud amount data from ECMWF ERA Interim reanalysis, and surface albedo retrievals according to the method proposed in [1]. The obtained results were tested against experimental data of the Meteorological Observatory of Moscow State University (MSU MO, 55.7N, 37.5E), which included long-term measurements of erythemally weighed radiation, and UV radiation in the spectral range 300-380 nm. The comparisons were made with the cloud UV transmission estimates, obtained by the standard TOMS LER approach [2]. We showed that the cloud UV transmission estimates from the proposed method gave a better agreement with the experimental data compared with the results obtai...

Influence of atmospheric parameters on downward longwave radiation and features of its regime in Moscow

Measurement results of downward longwave radiation (DLR) in a wavelength range of 3.5–50 μm are considered which have been obtained with the use of a precision IR radiometer (Eppley pyrgeometer) of the PIR model at the Meteorological Observatory of Moscow State University in 2008–2010. The influence of air temperature and atmospheric moisture content on the DLR values has been analyzed; correlations between DLR and the above parameters have been found. The effect of clouds on DLR has been estimated: DLR increases by about 30% in daytime and by 25% in nighttime under overcast low clouds. The annual average DLR in Moscow is 305 W/m2, with a minimum in December–March and a maximum in July–August. Variations in DLR throughout a year can exceed 250 W/m2. The daily average amplitude is 18–33 W/m2 in summer and 6–13 W/m2 in winter. An increase in DLR by about 40 W/m2 is noted under conditions of haze from forest and peat-bog fires and an aerosol optical depth of about 4 at a wavelength of 500 nm.

Hydrocarbonates in atmospheric precipitation of Moscow: Monitoring data and analysis

Based on atmospheric precipitation monitoring data for Moscow, we have revealed a number of episodes when the content of hydrocarbonates repeatedly surpasses the equilibrium level. These facts are associated with the complex structure of precipitation, which is caused by differences in the chemical composition of condensation nuclei. As a result, the underlying surface involves two groups of drops with acidities of different nature. The acidity of the first (“metal”) group is determined by the carbonate equilibrium with atmospheric CO2 and dissolved carbonates of alkaline and alkaline earth metals. The acidity of the second (“ammonium”) group is characterized by the balance between ammonia absorbed from the air and atmospheric acids. Because of this, the precipitation acidity measured during the monitoring is regulated not only in the air but also in the condensate collector. The mixing of the metal and ammonium groups of precipitation is accompanied by only a partial conversion of hydrocarbonates into dissolved CO2. Its termination is hindered when CO2 actually ceases to enter the atmosphere due to mass-exchange deceleration. As a result, the content of hydrocarbonates in the collector exceeds the equilibrium level. Some estimates indicate that the acidity of the ammonia component of precipitation can be much higher than the acidity according to monitoring data. This should be taken into account in estimating the health and environmental impacts. The true level of acid rain hazard can be estimated only by measuring the acidity of individual drops, whereas the results obtained with modern tools of monitoring can underestimate this hazard.

Acidity and mineral composition of precipitation in Moscow: Influence of deicing salts

Monitoring data and analysis of the variation in acidity and mineral composition of atmospheric precipitation in Moscow in 2012 are presented. We have found that the chloride anions in the precipitation are largely caused by chlorides of deicing salts. Here, the chloride anions, along with metal chlorides (components of deicing salts), are partly caused by dissolved hydrogen chloride. The appearance of hydrogen chloride in the atmosphere of Moscow has been shown to result from heterophase chemical reactions involving deicing salts. We have obtained preliminary estimates for the scales of the effect of these salts on the mineral composition and acidity of precipitations in Moscow.

Atmospheric optical properties over the Russian steppe during summer

Atmospheric transmittance is estimated by measuring the direct‐normal solar irradiance at the surface by a sun‐photometer or a spectro‐radiometer. Both of these types of instruments were used to determine the most variable components of the atmospheric transmission, aerosol optical thickness (AOT) and precipitable water vapor (PW) in cm, during an international field experiment, KUREX91, held in July, 1991 in the Streletskaya Steppe Biospheric Reserve near Kursk, Russia. A narrow field of view sun‐photometer provided AOT in 7 discrete spectral channels from 440‐nm to 1030‐nm and PW from observations in the 940‐nm channel. A spectro‐radiometer provided AOT at 70 spectral intervals in the 380‐nm to 550‐nm range. The latter also provided measurements of diffuse sky irradiance at the surface. Both the instruments were calibrated by the Langley plot method or the long‐Bouguer method as it is known in the Russian literature. The derived AOT are inverted to obtain aerosol size distribution with the help of an a...

Long-Term Variability of UV Irradiance in the Moscow Region according to Measurement and Modeling Data

We have found distinct long-period changes in erythemal UV radiation (Qer) characterized by a pronounced decrease at the end of the 1970s and a statistically significant positive trend of more than 5%/10 years since 1979 over the territory of the Moscow region according to the measurements and reconstruction model. The positive Qer trend is shown to be associated mainly with a decrease in the effective cloud amount and total ozone content (TOC). Due to these variations, UV resources have significantly changed in spring for the population with the most vulnerable skin type I, which means a transition from the UV optimum to UV moderate excess conditions. The simulation experiments using the INM-RSHU chemistry climate model (CCM) for several scenarios with and without anthropogenic factors have revealed that the variations in the anthropogenic emissions of halogens have the most significant impact on the variability of TOC and Qer. Among natural factors, noticeable effects are observed due to volcanic aerosol. The calculations of the cloud transmittance of Qer are generally consistent with the measurements; however, they do not reproduce the observed value of the positive trend.

CLEAR-SKY RADIATIVE AND TEMPERATURE EFFECTS OF DIFFERENT AEROSOL CLIMATOLOGIES IN THE COSMO MODEL

We estimated the effects of the different aerosol climatologies in the COSMO mesoscale atmospheric model using long-term aerosol measurements and the accurate global solar irradiance observations at ground at the Moscow State University Meteorological Observatory (Russia) and Lindenberg Observatory (Germany) in clear sky conditions. The differences in aerosol properties have been detected especially during winter months. There is a better agreement of MACv2 aerosol climatology with measurements forMoscowconditions compared with Tegen aerosol climatology. However, we still have a systematical negative bias of about 2-3% in global solar irradiance at ground for both sites. A noticeable sensitivity of air temperature at2 metersto the net radiation changes of about1°Cper 100 Wm-2 due to aerosol has been evaluated, which approximately is around -0.2 – -0.3°C, when accounting for real aerosol properties.